April's Ag Advice by April Borders Can your local fertilization program be improved? Are you using the best management practices available to you? These practices can enable producers to be profitable while also protecting the environment.
Managing fertilizer consists of applying the right product, in the right amount, at the right time, to the right place. In order for your management practices to be considered "best," all four considerations must be right.
First, choose the right product. Consider the ration of nutrient elements and forms the crop needs. Look at the appropriate solubility, salt index, and slow-release characteristics. Also think about blending and handling properties. And then, of course, consider the price.
Second, choose the right rate to apply. This requires a lot of background work. Sampling your soils is a good place to start. Consider the crop's yield potential and balance its removal of nutrients. Make sure that you apply credits to other sources like manures and previous crops. Weigh all properties that will influence your next year's crop and look at the data to determine a rate that is economically sound.
Third, apply your fertilizer at the right time. For producers that are considering fall application of nitrogen (N), you need to be aware of the potential to lose fall-applied N to leaching. The potential loss occurs when fertilizer N is applied to soils still above 50 degrees. The warm temperatures allow bacteria in the soil to convert the fertilizer N (NH4+) to nitrate N (NO3-).
The ammonium N does not leach since it is positively charged and sticks to the soil, allowing water to pass through without leaching nitrogen down into the soil profile. Nitrate-N, on the other hand, is just the opposite. It is negatively charged, does not stick on soil, and is readily leached. The goal then would be to apply fall fertilizer when soils have cooled and microbes are no longer active.
The amount of fall-applied N that is converted to nitrate is really not a concern unless we are faced with a lot of moisture, since water movement below the root zone will leach N out of the profile. Our recent dry fall
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and winter season have been great for preventing leaching losses.
However, these same dry conditions allow non-incorporated fall applied urea to remain on the surface for long periods, permitting significant volatil-ization losses to occur. The cool fall temperatures likely slow volatilization losses but the lack of rain for long periods allows the losses to accumulate if urea is not incorporated.
Fourth, place the nutrients where they are needed and keep them there. Map and manage soil variability among and within fields. Band or incorporate wherever possible. Keep a safe distance from the seed in order to avoid seedling injury. Use conservation tillage to minimize runoff and erosion. Consider growing a cover crop to help retain mobile nutrients for the next growing season.
Improved nutrient management requires time and work. Look for ways to incorporate better practices, as you do your nutrient management program will evolve and become even better and more profitable.