Mineralization of manure nutrients

ABSTRACT:

In order to apply manure or compost to fulfill the nutrient requirements of a crop, knowledge of the amount of nutrients mineralized following application is needed. Nutrient mineralization from applied manure depends on temperature, soil moisture, soil properties, manure characteristics, and microbial activity. Since these factors cannot be accurately predicted, nutrient mineralization from applied manure can only be approximated. Nitrogen (N) availability from applied manure includes the inorganic N (NO₃-N and NH₄-N) in manure plus the amount of organic N mineralized following application. Nitrogen mineralization differs for different manure types since the inorganic/organic fraction and quality of organic N varies among manure types. Mineralization of organic N is expected to be low for composted manure (∼ 18%) and high for swine or poultry (hens) manure (∼ 55%). Phosphorus (P) availability from all animal production sources of manure is high (> 70%), as most of the manure P is inorganic and becomes plant-available after application. Potassium (K) availability from manure is nearly 100%; therefore, manure can be used similar to K fertilizer. When manure was analyzed for plant-available nutrients, greater than 55% of calcium (Ca) and magnesium (Mg) and less than 40% of zinc (Zn), iron (Fe), manganese (Mn), copper (Cu), sulfur (S), and boron (B) were plant-available. To effectively utilize the nutrients in manure, their mineralization potential should be considered when determining application rates.