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Canola fertilizer rates when skip row seeding.
When drilling canola a common strategy to improve seeding rate accuracy is to only use every other row which effectively doubles the rate of seed going through each meter. There are also many producers who utilize air seeders and just prefer the wider spacing. Every season I get several questions about determining total fertilizer rates if the seed is dropped every other row but fertilizer is dropped every row. Regardless of whether or not fertilizer goes down every row it is important that the amount of salts placed with seed does not exceed the limit. The table below provide the limits in terms of lbs of salt per acre. If using 18-46-0 (DAP) or 11-52-0 (MAP) this is equivalent to pounds of N per acre. However if the fertilizer you use contains potassium (K) or sulfur (S), those have to be considered. An easy rule of thumb for determining total salt level of a fertilizer is pounds of N + K + 1/2 S.
Maximum amount of salt that can be applied in furrow with canola seed. Application rate should be at or below this value.
In a scenario in which canola is seeded in skip rows but every row will get fertilizer the total amount of fertilizer can be doubled. For example on a 15″ row spacing the max salt rate is 5 lbs per acre. If you were using DAP as your starter that maximum rate to place in furrow would be 28 lbs of DAP per acre. If using a drill set of 7.5″ spacing and putting fertilizer down every row the max rate would increase up to 56 lbs DAP per acre.
Seed, colored blue, is placed in every other row while an equal amount of fertilizer, dark grey circles, is placed in every row.
Some producers may have the capability of applying different rate in every other row. In this scenario it is important to maintain that safe rate in the seed furrow. In the opposite row, fertilizer rate can go as high as you wish or the equipment can handle.
Seed, colored blue, is placed in every other row while fertilizer, dark grey circles, is placed in every row. In this scenario a high rate is placed in the row without seed.
Now the big question is, “Is between row fertilization a good idea?” While we do not have results on this style of application (trials will be going out this year) we can draw upon upon similar work in other crops. For me the best win would be the second scenario in which a higher rate could be place between the rows. In this row I would use a urea and DAP blend. Any time we can put urea below the soil surface its a win and in fields with very soil soil test phosphorus (P) it would create something similar to the deep P bands once popular in corn production. Now if the field had adequate soil test P, I would focus on urea between rows. Keep in mind it is never a good to place urea in furrow with canola seed. For the average producer who is using a box drill the first scenario is the only option. In this case the rate of the between row bands will be reduced however I still believe on fields with very low soil test P this is potentially a great way to get the rest of it on. Remember if on 15″ and using DAP max rate only gets 12.9 lbs of P2O5 down. If fertilizer is dropped down every tube that number increases to about 26 lbs P2O5, which is still not enough for fields with low soil test P, but is better. With hope we will have some good results to share from the 2015-2016 canola crop.
Phosphorus fertilizer recommendations based upon Mehlich 3 P test, reported as STP index (ppm * 2)
Canola Planting Considerations.
Pre- and Early-Season Weed Management-
Dr. Angela Post- Small Grains Extension Weed Scientist
Winter canola is an excellent rotational partner with wheat. Integrating canola into a wheat system allows for the cleanup of weedy fields with primarily grassy weed problems. Conventional and Roundup Ready (RR) varieties are excellent choices for managing most grassy weeds including ALS-resistant populations, because grass-only herbicide options can be used in canola without crop injury. For specific grasses that are very difficult to control, like cereal rye and jointed goatgrass, it is advisable to use canola in year one of your rotation and Clearfield wheat in the second year of your rotation before going back to conventional wheat varieties. Due to sensitivity of canola, Clearfield wheat varieties should not be used the year prior to rotating into canola.
Canola planting time is just around the corner and many are going out now with preplant burndown applications. Remember that canola is sensitive to dicamba, 2,4-D, and MCPA and these products should not be used inside of 30 days before planting. Glyphosate, glufosinate and paraquat are all potential options for removing broadleaf weeds in no-till systems prior to planting. These products have no planting restriction for canola. Tillage is the best option to remove weeds in conventionally tilled systems.
It is important to consider your previous herbicide choices when planning for canola in the fall. Many herbicides used for spring weed control in wheat can limit rotation to winter canola. These include all Group 2 herbicides all of which have long rotation restrictions to canola, meaning you cannot plant canola in these fields for 18-24 months depending on the product. See Table 1 for a list of specific restrictions. If you have used one of these products in wheat in the spring, you must plant a canola variety with the SURT trait. Examples of varieties with this trait include: DKW 45-25, DKW 46-15, DKW 47-15, HyClass 115W, HyClass 125W. All of these varieties are also RR. Kansas State also has an open-pollinated non-RR variety called Sumner with the SURT trait for growers that prefer to grow conventional canola. Note that the SURT trait is not a genetically modified trait.
No additional in-season herbicide options have been added to the toolbox for winter canola growers in the upcoming season. Both trifluralin (Treflan) and ethalfluralin (Sonolan) can still be used as preemergent weed control options in canola in conventionally tilled systems. Both need to be mechanically worked into the ground and need an activating rainfall to work properly. Quizalofop (Assure II), sethoxydim (Poast), and clethodim (Select and many generics) are the grass control herbicides available for use in canola and can be used on any canola variety including RR varieties. Roundup Ready canola growers are allowed two applications of glyphosate at 22 oz/A each over the top of the emerged crop. Clopyralid (Stinger) is the only over-the-top broadleaf control option other than glyphosate. These weed control applications should be made early in the season between 2- and 6-leaf canola, and prior to bud formation, while weeds are still very small. Applications should be spaced at least 14 days apart. Early applications will eliminate fall weed competition with canola and protect yield. For more information or questions involving weed management in canola contact Extension Weed Specialist Angela Post at 405-744-9588 and follow @OSUWeedScience.
Table 1. Rotation restrictions for planting canola following wheat. For herbicides
applied in crops other than wheat please refer to the herbicide label.
1Minimum interval between herbicide application and seeding canola. Refer to full herbicide labels for specific information as geography, pH, and rainfall may affect this interval.
2Rotation restriction can be overcome with use of a SURT canola variety.
3Rotation intervals depend on geography.
4Rotation interval depends on herbicide rate.
Pre plant fertilizer concerns with Canola
Dr. Brian Arnall- Precision Nutrient Managment Extension Specialist
When it comes to pre-plant fertility issues with canola, I typically have two soap boxes. But at this point in the canola game we are behind in terms of getting soil samples collected or applying lime and getting a boost at emergence. So assuming pH is good and you know what your soil nutrient level is we can move on to planting. One thing that over the past seven or eight years keeps coming up is the importance of starter fertilizers and the rates and sources used. Getting that little canola plant off to a good start is extremely important however with that little bitty seed a little goes a long way.
The figure below shows the impact of DAP (18-46-0) placed in row, on relative canola stands, when canola was planted in 15” rows. At 5 lbs/A of N or 28 lbs/A of DAP, the canola stand is reduced to 75%. While this seems like a great loss, the compensating nature of canola and the fairly high seeding rates used, this is a manageable level. The benefits of the additional nitrogen and phosphorus applied with the seed also help out-weigh the loss of stand. The addition of the P near the germinating seed is vital. The phosphorus aids in early root and shoot growth, helping the crop to get off to a good start. In areas where soil pH is of concern the P near the young seedling will reduce aluminum toxicity and allow the plant to tolerate the low pH. Keep in mind, while banding P will help in acidic soils, canola is still very sensitive and will not tolerate the same low pH conditions as our winter wheat’s.
Impact of DAP (18-46-0) placed in-row on canola stand in terms of lbs N ac-1.
One very important factor to keep in mind is the impact of the critical rate and row spacing. The 5 lbs of N per acre critical level set for 15” row spacing is increased to 10 lbs on 7.5’s and cut to 2.5 lbs on 30’s. The change in rate is because we use lbs per acre. So if you apply the same amount of material per acre on a 15” spacing and a 30” spacing there is actually twice as much material in the 30” row. Table 1, shows the equivalent amount of N placed in row for popular row spacing’s.
Equivalent amount of N based on 15″ row spacing.
Oklahoma State has released a smart phone app, available for both apple and android devices, to aid in determining maximum in-furrow rates. Canola Starter app provides guidelines based upon the nutrient concentrations of the fertilizers you plan to use. The final note on in-furrow fertilizer with Canola, avoid using urea. The likelihood of injury from the urea converting to ammonia greatly outweighs any potential benefits. For further information, comments, or questions please contact Dr. Brian Arnall Extension Precision Nutrient Specialist 405-744-1722 or following me on Twitter @OSU_NPK.
Canola Starter available on iOS and Android. For more information see http://www.dasnr.okstate.edu/apps.
Winter canola planting decisions:
Josh Lofton- Cropping Systems Specialist
Josh Bushong- Extension Associate
Stand establishment is one of the most critical practices in canola planting. This is not only because these stands are highly influential to end of the season yields but because getting the crop up with adequate growth will be critical to give the plants the best over-winter survivability possible. To accomplish this, growers need to make sure they make good field selection and follow good planting practices
Field Selection:
Soil nutrients are a critical aspect. Soil samples should be collected on a regular basis to ensure optimum productivity. Also, ensure recommendations for winter canola are followed, as nutrient recommendations for other crops may be invalid. For more information canola fertilizer management refer to the nutrient management section by Dr. Arnall.
Winter canola grows similar to winter wheat. Fields that can adequately produce wheat have the potential to produce canola. These include, well-drained soils with adequate soil nutrients. However, canola can be more sensitive than wheat. One aspect that canola can be more sensitive to is soil pH. While wheat can be grown in soils as low as 5.5 without significant yield loss, canola must be grown on soils with pHs above 5.8. In fact, canola is best grown in soils with soil pHs ranging from 6.0 to 7.0. Therefore, it is essential that if fields have lower pH, lime be applied with adequate time to neutralize the acidic soil pH before rotating into canola.
In addition to all the soil conditions, crop rotation should be considered prior to planting canola. One of the major hindrances in growing canola in rotation with other crops is herbicide carry-over. For detailed information regarding this aspect, refer to table 1 in the weed management section. To account for this, detailed field records should be kept and consulted before rotating with canola.
Planting Date:
Planting time depends on many aspects. Insured growers should plant within the constrained planting dates. For Oklahoma, the earliest planting date is September 10th with the latest date being October 10th. However, within these guidelines, seedbed and environmental conditions should be the driving factor to determine when to plant. The goal of these planting dates is to have the crop germinate, emerge, and establish 6-8 true leaves prior to the first killing freeze. As a general rule, the crop should be planted 4 to 6 weeks before this freeze. To achieve good establishment of the crop, canola should be planted into firm seedbed with adequate soil moisture. If canola is planted into dry soil (dusted in), the effective planting date will be delayed until adequate conditions for germination and emergence exist. In no-till systems, it is important to remember that canola emergence and growth will be slightly delayed. Therefore, if adequate conditions exist, no-till fields should be planted before similar conventionally tilled fields.
Uneven canola emergence. Canola on left emerged later and did not
have enough time to put on adequate growth (Photo courtesy of Josh
Bushong)
Planting depth, plant spacing, and seeding rate:
Since canola is a small seeded crop, shallow planting is required. For best germination and emergence, seeds should be planted between 0.5 and 1 inch. If adequate moisture is available deeper, planting depth can be increased. However, deeper planting has the potential to decrease germination, percent emergence, and early fall growth, so deeper planting should only be used when the planting condition advantage is present and only on certain soils. Therefore, caution should be used in planting deeper than 1 inch. Furthermore, even though moisture may be present deeper, seeds should not be planted deeper than 1.5 inches.
Oklahoma growers have options when deciding row spacing used for planting canola and depend on what equipment there is available and their production system. Since canola is typically rotated within a winter wheat production system, box drills and air seeders are typically widely available. Row-spacing for these can range from 6 to 15 inches. Row spacing within this range has little impact on final yields. As producers move from drills and air seeders to planters, row spacing typically increases from 15 up to 30 inches. All of the row-widths have the potential to produce adequate canola. Some, however, will be more beneficial than others. Narrow row spacing has the potential to result in early canopy closure, reduce potential weed competition, and may help reduce shatter prior to harvest (especially when direct harvested). Wider spacing, however, allows for some flexibility in specialized planter attachments used, especially row-cleaners, which can be greatly beneficial in no-till systems.
Seeding rates for canola in Oklahoma range from 1 to 5 lbs/A. However, row spacing plays a critical role on seeding rates. When canola is planted on less than 15 inch spacing, some flexibility exists for planting rates. Higher seeding rates can produce more uniform stands, uniform maturity, and thinner stalks that can greatly help harvest efficiency. Too high of stands can increase disease incidence, winterkill, and lodging. When row spacing is increased beyond 15 inches, care should be taken not to over seed. High seed populations can increase fall growth and potentially increase hypocotyl height, which in turn can lead to high winterkill. Optimum populations for this wider row spacing typically range from 2 to 3 lbs/A.
For further information, comments, or questions please contact Josh Lofton Extension Cropping Systems Specialist at 405-744-3389 or follow me on Twitter @OSU_oilseeds.
While producers have faced many challenges over the last couple of seasons in Oklahoma agriculture, the outlook for winter canola looks very promising for the upcoming season. Producers should focus on taking all of the right steps to ensure the 2015-2016 crop starts on the right foot and takes full advantage of the promising conditions this season. Good luck to everyone one on their upcoming production season and if anyone from Oklahoma State extension can help or assist in any way, please feel free to contact.
Some thoughts on pre-plant nitrogen and a little outside the box thinking
It is that time of year, every Co-op I drove by the other day had a line of trucks pulling anhydrous tanks and the spinner spreaders were being loaded. For those of you who haven’t applied your nitrogen yet lets discuss the options traditional and nontraditional.
Anhydrous Ammonia, 82-0-0: by far the most widely used N source is the southern Great Plains. While it is not the most enjoyable to work with it is the cheapest per pound of N and that leads to its wide spread use without Oklahoma wheat production. Just a few simple rules with NH3, get it in the ground and close the row behind you. In conventional till this is usually easier unless the ground is too wet or too dry. In no-till this may be a little more challenging but usually easily accomplished. With the rise in low disturbance applicators I am seeing more and more acres of no-till receiving NH3. Last year I was in a field of stripper stubble and I had a hard time finding where the rig had run, minus wheel tracks.
Urea, 46-0-0: is second on the hit list in nitrogen sales in our state. It is a safe source that is easily handled and applied. In a conventional till system where the urea can be worked in shortly after application it is a very efficient and effective source. Unfortunately when it is applied to the soil surface and rain is the method of incorporation we can experience between 5-60% N losses. The losses come from how urea is converted to plant available ammonium (NH4). For urea (NH2)2CO2, to be converted to plant available NH4 it needs the enzyme urease. Urease is present everywhere but in the highest concentrations on plant residue. The figure below shows the reaction, urease converts urea into NH3 as soon as the prill dissolves. In the presence of moisture the NH3 (gas) is turned immediately to NH4 (solid) and is absorbed onto the soil particle.
Graphic of Urea’s conversion to plant available ammonium.
The problems come when there is no soil particle for the NH4 to bind with. It usually takes 0.50 inches of rain or irrigation to fully dissolve and incorporate urea into the soil. So if we only get a few tenths or hundredths, even heavy dews, some of the urea will dissolve, be converted to NH3 then NH4 and be left on the plant/residue. When the moisture dries, some or all of the NH4 goes back to NH3 and will gas off into the atmosphere. I have even seen this happen when urea is applied on a wet/damp soil, not incorporated and it doesn’t rain for significant period of time. If the temps are cooler the urease is slower so less of the urea is converted to NH4, but if the temps are warm 60+ degrees these little enzymes can act very quickly.
Urea placed on the surface of a wet soil under two temperature regimes. White text is the number of hours after application.
Urea placed on dry soil, Top row: dry soil no water added, Bottom left, moisture added from subsurface, Bottom right : simulated rain fall event of 1/2″. White text is the number of hours after application.
Below is a short video on using urea fertilizer.
While the recent rains are a blessing and will surely help germination, it is not aiding our N use efficiency especially in no-till. That is why in some parts of the state you may see some grain drills running right now. Some of those producers are not planting wheat they are actually applying there pre-plant urea. I have even been told in the SW part of the start some producers are using air-seeders to apply their urea. While this seems like a costly venture I have worked with the Ag Economist to create a calculator to figure up the break even for when it would pay to use an air-seeder over the traditional spinner spreader in no-till. We hope to put the finishing touches on it in the next few days. When it is completed it will be shared on this blog.
Liquid Urea Ammonium Nitrate, 32-0-0 or 28-0-0: while this is one of the more expensive forms of N many producers are utilizing this source because the can pre buy and store on site and as sprayer get larger they can cover a significant amount of ground quickly. For the most part UAN is used in no-till and is a great source. I always recommend that applicators use streamer nozzle or streamer bars to apply UAN. When UAN is applied via a flat fan nozzle it spreads the fertilizer across the residue allowing a significant portion to be tied up. The streamers concentrate the fertilizer into streams/bands reducing contact with residue and increasing the amount of UAN that reaches the soil surface.
Timing and Rates
The cost of anhydrous, about $0.1 to 0.12 less per pound N less than urea is driving its use this year. The lower price is also driving a significant about of producers to go with 100% of their N pre-plant. While this makes for sound economics now having all of your N upfront is like putting all of your eggs in one basket. If we do get that cold and wet winter as some are calling for this presents a great chance for the N to move down the soil profile and down the slope. I have always recommended split application. This allows a producer to judge the crop throughout fall, winter and even yearly spring and adjust his or her N plan accordingly. For those who plan to graze there is still a need to get enough N down to produce fall forage, this may be 50 to 80 lbs of N, but for grain only production planted later in the fall a typical crop may only need 20-30 lbs of N before going into winter. The old rules of thumb, 2 lbs N per bushel and 30 lbs N per 100 lbs of gain still work and are better than a guestimate but we have better ways. Right now is the time to plan to apply N-rich strip, a strip in the field with 40 to 50 lbs more than the rest of the field. These strips can be applied with a variety of applicators, but as long as the N goes down in at least an area 10 ft wide by 300 ft long it is good to go.
Just a few of the applicators used for putting out N-Rich Strips. ATV Sprayer, Receiver Hitch mounted Sprayer, Road sprayer with a rear boom, pull type spinner, large sprayer, push spreader. Not shown is NH3 applicator.
Below is a N-Rich Strip 101 video.
If you have got the N-Rich strips out you can set back and watch to see when and if they develop. If you can see the strip you know you need too fertilize.
While many are not ready to think about top-dressing yet, it is never too early. Don’t be afraid to think outside the box. Oklahoma’s springs tend to present the perfect conditions for N loss when urea is the primary N source. This year in a 4R Top-dress Nitrogen Application Demo, at Lahoma and Chickasha, we are going to apply just about every available commercial source in about every possible manor. Urea will be broadcast, coated with inhibitors, applied with a grain drill, NH3 will be knifed in, and UAN will be applied with flat fan nozzles, streamer nozzles and knifed in. As technologies improve and the cost of N remains relatively high the options for top-dress N application will continue to improve. The economics of wheat production don’t look great right now so don’t be afraid to think outside the box, even if it does raise the eyebrows of your neighbors. Fill free to contact myself or your local extension educator if you have any questions about N application.
John Deere double disk drill used to apply urea in-season.
WAKO NH3 applicator used for in-season application.
Time to start topdressing wheat
My favorite part of the blog “Don’t have an N-Rich Strip? It’d be a lot cooler if you did.”
There are few crop inputs that deliver as much return on investment as nitrogen fertilizer. It takes approximately two pounds of nitrogen, costing approximately $1.00, to produce one bushel of grain worth about $5.00. Of course, nitrogen is not the only yield determining factor in a wheat crop. Also, the law of diminishing marginal returns eventually kicks in, but nitrogen fertilizer is still one of the safest bets in the house.
Top dress nitrogen fertilizer is especially important because it is applied and utilized at a time when the plant is transitioning from vegetative to reproductive growth. Several things, including the number of potential grain sites, are determined just prior to jointing and it is imperative that the plant has the fuel it needs to complete these tasks. Jointing also marks the beginning of rapid nitrogen uptake by the plant which is used to build new leaves, stem, and the…
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How to make $100,000 in a day
This is a familiar soap box. SOIL SAMPLE, SOIL SAMPLE, SOIL SAMPLE.
No, this blog post is not about a get rich quick scheme, but there is a way for the average wheat farmer in the southern Great Plains to add $50,000 to $100,000 to the bottom line in a single day. Most soil tests I have pulled this summer have shown 50 to 90 lb/ac of NO3-N in the top 18 inches of soil. Ninety pounds of N equates to about $45 of N fertilizer, and this knowledge could save a 2,500 acre wheat farmer in excess of $100,000 in fertilizer cost. Soil testing is laborious, but the potential economic returns for spending a day or two soil sampling are outstanding.
There is still time to soil sample. Soil samples only take a few days to process once they are in the OSU lab. It is not unusual for transit time to the lab to the slowest part of the process…
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Nutrient Products: Stabilizers, Enhancers, Safeners, Biologicals and so on.
In this blog I am not going to tell you what to use or what not to use. In fact I will not mention a single product name. What I will do is hopefully provide some food for thought, new knowledge and direction.
First I want to approach a topic I have been called out on several times. I believe there is a stigma that University researchers and extension specialists do not want products to work. It may seem that way at times but it is far from the truth. The reality is that all of us are scientists and know someone may be inventing the product that changes nutrient management as we speak. The issue is that most of us have been jaded. While I may be younger I have over 11 years experience, testing “products” in the field, and that includes dozens of products. I have sprayed, spread, tossed, drilled, mixed and applied everything under the sun, with hopes that I will see that one thing I am always looking for, MORE GRAIN…
The truth is Everything works Sometimes yet Nothing works ALL the time. I and others in my profession do not expect anything to work 100% of the time, I am personally looking for something that will provide a checkmark in the win column 50% of the time. A win is the result of one of two things, more money in the producers pocket or less nutrients in the water or air. Products can increase vigor, nutrient uptake, chlorophyll concentration, greenness but not yield. What Co-op or elevator pays for any of those attributes? Grain makes green.
So many safeners, stabilizers, enhancers, biologicals, and on and on are available, so what should a producer do? Here are few things to think about. Ask yourself “ what part of my nutrient management plan can I get the most bang from improving”?
If the answer is Nitrogen (N) there are three basic categories: Urease inhibition, Nitrification inhibitor, and slow release. All are methods of preventing loss; the last two are preventing loss from water movement.
Urease inhibitors prevent the conversion of Urea to NH3 (ammonia). This conversion is typically a good thing, unless it happens out in the open. Ideally any urea containing product is incorporated with tillage or rain. However, in No-till when urea is broadcast and no significant rainfall events (>0.5”) occur, N loss is likely. The urea prill starts dissolving in the presence of moisture, this can be a light rain or dew, and urease starts converting urea into NH3. As the system dries and the day warms, if there was not enough moisture to move the NH3 into the soil the wind will drive NH3 into the atmosphere. Nitrogen loss via this pathway can range from 5% to 40% of the total N applied.
Graphic of Urea’s conversion to plant available ammonium.
Urea placed on a wet soil under two different temperatures. Number in white is hours after application.
Urea placed on a dry soil, on top no water added, bottom left is moisture from the subsurface, and bottom right is simulated rain fall of 1/2″. Number in white is hours after application.
Nitrification inhibitors prevent the conversion of NH4 into NO3. Both are plant available N sources but NH4 is a positively charged compound that will form a bound with the negatively charged soil particles. Nitrate (NO3) is negatively charged and will flow with the water, in corn country that tends to be right down the tile drainage. Nitrate will also be converted to gasses under wet water logged soil conditions. Nitrate is lost in the presence of water, this means I do not typically recommend nitrification inhibitors for western OK, KS, TX dryland wheat producers.
Slow release N (SRN) comes in a range of forms: coated, long chain polymer, organic and many versions in each category. Again, water is the reason for the use of SRN sources. Slow release N whether coated or other have specific release patterns which are controlled by moisture, temperature and sometimes microbes. The release patterns of SRNS are not the same and may not work across crops and landscapes. For instance in Oklahoma the uptake pattern of nutrients for dryland corn in the North East is not that same as irrigated corn in the West. The little nuances in the growth pattern of a crop can make or break your SRN.
While N products have been on the market for decade’s phosphorus enhancers and stabilizers are relatively new, resulting in many of my peers holding back on providing recommendations until field trials could be conducted. At this point many of us do have a better understanding of what’s available and are able to provide our regional recommendations. Phosphorus products are not sold to prevent loss like their N counterparts; they are sold to make the applied P more available. On a scale of 1 to 10, P reactivity with other elements in the soil is a 9.9. If there is available Ca, Mg, Fe, or Al, phosphorus is reacting with it. In the southern Great Plains it is not uncommon for a soil to have 3,000-5,000 lbs of available Ca, a soil with a pH of 4, yes we have many of those, will have approximately 64,000 lbs of Al in the soil solution. That’s a lot of competition for your fertilizer P and for any substance that is trying to protect it.
I have been testing “biologicals” of all shapes and forms since 2003. While I have not hit any homeruns I have learned quite a bit. Many of these products originate from up north where the weather is kind and organic matter (OM) is high. Where I work the average OM is 0.75% and soil temp is brutal and unforgiving. Our soil does not have many reserves to release nor is it hospitable to foreign bodies.
Soil temperature for Stillwater OK under sod and bare soil conditions. Graph from http://www.Mesonet.org.
I hope you are still hanging on as this next topic is a bit of a soap box for me. Rate, Rate, Rate this aspect is missed both by producers and academia and it drives me crazy. If your crop is sufficient in any growth factor adding more will not increase yield. It goes back to Von Liebig’s LAW of the Minimum. I see too many research studies in which products are tested at optimum fertilization levels. This is just not a fair comparison. On the other hand, time and again I see producers sold on a product because they applied 30% less N or P and cut the same yield. If you let me hand pick 100 farms in Oklahoma I could reduce the N rate by 30% of the average and not lose a bushel on 75 of the farms. Why? Because the rate being used was above optimum in the first place, there is no magic just good agronomy. The list of products that increase the availability of nutrients is a mile long. Increasing nutrient availability is all well and good if you have a deficiency of one of those nutrients. If you don’t, well you have increased the availability of something you did not need in the first place.
University researchers and extension professionals seem to live and die by the statistics, and are told so regularly. We do rely upon the significant differences, LSD’s, and etc to help us understand the likely hood of a treatment causing an effect. However if I see a trend develop, or not develop, over time and landscape regardless of stats I will have no problem making recommendations. The stats help me when I do not have enough information (replications).
Too wrap up, have a goal. Do not just buy a product because of advertised promises or because a friend sells it. There is a right time and place for most of the things out there, but you need to know what that is and if it suits your needs. I also recommend turning to your local Extension office. We do our best to provide unbiased information in hopes of making your operation as sustainable as possible. If you are looking at making sizable investments do some reading, more than just Google. Testimonies are great but should but should not be enough to cut a check. Google Scholar www.google.com/scholar is a good resource for scientific pubs. I have done my best to put together a list of peer reviewed publications and their outcomes. To make the review work I had to be very general about outcome of the research. Either the product increased yield or decreased environmental losses or it had no impact. This was not easy as many of the papers summarize multiple studies. I did my best to make an unbiased recommendation but some could be argued. http://npk.okstate.edu/Trials/products/Product_Peer_Review.8-21-2014.pdf
Banding P as a Band-Aid for low-pH soils.
In the mid-1970s Dr. Robert Westerman banded 18-46-0 with wheat at planting in a low-pH soil near Haskel Ok. The impact was immediately evident. Soon after Oklahoma State University recommended the “Banding of Phosphate in Wheat: A Temporary Alternative to Liming” Figure 1. This method was a Band-Aid solution for the significant amount Oklahoma winter wheat production area which was either too far from a reliable lime source or under a short term lease contract.
Figure 1. The cover of an extension brochure distributed in Oklahoma during the 1980s.
Still today grain producers throughout the United States commonly farm a large percentage of land that is not their own. In the leasing process agreements can widely vary both on length of the lease and the amount of inputs that the land owner will pay. The wheat belt of Oklahoma is known for having large areas with low soil pH levels. A survey of soil samples submitted to the Oklahoma State University Soil, Water, and Forage Analytical Laboratory in 2011 under the winter wheat crop code showed 38% of the samples having a soil pH level below 5.5 (Figure 2). In Oklahoma short term leases with limited shared expenses have limited the access to agricultural lime for remediation of acidic soils. In the dry environment it may take up to one year before the lime applied has completely corrected the soil acidity problem. In a situation where the lease agreement is only for one to two years there may be no economic benefit for the producer to apply lime especially in regions where winter wheat average yields range from 20 to 40 bushel per acre. The current recommendation for winter wheat producers working on low-pH short term lease ground is to apply 30 lbs P2O5 ac-1 ( 65 lbs 18-46-0 ac-1) with the seed for grain only wheat and 60 lbs P2O5 ac-1 (130 lbs 18-46-0 ac-1) for dual-purpose wheat production. This recommendation however is for soils with adequate soil test P, but low soil pH. When soil test P is below optimum the 30 or 60 units is applied in addition to the amount needed to reach 100% sufficiency.
Banding P is considered a “Band-Aid” as the problem of soil acidity is not re-mediated it is only masked. If not addressed the pH of the soil will continue to fall over time. Aluminum and manganese toxicity is the greatest issue associated with soil acidity. Available aluminum, a predominant mineral in the regions soils, is pH dependent. A change of 1.0 pH level changes available Al by 1000 fold. For example a soil with a pH of 5.0 will have an approximate Al concentration of 27 ppm, critical level of winter wheat is 27 ppm, while a soil with a pH of 4.0 will have an Al concentration of approximately 27,000 ppm. Aluminum and manganese toxicity does not only impact grain yield but it has an even greater impact on biomass production. Kariuki et al (2007) recorded the impact of soil acidity on eight current winter wheat lines. Correcting soil acidity increased wheat grain yield by 82% and increased forage production by 150%. For Oklahoma the forage produced by the wheat crop is as important as the grain. Oklahoma is unique in that approximately 50% of the four million acres of winter wheat are grazed annually much of this under the dual –purpose “Graze-N-Grain” management. To maintain productivity on the land without the long term investment of Ag lime producers have been applying phosphorus fertilizer to alleviate the impact of aluminum toxicity.
Figure 2. Summary of the soil pH values for the 614 samples submitted to the Oklahoma State University Soil, Water, Forage, Analytical Laboratory under wheat crop code during the time frame of 1-1-2011 11-30-2011.
In 1992 Boman et al reported that impact banding phosphates with seed on winter wheat forage production (Figure 3). Across the four locations the addition of P increase yield from 2 to 4 fold. The work by Kaitibie et al (2002) documented an additional aspect of banding P. In the variable and often arid climate of Oklahoma the activation of lime can take a significant amount of time, in upwards of one year. In comparison banding P has an immediate impact on the alleviation of metal toxicities. Figure 4 shows the incorporation of lime improved forage yield but not to the degree of banding P. For continuous winter wheat producers the time between application of lime and planting can be quite short. Typically the previous crop will be harvest in mid-June and in the best case scenario lime would be applied and incorporated by mid-July. At this point there is only 60 days until the next wheat crop is planted in early to mid-September.
Figure 3. The impact of banding phosphate with seed at planting in acidic soils on winter wheat forage production in Oklahoma. Chart adapted from Boman et al. 1992.
Figure 4. The impact of applying of phosphate fertilizer and lime on the forage production of two winter wheat cultivars in Oklahoma. Chart adapted from Kaitibie et al. 2002.
For many with short term leases banding P is still the only viable solution for wheat production in low-pH soils. However there is ground being farmed by the owner or is under long-term lease that is still receiving this Band-Aid approach. At the 1980-1990 fertilizer and lime prices there is good reason to continue this method. However the cost of P fertilizer has quadrupled since the 1970’s. The last ten year average price of P2O5 was $0.42 per pound while it cost an average of $0.10 in the 70s. So for those who own or are able to work out beneficial lease agreements Table 1 should be of interest. By year three the cost of phosphate exceeds the cost of lime. If you were to use the values from the 1980’s of $0.20 per pound of P2O5 and $25 per ton ECCE lime it was not until year five, the last year before reapplying lime, did the cost of P exceed cost of lime.
Table 1. Cumulative cost per acre of applying phosphorus and lime to remediate aluminum and manganese toxicity based on a five year liming cycle. The 30 lb P2O5 rate is recommended for grain only production while dual-purpose wheat require 60 P2O5. Prices based on current quotes of DAP at $590 a ton ($0.41 lb P2O5) and Ag lime at $30 per ton ECCE.
As the 2014 winter wheat and canola crop is being transported to the bins it is extremely important to take advantage of this time to take soil samples from as many fields as possible. Soil pH issues must be understood and addressed. I often remind producers soil pH plays an exception number of roles. Not only does it impact yield as shown before but it impacts rooting (ability to survive stresses), nutrient availability, and herbicide activity. Our SU herbicides (Finesse, Powerflex, and Maverick) that are used widely across the state are negatively impacted by low soil pH. Figure 5 shows how at a pH of 5.6 Glean is down to a 50% concentration in the soil approximately two weeks after application. So when it comes time to make the call for phosphorus or lime try to weigh all of these aspects, at current prices P is not that much cheaper, improving pH will improve yield and potentially improve weed control.
Figure 5. The concentration of Glean (Cholorsulfuron) remaining in too soils (pH 7.5 and pH 5.6) over a twelve week period.
Citations
Boman,R.K., R.L. Westerman, G.V. Johnson, and M.E. Jojola. 1992. Phosphorus fertilization effects on winter wheat production in acid soils. In Soil Fertility Highlights, Agronomy Department Oklahoma Agricultural Experiment Station, Oklahoma State University.Agronomy 92-1 pg171-174
Kaitibie,S., F. M. Epplin, E.G. Krenzer, and H. Zhang. 2002. Economics of lime and phosphorus application for dual-purpose wheat production in low-pH soils. Agron. J. 94:1139:1145.
Kariuki, S.K., H. Zhang, J.L. Schroder, J. Edwards, M. Payton, B.F. Carver, W.R. Raun, and E.G. Krenzer. 2007. Hard red winter wheat cultivar responses to a pH and aluminum concentration gradient. Agron J. 99:88-98.
First hollow stem advisor available on Mesonet
This is a great tool. It looks like we have very little time between green-up and hollowstem.
The advisor uses a mathematical model that predicts the probability of first hollow stem based on soil heat units and wheat first hollow stem category (early, middle, or late). The model was developed by J.D. Carlson at OSU using first hollow stem data from the wheat variety testing program, and model development was made possible through a grant from the Oklahoma Wheat Commission.
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Nitrogen Rich Strips
The Nitrogen Rich Strip, or N-Rich Strip, is a technique/tool/process that I spend a great deal of time working with and talking about. It is one of the most simplistic forms of precision agriculture a producer can adopt. The concept of the N-Rich strip is to have an area in the field that has more nitrogen (N) than the rest. Due to our fertilizer applicators this is typically a strip. The approach maybe somewhat new but at one point most producers have had N-Rich Strips in their fields, albeit accidentally. Before the days of auto-steer it was not uncommon, and honestly still is not, to see a area in the field that the fertilizer applicator either doubled up on or skipped. In our pastures and dual purpose/graze out wheat every spring we can see the tell-tale signs of livestock deposits. When over laps or “Cow Pox” become visible we can assume the rest of the field is behind in nitrogen. I like to tell producers that the goal of the N-Rich strip is to make a really big cow pie.
- Cow Pox, Image courtesy Kaitlyn Nelson
What I like most about the N-Rich Strip approach is its Simplicity. The N-Rich Strip is applied and; Scenario 1. The N-Rich Strip becomes visible (Greener) you APPLY NITROGEN, Scenario 2. The strip is not visible you Option A. DON’T APPLY NITROGEN Option B. Apply Nitrogen Anyways. The conclusion to apply N or not is based on the reasoning that the only difference between the N-Rich Strip and the area 10 ft from it is nitrogen, so if the strip is greener the rest of the field needs nitrogen. If there is no difference N is not limiting and our research shows N does not have to be applied. However producers who decide to be risk adverse (in terms of yield) can apply N but it would be advised to do so at a reduce the rate. Now is a good time to note that the N-Rich Strip alone provides a Yes or No, not rate recommendation. At OSU we use the GreenSeeker optical sensor and Sensor Based Nitrogen Rate Calculator (SBNRC) to determine the rate, but that discussion will come later. I equate the change from using yield goal N rate recs to the N-Rich Strip as to going from foam markers to light bars on a sprayer. Not 100% accurate but a great improvement.
N-Rich Strip in no-till wheat near Hobart OK.
Now that we have covered the WHY, lets get down to the nuts and bolts HOW, WHEN, WHERE.
How the strip is applied has more to do with convenience and availability than anything else but there are a few criteria I suggest be met. The strip should be at least 10 ft wide and 300 ft long. The rate should be no less than 50 lbs N (above the rest of the field) for grain only wheat and canola, 80 lbs N for dual purpose wheat. The normal recommendation is that when applying pre-plant either have a second, higher rate programmed into the applicator or make a second pass over an area already fertilized. Many will choose to rent a pull type spreader with urea for a day, hitting each field.
Becoming more popular are applicators made or adapted for use. ATV sprayers are the most common as they can be multi-purpose. In most cases a 20-25 gallon tank with a 1 gpm pump is placed on the ATV with an 8-10ft breakover boom. The third applicator is a ride away sprayer with a boom running along the rear of the trailer. In all cases when liquid is the source I recommend some form of streamer nozzle. In most cases there is not a great deal of thought put into what source. I recommend whichever source is the easiest, cheapest, and most convenient to apply.
Vincent N-Rich Strip Applicator, Ponca City OK
Oklahoma State Univ. N-Rich Strip Applicator
Gard N-Rich Strip Applicator, Fairview Ok
When the strip is applied in winter crops proper timing is regionally dependent. For the Central Great Plains, ideally the fertilizer should be applied pre-plant or soon after. However, in most cases as long as the fertilizer is down by the first of November everything works. This does not say a strip applied after this time doesn’t work but it leaves more room for error. There is a chance the crop could already be stressed or the nitrogen tied up and not release in time. However when the N-Rich Strip approach is used on the Eastern Shore in Virginia and Maryland the strips have to be applied at green up. The soils in that region are very deep sands and nitrogen applied in the fall may not make it to the spring. Also most wheat producers in the area make three or more applications of nitrogen unlike the two (pre and top) of the Great Plains. It is always important to make the tools fit your specific regional needs and practices and not the other way around.
Where is actually the biggest unknown. The basic answer is to place the N-Rich Strip in the area that best represents the field. Many people question this as it doesn’t account for spacial variability in the field, and they are correct. But my response is that in this case spatial variability is not the goal, temporal variability is. Keeping in mind the goal is to take a field which has been receiving a flat yield goal recommendation for the last 30+ years and make a better flat rate recommendation. My typically request is that on a field with significant variability either apply a strip long enough to cross the zones or apply smaller strips in each significant area. This allows for in-season decisions. I have seen some make the choice to ignore the variability in the field, made evident by the strip, and apply one rate and others choose the address the variability by applying two or more rates. One key to the placement of N-Rich Strips is record keeping. Either via notes or GPS, record the location of every strip. This allows for the strips to be easily located at non-response sites. It is also recommended to move the strip each year to avoid overloading the area with N.
I hear a great deal of talk about how it would take to much time to put out the N-Rich Strip. However the majority of producers that do it once on one field, end up doing it every year on every field. There is very likely someone in your area who is using the N-Rich Strips. As top-dress grows closer keep an eye out for a blog “Using the GreenSeeker Sensor and Sensor Based Nitrogen Rate Calculator”.
For more information on N-Rich Strips check out the YouTube video below, visit http://www.npk.okstate.edu or contact me directly at b.arnall@okstate.edu. I have lots of material I am happy to share and distribute.
See the YouTube Video http://www.youtube.com/watch?v=kJ3DSwWYgE8
Down and Dirty with NPK 