On an episode of Real Ag Radio Peter “Wheat Pete” Johnson answered a listener question about the best practices for spreading manure on farmland. Johnson emphasized the importance of considering factors such as soil type, weather conditions, and current soil nutrient levels before determining how often to spread manure.
The first step, according to Johnson, is to conduct a soil test to determine the current levels of nutrients in the soil. This information will help farmers understand the value of the manure and determine whether or not it is necessary to spread it on a particular piece of land. For example, if the soil test shows that the levels of phosphorus and potassium are low, spreading manure can be very beneficial, as it provides these essential nutrients.
However, if the soil test shows that these nutrient levels are already high, spreading manure may not be necessary and could actually be harmful. Johnson notes that over-application of manure can lead to environmental concerns, such as phosphorus and nitrogen runoff, which can be harmful to nearby bodies of water.
In addition to soil test results, farmers should also consider the type of manure being spread and the nitrogen cycle of the soil. For example, poultry manure has a high amount of ammonia nitrogen, which is most effective when spread in the spring and quickly incorporated into the soil. Hog manure, on the other hand, has more organic nitrogen, which takes longer to cycle and release nutrients into the soil.
Johnson says the economic considerations of spreading manure, such as the quickness to action and the components of different types of manure. He explained that while poultry manure has high levels of ammonia nitrogen, beef and dairy manure have high levels of phosphorus, which can be beneficial for crops that require more of this nutrient.
In terms of the frequency of spreading manure, Johnson suggested that it is best to spread it every two to three years on average, depending on the nutrient needs of the soil. This allows the nutrients in the manure to be fully utilized by the crops without the risk of over-application.
Johnson emphasizes the importance of responsible manure management to ensure that environmental concerns are mitigated. He suggests farmers work with agronomist to develop a nutrient management plan that considers soil types, weather conditions, and other factors to determine the best practices for spreading manure.