Efficient allocations of irrigation water and nitrogen fertilizer in corn production
2004
Lu, Y.C. | Camp, C.R. | Sadler, E.J.
N-fertilizer and irrigation water are major inputs to corn production and efficient use of these inputs is essential for profit maximization and resource conservation. To use these inputs efficiently, knowledge about plant responses to N-fertilizer and irrigation water, or production functions, is essential. Corn production functions were estimated using the data from experimental plots in Florence, South Carolina, U.S.A., from 1999 through 2001. There were three irrigation treatments and four N-fertilizer regimes. Several forms of production functions were fitted to the data and the quadratic form of the production function was found to have the best fit for the data. The estimated production functions were then used to determine the optimal levels of water and N-fertilizer applications under both yield-maximizing and profit-maximizing strategies. Results indicate that the yield-maximizing strategy called for more water and N-fertilizer and yielded smaller net returns than the profit-maximizing strategy. In 1999, for example, under the current average prices of corn, water, and N-fertilizer, the yield-maximizing strategy required 667 ha-mm of water and 224 kg of N-fertilizer to produce 10.4 Mg/ha of corn and $5.42 of net returns; whereas the profit-maximizing strategy required only 556 ha-mm of water and 174 kg of N-fertilizer to produce 9.87 Mg of corn and $57.38 of net returns. The least-cost combinations of water and N-fertilizer application levels for a given output were also determined. The results provide useful information to farmers to make N-fertilizer and irrigation decisions for profit maximization and for resource conservation.
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