Average returns and risk characteristics of site specific P and K management: Eastern corn belt on-farm trial results

The objective of this study was to provide an economic assessment of site specific management (SSM) of P and K. The data were collected from 1993 to 1995 in farmer managed on-farm trials coordinated by Purdue University and DeKalb-Agra, a Waterloo, IN, agricultural input supply and marketing cooperative. Whole field management (WFM) was compared with SSM using either three acre grids or soil type for soil sampling and fertilizer recommendations. The data indicate that site specific P and K application on corn (Zea mays L.), soybean [Glycine max (L.) Merr.], and wheat (Triticum aestivum L.) did not reliably increase net returns. The main effect of the site specific P and K applications on physical quantities of fertilizer was to redistribute the nutrient applications within fields. Both grid and soil type treatments had lower net return standard deviations than WFM. Both mean-variance and stochastic dominance (SD) analyses indicate that the soil type approach dominated the WFM for risk averse decision makers.