Home » Posts tagged 'sustainability'

Tag Archives: sustainability

Soil Your Undies: When a Great Demo Gets Asked to Do Too Much

September 17, 2026 3:06 pm / Leave a comment

I often say that in K–12 education we teach a lot of things in black and white. Students first need to understand the basic concepts: plants need nutrients, microorganisms decompose organic matter, and soils are biologically active. Then somewhere through a bachelor’s degree, or simply through enough years of experience, we learn that agriculture is rarely that black and white. There are a lot of shades of gray. Keep studying, researching, farming, or advising long enough and you eventually realize there aren’t just 256 shades of gray. There is also ROYGBIV. There is a whole spectrum of interactions and conditions that determine what happens in the soil.

I think the “Soil Your Undies” demonstration fits that progression perfectly. It is a great black and white teaching tool. Bury a pair of 100% cotton underwear, wait several weeks, and dig them back up. Sometimes there isn’t much left besides the elastic waistband. Students can see that something happened belowground, and that opens the door to conversations about microorganisms, decomposition, carbon cycling, and the fact that soil is a living system. As a teaching demonstration, that is hard to beat.

Where I become more cautious is when we take that intentionally simple lesson and make a much more complicated conclusion: the pair with less cotton remaining came from the healthier soil or represents the better management practice. That is where we need to move beyond black and white.

SOIL YOUR UNDIES Challenge pulled from USDA Natural Resources Conservation Service Facebook page posted on June 21, 2024

To begin with we must know what the microbes are eating.

Cotton fiber itself gives us the first clue about what this test measures. Cotton is approximately 95% cellulose, and standardized cotton strips have been used by soil scientists for decades specifically as an index of cellulose decomposition (Latter et al., 1988; Tiegs et al., 2013). Cellulose is a long chain of glucose molecules and one of the major structural components of plant material. Its decomposition depends on organisms capable of producing cellulolytic enzymes that break those chains into smaller compounds that microorganisms can use.

Therefore, when cotton underwear disappears, we can make a scientifically defensible statement: the soil environment supported cellulose decomposition during the time the underwear was buried. That is useful information but notice how specific that statement is. We did not measure the total number of microorganisms, microbial diversity, or every biological process occurring in that soil, and we certainly did not measure everything encompassed by the much broader term soil health. Research comparing cotton-strip decomposition with microbial biomass illustrates that distinction. Walton and Allsopp (2007) found a relatively poor relationship between cotton-strip measurements and microbial biomass measured by substrate-induced respiration (r² = 0.26). They recommended using cotton strips alongside other physical and chemical soil indicators rather than as a stand-alone biological measurement. Soil can contain a substantial microbial population without necessarily destroying a pair of underwear quickly.

Is breaking down cellulose what the soil needs to be doing?

Cellulose decomposition is important. Crop residues contain cellulose, and their decomposition is part of carbon and nutrient cycling. But agriculture does not necessarily need every microbial process operating at its maximum rate all the time. Depending on the production system, time of year, and management objective, we may be more interested in nutrient mineralization or immobilization, aggregate formation, disease suppression, nitrogen transformations, carbon stabilization, or simply keeping residue on the soil surface. Faster cellulose decomposition is therefore not automatically better; it tells us that this specific biological process was occurring more rapidly under those conditions. This does not make the cotton test wrong. It means we need to be precise about the question it answers.

The scientific cotton-strip assay has successfully detected differences in cellulose decomposition among soils and management systems. Nachimuthu et al. (2022), for example, found differences in cotton-strip degradation among long-term crop rotation and tillage treatments. That supports the conclusion that management can affect cellulose decomposition. It does not automatically establish that the management practice producing the fastest cellulose decomposition created the healthiest soil. Margenot and Wade (2023) raised a similar concern about the interpretation of soil enzyme activities, cautioning against taking a measurement of a specific biological process and assuming that it scales directly to broader soil functions or outcomes. Measuring a process and determining what that process means for the functioning of the soil are two different questions.

Now add some gray: nitrogen

This is where the soil fertility specialist in me starts asking questions. Cotton provides microorganisms with a lot of carbon but almost no nitrogen. Yet microorganisms cannot live on carbon alone. They need nitrogen to produce proteins and enzymes and to build new microbial biomass. The microorganisms colonizing that cotton therefore must obtain much of what they need from the surrounding soil. Imagine taking one soil and thoroughly mixing it. We start with the same microbial community, organic matter, texture, pH, temperature, and water content. Divide it into two treatments and bury identical pieces of cotton. The only major difference is mineral nitrogen: one treatment has very little available NH₄-N and NO₃-N, while the other has an adequate supply. Would the underwear necessarily decompose at the same rate? There is good reason to believe it may not.

Nottingham et al. (2018) examined nutrient limitation during cellulose decomposition by adding cellulose and individual nutrients to soils. Nitrogen addition produced the largest fungal growth response associated with cellulose, and the researchers concluded that nitrogen was an important limitation to fungal growth and cellulose decomposition in the soils they studied. The implication for our underwear is important. Cotton in the higher N soil could potentially disappear faster without that soil starting with more microorganisms or a “healthier” microbial community. The organisms capable of decomposing cellulose may simply have better access to the nitrogen required to grow and produce the enzymes needed to exploit this large carbon source. That does not mean adding nitrogen fertilizer will always make underwear disappear faster. Microbial responses to N depend on the soil, microbial community, nutrient status, substrate, and environment. Other nutrients may become limiting, and long-term N additions can alter microbial communities and decomposition processes in ways that are very different from a short-term response to available N. That complexity is exactly the point: we started with a black-and-white demonstration of biological activity, but bringing in the mineral N conversation now add many shades of gray.

Then comes pH—and more color

Soil pH adds another layer because it does more than simply make microbes “more” or “less” active. It can change which groups of microorganisms are most active. I have plenty of work discussing how quickly soil pH can change across landscape and how much our management also significantly impacts soil pH. Across agricultural soils, bacterial growth and diversity generally increase as strongly acidic soils approach neutral conditions, while fungi tend to become relatively more important as pH declines. Rousk et al. (2009, 2010), working across soils ranging from approximately pH 4 to 8, documented substantial shifts in bacterial and fungal growth and in the fungal relationship across the pH gradient. That distinction matters for an underwear test because both bacteria and fungi participate in cellulose decomposition. A lower-pH soil may have reduced bacterial growth while maintaining a comparatively greater fungal contribution. At a higher pH, the balance can shift toward bacteria. The microbial community doing the work can therefore change substantially without a corresponding black-and-white change from “poor biology” to “good biology.”

There is also evidence that pH can affect cellulose decomposition itself. Work with volcanic soils found that cellulose decomposition potential was related to both soil pH and microbial N availability, rather than simply to the amount of microbial biomass present. This creates an interesting possibility for the underwear demonstration: two soils could contain similar amounts of microbial biomass but decompose cotton at different rates because one provides a more favorable chemical and nutritional environment for the organisms capable of using cellulose. I would also be careful about turning that into another simple rule such as “higher pH equals faster cotton decomposition.” As soils move from strongly acidic conditions toward the range where many agricultural crops are grown, bacterial activity generally increases, but fungi, bacteria, extracellular enzymes, nutrient availability, and cellulose decomposition do not all respond to pH in exactly the same way. Very acidic conditions can suppress some processes while favoring organisms better adapted to acidity. That is a much more interesting biological story than simply labeling one soil as having more microbial activity than another.

Then comes ROYGBIV

Nitrogen and pH are only two variables. Soil moisture determines whether microorganisms can remain active and whether substrates and nutrients can move through the soil. Texture influences water retention, aeration, nutrient availability, aggregation, and microbial habitat, so identical cotton buried in a sandy soil and a clay soil is not necessarily experiencing the same environment. Phosphorus, sulfur, or another nutrient can limit microbial growth even when carbon and nitrogen are abundant. Finally, the microbial community itself matters because different bacterial and fungal populations differ in their ability to produce the enzymes needed to attack cellulose.

What we see when we dig up the underwear is therefore the integrated result of microbial community × substrate × nitrogen × other nutrients × moisture × pH × texture × time, along with interactions among them. A difference in cotton decomposition is real, but the underwear alone cannot tell us which of those factors produced the difference. More importantly, it cannot tell us whether the difference represents better or worse management. That distinction between a soil health indicator and the soil function or outcome it is intended to represent is increasingly being emphasized in the soil health literature (Maharjan et al., 2024).

That is no longer black and white. That is ROYGBIV.

Keep burying the underwear

None of this is an argument to stop Soil Your Undies. Keep doing it. Use it in classrooms, bury underwear at field days, have students predict what will happen, and put underwear in contrasting soils so they can see that decomposition happens below ground. It makes an invisible biological process visible, and that makes it a great teaching tool.

Where I think we need to be more careful is when we turning that demonstration into a scorecard for soil health or management practices. A producer should not dig up two pairs of underwear and conclude that the field with less cotton remaining necessarily has more microorganisms, better management, greater fertility, or healthier soil. Too many biological, chemical, and environmental factors influence cellulose decomposition for the underwear alone to support those conclusions.

Perhaps that distinction provides an even better way to use the demonstration. With younger students, Soil Your Undies can teach the black and white: microorganisms live in soil and decompose organic materials. With more advanced students, farmers and agronomists, the same demonstration can teach the gray by asking, why did these two pieces of cotton decompose differently? Once we start asking about water, nitrogen, pH, texture, nutrients, microbial communities, and all of the possible interactions, we get to ROYGBIV.

This distinction becomes especially important when the demonstration is used with students or audiences without an agricultural or soil science background. If two management systems are compared and the one with less cotton remaining is presented as the “better” practice, we may be teaching a conclusion the test cannot support. Those audiences may not yet have the background to recognize the effects of moisture, nitrogen, pH, texture, or microbial community on cellulose decomposition. The demonstration can then unintentionally introduce bias toward management practice rather than teach how complex soil biological processes really are.

So, keep burying the underwear. Just don’t ask it to answer more than it can.

Graphic showing factors impacting cellulosic breakdown in soils. Created with the assistance of CHATGPT

References

Chew, I., Obbard, J.P., & Stanforth, R.R. 2001. Microbial cellulose decomposition in soils from a rifle range contaminated with heavy metals. Environmental Pollution 111:367–375. doi:10.1016/S0269-7491(00)00094-4.
Latter, P.M., Bancroft, G., & Gillespie, J. 1988. Technical aspects of the cotton strip assay in soils. International Biodeterioration 24:25–47. doi:10.1016/0265-3036(88)90073-5.
Maharjan, B., Das, S., Thapa, V.R., & Sharma Acharya, B. 2024. Soil health cycle. Agrosystems, Geosciences & Environment 7:e20504. doi:10.1002/agg2.20504.
Margenot, A.J., & Wade, J. 2023. Getting the basics right on soil enzyme activities: A comment on Sainju et al. (2022). Agrosystems, Geosciences & Environment 6:e20405. doi:10.1002/agg2.20405.
Nachimuthu, G., Hundt, A., Palmer, B., Schwenke, G.D., & Knox, O.G.G. 2022. Cotton strip assay detects soil microbial degradation differences among crop rotation and tillage experiments on Vertisols. Journal of Microbiological Methods 200:106558. doi:10.1016/j.mimet.2022.106558.
Nottingham, A.T., Hicks, L.C., Ccahuana, A.J.Q., Salinas, N., Bååth, E., & Meir, P. 2018. Nutrient limitations to bacterial and fungal growth during cellulose decomposition in tropical forest soils. Biology and Fertility of Soils 54:219–228. doi:10.1007/s00374-017-1247-4.
Rousk, J., Brookes, P.C., & Bååth, E. 2009. Contrasting soil pH effects on fungal and bacterial growth suggest functional redundancy in carbon mineralization. Applied and Environmental Microbiology 75:1589–1596.
Rousk, J., Bååth, E., Brookes, P.C., Lauber, C.L., Lozupone, C., Caporaso, J.G., Knight, R., & Fierer, N. 2010. Soil bacterial and fungal communities across a pH gradient in an arable soil. ISME Journal 4:1340–1351.
Tiegs, S.D., Clapcott, J.E., Griffiths, N.A., & Boulton, A.J. 2013. A standardized cotton-strip assay for measuring organic-matter decomposition in streams. Ecological Indicators 32:131–139. doi:10.1016/j.ecolind.2013.03.013.
Walton, N.G., & Allsopp, D. 2007. Comparison of methods for measuring soil microbial activity using cotton strips and a respirometer. Journal of Microbiological Methods 69:322–329.

OSUNPK Fertilizer Market Outlook: Nitrogen Decline Pauses 9.7.26

September 7, 2026 12:51 pm / Leave a comment

The most important fertilizer-market development of the past two weeks is not another sharp price move, but the pause that followed August’s nitrogen decline. Oklahoma’s September 4 report shows urea down only $4.40 per ton, UAN 32% down $5.72, and anhydrous ammonia down $5.00. UAN 28%, phosphate, potash, AMS, and ATS were unchanged. Looking back four weeks, however, the nitrogen correction remains substantial: urea is down 6.6%, UAN 28% is down 8.7%, UAN 32% is down 5.7%, and NH3 is down 5.8%.

Price-source note: The accompanying graphic’s Oklahoma average, minimum, and maximum come from the USDA Agricultural Marketing Service Oklahoma Production Cost Report. USDA does not identify contributing dealers. Named public dealer cash quotes, including Two Rivers Cooperative, are tracked separately and are not blended into USDA statistics.

USDA attributes the quiet local market to weak demand under persistent heat and drought. That distinction matters. Stable prices caused by limited field activity do not necessarily indicate that replacement costs or global supply risks have settled. As fall demand develops, local bids may respond differently depending on dealer inventory, transportation, and when replacement tons were purchased.

Nitrogen markets continue to balance large international buying programs against improved availability. In recent public commentary, StoneX fertilizer analyst Josh Linville pointed to India’s 1.7-million-ton urea purchase and identified Brazil as the next major demand cycle to watch. A completed Indian tender can absorb prompt supply, but the next direction depends on whether Brazilian demand arrives strongly enough to keep exporters engaged. Product type also matters because Brazil typically needs granular urea, while much of China’s available export supply has been prilled.

Phosphate remains a different story. Oklahoma DAP and MAP prices were unchanged, but the global market still carries support from restricted Chinese exports and elevated sulfur and ammonia costs. Linville also highlighted the arrival of Moroccan phosphate cargoes following the suspension of U.S. countervailing duties, including an MAP vessel that is more relevant to U.S. demand than the earlier TSP shipment. Additional import competition could improve availability, but one or two vessels do not by themselves reset the market.

Sulfur is part of that phosphate equation. It is required to manufacture phosphoric acid, so constrained sulfur trade can support DAP and MAP production costs. The same global pressure does not translate directly into identical local movement for AMS and ATS; both remained unchanged in Oklahoma this period. Those products should therefore be evaluated on actual sulfur need, formulation, and local cash price rather than assumed movement from phosphate headlines.

The next items to watch are Oklahoma rainfall and fall field activity, Brazilian urea purchasing, additional Indian tenders, Chinese export volumes, Moroccan phosphate arrivals, sulfur availability, and inland freight. These forces remain capable of moving in opposite directions, so the current pause should not be read as a firm price forecast.

For Oklahoma producers, this is a good time to compare products on both dollars per ton and cost per pound of the needed nutrient. Quotes should be placed on the same pickup or FOB basis, with application, blending, delivery, and tax separated before making comparisons.

Fertilizer markets, local prices, and availability can change quickly. Confirm current prices and terms with local dealers before purchasing.

Market Sources

USDA Agricultural Marketing Service. Oklahoma Production Cost Report, September 4, 2026. https://www.ams.usda.gov/mnreports/ams_3621.pdf
Josh Linville, StoneX. Public fertilizer-market commentary on India’s urea tender, Brazil’s demand cycle, and Moroccan phosphate arrivals. https://www.linkedin.com/posts/joshua-linville-9555a711_indias-urea-tender-just-gave-a-fading-rally-activity-7488273113961476098-Mepg
CoBank. Why Higher Fertilizer Prices Are Here to Stay, August 13, 2026. https://www.cobank.com/knowledge-exchange/why-higher-fertilizer-prices-are-here-to-stay
World Trade Organization. Fertilizer Trade Impacted by Strait of Hormuz Conflict, July 10, 2026. https://www.wto.org/english/blogs_e/data_blog_e/blog_dta_10jul26_451_e.htm

This report is produced via Chat GPT Plus Work, with review by Brian Arnall.

OSUNPK Fertilizer Market Outlook: Local Nitrogen Prices Break Lower 8.24.26

August 24, 2026 8:43 am / Leave a comment

The most important movement of the past two weeks is the decline in Oklahoma nitrogen references. From August 7 to August 21, UAN 28% fell $39.70 per ton, urea fell $38.73, and anhydrous ammonia fell $46.00. USDA attributes the weakness to reduced demand as persistent heat and limited rainfall constrain field activity across the state.

Price-source note: The accompanying graphic’s Oklahoma average, minimum, and maximum come from the USDA Agricultural Marketing Service Oklahoma Production Cost Report. USDA does not identify its contributing dealers. Named public dealer cash quotes, including Two Rivers Cooperative, are monitored separately and are not blended into the USDA statistics.

The local decline does not mean that global nitrogen risk has disappeared. StoneX reported August 19 that India secured about 1.7 million metric tons in its latest urea tender with ample offers, including an expected contribution from China. That supply response eased immediate pressure, but attention now shifts toward Brazil’s September-through-December import window. Brazil needs granular urea, while much of China’s available export supply is prilled, so timing, product form, and destination still matter.

Josh Linville’s August 12 market commentary likewise described a well-supplied Indian tender and a weaker NOLA urea market, while cautioning that UAN and ammonia manufacturers held strong forward sales books. That distinction matters in Oklahoma: a softer urea benchmark can move faster than UAN or ammonia when producers have already covered substantial forward demand. Local weather can amplify the difference by weakening spot demand even while manufacturer positions remain supported.

Phosphate prices were nearly unchanged in the Oklahoma report, but their cost structure remains exposed to ammonia and sulfur. CoBank noted August 13 that Middle East disruptions and Russian supply constraints have affected ammonia production and sulfur availability, while China’s phosphate exports remain sharply restricted. Linville also highlighted sulfur as a bottleneck because a large share of globally traded sulfur normally moves through the Strait of Hormuz. Those pressures can raise the cost of producing DAP and MAP even when local posted values are temporarily steady. They also deserve attention for AMS and ATS, although Oklahoma’s reported averages changed little this period.

Potash remains the quietest major nutrient. Its production base is less directly tied to Middle East natural gas and sulfur, although ocean freight and broader logistics can still affect delivered replacement costs.

Over the next several weeks, watch Oklahoma rainfall and fall field demand, Brazil’s urea buying pace, the mix of Chinese exports, further Indian tenders, phosphate operating rates, sulfur availability, and freight. These forces point in different directions, so the current local nitrogen decline should be read as a market development rather than a definitive forecast.

For Oklahoma producers and dealers, the practical step is to compare current cash quotes on the same pickup or FOB basis and separate material price from delivery and application. Soil-test needs and product fit should remain central; price movement alone does not determine the best nutrient plan.

Fertilizer markets, local prices, and availability can change quickly. Confirm current prices and terms with local dealers before making purchasing decisions.

Market Sources

USDA Agricultural Marketing Service. “Oklahoma Production Cost Report,” August 21, 2026. https://www.ams.usda.gov/mnreports/ams_3621.pdf
StoneX. “Brazil’s Urea Import Window Now Decides Where Global Tonnes Land Next,” August 19, 2026. https://www.stonex.com/en/insights/brazil-s-urea-import-window-now-decides-where-global-tonnes-land-next/
Hoosier Ag Today. “Josh Linville: Fertilizer Markets,” August 12, 2026. https://www.hoosieragtoday.com/2026/08/12/josh-linville-fertilizer-markets/
CoBank Knowledge Exchange. “Why Higher Fertilizer Prices Are Here to Stay,” August 13, 2026. https://www.cobank.com/knowledge-exchange/why-higher-fertilizer-prices-are-here-to-stay

This report is produced via Chat GPT Plus Work, with review by Brian Arnall.

Cheap Nitrogen is not always the best Nitrogen, Timing matters

August 13, 2026 6:52 am / 1 Comment on Cheap Nitrogen is not always the best Nitrogen, Timing matters

Brian Arnall: Precision Nutrient Management Extension Specialist, Oklahoma State University

In 2020, we published a summary of four OSU trial series comparing pre-plant nitrogen (N) to in-season N in grain-only winter wheat. https://osunpk.com/2020/09/10/value-of-in-season-application-for-grain-only-wheat-production/ Since then, three of those trial series have made it through peer review, and additional analyses have added considerably more data to the story. From both historic data from Dr. Raun’s program and new work. All together, these studies now represent more than 90 Oklahoma site-years across a wide range of environments, N rates, and application timings. So, after several more years of research, has the conclusion changed?

Does waiting to apply nitrogen cost wheat yield?

Across these studies, moving N from pre-plant to a properly timed in-season application generally maintained or increased grain yield. How often in-season N increased yield varied among datasets. Souza et al. found that winter wheat could recover from early N stress without sacrificing yield over a surprisingly wide application window. In other studies, in-season N was statistically similar to pre-plant N. The important point is that delaying N did not automatically mean giving up yield.

The Regional N study started by Dr. Raun 2in 2009, adds an important environmental piece to the story. Split N out yielded pre-plant N in approximately 29% of the 52 site-years, specifically those classified as highly responsive to N. These years tend to be wetter environments with greater yield potential. In the remaining 71%, split and pre-plant N produced statistically similar yields. Across all 52 site-years, splitting N never resulted in a significant yield loss compared with pre-plant N.

When a yield advantage with in-season N occurred, it could be meaningful. One study found a single in-season application produced approximately 8% greater yield than a full-rate pre-plant application. Sharry’s Gallagher/Green Hammer study found a single Feekes 4 (spring green up) application averaging approximately 11% greater yield than a single pre-plant application across two varieties and four site-years. The Regional N analysis found an approximately 5.4 bu/ac, or 14%, advantage for split N over pre-plant N in highly N-responsive environments, while there was no difference in the remaining environments. The message isn’t that in-season N always produces more wheat. It doesn’t. Properly timed in-season N generally maintained yield, and about 58% of the time increased it.

Protein Tells an Even More Consistent Story

Protein responded more consistently to N timing than yield. Later N increased grain protein across nearly every dataset. In the Regional N study, split N increased protein by 0.8 percentage points above the pre-plant compared with a 1.1-point increase from all N applied in-season. That advantage occurred across every environmental response category. In the end yield response to delayed N depends heavily on environment. The protein response is considerably more consistent.

If In-Season N Works, Is There a Reason to Split It?

Once the decision is made to move N away from a full pre-plant application, another question follows: should some N still go out pre-plant and the remainder in-season, or can the entire rate wait until the growing season? Two datasets tested that question directly, and neither found a consistent yield advantage to splitting N over a single, well-timed in-season application.

Sharry’s study found that a single green up application out-yielded both two-way and three-way splits by approximately 4.4 to 9.4 bu/ac at the site-years where treatments differed. At no site-year did a split application out-yield the single in-season timing. Abiola (2025) reached essentially the same conclusion. A single in-season application matched or exceeded a 50/50 pre-plant/in-season split across the timings evaluated. There was, however, an important exception. As the single in-season application was pushed into late March and April, having some N already applied reduced the potential downside.

Splitting N appears to be more about risk management than yield management.

Putting some N out early provides insurance against weather, field conditions, equipment problems, or other factors that prevent the planned in-season application from being made on time. If a single in-season application can be made at the proper time, however, these data provide little evidence that splitting N improves yield. So, in the end you reduce the “risk” but double application cost.

Timing Still Matters

None of this should be interpreted as saying N can be applied whenever it is convenient. The window for applying N to grain-only winter wheat is wider than many growers assume, but it isn’t unlimited. As application moves later, the opportunity for unfavorable weather to interfere with N availability becomes increasingly important.

The Regional N study provides a good example. For post top-dress applied N rainfall alone explained 27% of the site-to-site variation in how much the crop responded to N. The environments where split N increased yield over pre-plant N were generally the wetter, higher-yielding environments.

Waiting on N is a management strategy. Waiting too long is not.

Moving N in-season allows the rate decision to be made when considerably more is known about stand, growing conditions, and yield potential. But that flexibility only has value if the application is made while the crop can still effectively use the N. The data shows that the most risk adverse timing falls in the January to mid-March time frame.

What About Fertilizer Price?

Agronomy is only part of the decision. Anhydrous ammonia can provide a substantial cost-per-pound-of-N advantage over fertilizer sources typically used for in-season applications. When that price gap becomes large, the in-season strategy needs to create enough additional value through yield, protein, improved N-rate decisions, or reduced N loss to pay for the more expensive source.

The break-even calculation is straightforward: Additional N cost per acre ÷ wheat price = additional bushels needed to break even. At a 100 lb N/ac rate, every $0.10/lb difference in N price represents $10/ac in fertilizer cost.

For example, if the in-season N source costs $0.30/lb N more, that is a $30/ac disadvantage before the crop is planted. At $4.00 wheat, in-season N needs to produce 7.5 additional bu/ac to cover that difference. At $5.00 wheat, it needs 6 bu/ac, and at $6.00 wheat, it needs 5 bu/ac.

The range becomes fairly large as the difference in N price changes. At a 100 lb N/ac rate and wheat prices between $4 and $6/bu, a $0.20/lb N-price difference requires roughly 3 to 5 additional bu/ac, while a $0.50/lb difference requires roughly 8 to 13 additional bu/ac.

That doesn’t make either strategy automatically more profitable. In environments where yield is the same, the cheaper N source has the economic advantage. Where in-season N increases yield or protein, the economics can move in the other direction. There is also another economic benefit to waiting that is harder to put into a simple table: by waiting, the producer can adjust the N rate to the yield potential that is there rather than the yield potential hoped for before planting.

So fertilizer price adds another question to the N-timing decision: How much is the flexibility of waiting worth this year?

After more than 90 Oklahoma site-years, there is little evidence that grain-only winter wheat inherently benefits from having the entire N requirement available before planting. A properly timed in-season application generally maintains yield and can increase yield under responsive conditions. The opportunity to increase grain protein is even more consistent. Waiting also allows the final N decision to be made when the producer knows considerably more about the crop, weather, and realistic yield potential.

Splitting N does not appear to provide an additional yield benefit over a single, properly timed in-season application. Its primary value is insurance against missing that application window. But fertilizer price matters. When anhydrous or another pre-plant source provides N substantially cheaper than the available in-season source, those savings have real value and should be weighed against the potential benefits of waiting. There isn’t one N-timing strategy that wins every year. The goal isn’t simply to maximize yield or minimize fertilizer cost. It is to choose the N source, rate, and timing combination that provides the best economic return for the conditions in front of you.

These conclusions apply to grain-only winter wheat. Dual-purpose wheat requires sufficient fall growth for forage production and has a different early-season N requirement.

If you have any questions or comments, please feel free to reach out.

Brian Arnall
b.arnall@okstate.edu

Sources

Souza, J.L.B., Antonangelo, J.A., Silva, A.O., Reed, V., and Arnall, B. 2022. Recovery of Grain Yield and Protein with Fertilizer Application Post Nitrogen Stress in Winter Wheat (Triticum aestivum L.). Agronomy 12:2024.

Abiola, S.O., Souza, J.L.B., Sharry, R., Derrick, J.R., Maatougui, M., and Arnall, D.B. 2025. Split nitrogen applications provide no benefit over a single well timed application in rainfed winter wheat. Frontiers in Plant Science 16:1698494.

Ballagh, B., Ballagh, A., Bushong, J., and Arnall, D.B. The Effect of Nitrogen Fertilizer Placement and Timing on Winter Wheat Grain Yield and Protein Concentration.

Sharry, R. 2025. Response to nitrogen timing of varying winter wheat genotypes Dissertation, https://hdl.handle.net/20.500.14446/344867

Regional N study. 52 Oklahoma site-years, 2009–2023, Okstate Soil Fertility data unpublished.

OSUNPK Fertilizer Market Outlook — July 27, 2026

July 27, 2026 3:47 pm / Leave a comment

Produced by Chat GPT Work, reviewed by Brian Arnall, OSU Precision Nutrient Management.

Oklahoma fertilizer markets moved in two different directions during the latest reporting period. Nitrogen prices generally declined, while phosphate and potash remained nearly steady. That local stability does not mean the broader market is free of risk. International production costs, sulfur availability, trade flows and large import programs continue to influence the prices Oklahoma producers may encounter later in the season.

The USDA’s July 24 Oklahoma report placed urea at an average of $672.29 per ton, down $14.42 from the previous report. UAN 28 declined $16 to $472.60, UAN 32 fell $5 to $548.86, and anhydrous ammonia declined $29 to $947. One reported urea quote fell by approximately $300 per ton, while an NH₃ quote moved below $900 and a UAN 28 quote dropped below $400. Those individual movements contributed to unusually wide ranges and should not be treated as representative statewide prices without verification.

The USDA attributed part of the softer market to reduced fertilizer demand during triple-digit heat. Seasonal demand also appears less urgent following major spring and early-summer applications. However, the spread between low and high quotes remains substantial: $365 per ton for urea, $232 for UAN 28 and $225 for NH₃. Those differences make product basis, location and service charges particularly important when comparing offers. (USDA Oklahoma Production Cost Report)

International nitrogen conditions remain uncertain. Fertilizer-market analyst Josh Linville recently identified the resumption of vessel traffic through the Strait of Hormuz and the possibility of renewed Chinese urea exports as potentially bearish influences. Either development could improve global availability. However, fertilizer remains expensive relative to grain prices, and freight, energy or geopolitical disruptions could quickly change the cost calculation. (Josh Linville market commentary)

Oklahoma phosphate prices showed little immediate movement. DAP averaged $952.78, an increase of $2.22, while MAP held at $942.88. The local numbers appear quiet, but upstream phosphate conditions deserve attention. Linville has noted renewed strength in international phosphate values as limited sulfur availability and high production costs constrain output.

Sulfur matters because it is used to produce sulfuric acid, a critical input in manufacturing phosphoric acid and finished phosphate fertilizers such as DAP and MAP. Ammonia is another important production input. Consequently, higher sulfur or ammonia costs can support phosphate prices even when Oklahoma retail quotations have not yet responded. This is an upstream warning signal rather than a prediction that local prices must rise. (Josh Linville on phosphate and sulfur, World Bank fertilizer-market analysis)

Potash remained the quietest major nutrient in Oklahoma. The reported average increased only 75 cents to $491.55, with a range of $460 to $550. Global potash supply is geographically broader than the supply chain for several nitrogen and phosphate inputs. Expanded or recovering shipments from major producing regions may help moderate market pressure, although trade restrictions, transportation constraints and regional demand can still affect delivered costs.

International buying also remains important. India reported importing more than 3.2 million metric tons of urea and DAP during its first fiscal quarter and is pursuing longer-term overseas supply agreements. Large import programs can affect competition for available urea and phosphate cargoes, especially when export availability is already uncertain. (Times of India fertilizer-import report)

For Oklahoma producers, the current report offers a somewhat more favorable nitrogen signal, but not a uniform one. Wide quote ranges mean that comparison shopping may be as important as the regional average. Phosphate prices are locally stable, while sulfur availability and production costs remain meaningful external risks. Potash is comparatively steady.

Before acting on any quotation, confirm the nutrient analysis, cash-price basis, pickup or delivery terms, quote expiration and whether application or blending charges have been separated. UAN quotations should always be identified as either 28% or 32% before comparison.

Market Sources

How Much Nitrogen Does Double Crop Corn Need in Oklahoma?

June 26, 2026 1:49 pm / Leave a comment

Kelby Linn, MS Precision Nutrient Management
Emily Staton, MS Precision Nutrient Management
Josh Lofton, Cropping Systems Management
Brian Arnall, Precision Nutrient Management

Double crop (DC) corn is gaining attention in Oklahoma as producers look for opportunities to increase productivity following wheat harvest. While DC soybeans and sorghum remain common options, corn can serve as an alternative when planting windows are missed or when producers want to diversify their rotation. In Oklahoma systems, it is suggested DC corn is followed by a full season soybean crop the next year. This allows producers to maintain an intensive cropping system while maximizing land use. However, managing fertility in DC corn can be challenging because the crop is grown under a different environment than full season corn. One of the questions producers ask is how much nitrogen (N) is needed to maximize returns. Nitrogen is typically the largest fertilizer expense in corn production, but applying more N does not always result in higher yields. Recent Oklahoma research suggests DC corn may require less N than many would expect.

Understanding the System

To evaluate N requirements under Oklahoma DC conditions, field trials were conducted across 11 site years during the 2024 and 2025 growing seasons (Table 1). Corn was planted directly into wheat residue following harvest, creating a true DC production system. Nitrogen was applied as urea (46-0-0) at 13 rates ranging from 0 to 180 lbs N/acre in 15 lb N increments. The following data was collected: biomass production, grain yield, and grain quality responses across environments. The goal was to identify how much N is needed to maximize yield and profitability in Oklahoma DC corn.

Table 1. Field study locations for the 2024 and 2025 double crop corn trials in Oklahoma. Each location is listed with respective planting dates, corn varieties, planting populations and harvest date.

Location	Planting	Variety	Population	Harvest
Perkins	6/28/2024	DK119-30	20k	11/9/2024
Perkins	7/11/2025	DKC117-27RIB	20k	11/14/2025
Stillwater	6/30/2024	DK119-30	20k	11/11/2024
Stillwater	7/12/2025	DKC117-27RIB	20k	11/13/2025
Perry	6/28/2024	DK119-30	20k	11/16/2024
Perry	7/7/2025	DKC117-27RIB	20k	11/12/2025
Perry (Irrigated)	7/7/2025	DKC117-27RIB	28K	11/12/2025
Lahoma	7/9/2025	DKC117-27RIB	20k	11/18/2025
Fort Cobb (Irrigated)	7/2/2025	DKC117-27RIB	28K	11/15/2025

Yield Response: Nitrogen Helped, But Only to a Point

Across all harvested site years, N applications significantly influenced grain yield when environment was not the limiting factor. Average yields ranged from 40 to 94 bu/ac, demonstrating how variable DC corn performance can be from year to year and field to field (Staton, 2026) (Figure 1). While some locations responded positively to N fertilizer, others showed little response even when rates reached 180 lbs N/ac. The consistent finding was yield responses often plateaued around 60 lbs N/ac. Once this point was reached, additional fertilizer rarely produced enough additional grain to justify the added cost. Across two Oklahoma studies representing 11 site-years, unfertilized double-crop corn averaged approximately 52 bu/ac. That finding highlights just how much nitrogen can be supplied by the soil through residual nitrate and mineralization before fertilizer is applied. These results suggesting existing soil N and nutrient mineralization contributed significantly to crop demand (Staton, 2026).

Figure 1. Increase in yield of the highest yielding treatment as compared to the non-fertilized check yields of each location. Adapted from Staton (2026)

The Real Story: Return on Investment

While producers naturally focus on maximizing yield, these fertilizer decisions should be based on profitability. Average economic return peaked near 60 lb N/ac. Beyond that rate, additional fertilizer consistently reduced profit (Figure 2). Although individual economic returns varied among environments, the agronomic data suggest producers should approach DC corn fertility programs with realistic yield expectations. Unlike high yielding full season corn, DC systems often encounter environmental limitations that reduce the return on additional fertilizer investment.

Figure 2. Average profit response to nitrogen rate in US dollars (USD)/ac. Adapted from Staton (2026).

What This Means for Oklahoma Producers

The results from this study closely align with previous Oklahoma research evaluating N response in DC corn. Wyma (2022) reported approximately one additional bushel of grain for every 1.8 lbs N applied above the unfertilized control, similar to Staton (2026) who observed one additional bushel for every 1.7 lbs N in responsive environments. Together these studies suggest Oklahoma DC corn requires approximately 1.75 lbs N for every additional bushel of expected yield above 50 bu ac^-1.

The goal of nitrogen management is not to apply the most fertilizer, it is to apply the right amount. Two independent Oklahoma studies now indicate that double-crop corn often requires substantially less N than full-season corn. Matching N rates to realistic yield potential can improve profitability while reducing unnecessary fertilizer costs.

Take Home

Double crop corn is a economically viable option in Oklahoma.
Use lower total N rates than full-season corn.
Across two independent studies’, the unfertilized corn averaged about 50 bushels per acre.
1.75 lb N per expected additional bushel above the unfertilized expectation.
Base final N rates on realistic yield potential and expected moisture.
Consider residual soil nitrate following wheat before increasing fertilizer rates.
Avoid applying N beyond expected crop demand.

References

Alcoz, Mercedes M., Frank M. Hons, and Vincent A. Haby. 1993. “Nitrogen Fertilization Timing Effect on Wheat Production, Nitrogen Uptake Efficiency, and Residual Soil Nitrogen.” Agronomy Journal 85(6):1198–1203. doi:10.2134/agronj1993.00021962008500060020x.

Chang, Jen-Hu. 1981. “Corn Yield in Relation to Photoperiod, Night Temperature, and Solar Radiation.” Agricultural Meteorology 24:253–62. doi:10.1016/0002-1571(81)90049-2.

Kravchenko, Anatoliy G., and Kurt D. Thelen. 2007. “Effect of Winter Wheat Crop Residue on No-Till Corn Growth and Development.” Agronomy Journal 99(2):549–55. doi:10.2134/agronj2006.0192.

Liu, Zheng, Jia Gao, Fei Gao, Shuting Dong, Peng Liu, Bin Zhao, and Jiwang Zhang. 2018. “Integrated Agronomic Practices Management Improve Yield and Nitrogen Balance in Double Cropping of Winter Wheat-Summer Maize.” Field Crops Research 221:196–206. doi:10.1016/j.fcr.2018.03.001.

Staton, Emily. 2026. “Nitrogen Management in Double Crop Corn” M.S., Oklahoma State University, United States — Oklahoma.

Wyma, Rhiannon Nichole. 2022. “Corn Grain Yield Response to Nitrogen Rate and Plant Population in Full and Double-Crop Systems.” M.S., Oklahoma State University, United States — Oklahoma.

Bigger Isn’t Always Better: The Relationship Between Plant Size, Yield Potential, and Yield Stability in Summer Crops

June 21, 2026 11:41 am / Leave a comment

Josh Lofton, Cropping Systems Specialist

In the last several years, warmer springs and higher/widespread rainfall have resulted in summer crops reaching with a high amount of vegetative growth. This season has been quite different for the most part, cooler temperatures and more sporadic rainfall has resulted in much smaller plants. So that begs the question, are larger or smaller plants better for yield in Oklahoma. While many that have spent time in Oklahoma will probably have a preference, there is no direct answer to this question.

Larger plants generally have more leaves, more stems, more branches, and more overall biomass. They often appear healthier and more productive throughout the growing season.

In higher rainfall and lower stress environments, this assumption is true. Greater vegetative growth can support higher yield potential because larger plants capture more sunlight, accumulate more photosynthates, and develop a greater capacity to support grain or seed production.

However, in Oklahoma and throughout the Southern Great Plains, yield potential and yield stability are not always the same thing.

The challenge facing producers across this region is that crops must balance the opportunity to maximize yield with the risk of running short on water during critical reproductive growth stages. As a result, the plant with the greatest theoretical yield potential is not always the plant that produces the most grain across a range of environmental conditions.

The Tradeoff Between Yield Potential and Yield Stability

Many may have heard of this difference. Even you if have not directly of these concepts, most in Oklahoma will be familiar with the trade-offs

Yield potential refers to the maximum yield a crop can achieve when environmental conditions are favorable, and resources are not limiting.

Yield stability refers to a crop’s ability to maintain performance across varying environmental conditions, including drought, heat stress, and erratic rainfall.

These two characteristics are often related, but they are not always aligned.

High vegetative growth frequently possesses greater yield potential because they can intercept more sunlight and support more reproductive structures. However, those same plants often require greater amounts of water throughout the season.

In contrast, plants with more moderate growth habits may have slightly lower maximum yield potential, but they often maintain more consistent performance when environmental stresses occur.

So the difference between excessive, adequate, and too low vegetative production is not consistent and is impacted by a part of the year not yet experienced.

For producers in the Southern Great Plains, where growing conditions can change dramatically from one season to the next, yield stability can be just as important as maximum yield potential.

Why More Growth Often Means More Yield Potential

The relationship between vegetative growth and yield begins with photosynthesis.

More leaves generally mean:

Greater sunlight interception
Greater photosynthetic capacity
More carbohydrate production
More potential reproductive sites

And when we are talking about farming, what we are often farming is the sunlight indirectly through the crops we are growing. Therefore, the higher amount of sunlight that can be captured, this higher potential yield can be.

In soybean, larger plants often produce more nodes and branches, creating additional locations for pod formation.

In grain sorghum, larger canopies can support greater grain production when moisture remains adequate through grain fill.

In corn, larger plants often contribute to greater kernel production and kernel weight under favorable conditions.

Because of these relationships, management practices that encourage vigorous growth are frequently associated with high yield environments.

The key phrase, however, is under favorable conditions.

The Hidden Cost of Large Plants

Every leaf that captures sunlight also loses water.

As plant size increases, so does transpiration demand. Larger plants require more water simply to maintain normal physiological activity.

This creates a challenge in many Oklahoma production environments.

Rainfall is often adequate during early vegetative development, allowing crops to establish large canopies and accumulate substantial biomass (often during the months of April and early May). However, the period from flowering through grain fill frequently coincides with:

Higher temperatures
Greater evaporative demand
Less reliable rainfall
Increasing soil moisture depletion

This can be a two-fold issue. One, higher vegetative production early could have utilized and drained total surface and subsurface moisture, which is now not available during reproductive growth. However, it also increased daily moisture demand. This can result in with similar soil moisture and rainfall, a smaller plant will have a lower moisture demand than a larger plant.

The consequence is often a reduction in grain or seed production precisely when yield is being determined.

Soybean: A Classic Example

Soybean perhaps provides the best illustration of this concept.

When moisture is abundant, larger soybean plants can be extremely productive. Additional nodes and branches create opportunities for greater pod production, and large canopies intercept significant amounts of sunlight.

However, soybean also possesses one of the longest reproductive periods among major summer crops.

A soybean crop must successfully retain flowers, maintain pods, and fill seeds over an extended period. Water stress at any point during this process can reduce yield.

Large soybean plants often consume considerable amounts of water during vegetative growth. If drought develops during pod set or seed fill, those plants may experience:

Increased flower abortion
Increased pod abortion
Reduced seed size
Premature canopy senescence

In contrast, a more moderate-sized soybean plant may use less water during early development and preserve soil moisture for reproductive growth.

While that plant may possess fewer nodes or branches and therefore slightly lower maximum yield potential, it may be better positioned to maintain yield under stressful conditions.

Seeing this in practice

Previous research conducted in Oklahoma provides a practical example of the tradeoff between maximizing yield potential through vegetative growth and maintaining yield stability under water-limited conditions. In this study, soybean plant architecture was manipulated through physical plant growth regulation, allowing us to evaluate how changes in plant size influenced yield across contrasting environmental conditions.

As shown in Figure 1, plant growth regulation substantially reduced soybean height compared to untreated plants. Three weeks after treatment implementation, regulated plants ranged from 5–10 inches shorter than untreated plants. These reductions in height were accompanied by fewer mainstem nodes, but plants compensated by producing more branch nodes and increasing canopy coverage. The response was relatively consistent across both growing seasons, demonstrating that soybean plants can modify their growth habit when mainstem development is restricted.

Figure 1. Impact of plant growth regulation (physical removal) on soybean plant height compared to untreated plants. Data were collected across the 2022 and 2023 growing seasons.

While reduced plant size altered canopy architecture, the impact on yield differed substantially between years (Figure 2). In 2022, when environmental conditions were generally favorable and resources were less limiting, plant growth regulation did not improve yield. In fact, yields were slightly lower than the untreated control. This response likely reflects the reduced yield potential associated with smaller plants, as larger soybean canopies often intercept more light, accumulate greater biomass, and support higher seed production when adequate moisture is available throughout the season.

However, the response was markedly different during 2023, when moisture became increasingly limiting later in the growing season. Under these conditions, regulated plants significantly outyielded the untreated plants. The smaller canopy likely reduced seasonal water use and delayed soil moisture depletion, leaving more water available during critical reproductive growth stages. In contrast, larger untreated plants developed greater vegetative biomass and therefore higher water demand earlier in the season. Although these larger plants possessed greater theoretical yield potential, they were more susceptible to late-season drought stress when water availability became limited.

These results illustrate an important principle for summer crop production systems in water-limited environments. Larger plants often possess higher yield ceilings because of their greater vegetative growth and capacity to capture resources. However, that same vegetative growth can increase transpiration demand and accelerate soil water depletion, increasing the risk of yield loss if drought develops later in the season. Smaller plants may not achieve the same maximum yield potential in favorable years, but they often provide greater yield stability by reducing water demand and preserving resources for reproductive development. Consequently, the optimal plant size is often a balance between maximizing yield potential and minimizing drought risk, particularly in environments such as Oklahoma where late-season moisture stress is common.

Figure 2. Impact of plant height regulation on soybean yield during the 2022 and 2023 growing seasons. Yield responses differed between years, highlighting the tradeoff between maximum yield potential and yield stability under water-limited conditions.

Lessons from Grain Sorghum

Grain sorghum offers another excellent example.

One reason sorghum has traditionally been viewed as a drought-adapted crop is its ability to regulate water use throughout the season. Traits such as leaf rolling, reduced transpiration, and stay-green characteristics help preserve plant function during grain fill.

Many of these mechanisms do not necessarily maximize growth early in the season. Instead, they improve the likelihood that the crop can complete grain development under stressful conditions.

This strategy may occasionally sacrifice maximum yield potential in highly favorable years, but it often improves yield stability across multiple growing seasons.

Managing for Consistency Versus Chasing Maximum Yield

One of the most important questions growers must answer is whether they are managing for maximum yield potential or maximum yield consistency.

In highly productive environments with irrigation or reliable rainfall, encouraging aggressive vegetative growth may be appropriate because water limitations are less likely to restrict grain fill.

In contrast, dryland production systems throughout much of Oklahoma often reward a more balanced approach.

The goal is not necessarily to produce the largest crop canopy possible. Rather, it is to produce enough canopy to efficiently intercept sunlight while preserving sufficient water to support reproductive growth later in the season.

Bigger Isn’t Always Better—Especially in Dryland Systems

This does not mean smaller plants are inherently superior.

A very small plant may lack sufficient leaf area to fully utilize available sunlight and may never achieve high yield potential regardless of rainfall conditions.

The ideal crop is rarely the smallest or the largest plant in the field.

Instead, the most successful crops are often those that achieve a balance between vegetative growth and resource conservation.

They develop enough biomass to support high levels of photosynthesis while avoiding excessive water consumption before reproduction begins.

Final Thoughts

Across Oklahoma and the Southern Great Plains, crop production is often a matter of managing risk as much as maximizing yield.

Larger plants frequently possess greater yield potential because they capture more sunlight and produce more biomass. However, that potential comes with increased water demand. When rainfall becomes limiting during flowering, grain fill, pod set, or seed development, those larger plants can become more vulnerable to stress.

Smaller or more moderately sized plants may not always produce the highest yields in ideal environments. However, they often provide greater yield stability because they conserve resources and maintain reproductive growth when environmental conditions deteriorate.

For soybean in particular, this tradeoff is frequently observed. The largest plants in July are not always the highest-yielding plants in October. More often, the most successful plants are those that balance growth with resource conservation, preserving enough water to support reproduction when it matters most.

In the Southern Great Plains, where late-season drought remains one of the greatest limitations to crop production, understanding the difference between yield potential and yield stability may be just as important as understanding yield itself.

Banding P for Acidic Soils: Its not the time to be paying for poor practice.

April 24, 2026 1:09 pm / 2 Comments on Banding P for Acidic Soils: Its not the time to be paying for poor practice.

I am bringing this topic back to the surface now with the current outlook on phosphorus fertilizer. If you have heard its not only becoming more expensive but the supply is short and will likely stay short through summer into the fall, which wont help prices. So this year’s wheat crop, we need to be prepared to be smart with Phosphorus, and applying an extra 30lbs to band aid for soil acidity should not be in the cards. Look at it this way, if the phosphorus was at $0.66 a lb that $20 that could be spent on a ton of lime. That lime will last 3-5 years, while that P needs to be added every year. Not only that, but the lime will help root growth (better when we dry up), produce significantly more biomass, and make the phosphorus you’ve applied in the past available again for plant uptake. So make the plans now to soil sample as soon as this crop is off, you can get a soil test recommendation and plan for the lime trucks. This is also not the year to just apply phosphorus for the sake of applying. Soil tests are inexpensive relative to buying excess fertilizer.

Current quotes on 4.24.26 are at $0.54 + per lbs P2O5 with DAP at $830 a ton.

Quick Fertilizer Price Calculation:
Urea at $860 a ton means N is $0.93 a lbs.
DAP at $830 has $334 worth of $0.93 nitrogen and $495 of phosphorus at $0.54 a lb.

Banding P as a band-aid for soil acidity, not so cheap now.

Original Blog Posted in 2021

Whoi Cho, PhD student Ag Economics advised by Dr. Wade Brorsen
Raedan Sharry, PhD Student Soil Science advised by Dr. Brian Arnall
Brian Arnall, Precision Nutrient Management Extension.

In 2014 I wrote the blog Banding P as a Band-Aid for low-pH soils. Banding phosphate to alleviate soil acidity has been a long practiced approach in the southern Great Plains. The blog that follows is a summary of a recent publication that re-evaluated this practices economic viability.

Many Oklahoma wheat fields are impacted by soil acidity and the associated aluminum (Al) toxicity that comes with the low soil pH. The increased availability of the toxic AL³⁺ leads to reduced grain and forage yields by impacting the ability of the plant to reach important nutrients and moisture by inhibiting root growth. Aluminum can also tie up phosphorus in the soil, further intensifying the negative effects of soil acidity. More on the causes and implication of soil acidity can be found in factsheet PSS-2239 or here (https://extension.okstate.edu/fact-sheets/cause-and-effects-of-soil-acidity.html). The acidification of many of Oklahoma’s fields has left producers with important choices on how to best manage their fields to maximize profit.

Wheat Trial, Cimarron Valley Research Station

Two specific management strategies are widely utilized in Oklahoma to counter the negative impacts of soil acidification: Lime application and banding phosphorus (P) fertilizer with seed. While banding P with seed ties up Al allowing the crop to grow, this effect is only temporary, and application will be required every year. The effects of liming are longer lasting and corrects soil acidity instead of just relieving Al toxicity. Historically banding P has been a popular alternative to liming largely due to the much lower initial cost of application. However, as P fertilizers continue to increase in cost the choice between banding P and liming needed to be reconsidered.

A recent study by Cho et al.,2020 compared the profitability of liming versus banding P in a continuous wheat system considering the impacts that lime cost, wheat price and yield goal has on the comparison. This work compared the net present value (NPV) of lime and banded P. The study considered yield goal level (40 and 60 bu/ac) as well as the price of P₂O₅ fertilizer and Ag Lime. The price of P₂O₅ used in this study was $0.43 lb^-1while lime price was dictated by distance from quarry, close to quarry being approximately $43 ton^-1 and far being $81 ton^-1. For all intents and purposes these lime values are equivalent to total lime cost including application. Wheat prices utilized in the study were $5.10 bu^-1 and $7.91 bu^-1. It is important to note that baseline yield level was not considered sustainable under banded P management in this analysis. This resulted in a decrease in yield of approximately 3.2 bu ac^-1 per year. This is attributable to the expected continued decline in pH when banding P is the management technique of choice.

The analysis in this work showed that lime application is cost prohibitive in the short term (1 year) when compared with banding P regardless of lime cost, yield goal level, and wheat value (within the scope of this study). This same result can be seen over a two-year span when yield is at the lower level (40 bu ac^-1). While in the short-term banding P was shown to be a viable alternative to liming, as producers are able to control ground longer lime application becomes the more appealing option, especially when producers can plan for more than 3 years of future production. In fact, under no set of circumstances did banding P provide greater economic return than liming regardless of crop value, yield, or liming cost when more than 3 years of production were considered and only under one scenario did banded P provide a higher NPV in a 3-year planning horizon.

While historically banding P was a profitable alternative to lime application for many wheat producers the situation has likely drastically changed. At the time of writing this blog (09/17/2021) Diammonium Phosphate (DAP) at the Two Rivers Cooperative was priced at $0.78 lb^-1. of P₂O₅. This is a drastic increase in P cost over the last year or so since Cho et al. was published in 2020. With P fertilizer prices remaining high it will be important for producers to continue to consider the value of liming compared to banded P. This is particularly crucial for those producers who can make plans over a longer time frame, especially those more than 3 years.

Addendum: As fertilizer prices have continued to rise a quick analysis utilizing the $0.78 lb^-1of P₂O₅was completed to consider the higher P fertilizer cost. Under this analysis an estimated decrease in NPV of approximately $38 an acre for P banding occurred. When considering this change in NPV, lime application becomes the more profitable option for alleviation of soil acidity symptoms even in the short term (assuming lime price values are equivalent to the previous analysis). This underlines the fact that it is imperative to consider the impact on profitability of the liming vs. banding P decision in the current economic climate for agricultural inputs.

Link to the Open Access Peer Reviewed publication “Banding of phosphorus as an alternative to lime for wheat in acid soil” https://doi.org/10.1002/agg2.20071

Mechanisms of Soil Fertility: Looking at Biologicals and MOA

April 3, 2026 12:23 pm / Leave a comment

Brian Arnall, Oklahoma State University Precision Nutrient Management

The use of biological products in commercial agriculture has expanded rapidly, with large corporations entering a space once dominated by smaller groups. This has created an arms race, with nearly every company offering a biological product. Over the past twenty years, I have had the opportunity to test products from the biggest groups with billions in backing, to solutions raised in stock tanks delivered in Braums milk jugs. It is critical to understand what is in the jug and the biological function it is expected to perform. Like herbicides, knowing the mode of action determines whether the product fits the intended purpose. No different than herbicides and knowing mode of actions. It’s important to know and understand that if you are trying to kill ryegrass 2.4-D, a broadleaf herbicide is not the right answer.

So what are we working with that’s in these products?

My approach has been to classify the products by operation not by species or genre. Doing so I have grouped products into five biological classifications and a sixth group, which is often in concluded in conversations.

Decomposers / Organic Matter Mineralizers
Nitrogen Fixers (Symbiotic and Associative)
Symbiotic Root Associations (Mycorrhizae, PGPR)
Nutrient Solubilizers
Biological Pest Control
Plant Growth Regulators (Hormonal Effects)

So, let’s dig into each of the mechanisms.

Decomposers / Organic Matter Mineralizers

Decomposition is carried out by a diverse group of organisms including fungi (e.g., Trichoderma, Aspergillus), bacteria (e.g., Bacillus, Pseudomonas), and actinomycetes (e.g., Streptomyces), each contributing to the breakdown of organic materials through different enzymatic pathways. This process of decomposing organic matter releases the nutrients tied up into plant available forms. The release of nitrogen is usually first thought, but this process adds significant amounts of potassium, calcium, and magnesium.
The process occurs both in the soil and on the soil surface. While it seems simple in application though this is a complex process. Let’s start with the soil pool, triggering decomposition of a system where the previous crop was wheat is significantly different than following corn. Following wheat, the carbon nitrogen ratio will be very high (see sugar blog), so while decomposition will release cations such as potassium and calcium, it is very likely to immobilize and residual nitrogen in the system. However, in fields that previously had corn the carbon to nitrogen ratio is much closer and the probability of seeing nitrogen release is much higher (Kuzyakov & Blagodatskaya, 2015). The process is similar for surface residues, but the rate is heavily controlled by rainfall. While both the soil and surface systems require moisture for the process to progress, the surface moisture is much more dynamic with frequent wetting and drying. Rain or irrigation is also needed to move the nutrients into the root zone.

One aspect of increasing decomposition of OM that I do not have a handle on is the long-term impact of expediting OM breakdown in and on the soil, especially in the central plains. As mentioned in the sugar blog, you would hope that the increase in nutrients from OM decomposition would increase plant growth enough to replenish the OM that was burned up. One caveat to this is that the decomposition would have to add nutrients that are deficient. Otherwise, there is no increase in plant growth and hypothetically the system is not net negative on OM. When it comes to decomposing surface residue, I have always been a bit hesitant in Oklahoma as I see having surface coverage to preserve soil moisture typically has a greater value than the nutrients from the residue.

Nitrogen Fixers (Symbiotic and Associative)

Nitrogen fixation is carried out by both symbiotic organisms such as Rhizobium and Bradyrhizobium, which form nodules on plant roots and supply significant nitrogen, and associative organisms such as Azospirillum and Azotobacter, which reside in the rhizosphere and contribute smaller, more variable amounts of nitrogen. Symbiotic nitrogen fixation, such as we have come to expect from legumes, is tightly regulated by the plant, with carbon supplied to the microbe in exchange for fixed nitrogen, making it one of the most efficient biological nitrogen inputs in agriculture.

Associative nitrogen fixation is not directly coupled to plant demand, and nitrogen contributions are typically limited by carbon availability and environmental conditions (Kennedy et al., 2004). While these organisms possess the ability to fix atmospheric nitrogen, the magnitude of nitrogen contribution, particularly from non-symbiotic systems, is highly variable and often limited under field conditions. We know that in soybean nodulation is greatly reduced when excess nitrogen is present in the soil, basically the plant does not need rhizobia, so it does not trigger symbiosis. I expect that as we move symbiotic fixation out of legumes that this mechanism does not change. Finally fixed N is no different than fertilizer N, if you add more then the crop needs, its lost. Therefore, if I am planning to use a N fixer, I would significantly reduce the amount of fertilizer N apply well below crop demand. Otherwise, the money spent on the N fixer is a waste. The only argument I have heard for this is the security blanket, making sure that if more is needed than normally the system is covered. But I circle back to the question about a system with high levels of residual N and rhizobium nodulation.

Symbiotic Root Associations (Mycorrhizae, PGPR)

Symbiotic root associations include arbuscular mycorrhizal fungi (e.g., Rhizophagus, Funneliformis) that extend the effective root system and improve nutrient uptake, particularly phosphorus, as well as plant growth-promoting rhizobacteria (e.g., Pseudomonas, Bacillus) that influence root development and plant signaling through multiple biochemical pathways (Smith & Read, 2008). In my visits with soil microbiologist, I have been left with the understanding that these relationships are not generic, but quite specific. There is significant influence of genotype and environment. And even more interesting is that the majority expect that the plant needs to signal for this relationship to happen.

The effectiveness of these associations is highly dependent on soil conditions, existing microbial communities, and nutrient availability, with responses often diminishing in systems where nutrients are not limited or where native populations are already established. I was able to follow along with some work down at OSU a few years back that was working with sorghum looking for symbiotic relationships to improve water and nutrient uptake specifically phosphorus. The work was successful, the researchers were able to identify a AMF that created a symbiotic relationship with sorghum, with a few caveats. First land race cultivars had a much higher incidence of symbiosis. For the landraces it worked well in extremely nutrient depleted soils and any additions of N or P reduced forage yield over the none. In the end the researchers were able to show improved the grain yield in landraces above fertilized, but these yields did equal fertilized hybrids. This work had great impact on small holders in developing counties with limited resources.

Nutrient Solubilizers

Nutrient solubilization is carried out by organisms such as Bacillus, Pseudomonas, and Aspergillus, which increase nutrient availability through mechanisms including organic acid production, proton release, and chelation, allowing nutrients like phosphorus and micronutrients to become more accessible in the rhizosphere.

Phosphorus-solubilizing fungi, such as Aspergillus and Penicillium, function similarly to bacterial solubilizers but are often more effective at producing strong organic acids. These acids can lower pH in localized zones and release phosphorus from mineral-bound forms, particularly in soils with high fixation capacity. Fungal systems can operate across a wider range of environmental conditions and may play a larger role in longer-term phosphorus cycling. However, as with bacterial systems, these effects are generally localized and dependent on soil chemistry (Richardson et al., 2009). I tend to see these having the greatest benefits in systems that have historically received manures or long-term applications of fertilizer P. I do not believe this is a good fit for soils with limited available phosphorus, as it is trying to focus the soil into something, it does not want to do or have too spare.

Potassium-solubilizing organisms, including species such as Bacillus mucilaginosus and Frateuria aurantia, contribute to the release of potassium from primary minerals like feldspars and micas. These microbes facilitate mineral weathering through acidification and chelation processes that slowly break down mineral structures. While the mechanism is well understood, the rate of potassium release is typically slow relative to crop demand. As a result, these organisms are more influential in long-term soil development than in short-term fertility management (Sheng & He, 2006).

Micronutrient-mobilizing organisms, particularly Pseudomonas and Bacillus species, enhance availability through the production of siderophores and other chelating compounds. These molecules bind metals such as iron and zinc, increasing their solubility and facilitating uptake in the rhizosphere. This process is especially important in soils where micronutrients are present but not readily available due to chemical constraints. However, the impact is typically limited to the immediate root zone and depends on both microbial activity and soil conditions (Ahmed & Holmström, 2014).

Biological Pest Control

Biological pest control organisms, including species such as Bacillus, Pseudomonas, and Trichoderma, function by suppressing pathogens through several well-documented mechanisms. These include the production of inhibitory compounds, competition for space and nutrients, direct antagonism of pathogens, and the activation of plant defense systems through induced systemic resistance. While these mechanisms are well established under controlled conditions, their effectiveness in field environments is highly dependent on environmental conditions, pathogen pressure, and the ability of the organism to persist and colonize the soil or plant surface (Lugtenberg & Kamilova, 2009).
I’ve been working with a lot of folks from Brazil who historically make four to six nemacide applications in soybean, but utilizing Pseudomanas they have been able to reduce that number by half or more. The caveat, as I understand, the application rates needed are significantly higher than anything I have seen in the US. If you look through the literature, you are seeing more and more documentation of this such as Li et al. 2022. But as Spescha et al. (2023) documented, different biological control agents operate through complementary mechanisms, including infection, toxin production, and host targeting. However, effectiveness depended on environmental conditions and interactions among organisms, reinforcing that biological control outcomes are system-dependent rather than universally consistent.

Plant Growth Regulators (Hormonal Effects)

This group differs slightly, as the primary effect is not direct nutrient cycling but modification of plant physiological response. This group is one I hold the greatest expectations for. I mean we have been using PGRs in crop production for decades, we just did not have an inkling of how many PGRs exist.

Plant growth regulator effects are associated with organisms such as Azospirillum, Bacillus, and Pseudomonas, which can influence plant development through the production of phytohormones and related compounds. These microbes produce substances such as auxins, cytokinins, and gibberellins that alter root architecture and plant growth patterns, and in some cases reduce stress responses through enzymes like ACC deaminase. Rather than supplying nutrients directly, these organisms modify how plants respond to their environment and utilize available resources. However, just like everything previously discussed the magnitude of response is often subtle and highly dependent on environmental conditions and crop system interactions (Glick, 2012).

Final thoughts.

There is one situation that pops up that I do not agree with, based upon my limited understanding of soil microbiology. Its adding more of what is already there. The soil system is a dynamic system. While there are population booms and bust, it supports what it is able to. Adding more of what is already there is like dropping a million rabbits into a prairie that has rabbits already. The current population is where it is because that is what the system can support. Adding means one of two things, a lot of rabbits die immediately, or they overwhelm the system and another animal species dies off due to lack of resources. Also, most microbiologists tell me the system is amazing at signaling and finding what it wants. It may take a season, but it will be there, in the quantities that soil needs, just given time.

So, the final slide in all my biological additives talks ends with this statement. My experiments show one thing. The impact of adding these products on crop yields is very consistently inconsistent. I’ve had many show a significant positive response, once. I have struggled to ever get repeated successes. It is my belief that I will have more success improving the soil biome by managing the soil (no-till, crop rotation, cover crops) than I will ever have with adding a product.

Final comment, Read the label. Many of the biological products I have tested are not singularly pure species. There are many blends of species and organisms which encompass many of the modes. A lot of these blends also contain extras such as humics, fulvics, carbohydrates, and sugars, see previous blogs.

Take-Home Messages

Biological products function through specific mechanisms, not as broad “boosters,” and understanding that mechanism is critical to proper use.
The presence of a biological function does not guarantee a yield response, outcomes are driven by soil, crop, and environmental conditions
Decomposers and carbon-driven systems can immobilize or mineralize nitrogen, depending largely on residue quality and system balance
Mycorrhizae and PGPR improve access to existing nutrients, not total nutrient supply
Nutrient-solubilizing organisms mobilize nutrients already present in the soil
Plant growth regulators influence plant signaling and development
Adding biological organisms to soil does not guarantee establishment or persistence, as soil systems can regulate microbial populations.
Management practices such as no-till, crop rotation, and cover crops are effective at improving soil biological function
Across all biological products, mechanism exists, but response depends on the system

Any questions or comments please reachout to me @ b.arnall@okstate.edu

Citations

Ahmed, E., & Holmström, S. J. M. (2014). Siderophores in environmental research: Roles and applications. Microbial Biotechnology, 7(3), 196–208.

Glick, B. R. (2012). Plant growth-promoting bacteria: Mechanisms and applications. Scientifica, 2012, 963401

Kennedy, I. R., Choudhury, A. T. M. A., & Kecskés, M. L. (2004).

Non-symbiotic bacterial diazotrophs in crop-farming systems. Plant and Soil, 266, 65–79.

Kuzyakov, Y., & Blagodatskaya, E. (2015).

Microbial hotspots and hot moments in soil. Soil Biology and Biochemistry, 83, 184–199.

Lugtenberg, B., & Kamilova, F. (2009). Plant-growth-promoting rhizobacteria. Annual Review of Microbiology, 63, 541–556.

Richardson, A. E., Barea, J. M., McNeill, A. M., & Prigent-Combaret, C. (2009). Acquisition of phosphorus and nitrogen in the rhizosphere and plant growth promotion by microorganisms. Plant and Soil, 321(1–2), 305–339.

Sheng, X. F., & He, L. Y. (2006). Solubilization of potassium-bearing minerals by a wild-type strain of Bacillus edaphicus and its mutants and increased potassium uptake by wheat. Canadian Journal of Microbiology, 52(1), 66–72. https://doi.org/10.1139/w05-117

Smith, S. E., & Read, D. J. (2008).

Mycorrhizal symbiosis. Academic Press.

Spescha, A., Weibel, J., Wyser, L., Brunner, M., Hess Hermida, M., Moix, A., Scheibler, F., Guyer, A., Campos-Herrera, R., Grabenweger, G., & Maurhofer, M. (2023). Combining entomopathogenic Pseudomonas bacteria, nematodes and fungi for biological control of a below-ground insect pest. Agriculture, Ecosystems & Environment, 348, 108414.

Ye S, Yan R, Li X, Lin Y, Yang Z, Ma Y and Ding Z (2022) Biocontrol potential of Pseudomonas rhodesiae GC-7 against the root-knot nematode Meloidogyne graminicola through both antagonistic effects and induced plant resistance. Front. Microbiol. 13:1025727. doi: 10.3389/fmicb.2022.1025727

The Mechanics of Soil Fertility: Use of Sugar in Field Crops

April 1, 2026 11:59 am / Leave a comment

Jolee Derrick, Precision Nutrient Management Ph. D. Student
Grace Williams, Soil Microbiology Ph. D. Candidate
Brian Arnall, Precision Nutrient Management Specialist

Recently, there has been increased interest in adding sugar to spray tank mixes, whether for post-emergence weed control or foliar nutrient applications. While there is limited work on impact of sugar inclusion in herbicide applications, some papers have posed potential enhancement (Devine and Hall, 1990). But since this is coming from a soil science group, we will only focus on soil impact. Following up the last blog, unlike humic substances, which represent more complex and relatively stable carbon forms, sugar is a highly labile carbon source. This rapid utilization of simple carbon sources is well documented to stimulate microbial activity and growth (Kuzyakov and Blagodatskaya, 2015). The general idea of utilizing sugar applications is that sugar has the capacity to improve spray performance, stimulate biological activity, increase organic matter mineralization, and ultimately result in improved yields.

Sugar additions can influence soil processes differently depending on system conditions. In systems with higher residual nitrogen and organic matter, responses may differ from those observed in Oklahoma production environments, where soils are typically lower in organic matter and microbial activity can occur for much of the year. Understanding how sugar functions in these systems requires a basic discussion of carbon dynamics. Sugar itself is almost entirely carbon and is readily consumed by microbes. It’s a simple molecule, which allows it to dissolve easily in water and be quickly utilized in the soil system. Crop residues, like wheat straw, are also carbon-rich but much more complex. They contain cellulose, hemicellulose, and lignin which are long carbon chains that take time to break down because microbes need specialized enzymes to access them.

For the sake of simplicity, we can group carbon into two key pools: labile carbon and particulate organic matter (POM). Labile carbon includes easily decomposed materials, which include the previously mentioned simple sugars that microbes can metabolize rapidly. These pools differ in turnover time and microbial accessibility, with labile carbon driving short-term microbial responses (Cotrufo et al. 2013). POM breaks down more slowly and serves as a longer-term nitrogen source through residue breakdown.

Soil microorganisms require both carbon and nitrogen to grow and maintain biomass, typically at a ratio of approximately 24 parts carbon to 1 part nitrogen. When readily available carbon is abundant, but nitrogen is limited, microbes increase their nitrogen demand and begin scavenging nitrogen from the surrounding soil. This process, better known as nitrogen immobilization, temporarily reduces nitrogen availability to crops. Additions of readily available carbon sources have consistently been shown to increase microbial nitrogen immobilization in soil systems (Recous et al. 1990).

In systems where sufficient nitrogen is present, microbial populations can expand rapidly. Fast-growing microbial species may dominate, continuing to immobilize nitrogen within their biomass. Eventually, when nitrogen becomes limiting, microbial populations decline to levels the system can support. This boom-and-bust cycle can disrupt nitrogen availability during critical stages of crop growth. These rapid shifts in microbial population and activity following carbon inputs are commonly observed in soil systems receiving easily decomposable substrates (Blagodatskaya and Kuzyakov, 2008).

This dynamic becomes especially relevant when considering residue management practices common in Oklahoma. Under no-till or limited-tillage systems, the crop residues have wide carbon-to-nitrogen (C:N) ratios, creating conditions where nitrogen immobilization can occur during the growing season.

Table 1 provides approximate C:N ratios for several crops commonly grown in Oklahoma. When additional carbon is introduced into these systems without accompanying nitrogen, the likelihood of microbial immobilization increases. While immobilization is not bad, it does create a question mark as Oklahoma’s variable climate means the following release of nutrients will be unpredictable.

Table 1. Table depicting the range of C:N ratios for residues of commonly utilized crops in Oklahoma. Ratios were obtained from Brady, N. C., & Weil, R. R. (2017). The Nature and Properties of Soils (15th ed.)

Now consider conventional tillage systems. In Oklahoma, no-till systems typically contain 2 to 3 percent organic matter, which is relatively high given our climate and extended periods of microbial activity. Conventional tillage systems often fall between 0.75 and 2.25 percent organic matter. Because soil organic matter is approximately 58 percent carbon, this represents a substantial difference in the soil carbon pool.

Tillage can temporarily enhance microbial access to both previously mentioned carbon pools. When tillage exposes previously protected carbon, microbial activity increases rapidly. This initial flush can temporarily increase nitrogen mineralization as organic nitrogen is converted to plant-available forms. However, this phase is short-lived. As microbial populations expand, nitrogen demand increases, leading to immobilization and reduced nitrogen availability.

Hypothetically, increased microbial growth and activity would rapidly mineralize organic matter, trigger a surge in NO₃⁻, deplete soil organic matter, and as resources become limiting and the environment can no longer sustain elevated microbial populations, this boom would be followed by a population crash. This relationship is ultimately driven by the soil C:N ratio, which introduces an interesting additional complexity of residue. Different residues bring very different carbon-to-nitrogen balances into the system, and microbes respond accordingly. High carbon residues give microbes plenty of energy but very little nitrogen, so they pull N out of the soil to meet their needs. Residues with lower C:N ratios (soybean, alfalfa, etc.) do opposite, releasing nitrogen as they break down. Now the real question becomes where the critical point sits, and when does management push the system from the threshold of immobilization and mineralization.

These hypotheses form the foundation for new research currently underway through the Precision Nutrient Management Program. Initial proof-of-concept work has already been completed, providing a necessary steppingstone to address these questions.

Figure 1. Graph depicting the different concentrations of nitrate leached corresponding to applied treatments in the proof-of-concept work

The preliminary work (Figure 1) evaluated different sugar sources applied alongside a high-nitrogen product to assess the extent of nitrogen immobilization. Although these studies were conducted using potting soils, clear trends were apparent. Treatments containing sugar consistently showed greater nitrogen immobilization compared to treatments without sugar. This response is consistent with studies showing that additions of simple carbon substrates stimulate microbial growth and increase nitrogen immobilization (Dendooven et al. 2006). Building on this work, an active field-based research project is underway to evaluate how sugar additions influence nitrogen availability and microbial dynamics under real-world Oklahoma production conditions.

From an agronomic standpoint, sugar functions primarily as a readily available carbon source that stimulates microbial growth. In nitrogen-limited systems, this response increases the likelihood that nitrogen will be incorporated into microbial biomass rather than remaining immediately available for crop uptake.

Finally, we conclude with a conceptual consideration. If increased OM mineralization leads to greater plant biomass, this process may partially offset losses of OM. Greater biomass production could return more residues to the soil, contributing to the OM pool in the upper soil profile. Therefore, the system may compensate for OM mineralization through the rebuilding of organic matter via plant inputs. However, the stabilization of this carbon depends on microbial processing and physical protection within the soil matrix (Cotrufo et al. 2015)

However, while the underlying logic is sound, this concept has not been extensively studied within Oklahoma cropping systems. This blog does not address the impact of sugar applications on residue breakdown, and the potential impact of such. Future research through the Precision Nutrient Management Program will further investigate the mineralization process to better understand carbon dynamics within these systems.

Take Home:

Oklahoma production systems generally have lower residual N and high carbon residues, creating conditions conducive to N immobilization
Adding sugar increases microbial growth, creating population booms that will momentarily increase mineralization, but then immediately immobilize residual nitrogen.
Tillage can amplify the negative effects of sugar by exposing more carbon and reducing soil organic matter
Proof-of-concept work shows sugar triggered a net nitrogen immobilization in a carbon heavy environment
Proof-of-concept work also suggests that when additional nitrogen is present, sugar additions may shift the system toward net mineralization rather than immobilization.

Work Cited:

Blagodatskaya, E., & Kuzyakov, Y. (2008). Mechanisms of real and apparent priming effects. Biology and Fertility of Soils, 45, 115–131.

Brady, N. C., and R. R. Weil. “The Nature and Properties of Soils, 15th Edn (eBook).” (2017).

Cotrufo, M. F., Wallenstein, M. D., Boot, C. M., Denef, K., & Paul, E. (2013). The Microbial Efficiency-Matrix Stabilization (MEMS) framework. Global Change Biology, 19, 988–995.

Cotrufo, M. F., Soong, J. L., Horton, A. J., Campbell, E. E., Haddix, M. L., Wall, D. H., & Parton, W. J. (2015). Formation of soil organic matter via biochemical and physical pathways of litter mass loss. Nature Geoscience, 8(10), 776–779.

Dendooven, L., Verhulst, N., Luna-Guido, M., & Ceballos-Ramírez, J. M. (2006). Dynamics of inorganic nitrogen in nitrate- and glucose-amended alkaline–saline soil. Plant and Soil, 283(1–2), 321–333.

Devine, M. D., & Hall, L. M. (1990). Implications of sucrose transport mechanisms for the translocation of herbicides. Weed Science, 38(3), 299–304.

Kuzyakov, Y., & Blagodatskaya, E. (2015). Microbial hotspots and hot moments in soil: Concept & review. Soil Biology and Biochemistry, 83, 184–199.

Recous, S., Mary, B., & Faurie, G. (1990). Microbial immobilization of ammonium and nitrate in cultivated soils. Soil Biology and Biochemistry, 22, 913–922.

Down and Dirty with NPK

Tag Archives: sustainability

ABOUT ME

osunpk

Follow Blog via Email

Categories

Soil Your Undies: When a Great Demo Gets Asked to Do Too Much

OSUNPK Fertilizer Market Outlook: Nitrogen Decline Pauses 9.7.26

Market Sources

OSUNPK Fertilizer Market Outlook: Local Nitrogen Prices Break Lower 8.24.26

Market Sources

Cheap Nitrogen is not always the best Nitrogen, Timing matters

OSUNPK Fertilizer Market Outlook — July 27, 2026

Market Sources

How Much Nitrogen Does Double Crop Corn Need in Oklahoma?

Bigger Isn’t Always Better: The Relationship Between Plant Size, Yield Potential, and Yield Stability in Summer Crops

Banding P for Acidic Soils: Its not the time to be paying for poor practice.

Banding P as a band-aid for soil acidity, not so cheap now.

Mechanisms of Soil Fertility: Looking at Biologicals and MOA

Take-Home Messages

The Mechanics of Soil Fertility: Use of Sugar in Field Crops

Post navigation