to guide your application strategy Achieve nutrient management success the right way by focusing on the source, rate, timing, and placement of manure. by Deanne Meyer
F
or farmers, local geography and climate determine the limiting nutrient for manure application. That being said, for much of the United States, phosphorus or nitrogen limit manure nutrient application. A guide to manage manure nutrients is to use the four R’s: the right source, the right rate, the right time, and the right place. This also assumes there is a target crop yield and nutrient composition. Why do people care about these four R’s? Efficient and sustainable livestock production relies on them. For many,
feed nutrients are imported to farms. Nutrient management is an iterative process that allows you to more efficiently use residual feed nutrients for crop production.
Nutrient composition varies Let’s start with a review of the four R’s. Right source. Manure solids, slurry, and liquids have different concentrations and ratios of organic and plant (ammoniacal) nitrogen. Organic nitrogen requires soil microbes to mineralize the nitrogen to ammonium. Much research focuses on better prediction of mineralization rates. Animal diet,
22 | Journal of Nutrient Management | February 2020
F3 22-23 Q1 2020 4Rs.indd 2
housing and manure collection, storage, and treatment all influence the composition of manure that is applied. For all animal facilities, manure from replacement animals will have a different nutrient composition than that of the mature animals. Testing manure sources provides farm specific nutrient composition to predict plant availability. Identify sampling protocols for soil and manure. Your local or state Cooperative Extension Service or Natural Resources Conservation Service office may have established recommendations for sampling and plant nutrient application guidelines. jofnm.com
1/16/20 11:40 AM
