Home » Posts tagged 'soil fertility'

Tag Archives: soil fertility

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

View Full Profile →

Enter your email address to follow this blog and receive notifications of new posts by email.

Join 3,943 other followers

Yellow Wheat the 2020 Edition.

I have been trying to write this blog addressing the yellow wheat for about two weeks now. But with finally finding a dry”ish” day or two and a lot of calls and emails about yellow wheat, I am just now getting to it.
So the short story is there is a lot of wheat out there in the state that is show signs of chlorosis, or yellowing. I wish I could say I have all the answers for you in this article, but I will have to lay heavily upon the agronomist best answer, “Well it Depends.”.

Cow pox showing up in a wheat field in Kay County.

First we will start with the things I know least about and then move on to things that are more in my wheelhouse. In the last two weeks I have been on multiple email strings trying to chase down the cause of chlorosis in fields all over the state.  One of these included Dr. Bob Hunger and the Plant Disease & Insect Diag Lab (PDIDL) and in one field his final thought was “So, my best guess is cold and wet soils along with fungi colonizing the older leaves that are starting to senesce.” At the same time I am finding regular occurrence of Tan Spot and Leaf Rust increase. All these pathogen cause some level of chlorosis and if you do not get down and pull some samples you will never know the cause.

Originally thought to be leaf rust, but corrected by Dr. Hunger who suggested it is early stages of striped rust, found in Stillwater Oklahoma 3.27.2020.

 

A new for me this year is what I am calling the herbicide ding. I was able to get over a lot of my wheat that first week of March with a shot of herbicide, everything was almost to hollowstem. The wheat really got dinged. Very visual yellowing and stunting of the plants. Talking with Dr Manucheri, she had seen the same thing in her plots in Tipton. I have also visited several farmer fields with the same symptoms. Dr. Manucheri shared with me the Finesse label. Directly from the label “Temporary discolorations and/or crop injury may occur if herbicide is applied when the crop is stressed by severe weather conditions (such as heavy rainfall, prolonged cold weather, or wide fluctuations in day/night temps), disease or insect damage, low fertility, applications to course soils, or when applied in combination with surfactant and high rates of liquid fertilizer solutions.” This can be found on page 5, http://www.cdms.net/ldat/ldFSL002.pdf . You can just about mark off every weather and application condition mentions, on the same field.

Image collected 3.25.20. The right side was treated with Powerflex on 3.5.20. The left side was not treated so that sorghum could be planted in April.

Now to the yellow wheat I can comfortably talk about. There is nitrogen deficiencies out there. That should not come as a shock with the amount of rain we have received over the last couple months. I also believe that a fair amount of the wheat crop out there is a bit lacking on roots department.

 

The overarching wet cools soils that we have more than likely have led to reduced root exploration in some areas. And if you combine short roots with a nitrate leaching then the probability of N being out of the reach of the crop is high. Then the question is “Is there still time to do anything?”. The trip I look over the weekend (3/28, 3/29) that encompassed a great deal of the North Central Ok wheat belt showed me that the majority of the wheat had really progressed physiologically in the last two weeks. At this point, a positive return on N investment hinges on the stage the wheat is at.

Our delayed N work over the past several years show that we have maintained the yield on our trials even when fertilizer was delayed into the first week of April. https://osunpk.com/2019/08/14/how-long-can-wheat-wait-for-nitrogen-one-more-year-of-data/

Each graph is from a location where the delayed N study was preformed. The objective of our study was to determine the impact of prolonged nitrogen deficiency on winter wheat grain yield and protein. Eight studies were conducted with 11 N application timings in no-till dryland conditions. A pre-plant treatment of 90 lbs ac-1 of N was broadcast applied as ammonium nitrate (AN). We used AN as our source because we wanted to measure the crops ability to recover and eliminate the impact of source efficiencies. When visual symptom differentiation (VSD) was documented between the pre-plant and the non-fertilized check, i.e the N-Rich Strip showed up, top-dress applications were performed every seven growth days (GDD> 0) (https://www.mesonet.org/index.php) until 63 growth days after VSD at all sites. The only N the treatments received where applied according to treatment structure. No pre-plant N was applied on the trials other than the Pre-plant treatment.

This table shows the application dates of the 10 site years of the delayed nitrogen study. The first column is the location, to the right of the location is two rows the top is grain yield and the bottom is grain protein. Each of the following columns corresponds to an application date. Applications began at each study when the The colors are related to whether that application was statistically (Alpha=0.05) worse than, equal too, or better than applying nitrogen at the first sign of deficiency (0DAVD). For this comparison it is important to know that at no location did preplant have significantly greater yield than 0DAVD.In the majority of those years that first week of April corresponded with the growth stage  Feekes 8, last leaf just visible. As the crop moves beyond that point, catching up did not happen. Currently there is wheat out there in the state that has not hit hollow stem (Feekes 6) and there is wheat at Flag leaf (Feekes 9).

 

The Feekes Scale focused in on the stem extension growth phase. The period extends from hollow-stem (Feekes 6) to boot (Feekes 10).

The high rainfall totals we have could have also led to another deficiency sulfur. In the past S deficiency is fairly hard to find in Oklahoma. Our long history of low S using winter wheat and high sub-soil S levels have kept the response to Sulfur low, but not uncommon. Sulfur is a mobile nutrient and will also be lost via leaching especially in sandy soils in the northern part of the state. Sulfur deficient is different from N in that it shows in the newer growth as a general yellowing of crop. Kansas State has a lot of great resources on sulfur management in wheat.  https://webapp.agron.ksu.edu/agr_social/m_eu_article.throck?article_id=2132

https://bookstore.ksre.ksu.edu/pubs/MF2264.pdf

Sulfur deficiency in wheat. Photos by Dorivar Ruiz Diaz, K-State Research and Extension

If your wheat is yellow and before you call the fertilizer applicator, first confirm it is nitrogen and or sulfur and not something else. A key point to nitrogen deficiency is that the cholorsis will be worst on the oldest leafs while new growth is green. If N deficiency is confirmed then figure out how far along your wheat is. If the crop is around hollow stem to Feekes 8,  if you can get the N on soon there is a good chance to get your money back plus. Keep in mind with air temps above 60 degrees UAN will burn the tissue so it is best to use streamer nozzles, which will still burn but the tissue damage is lessened. If you do not have access to streamers you can dilute the UAN with water and use flat fan nozzles. Cutting the UAN with water reduce the impact of leaf burn, I typically recommend at least 2 part UAN to 1 part water, but a 1 to 1 is the safest.

Image of wheat with forage burn from UAN applied with streamer nozzles. Application was made two days prior with air temps where above 80 degrees.

If you have any questions or concerns please feel free to email any questions you may have.

Brian Arnall
b.arnall@okstate.edu

 

Soil calcium and magnesium levels: Does the ratio make a difference?

Guest Author
Dorivar Ruiz-Diaz,
Nutrient Management Specialist
Kansas State University

Is it important to have the proper ratio of calcium (Ca) and magnesium (Mg) in the soil? Producers may ask this question as they have their soil tested for nutrient levels in the summer before wheat planting begins. This question may also arise at the moment of lime purchase, which can be an important source of Ca and Mg.

Calcium and Mg are plant-essential nutrients. All soils contain Ca and Mg in the form of cations (positively charged ions, Ca++ and Mg++) that attach to the soil clay and organic matter; these are also the forms taken up by crops. The relative proportion of these elements, as well as the total amount in the soil, depends mainly on the soil parent material. In Kansas soils, the levels of Ca and Mg are typically high and crop deficiencies are rare.

Soils typically have higher Ca levels than Mg. Table 1 gives the amount and ratios of Ca and Mg for some soils in Kansas. Both nutrients are present in large quantities. Unusual cases of Ca or Mg deficiencies may be found in areas of very sandy soils.

Table 1. Calcium, magnesium, and Ca:Mg ratio for several Kansas soils
Ca Mg Ca:Mg ratio
Soil cmol/kg
Canadian-Waldeck 42 11 3.7
Carwile 22 4 5.2
Chase 198 30 6.7
Crete 111 29 3.8
Harney 202 15 13.2
Harney-Uly 200 12 16.1
Keith 127 38 3.3
Las 176 37 4.8
McCook 35 8 4.5
Onawa 163 28 5.8
Ortello 19 6 3.3
Parsons 80 23 3.5
Tully 158 38 4.2

 

Why would the ratio of Ca to Mg be important? The concept of an optimum Ca:Mg ratio started in the 1940s under the “basic cation saturation ratio” theory. The theory is that an “ideal soil” will have a balanced ratio of Ca, Mg, and potassium (K). According to this theory, fertilization should be based on the soil’s needs rather than crop’s needs — focusing on the ratio of crop nutrients present in the soil. This concept of an ideal Ca:Mg ratio has been debated by agronomists over the years. The suggested ideal ratio according to the theory is between 3.5 and 6.0, but this has never proven to be of significance.

There is very little research evidence to support any effect, either positive or negative, of the soil Ca:Mg ratio on crop production and yield. What research studies have been conducted in the laboratory and in the field show no effect of Ca:Mg ratio on crop yield. Despite this, the promotion of the ratio concept persists today. Furthermore, the initial work that derived this concept did not differentiate between crop response (alfalfa) due to the change in Ca:Mg ratio and the improvement in soil pH from lime application. It is reasonable to conclude that crop response can be expected from changes in soil pH rather than any change in the ratio of Ca:Mg.

One example of research conducted on this topic over the years is shown in Table 2. In that experiment, McLean and coworkers demonstrated the lack of relationship between Ca:Mg ratio and crop yield for several crops. The range of Ca:Mg ratios observed for the highest yields were not different from those observed for the lowest yields. The conclusion from that study was that to achieve maximum crop yield, attention should center on providing sufficient levels of these nutrients rather than attempting to find an adequate ratio. Therefore when these nutrients are present in optimum levels for plant growth, the relative ratio in the soil seems irrelevant.

Table 2. Ratio of Ca:Mg for five crop-years comparing the highest and lowest yields obtained
Corn Corn Soybean Wheat Alfalfa Alfalfa
Yield level Ca;Mg ratio
Highest five 5.7 – 26.8 5.7 – 14.2 5.7 – 24.9 5.7 – 14.0 5.7 – 26.8 6.8 – 26.8
Lowest five 5.8 – 21.5 5.0 – 16.1 2.3 – 16.1 6.8 – 21.5 8.2 – 21.5 5.7 – 21.5

Adapted from: McLean, E.O., R.C. Hartwig, D.J. Eckert, and G.B. Triplett. 1983. Basic cation saturation ratios as a basis for fertilizing and liming agronomic crops. II. Field studies. Agronomy Journal 75: 635-639.Ada – 21.veeio of Ca:Mg for five crop-years comparing the highest and lowest yields obtainedto the diseaseeo produced by Dan Don

In conclusion, trying to manage the ratio of Ca:Mg should not be used for a nutrient application or liming program. The center of attention should be to ensure that levels of Ca and Mg in the soil will not limit optimum plant growth. The relative concentration of Ca and Mg in commercial ag lime can be highly variable, and application should be based on the effective calcium carbonate (ECC) to achieve a target soil pH.

Dorivar Ruiz-Diaz, Nutrient Management Specialist
Kansas State University
ruizdiaz@ksu.edu

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.