ABOUT ME

osunpk

osunpk

Since 2008 I have served as the Precision Nutrient Management Extension Specialist for Oklahoma State University. I work in Wheat, Corn, Sorghum, Cotton, Soybean, Canola, Sweet Sorghum, Sesame, Pasture/Hay. My work focuses on providing information and tools to producers that will lead to improved nutrient management practices and increased profitability of Oklahoma production agriculture

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Recent Weather Causing Corn (and Sorghum) Injury From Pre-emerge Herbicides

While this is not about fertility in the southern Great Plains I feel it is a very important topic.  I will not be surprised if we don’t start seeing this in some of the corn and sorghum that was just planted before the rains. I would also add the over the years I often see bleaching in sorghum, that looks similar to zinc and/or iron deficiency, caused by atrazine injury.  This typically occurs when atrazine is applied prior to a heavy rain. The atrazine is washed down slope and into the rows, the injury is almost always seen in low lying areas.  The crop usually grows out of it.

Atrazine injury in sorghum. Heavy rains followed application.  Pic via Rick Kochenower.

Atrazine injury in sorghum. Heavy rains followed application. Pic via Rick Kochenower.

Brian A.

This article is written by Mr. Cody Daft, Field Agronomist Western Business Unit, Pioneer Hi-Bred

Have you noticed any corn leafing out underground prior to emergence? Have you seen tightly rolled leaves or plants that can’t seem to unfurl leaves and look buggy whipped? Almost all of the fields I have looked at recently have shown these symptoms in at least a portion of the field, and some fields this has been very widespread. The common denominator in all the fields I have viewed has been the herbicides applied were a metolachlor (Dual/Cinch type products) and the weather (cooler than normal, wetter than normal). Similar issues can be noted in grain sorghum to some extent.

The recent wet weather and water-logged soils have increased the possibility of corn injury from many popular soil applied herbicides. Corn growing in wet soils is not able to metabolize (degrade) herbicides as rapidly as corn growing in drier conditions. Plant absorption of herbicides occurs by diffusion. What this means is that the herbicide diffuses from locations of high concentration (application site on the soil) to low concentration (plant roots). The diffusion process continues regardless of how rapidly the corn is growing. In corn that is not growing rapidly (cool, wet conditions) corn plants can take up doses of herbicide high enough to show damage and a few differences in symptomology.

The unfortunate aspect of wet soil conditions is that additional stress is put on the plant not only to metabolize herbicide residues, but also to ward off diseases and insects. These additional stresses can impact a corn plant’s ability to metabolize herbicide.

The most common type of herbicide injury observed under these conditions is associated with chloroacetamide herbicides. These herbicides are used for control of grass and small seeded broadleaf weeds, and are seedling root and shoot inhibitors.

These products include the soil-applied grass herbicides such as:

  • Dual/Cinch/Medal II
  • Degree/Harness
  • Microtech/Lasso
  • Frontier/Outlook
  • Define/Axiom
  • And other atrazine premixes like Lumax (a premix of mesotrione (Callisto), s-metolachlor (Dual II Magnum), atrazine and a safener benoxacor).

What About The Injury Symptoms?

Before corn emergence:

  • Stunting of shoots that result in abnormal seedlings that do not emerge from soil.
  • Corkscrewing symptoms similar to cold/chilling injury.
  • Corn plants and grassy weeds may leaf out underground and leaves may not properly unfurl.

After corn emergence:

  • Buggy whipping – leaves may not unfurl properly.
buggy-whipping syndrom

Figure . Buggy-whipping symptom from carryover of PPO herbicides to corn.via https://www.pioneer.com/home/site/us/agronomy/library/herbicide-carryover/

 

 

What About Safeners?
Products like DUAL II Magnum herbicide contain the safener benoxacor which has been shown to enhance S- Metolachlor metabolism in corn. This enhanced metabolism can reduce the potential of S- Metolachlor injury to corn seedlings when grown under unfavorable weather conditions such as cool temperature or water stress. However, a safener is not the silver bullet, and slow plant growth may still have trouble metabolizing the herbicide even with a safener…but it does help the severity of damage/symptoms.

Will The Plants Recover?
Plants that have leafed out underground or show corkscrewed mesocotyl symptoms are likely to not recover or even emerge from below the soil. Larger plants that are already emerged that show tightly rolled leaves and are buggy whipped will most likely recover once the field sees drier conditions and we have warm weather and sun light to assist in better plant growth.

More Information Discussing Corn Injury From Pre-emerge Herbicides Here:

http://ipm.missouri.edu/IPCM/2009/4/Cool-Wet-Soils-Can-result-in-More-Corn-Injury-from-Preemergence-Residual-Herbicides/

 

Cody Daft
Pioneer Hi-Bred
cody.daft@pioneer.com

Variability in Tissue Testing/Plant Analysis

This article is written by Dr. George Rehm, University of Minnesota, Soil Fertility Specialist (retired).
See more of Dr. Rehm’s blogs at http://www.agbuzz.com

During the past two or three years, there has been an increase in the promotion for the use of tissue testing/plant analysis as a management tool in development of fertilizer programs.  At times, if you  read all of the advertising literature, you  might get the idea that the practice of plant analysis/tissue testing is so important that you can’t make a profit without it.  So, is this really a new and exciting management tool to be used by every crop producer?  A close examination of the facts without all of the advertisement leads to the answer: not really.

There are problems with placing dependence on the use of this management practice.  Some of the problems and pitfalls have been identified by Dr. Dan Kaiser, Associate Professor and Extension Soil Scientist at the University of Minnesota.  These are briefly described in the paragraphs that follow.

STAGE OF GROWTH at sampling is a major consideration.  With corn, for example, it’s impossible to compare analysis of plants sampled at the V5 growth stage with analysis of plants sampled at some later growth stage.  As the corn plants grow, nutrient concentration is diluted and concentrations, therefore, decrease.  If all other factors are equal, a concentration of nitrogen, for example, may be higher and adequate at V5.  The concentration percentage will be lower at V10 and still be adequate.  This concept has been verified by substantial research conducted by faculty at Land Grant universities.

In order for tissue testing/plant analysis to be meaningful, the results of analysis of the plant tissue must be compared to some standard.  For corn and other crops, these standards have not been developed for every stage of growth.  This is usually true for stages early in the growing season.  That’s primarily because concentrations are rapidly changing at those times.  So, what’s the point of analyzing corn plants at the V5 growth stage if there are no standards for nutrient concentrations at that growth stage?  I don’t know.  I don’t believe that there is general agreement among researchers knowledgeable about plant analysis as to what the adequate concentrations are in whole plant corn tissue at the V5 growth  stage.  With corn, accurate interpretation of plant analysis information is possible if plant samples (leaves) are collected at the time of silking.

At silking, however, it’s too late to apply nutrients that might correct a deficient situation.  So, analysis of corn leaf tissue at silking cannot be used to predict rates of any nutrients needed during the growing season.

TIME OF DAY used for sampling can also affect concentration of nutrients in specific plant parts.

Research has shown that this is especially true for nitrogen.  Nutrients may be more concentrated in plant tissue in the morning; but, as plants grow, the concentration can be diluted by dry matter added during the day that is the result of the normal growth process.  This effect of time of sampling just adds to the variability that may be experienced with plant analysis.

HYBRID AND?OR VARIETY can also have a substantial influence on “critical levels” associated with plant analysis.  Researchers are finding that the rate of nutrient accumulation is different among modern hybrids or varieties.  Therefore, it’s reasonable to expect that nutrient concentration in any plant part at any stage of growth will vary with hybrid or variety.  This is yet another source of variability in plant analysis.

It is known that nutrient concentration in plant tissue is affected by stage of growth at time of sampling, time of day used for sampling, and hybrid or variety.  There are obviously other factors that contribute to variability in the results of plant analysis.

Many have used the results of plant analysis as an aid in the diagnosis of a problem in a field.  Plant analysis was originally developed as a diagnostic tool.  When combined with companion soil samples, this tool has helped to solve many problems.  It is, however, a stretch to use this practice as a tool to predict the rate of any nutrient that should be applied to any crop.  It is simply not a predictive tool that can be used with confidence.  There are too may opportunities for error.

While there are several factors that can produce variability in the concentration of nutrients in plant tissue, there is only minimal variability in the laboratory procedures used in the analysis.  The analytical procedures have been standardized among laboratories by using “standards” with known concentrations.  If there problems with the laboratory analysis, the routine use of these “standards” will identify those problems.

Plant analysis/tissue testing is not something new.  The concept has been around for many years.  When used appropriately, it has value.  However, the ability of this management practice to predict rates of nutrients needed for crop production is now and has been limited.  Don’t expect any more than what this practice can deliver.

Dr. George Rehm,
University of Minnesota
Nutrient Management Specialist (retired)
rehmx001@umn.edu

Sampling for pH and liming in continuous no-till fields

This article is written by Dr. David Mengel, Kansas State University Soil Fertility Specialist. 

One question that commonly comes up with continuous no-till operations is: “How deep should I sample soils for pH?” The next common question is: “How should the lime be applied if the soil is acidic and the field needs lime?”

Sampling depth in continuous no-till

First, sampling depth. Should two sets of samples be taken, at different depths?

Our standard recommendation for pH is to take one set of samples to a 6 inch depth. On continuous no-till fields where most or all of the nitrogen (N) is surface applied, we recommend taking a second sample to a 3-inch depth. We make the same recommendation for long-term pasture or grass hayfields, such as a bromegrass field that has been fertilized with urea annually for several years.

Nitrogen fertilizer is the primary driving force in lowering soil pH levels, so N application rates and methods must be considered when determining how deep to sample for pH. In no-till, the effects of N fertilizer on lowering pH are most pronounced in the area where the fertilizer is actually applied. In a tilled system, the applied N or acid produced through nitrification is mixed in through the action of tillage and distributed throughout the tilled area.

Where N sources such as urea or liquid UAN solutions are broadcast on the surface in no-till system, the pH effects of the acid formed by nitrification of the ammonium will be confined to the surface few inches of soil. Initially this may be just the top 1 to 2 inches but over time, and as N rates increase, the effect of acidity become more pronounced, and the pH drops at deeper depths. How deep and how quickly the acidity develops over time is primarily a function of N rate and soil CEC, or buffering capacity.

Where anhydrous ammonia is applied, or liquid UAN is knifed or coulter banded below the surface, an acid zone will develop deeper in the soil, usually 2-3 inches above the release point where the fertilizer is placed in the soil. So if the ammonia is injected 8 inches deep, there will be acid bands 5 to 8 inches below the soil surface. As with long-term surface applications, these bands will expand over time as more and more N fertilizer is placed in the same general area. The graphic below illustrates the effect of a high rate of ammonia placed in the same general area in the row middle on a high CEC soil for more than 20 years.

The actual depth of the acid zone in fields fertilized with ammonia gets tricky as application depth can vary depending on the tool used to apply the ammonia. Traditional shank applicators generally run 6 to 8 inches deep, so a sample for pH measurement could be taken at 3-6 inches or 5-8 inches deep, depending on how deep the shanks were run. The new low-disturbance applicators apply the ammonia 4-5 inches deep. A sweep plow or V-blade applies ammonia only 3-4 inches deep. So sampling depth for pH should really depend on where the acid-forming N fertilizer is put in the soil.

Mengel and West, Purdue Univ.

Mengel and West, Purdue Univ.

 

Liming application methods in continuous no-till

Now, where do you place the lime in continuous no-till? If you surface apply N, then surface apply the lime. That’s a simple but effective rule. But remember that surface-applied lime will likely only neutralize the acidity in the top 2-3 inches of soil. So if a producer hasn’t limed for 20 years of continuous no-till and has applied 100 to 150 pounds of N per year, there will probably be a 4-5 inch thick acid zone, and the bottom half of that zone may not be neutralized from surface-applied lime. So, if a producer is only able to neutralize the top 3 inches of a 5-inch deep surface zone of acid soil, would that suggest he needs to incorporate lime? Not really. Research has shown as long as the surface is in an appropriate range and the remainder of the acid soil is above pH 5, crops will do fine.

Liming benefits crop production in large part by reducing toxic aluminum, supplying calcium and magnesium, and enhancing the activity of some herbicides. Aluminum toxicity doesn’t occur until the soil pH is normally below 4.8. At that pH the Al in soil solution begins to increase dramatically as pH declines further. Aluminum is toxic to plant roots, and at worse the roots would not grow well in the remaining acid zone.

This implies that the acid zones from ammonia are probably not a major problem. We have monitored ammonia bands in the row middles of long-term no-till for many years and while the pH got very low, below 4.5, we never saw any adverse impacts on the crop that would justify liming and using tillage to incorporate the lime. In fact, some nutrients such as zinc, manganese, and iron can become more available at low pH, which can be an advantage at times.

Yield enhancement is not the only concern with low-pH soils, however. Herbicide effectiveness must also be considered. The most commonly used soil-applied herbicide impacted by pH is atrazine. As pH goes down, activity and hence performance goes down. So in acid soils weed control may be impacted. We do see that in corn and sorghum production.

Liming products for no-till

When choosing a liming product, is there any value to using dolomitic lime (which contains a large percentage of magnesium in addition to calcium) over a purely calcium-based lime product? On most of our soils in Kansas we are blessed with high magnesium content. So as long as we maintain a reasonable soil pH, there normally is enough magnesium present to supply the needs of a crop. Calcium content is normally significantly higher than magnesium, so calcium deficiency is very, very rare in Kansas. The soil pH would need to be below 4.5 before calcium deficiency would become an issue. Before calcium deficiency would occur, aluminum toxicity or manganese toxicity would be severely impacting crop growth. So producers really don’t have to worry about a deficiency of calcium or magnesium on most Kansas soils.

What about the use of pelletized lime as a pH management tool on no-till fields? The idea has been around for a while to use pel-lime in low doses to neutralize the acidity created from nitrogen and prevent acid zones from developing. There is no reason it won’t work, if you apply enough product each year. Pel-lime is a very high-quality product, normally having 1800 to 2000 pounds of effective calcium carbonate (ECC) per ton, and can be blended with fertilizers such as MAP or DAP or potash easily.

But it is costly. As an example, at a cost of $160 per ton and 1,800 lbs effective calcium carbonate (ECC) per ton, 100 pounds of ECC pel-lime costs $8.80. If it costs $25 per ton to buy, haul, and apply a 50% ECC limestone, that equates to $2.50 per 100 pounds ECC.

If you were applying 100 pounds of urea-based nitrogen, it would take approximately 180 pounds of ECC to neutralize the acidity produced by the N. This would require 200 pounds of 1,800 pound ECC pel-lime or 360 pounds of 50% ECC ag lime. The cost would be around $16 per acre with pel-lime or $4.50 per acre with ag lime. So technically, the pel-lime option is fine. But it would cost more than 3 times as much, at least in this example. You can use your own figures regarding costs and ECC of different lime products available to you to do a similar calculation. Deciding which product to use is a simple economic choice.

Summary

Applying N fertilizer to soil will cause the soil to become acidic over time. Placement of the applied N and the level of soil mixing done through tillage determine where the acid zones will develop.  Make sure your soil testing program is focused on the area in the soil becoming acidic, and apply the lime accordingly.

Dave Mengel
Kansas State University
Professor Soil Fertility Specialist
dmengel@ksu.edu

Results from 1st year of Soybean Starter Work

In the spring of 2014 we initiated what was to be the first year of a three year project evaluating starter fertilizers for soybean production in the southern Great Plains.  The first and second year was and is being funded by the Oklahoma Soybean Board.

Year one was a bit experimental in that with so many products on the market we needed some initial work to help focus the direction for years two and three.  I also added a treatment which I knew would have significant negative impact, for extension reasons.  Keep in mind two locations in a single year does not make an experiment nor provide enough information to draw a definite conclusion.   It is however enough to learn some lessons from and for us to plan for our 2015 trials.

The 2014 trial consisted of 12 treatments, Figure 1 and Figure 2.  In these treatments I wanted to see the impact of a standard practice, see if a specific nutrient may be more so beneficial, and evaluate a few popular products.  The spring of 2014 started out dry so at one of our two locations we pre-watered.  This was done by hauling water to the Lake Carl Blackwell (LCB) 1000 gallons at a time and pumping through sprinklers.  The other site, Perkins, we delayed planting until we had moisture.

Treatment Structure and rates for the 1st year of the Soybean Starter Study.

Treatment Structure and rates for the 1st year of the Soybean Starter Study.

List of fertilizers and products used.

List of fertilizers and products used.

Image taken while planting the Soybean Starter study at Perkins.  A CO2 system was used to deliver starter fertilizers with seed.

Image taken while planting the Soybean Starter study at Perkins. A CO2 system was used to deliver starter fertilizers with seed.

The two locations were also selected due to differences in soil fertility.  The LCB site is has good soil fertility, with exception of phosphorus (P), and the Perkins site pH was an issue.  I would have expected a benefit from adding P at both of these locations.  Figure 4 shows the soil test results.

Soil Test results from LCB and Perkins.

Soil Test results from LCB and Perkins.

At LCB as expected some of the treatments (Thio-Sul) reduced stand, some unexpectedly reduced stand (Fe) and others had less impact on stand (APP 5.0) than expected.  The growth at LCB was tremendous, the 30 in rows covered over very quickly and the majority of the treatments hit me waist high by early August (I am 6’0”).  Many of the treatments showed greater growth than check.  But when it comes down to it, grain pays and green does not.  Statistically there were no treatments that out preformed the un-treated check, however the K-Leaf and 9-18-9 did make 3 and 2 bpa more than the check respectively.  What I am hypothesizing at this site is that the added nutrients, especially those with high P levels, significantly increased vegetative grown and these big plants were delayed into going reproductive and they started setting pods later in much hotter weather.  While riding in the combine I could see that the plots with compact plants with clearly defined rows out yielded those were the vines had crossed over and we harvested through more of a solid mat of mature plants.  A hot August is not uncommon and I am curious on whether this trend repeats itself.  If it does this may direct us into research evaluating ways to force/promote the reproductive stage to start in these big plants.  Even if we can force flowering to start earlier, it’s unknown whether yields will increase or not.

Yield and Stand counts from the 2014 LCB Soybean Starter Study.

Yield and Stand counts from the 2014 LCB Soybean Starter Study.

The Check plot at LCB were plants noticeably a bit smaller and more yellow than the neighbors with phosphorus.

The Check plot at LCB were plants noticeably a bit smaller and more yellow than the neighbors with phosphorus.

Soybeans at LCB on August 4th.

Soybeans at LCB on August 4th.

The same trends in treatments reducing stand can be seen at Perkins, however the impact was less extreme.  Perkins being planted later due to waiting on moisture forced a later flowering date and I believe reduced overall yields.  But the addition of P at this low pH site definitely made a difference.  While again no treatments were statistically greater than the un-treated check the 2.5 gpa APP, DAP broadcast, APP/H2O, and Pro-Germ/H20 treatments increased yield by 5.6, 4.2, 3.8 and 1.7 bpa respectively.

Yield and Stand Counts from the Perkins 2014 Soybean Starter Study.

Yield and Stand Counts from the Perkins 2014 Soybean Starter Study.

Take home from year one was that at LCB the addition of a starter fertilizer had little benefit and if done wrong could cost you yield while at the low pH site of Perkins an addition 2.5 gallons of APP did get a 5 bpa bump, but do to variability in the trial the increase was not statistically significant.  This year we will drop some of the treatments and incorporate a few new treatments.   Based on the current weather we look to potentially being able to start with better soil moisture at planting.  Again do not take this work and significantly adjust any plans you have for your 2015 soybean crop. This is however some interesting findings that I wanted to share and make everyone aware of.  Finally thank you to the Oklahoma Soybean Board for providing funding for this work. www.oksoy.org/ 

 

 

4 Keys to Reaching Grain Sorghums Yield Potential

When I started writing this blog (3.13.2105) Ok grain elevator cash bids for grain sorghum aka milo was 6.61-7.70 cwt (3.7-4.31 per bushel) and corn was at 3.64-4.06 per bushel. Meaning there is currently a premium on sorghum grain.  This difference among other things has increased the interest in planting sorghum.  Of late I have been quite successful, at least on a small-scale, at producing sorghum yield in the 120-150 bpa range, thanks to the advice of Rick Kochenower former OSU sorghum specialist.  Both of us believe that every year many producers are leaving significant bushels on the table due to one or two miss steps.  I wanted to take this opportunity to share what is in my opinion the keys in producing a bumper sorghum crop.  I should note that the primary key is out of our control, rain.

Key 1.  Planting date, the optimum planting date for grain sorghum is generally when soil temperatures reach 60° F and increase after planting.  For much of the region that I believe is best suited for sorghum this falls between April 1 and April 15 for south of I40 and April 15 and May 1 north of I40.  graph below shows the long-term average daily 4″ soil temp (bare soil) for Apache, Blackwell, Cherokee, and Vinita.  It is easy to see how your location within the state can impact soil temps.

Long term average 4 inch soil temps from Blackwell, Apache, Cherokee, and Vinita for bare soil.  Data from the Mesonet.org.

Long term average 4 inch soil temps from Blackwell, Apache, Cherokee, and Vinita for bare soil. Data from the Mesonet.org.

You should not forget however that tillage practices will also impact soil temps. The two graphs below show the  long-term average daily 4″ soil temp for Cherokee and Blackwell for both bare soil and under sod.  Note that when the soil is covered by residue it warms slower. The two figures also show that residue will have more impact in some areas more so than others.

Long term average  4 inch soil temps at Cherokee for bare soil and under sod.  Data from the Mesonet.org.

Long term average 4 inch soil temps at Cherokee for bare soil and under sod. Data from the Mesonet.org.

Long term average 4 inch soil temps at Blackwell for bare soil and under sod.  Data from the Mesonet.org.

Long term average 4 inch soil temps at Blackwell for bare soil and under sod. Data from the Mesonet.org.

My best word of advise is to keep a watchful eye on the Mesonet. While the long-term average is nice to know here in Oklahoma the difference in weather from one year to the next can be huge.  The figure below shows the  average daily 4″ soil temp (below sod) from Blackwell for the past five years.  Link to Mesonet Soil Temp page  Click here.

Average  4 inch soil temps at Blackwell for 2010, 2011, 2012, 2013, and 2014 for under sod.  Data from the Mesonet.org.

Average 4 inch soil temps at Blackwell for 2010, 2011, 2012, 2013, and 2014 for under sod. Data from the Mesonet.org.

Another great resource is a report on planting date written by Rick Kochenower presented to RMA. Link to report.

 

Key 2. Hybrid selection, primarily maturity group selection. Rick has created a great graphic that helps put a planting date window with maturity group.  It is always important to visit with your local seed dealer to find out what has been performing best in your region and consider the importance of stay-green, standablilty and disease packages. But for me the number one key is the selection of maturity group. This should be based upon planting date and harvest strategies. Below is a great graphic created by Rick, while this may not be scientific it is a great guide created via years of experience.  I also recommend that if you are planting a significant amount of acres you should diversify your maturity groups. Not only does this spread out he harvest window but it also you to spread the risk of high temps coming early or late.  An additional resource is the Sorghum Performance trial summary located on the Ok Panhandle Research and Extension Center website.  Click here.

Timeline for optimum planting date (N of I-40) and proper maturity groups.  Developed my Rick Kochenower (Chromatin seed)

Timeline for optimum planting date (N of I-40) and proper maturity groups. Developed by Rick Kochenower (Chromatin seed)

Key 3. Soil Fertility, while soil pH plays a big role on sorghum productivity but it is too late in the game to do much about it this year. So the most important things to keep in mind on fertilizing sorghum are your macro-nutrients nitrogen (N), phosphorous (P) and potassium (K).   It is my opinion that historically producers have underestimated the yield potential of sorghum and therefore lost yield due to under application on N. You should expect more than 60 to 80 bushel out of your crop if you put the right seed in the ground, at the right time and in the right way.
Ask around look at Rick’s yield data, producers in N. Central Ok on a good soil should be going for 125+ bpa easy. Unfortunately you are unlikely to hit these yield levels if you fertilize for a 75 bpa crop. An easy rule of thumb on N fertilization is 1.2 lbs of N per bushel, for a more exact number take a look at the image below.  This comes from the corn and sorghum PeteSheet and is the same table that comes from the Soil Fertility Handbook. (If you would like some Pete Sheets just send me an email requesting them at b.arnall@okstate.edu, Link to PeteSheets page).

Nitrogen, Phosphorus and Potassium Recommendations for corn and sorghum production.  Adapted from the Field guide and PeteSheet available at www.npk.okstate.edu

Nitrogen, Phosphorus and Potassium Recommendations for corn and sorghum production. Adapted from the Field guide and PeteSheet available at http://www.npk.okstate.edu

Key 4. Weed Control With sorghum utilizing a pre-plant herbicide with residual is extremely important due to the lack of over the top options.  Most times proper weed control will be accomplished by utilizing concept treated seed and use of labeled rates of a pre-emergent grass control herbicide combined with atrazine.

While I primarily focus of the four keys above there are a few other important items to consider.

Population: Prefer to think in terms of seeds per acre instead of lbs per acre.  This comes into to play with the use of a planter.  Rick Kochenower says “for seeding rate(on 30 inch rows), it isn’t  as critical as most people think it is.  Because most guys in Oklahoma tend  to under plant not over  plant.  I always suggested 45,000 but as you look at the last slide it really don’t matter much.  The way I always liked putting it is to make you sure have enough out there to not have to replant, because being late hurts more than having to few too many or too few plants.”

Row spacing:  I like 30, but many may not have a planter so I suggest at least plugging every other hole in the drill to be at a 12″-20″ spacing. Make sure your population is correct for your row spacing.  For this consult with your local seed dealer to match cultivar with row spacing and proper population.

Insects: Scouting for aphids and head midge is very important, these little critters are yield robbers and can gum up the works at harvest.

Harvest prep:  I almost put this as the fifth key.  By chemically maturing/terminating  your crop you are both able to increase harvest efficiency and preserve moisture for a following winter crop of wheat or canola.

While this is a good start I suggest a visit with your local OSU Extension educator, consultant or seed dealer for information about your specific situation.  Just know the crop has great potential to yield big if treated right.  I like to say don’t treat your sorghum crop like the stray you adopted, treat it like your hunting dog that you traveled halfway across the country to pick up.  Good luck in 2015 and I hope the rains fall when and were needed.

Saline and Sodic Seep Renovation A potential Positive Impact of Drought

This article is written by Dr. Jason Warren, OSU Soil and Water Conservation State Extension Specialist. 

The drought has caused numerous negative impacts on Agriculture in Oklahoma.  However its impact on our ability to renovate some types of Saline and/or Sodic soils has been a positive.  Saline and sodic seeps are referred to by many names, including: salt spots, alkaline spots or slick spots.  They are all similar in that they contain excessive amounts of salt or sodium that prevent plant growth.  However there are various differences that influence how we renovate these sites.

These areas are classified by the amount and type of salt present.  Saline soils are those that contain an EC greater than 4000 μmhos/cm and less than 15% Exchangeable sodium.  A Saline/sodic soil contains an EC greater than 4000 μmhos/cm and greater than 15% exchangeable sodium. Lastly, the Sodic soils contain less than 4000 μmhos/cm and greater than 15% exchangeable sodium.  Given these differences it is important to have soils from these barren areas tested before a renovation plan is developed.  The soil tests will provide recommendations for renovation and more detail on these strategies can be found in factsheet PSS-2226.

Beyond the classifications briefly mentioned above there are different ways in which these saline and sodic soils form.  Some of these soils are formed from parent material that contained excessive salt or sodium.   Others are formed when ground water moves to the surface through evaporation and deposits salt as the water is lost to the atmosphere.   The drought conditions we are current experiencing can impact our ability to renovate the latter.

2011

2013

 

Figure 1: The upper picture was taken in Feb. 2011 and the bottom picture was taken in April 2013.


Hydraulic seeps, those formed from the movement of groundwater to the surface, are often found in low lying areas of the landscape where the groundwater is close enough to the soil surface that water can be conducted through capillary force to the soil surface.  These forces are similar to those that allow use to suck water up through a straw but in the case of a saline seep evaporation from the soil surface provides the hydraulic gradient that pulls water from the water table.  The drought has caused the water table in many areas to subside and become too deep for these force to pull water to the surface and deposit salts.

Figure 1 shows a saline/sodic soil in 2011 and again in 2013.  This site had been treated with Gypsum as described factsheet PSS -2226 in 2007.  However, because of a shallow water table that persisted until the onset of drought in 2011 the renovation effort was not successful because there was insufficient movement of water through the profile to leach the salts down out of the soil surface.   These soils are in proximity to Stillwater Creek and Lake Carl Blackwell.  The water table has declined which allows limited rainfall experienced at this site in 2012-13 to move the salts down out of the soil surface.  This in turn has allowed crop establishment further improves water infiltration by protecting the soil from crusting.

The drop in most water tables across Oklahoma, particularly western Oklahoma where these salt spots are most common, provides for a unique opportunity to renovate hydraulic salt spots.  Again the first course of action is to collect a soil sample to determine what types of salts are present.  You can also make an effort to determine how the salt spot was formed.  This information can be found on the soil survey at http://websoilsurvey.sc.egov.usda.gov/App/HomePage.htm.  Your county extension educator or local NRCS can help to interpret this information.

We have observed that our success in renovating a hydraulic seep near Stillwater was greatly improved during this period of drought.  However, given the fact that our sub soils are generally dry throughout Oklahoma, which improves our ability to leach salts, the drought should improve our ability to renovate those formed from parent material as well.

Time to start topdressing wheat

osunpk:

My favorite part of the blog “Don’t have an N-Rich Strip? It’d be a lot cooler if you did.”

Originally posted on World of Wheat:

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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