On-Farm Agro-Economic Effects of Fertilizing Cropland with Poultry Litter
Journal of Applied Poultry Research , 17 , 2008

Harmel, D.R., Harmel, B., Patterson, M.C.

The profitability of using poultry litter as a fertilizer and soil amendment in cultivated agriculture was evaluated with the hopes of determining an economically optimal fertilization strategy. The traditional commercial (inorganic) fertilizer practice was compared with several hybrid litter and commercial N fertilization alternatives in terms of on-farm agro-economic effects. Six years of land management, crop yield, crop price, and fertilizer cost data were collected from 6 field sites in central Texas and utilized for economic analysis. Varying litter and inorganic fertilizer combinations resulted in minimal differences in corn and wheat yields; however, total fertilizer costs increased significantly as litter application rate increased (and commercial fertilizer rate decreased) in spite of dramatic cost increases for commercial fertilizer. The greatest average annual profits were determined to occur at the 1 and 2 tons/acre (ac) litter rates with 7 to 14% profit reductions for the commercial fertilizer-only treatment and the 3 tons/ac litter treatment. At litter rates greater than 3 tons/ac, diminishing returns were observed as fertilizer costs increased with no compensating greater yields to provide offsetting revenues. It is important to note that this economically optimal annual litter rate of 1 to 2 tons/ac is also environmentally optimal according to nutrient runoff and soil nutrient data collected on-site. These results provide the scientific basis to support the use of litter as a cost-effective, environmentally friendly fertilizer alternative in this and similar regions.