Determining the nutrient and nonnutrient contribution of compost to a dryland-organic farming system

This study partitioned the yield increase from a compost application into nutrient and nonnutrient fractions and determined the change in soil test nutrient levels due to the application. A compost made from dairy cow manure and bedding was applied to dryland wheat (Triticum aestivum ) in an organic fanning system. The nonnutrient to nutrient yield response ratio varied from 0.25:1 to 2.2:1. The compost application caused significant increases in soil exchangeable P, K and DTPA-extractable Zn and Mn. No changes in soil DTPA Fe or Cu were noted and soil exchangeable Na was constant or reduced. The increase in exchangeable K was high enough to be of some concern in soils already high in K. The compost applications produced significant nutrient and nonnutrient benefits at all levels of application.