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United States Department of Agriculture

Agricultural Research Service

Title: Processing Animal Manure to Optimize N to P Ratio and Reduce Offsite Discharges and Environmental Impact of Manure Nutrients

item Dao, Thanh
item Lefcourt, Alan
item Sikora, Lawrence
item Cavigelli, Michel

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: September 14, 1999
Publication Date: N/A

Technical Abstract: A considerable controversy exists over the importance of animal agriculture on the degradation of air quality and water resources in the Chesapeake Bay area and across the US at large. Outbreaks of coliforms and Pfiesteria that have killed fish and caused human illnesses are thought to be the result of the pollution of rivers and estuaries by animal manure organisms and nutrients. Increased nutrient loading of natural ecosystems is also attributed to atmospheric redeposition of emitted compounds. The N to P ratio of manure is much narrower than that required by crops. Research showed that joint applications of agricultural and industrial by-products reduced excessive amounts of bioavailable N and P in manure and on manured soils. Calcium, aluminum, and iron-rich by-products such as alum, caliche, and Class C fly ash suppressed plant-available P, ranging from 30 to 98%. The effective N:P ratio of treated manure was increased by a factor ranging from 1.5:1 to 18:1. The joint uses of composting and chemical amendments also indicated a significant reduction in manure volume and bioavailable P in the resulting compost. Water treatments residuals reduced water-soluble P by an average of 85% in composted treated-poultry litter. The residuals caused appreciable shifts toward the formation of insoluble mineral P fractions. Therefore, mineral and animal by-products, when combined in judicious proportion will stabilize manure N and P where uncovered manure storage is unavoidable or widened its effective N:P ratio for its use as a balanced source of plant nutrients in sustainable systems of grain and forage crop production.

Last Modified: 4/18/2015
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