Submitted to: Sustainable Agriculture
Publication Type: Abstract Only
Publication Acceptance Date: March 3, 1999
Publication Date: N/A
In the US, approximately 8.3 million tons of N, 2.5 million tons of P, and 8 million tons of K are excreted by farm livestock each year. These nutrients can be used to partially satisfy crop requirements, thereby reducing the purchase of fertilizers. Producers are under increasing pressures to manage manure as a source of nutrients that are valuable for crop growth and at the same time potentially detrimental to the environment. Calculating the appropriate application rate requires information on the nutrient content of the manure. Nutrient analyses performed rapidly on the farm using cheap and robust equipment could be a useful approach for determining manure nutrient contents. Several such Quick Tests are currently available. These tests are primarily designed to measure ammonium nitrogen (NH4+-N), but some also measure total N, total P, and total K. An experiment was conducted to evaluate seven Quick Tests for their ease of use and for their accuracy in manure nutrient prediction using slurries from several Maryland dairies. Analysis usually took less than 10 minutes per sample, and the equipment was relatively simple to use. Several of the Quick Tests have the potential for accurately predicting NH4+-N and dry matter content of slurries when compared to standard laboratory analysis. Some tests appear to be adaptable to a farm environment while others are more appropriate for research purposes. The ability to rapidly determine the nutrient content of manures will allow producers to accurately estimate manure application rates. The benefits are twofold: 1) it will reduce the amount of required purchased fertilizer; and 2) it will limit over-application of nutrients and minimize nutrient losses.