Nutrient Considerations For Low Corn Prices
February 2, 2016 Corn prices are low and many producers are asking tough questions about their nutrient management programs. Here are some suggestions for keeping fertilizer bills as low as possible without compromising the yield that brings much needed revenue.
Account for nutrient supplies already in the soil.
How much of each nutrient do you currently have in your soil? Take advantage of what’s already there. Soil test results provide the best guidance for deciding which nutrients should be applied and how much of them to use. If soil tests levels of phosphorus (P) and potassium (K) are high, there is little chance that an economic response to these nutrients will occur in the year of application. In such cases, producers can take advantage of existing soil nutrient supplies. However, this approach must be done with the understanding that supplies will be replenished later to avoid future nutrient deficiencies and associated revenue losses.
Taking nitrogen (N) credits for previous crops is an important part of buying only what’s needed. Many people also forget that with some crops, like alfalfa, lower N application rates may be justified for crops planted up to two years after termination of the stand.
An often overlooked, but effective tool is the soil nitrate test. This test helps producers account for the nitrate already present in their soils. If levels are high enough, freshly-applied N rates can be reduced, or in some cases, omitted. This test is particularly useful where manure applications have been made, previous crop yields were poor, or climatic conditions are dry.
Account for nutrient supplies on the farm or nearby. If you have access to manure, whether it’s on your farm or your neighbor’s, use it as effectively as possible. Also, be sure that you know the nutrient content of the manure and the rate at which manure is applied, so you can calculate how much of each nutrient is being put on. If you have previously felt that spreader calibration and manure testing were too time consuming or too expensive to deal with, this may be the year to reconsider. If manure application equipment is dated, it may be time to run the numbers and see if updated equipment capable of applying lower, agronomic rates can be justified. In some cases, manure application rates can be cut in half and still meet crop needs, allowing manure to be a nutrient source on more acres.
Time nutrient applications for highest efficiency. Spring N applications provide N at a time closer to crop need, reducing the chances for N loss. However, spring applications can also carry higher logistical risks, since conditions are typically wetter than the fall. In some areas, fall N applications can be effective if they are made when soil temperatures drop below 50-degrees F and remain there. Nitrification inhibitors can also reduce or eliminate N losses from fall to spring.
Splitting the total N rate across various times in the season can increase N recovery by the crop. Several options exist. A pre-plant application combined with a second application during early vegetative growth stages is common for corn.
Whenever possible, manure applications should be made close to the time of crop need, such as the spring.
Place nutrients for greatest efficiency. Generally, banded nutrient applications provide higher first-year recovery of applied P and K than do broadcast applications. Consequently, some universities suggest rate reductions when nutrients are applied in this manner. If short-term economic decisions dictate banding P and K at rates less than those of crop removal, producers and advisers may want to build in a plan for replenishing soil nutrient supplies in the future, when economic conditions improve. In fields with longer-term management strategies, a combination of a banded application with a broadcast application has the best chance for maximizing yields. Bands placed near the seed provide early season access to nutrients, while overall higher fertility levels in the bulk soil provide access to the larger root system later in the season.
Use the most effective fertilizer technologies available. Fertilizer technologies have come a long way. Look over options with your crop adviser. Nitrification inhibitors, urease inhibitors, and controlled release fertilizers are just some of the options available. Be sure to research these products thoroughly and examine university research that tests their efficacy. There are situations where these products provide an advantage. Know the conditions under which they have the best chances of making a difference.
Allocate money to the right nutrients. In times like these, many emphasize that N needs must come first. Before jumping to this conclusion, soil test levels of a field or field area must be examined. In the worst case, it may be found that N, P, and K are all in short supply. When this happens, crop response to any single nutrient will be limited if only that nutrient is applied. When P levels are low, the plant has a reduced supply of stored energy. Without enough energy, the plant is not effective in absorbing limited soil N, P, or K supplies. In these cases, if recommended rates of each nutrient cannot be afforded, it is best to band at least low rates of P and K near the seed as part of the N fertilization program. This balanced approach will maximize the effectiveness of all applied nutrients.
Prioritize fields and areas within fields. Allocating nutrient funds across the farm should be based not only on soil tests but also on economic evaluations of each field or field area. What is the break-even cost of production for each field in a farming operation? Which fields consistently make money, which ones are hit or miss, and which ones are just a drag on the business? Spending time looking at how fields have performed over time may help farmers and advisers focus resources on the money makers. The goal of such an analysis is to ensure that consistently profitable fields have the nutrients they need to maintain production and revenue levels. With precision agriculture, this evaluation can be brought to a higher level of resolution, extending the concepts to areas within a field, rather than the entire field.
Examine yield goals. Since many nutrient recommendations are based on yield expectations, setting realistic yield goals is important. One way to set realistic expectations is to look back at previous years’ performance, to get an idea of what typically happens, given specific levels of crop stress. Averages of several years of yields are often useful in setting goals.
Re-examine the basis for nutrient recommendations. Are nutrient recommendations based on the best science available? University research and publications set the standard for science-based nutrient management decisions. How do currently-used recommendations compare to these? If modifications or different approaches are being used, is there good information behind them? It may be time to look at the scientific guideposts, like university guidelines, to see how current management practices compare.
In Summary
When funds are limited and crop prices are low, it is paramount that nutrients be used as effectively as possible. Effective use is possible only when informed decisions are made. Keeping soil test information up-to-date, identifying profitable fields or field areas, using all nutrient sources available, and adopting nutrient management practices founded on proven scientific principles ensure the greatest chances for success.
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