ECONOMIC AND ENVIRONMENTAL IMPLICATIONS OF SOIL-NITROGEN TESTING - A SWITCHING-REGRESSION ANALYSIS

A simultaneous equations, or ''switching-regression,'' model is developed to assess the impact of soil nitrogen (N) testing on N fertilizer use, crop yields, and net returns in corn growing areas of Nebraska, The results indicate that when there is uncertainty about the quantity of available ''carry-over'' N, N testing enables farmers to reduce fertilizer use without affecting crop yields. However, the value of information from N tests depends critically on cropping history and soil characteristics. These findings have implications for environmental and technology transfer policies designed to reduce nonpoint source water pollution.