We have all seen the news headlines and experienced the challenges of the 2019 planting season first hand. Successful crop advisors will evaluate how the 2019 planting season impacted growers’ operations and look for ways to improve profitability while further mitigating risk. This maybe more profitable than simply hoping for better weather patterns and improved commodity prices.
Soil fertility recommendations have two key parts that are added together to arrive at a final nutrient application rate. Part one is crop removal. How much fertilizer do I need to apply to account for or replace the nutrients removed by harvesting a crop? The second part is how much fertilizer above crop removal do I need to apply to increase soil test levels from where they are to a target level over a given period of time. Most recommendation sets are built to move from the current soil test level to a target in 4 years, that time frame could also be extended to reduce application rates. Likewise, how much less than crop removal do I apply to reduce soil test levels to target levels over a given period of time.
Traditional soil fertility recommendations take the approach of predicting or forecasting crop yields for the coming year or two. That may be as accurate as forecasting the weather. When it comes to determining the amount of fertilizer needed to replace the nutrients removed by harvesting a crop, the 2019 planting season may show us that there maybe a more cost-effective way to approach this value that requires a shift in perspective.
Rather than forecasting yield using a 10-year average or a yield goal for future yield, and applying fertilizer in advance, shift your mindset to replace the nutrients that past crops have removed. For example, you may have forecasted a 200 bu/ac corn crop for 2019 sometime before planting the 2019 crop, spread fertilizer, and now due to late planting that yield may only reach 170-180 bu/ac. So effectively this leads to a 9-15% over application of fertilizer in 2019 by incorrect forecasting. The use of yield monitor data, storage structure estimates, and scale tickets of past yield values are significantly more accurate than forecasting future yields. Due to low yields in 2019, producers maybe looking for an agronomically wise place to cut fertilizer costs by 10-15% in 2020, here might be an option.
When forecasting yields these overages are often not accounted for in the subsequent years. In years when yield is higher than expected we can actually short for the following crops. While routine soil sampling can catch these variances, there maybe an economic or agronomic impact until the next sampling cycle, or longer.
The main questions. So, what’s in it for the producer? And what’s in for the fertilizer retailer? The producer’s key to future stability will be through better management. This process allows a producer to follow a low yielding year with an input reduction and hopefully be able to effectively maintain strong soil fertility after an exceptional yield year. The ag retailer that takes the effort to work through this transition building a stronger partnership with the producer in these tighter times will differentiate themselves in the marketplace. Better management is often the key to better profitability for both parties. Contact your ALGL agronomy representative with any questions you may have on this topic.
We put a great deal of effort and resources into ensuring quality with our analyses here at A&L Great Lakes Labs. We want the data that you receive from us to be of the highest quality so that it is of the most benefit to you and your operation. However, quality analysis is only one piece of the puzzle. Good quality data begins with a good quality sample, and how the sample is collected and handled after collection goes a long way to ensuring its usefulness.
Plant tissue testing can be a very valuable tool to use in your fertility program. However, there are a number of guidelines that should be followed to ensure that this information is useful to you.
If you have any questions about plant tissue analysis, please contact your A&L Great Lakes regional agronomist or call the lab at 260-483-4759 and we will be happy to assist you!
We have been fielding a wide variety of questions around soil nitrate and ammonium soil test levels. Many soil nitrogen levels from fall manure applications are indicating the need for supplemental nitrogen. Wet weather, and brief periods of warm weather, have led to nitrogen loss. When manure was applied later in the spring, the results are looking much more positive, often above the 25 ppm nitrate level that is universally considered adequate to produce a corn crop. There are some soil tests near or just below the 25 ppm nitrate threshold and may need to be reevaluated later in the season for a possible late season nitrogen application. This re-evaluation later in the season should allow time to evaluate nitrogen loss due to weather the remainder of the season and provides the opportunity to determine a realistic yield expectation. More information on interpretation of Presidedress Soil Nitrate Testing (PSNT) for Corn can be found on our website.
The traditional PSNT interpretations can be challenging to relate to. Providing that the samples were collected to a depth of 12” there is a simple “rule of thumb” to help make sense of a soil nitrate and ammonium value. Add the ppm of the nitrate and ammonium together and multiply by four. This is a relative nitrogen application rate available in the soil at the time of sampling. For example, sample 1 below would be 20 ppm nitrate + 10 ppm ammonium = 30 ppm x 4 = 120 pounds nitrogen. More on this concept can be found at https://www.agry.purdue.edu/ext/corn/news/timeless/AssessAvailableN.html.
While the traditional PSNT interpretations assume a continuous release of nitrogen to the soil from the mineralization of manure organic materials during the growing season, this calculation helps relate to a nitrogen level in the soil today. The difference between the estimated pounds of nitrogen, and a total nitrogen program for the season, is about the same as the PSNT interpretations would recommend.
It would be an understatement to say that the 2019 planting season has had its challenges, and has likely set the stage for a challenging growing season. Prolonged wet weather can be a factor in a number of critical stresses for the crop, including enhanced disease pressures, the prolonged impact of the standing water, and the potential for rooting impacts from possibly planting in less than ideal soil conditions. This newsletter contains a few articles that address questions that we have been receiving and those that we expect may arise in the new few weeks.
With so many factors that can cause crop stress, there will be an increased need to scout fields and diagnose problems during the 2019 growing season. Be sure to take a soil probe, shovel, soil sample bags, and plant sample bags with you to scout fields. A soil or tissue sample that comes back with an abnormal value is usually seen as valuable information in determining a cause, but it may be incomplete, as tissue or soil samples that comes back normal can also provide valuable information.
It is recommended that soil and plant tissue samples are collected together, as the relationship between these types of analyses can provide great insight.
If you can, be sure to brush up on crop physiology! That knowledge can be very helpful when diagnosing environmental and cultural crop challenges. For example, for the first few weeks the roots of a plant are prominently providing water to the growing seedlings and the nutrients are coming from the seed, so the information provided by a plant tissue analysis must be taken in context with many other factors. For more information check out our newsletter article “Get the Most from Early Plant Tissue Analysis”. Please call your ALGL agronomist if you have any sampling questions.
Early season field scouting is essential to ensure good emergence, detect potential weed and insect pressure, and monitor the effectiveness of your fertility program. The earlier an issue is detected, the better chance there is to correct the issue. One tool to help detect potential fertility problems is plant tissue analysis. However, to get useful results back from the lab, the proper plant part must be collected for the current growth stage of the crop.
The proper method for collecting early season corn tissue samples is to collect 15 or more whole plants to comprise a single sample. This is only referring to the above ground portion of the plant. This method is appropriate for corn up to 12 inches tall, or approximately V4 to V5. However, corn can be sampled too early to provide useful data for making decisions. During the first three weeks after emergence, much of the nutrient content of the young plant is not coming from the soil, but from the embryotic tissues within the seed. The young plants also have a very small seminal root system during the first few weeks which are not able to access the nutrients in a large volume of soil; the main role of this root system is to get water to the seed and new leaf tissues. Nutrient deficiencies during the first few weeks are likely caused by environmental conditions and do not necessary reflect low nutrient levels in the soil. An example of this situation is young corn plants turning purple. Purpling of young corn plants can be a symptom of a phosphorus deficiency, but can also occur on soils with adequate phosphorus levels when nighttime temperatures are low. Cool spring nights slow metabolic processes in the plant resulting in the buildup of anthocyanins, which appear purple. Tissue sampling of corn should be delayed until 3 to 4 weeks after emergence, or until the plants have developed a functional nodal root system in order to ensure that the tissue analysis is representative of the nutrients that are available to the plant.
Image 1: V4 corn plant showing purpling. Source: purdue.edu
Similar to corn, soybeans can also be sampled too early. Proper tissue sampling for all growth stages for soybeans is collecting 25 or more of the most recently mature trifoliates without petioles. The first leaves to appear on a recently emerged soybean plant are unifoliates, or cotyledons. The nutrient content of the cotyledons, sometimes referred to as seed leaves, does not accurately represent the nutrients available in the soil. Tissue sampling in soybeans should be delayed until the V2 growth stage. The V2 growth stage is reached when the second trifoliate has completely unrolled. It will generally take a minimum of 3 to 4 weeks after emergence to reach this stage. At this point, the first trifoliate is considered mature, and can be collected for tissue analysis.
Image 2: V2 soybean plant. Source: clemson.edu
Spring tissue sampling of winter wheat can be a very useful management tool. The timing of wheat sampling does not correspond to a specific growth stage though. The important factor when determining the appropriate time to sample wheat is that the wheat has broken dormancy and is actively growing again. Generally, wheat will be at a growth stage of Feekes 3 or 4 when this occurs. The appropriate method for collecting wheat samples at this stage is to collect 25 or more whole plants from ½ inch above the soil surface. One of the benefits of early season wheat sampling is to fine tuning a “green-up” nitrogen applications based on the nitrogen content of the plant at Feekes 5 (please visit the Purdue Extension News Release for more information).
Image 3: Feekes 5 wheat. Source: Kansas State University
Accurate plant tissue testing begins with proper sample collection and handling. Make sure to collect the proper plant part for the current growth stage of the crop, and collect the proper number to make the sample. This information can be found on the plant analysis page at algreatlakes.com. Always avoid soil contamination in your plant samples. Package samples in paper bags. If shipping is delayed, store samples in a cool location, but do not freeze. Never include roots with a plant sample. If you have any questions on proper plant tissue sampling, please contact the lab for assistance.
Many livestock and hay producers are dealing with forage stands, particularly alfalfa, that have been extensively damaged by this past winter and exceptionally wet conditions over the last 2 growing seasons. The following article from OSU provides timely information for producers to consider when determining their options for the upcoming growing season.
Herbicide resistant weeds are an ever-growing concern in production agriculture. One of the quickest ways to encourage weeds to develop resistance to a herbicide chemistry is to use less than the labeled rates of that herbicide. Knowing this, very few applicators will use less than labeled herbicide rates. However, what if an applicator is effectively applying less than labeled rates unknowingly due to the quality of their spray water?
This University of Florida extension article discusses how spray water chemistry impacts the performance of flumioxazin, a key ingredient in the effective control of herbicide resistant marestail. We offer two spray water analysis packages to help you identify the challenges with your spray water so you to make the most effective applications possible.
Anyone who has worked in the agricultural industry in the last few years has heard someone say, “the days of $7 corn and $17 beans are gone.” You may have even seen “In memory of…” decals on truck windows commemorating those commodity prices. The truth is prices are down and most agricultural economists predict that lower prices are going to be the norm for several more years. In these tight times, producers must critically evaluate every crop input from seed selection to herbicide program to fertility program. However, these decisions cannot be made with a short-sighted mentality of getting though the current season and hoping for better prices next year. These decisions have to be made with consideration of how it will impact their operation for the next three, five, or even ten years, especially if commodity prices remain low.
When selecting which seed to plant, it can be tempting to simply go with the highest yielding variety from the previous year’s variety trials. Yield is obviously important, but be sure to purchase a variety appropriate for your operation. For example, do not pay extra for traits to protect against diseases or pests that are not an issue in your region. On the other hand, when selecting an herbicide program, glyphosate alone has a very attractive price tag, but it is necessary to utilize herbicides with other modes of action occasionally to prevent glyphosate resistant weeds from taking over. It may cost a few more dollars per acre at the time, but will certainly be worth it in future years when glyphosate is still an affordable option for most of your weed control.
Soil fertility inputs can represent one of the highest costs in row crop production. In addition to the cost of the fertilizers, there are additional costs for soil sample collection, laboratory analysis, soil mapping and prescription software, and variable rate application. To help reduce costs, some producers may choose to reduce the intensity of soil sampling by using larger grids, fewer management zones, or only collecting a single composite sample from each field. Others may choose to reduce the frequency of sampling or completely abandon sampling all together. While these decisions will initially reduce input costs, how will they impact the productivity and profitability of the operation in the future?
The goal of any fertility program should be produce the greatest yield with the least amount of fertilizer. The most effective way to reduce fertilizer inputs is to identify the areas that require additional inputs and those that do not need any. Soil fertility levels and soil pH can vary greatly in a single field whether it is from natural soil variation or past fertility practices. Collecting a single sample from a field and making a flat rate application of fertilizer or lime based on that single sample is likely to result in an over application in some areas and under application in others. The smaller the area that a soil sample represents, the more confident you can be that the laboratory results accurately represent the area. Maintaining an intensive sampling program, whether grid or zone, is essential to assure the greatest return on your fertilizer investment.
Too often soil test results are used to make a fertilizer prescription and then discarded. There is a lot to be learned from reviewing previous soil test results. By evaluating the impact of a fertilizer or lime application on the soil test levels, future application rates and timing can be adjusted to better suit your soil type. For example, lime applications are intended to last for three to four years, but on some soils a lime application may only last one to two years and others soils it may last six or seven years. Soils that do not respond to fertilizer or lime applications as expected can only be identified with routine sampling frequency. It takes at least three sampling cycles to begin to identify trends such as this. If a field is sampled on a 4-year cycle, it will take eight years before any adjustments to the soil fertility program can be made with any confidence. By sampling more frequently, every two or three years, these trends can be more quickly identified and addressed.
Managing a successful farming operation means minimizing risk whenever possible. Maintaining a routine intensive soil sampling program is the best option for minimizing the possibility of excessive fertilizer application or losing yield from under application.
UAN (urea-ammonium-nitrate) solutions are routinely applied in the late spring and early summer to deliver nitrogen (N) to young crops. Because UAN is a nonpressurized solution, it can be used without the hazards associated with anhydrous ammonia and can be spread more uniformly than granular fertilizer. Certain pesticides may also be added, eliminating an extra pass through the field. UAN solutions are usually manufactured with a 32% N analysis, transported nearer the point of use, and then diluted (“cut”) to 28% or 30% N with water or a nutrient rich solution such as ammonium sulfate. The N analysis of UAN solutions is monitored throughout the supply chain to assure quality and consistency. A hydrometer is commonly used to check the N analysis of solutions, estimating the N content by solution density. A hydrometer reading will vary with the temperature of the solution. Nitrogen and density values will differ by source of 32% UAN solution.
The density of a cutting solution should also be considered when making dilutions. The density of ammonium sulfate (AMS) solution is usually higher than water, and can vary by source. For example, if a hydrometer reading is 1.28 g/cc for a UAN solution that was diluted with water to 28% N, diluting the same UAN solution to that density with AMS would result in a product with only 26% N. The UAN density corresponding to a given N content must be adjusted when diluting with a solution other than water. A hydrometer calibration (chart) can be developed using laboratory analyses of N, S and specific gravity on the various solutions (UAN, AMS, etc.) and mixtures that might be used. Once a calibration is developed, hydrometer readings, adjusted for temperature, can approximate the N content of the UAN solution. Periodic laboratory analyses should be performed to update the hydrometer calibration since the density of new UAN and cutting solutions can change.
The key component of any efficient nitrogen (N) program is minimizing the risk of loss. Nitrogen losses can greatly reduce a grower’s profitability and can have environmental consequences. With a better understanding of the mechanisms that cause N loss and the conditions that increase the risk of loss, we can better decide when and how much to apply.
Plants can only take up N in two forms, ammonium (NH4+) or nitrate (NO3-). Regardless of your source of N, whether it be synthetic fertilizer (anhydrous ammonia, ammonium sulfate, urea, etc.), manure, or compost, the product must first be converted or mineralized to the ammonium form of N. Ammonium can then be converted to nitrate by a microbial process called nitrification. While plants can take up either form, they are generally able to access more N in the nitrate form because it moves freely with the soil water that is taken up during evapotranspiration. On the other hand ammonium is relatively immobile in the soil because it is held by the soil’s cation exchange complex. The difference in the mobility of these two forms of N is the main reason we may lose N before a plant is able to utilize it. In this case, the mechanism for N loss is leaching. In a well-drained soil, a heavy rainfall can move water downward through the soil profile, nitrate can move with the water and may move too deep for our crops to access or may be completely lost from the field if the nitrate makes it to a drainage tile. Leaching losses can be best minimized by applying N as close as possible to the time when the crop can utilize the N. In corn, the greatest N uptake occurs from V8 until R1. Losses can be further reduced by splitting N applications throughout the vegetative growing season.
Another potential mechanism for N loss to occur is denitrification. Denitrification is a microbial process that occurs poorly drained, saturated soils. When soils are saturated, there is not enough oxygen for microbial activity to thrive. Under these conditions, certain microbes are able to scavenge the oxygen atoms from a nitrate molecule in order to survive. The remaining N is then lost to the atmosphere in a gaseous form. Extended periods of saturation, especially when soil temperatures are warm, can lead to a significant loss of N. It is estimated that 4-5% of plant available N can be lost for every day of saturation. Denitrification can be minimized by ensuring you have adequate drainage in poorly drained areas and avoiding applications prior to heavy rainfall.
Volatilization is another potential loss of N to the atmosphere. Volatilization is the conversion of ammonium to ammonia gas. This is most likely to occur when ammonium forming fertilizers such as urea, or manures are applied to the surface of a warm soil with a high pH. Volatilization can account for losses as high as 80% when topdressing wheat in excessively warm conditions. Volatile losses can best be avoided by maintaining soil pH between 6.5 and 7.0, using a urease inhibitor with urea-based materials, and applying when soil conditions are moist and cool.