High-quality corn silage in the bunker starts with a high-quality corn crop in the field. The odds of successfully growing a high-quality corn crop are dependent on many factors. Top producers manage the details they can control and thus, minimize the influence of the details they can’t, such as the environment, on their corn silage production. One such detail that can be controlled is proper fertility.
Proper fertilization is essential for producing a high-quality corn silage crop. Since a greater portion of the plant is harvested, the nutrient requirements for silage production are much different than corn grain production. Under-fertilizing can put a corn silage crop under stress, produce stunted plants and result in lower tonnage and reduced quality. The stress of poor fertility often leads to increased incidence of foliar and stalk rot diseases, which also have a negative effect on silage quality. On the other hand, over-fertilizing also has consequences. Over-application of nutrients, either commercial fertilizer or manure, can lead to off-site nutrient movement by runoff or leaching. Another more apparent negative is that in the current dairy economy, producers can’t afford to spend money on inputs that don’t provide good return on investment.
A current, accurate soil test is the best place to start a corn silage fertility plan. Like any journey, knowing where you are starting from is key to reaching your goals. The three essential nutrients for corn silage growth are nitrogen (N), phosphorous (P) and potassium (K). Nitrogen, the most important of these primary elements, is a mobile nutrient that needs to be supplied to the corn crop annually. Nitrogen needs for silage are pretty similar to corn grown for grain, ranging from 150 to 200 pounds per acre. Factors such as yield goals and previous crop are used for determining the optimum nitrogen rate for a grain crop and also hold true for silage. When determining the rate for a corn silage crop, be sure to take all of these factors into consideration. When applying manure, remember to start with an accurate analysis and use effective nitrogen rates.
Phosphorous is an immobile nutrient in the soil, which can be seen as both a positive and negative. On the positive side, soil phosphorous levels can be built up and “banked” for future crop use. The negative side of that is the potential for soil phosphorous levels to reach excessive levels in fields where manure or commercial fertilizer has been over-applied. This has real environmental implications, and for those reasons soil test results should be referenced before making phosphorous applications. Typical phosphorous fertilizer rates vary by soil type, so application rates should be site-specific. As with nitrogen, be sure to account for the phosphorous supplied by manure applications.
The next essential nutrient, potassium, has much higher requirements by corn silage than grain. Since two-thirds of the potassium is expressed in the stalk and foliage of the corn plant, silage harvest removes about three times more potassium from the field than corn grain harvest. With the high demand of a silage crop, fields with a long history of corn silage production may be deficient. A soil test should reveal which fields will benefit from potassium applications. The soil test will also take into account the physical characteristics of the soil that influence potassium availability and, ultimately, the fertilizer recommendation. When applying manure, account for potassium and adjust the rate accordingly.
By following these guidelines, corn silage producers can help ensure they successfully produce a high-quality corn silage crop.
Mark Schultz is a sales agronomist for BASF Plant Science. He can be reached at mark.schultz@basf.com.
Tags: Agronomy, BASF Plant Science, corn crop, corn silage, dairy feed, dairy nutrition, fertilization, Mark Schultz, NutriDense, soil test, stalk rot disease
