Crop Diversification Effects On Soil Nutrient Levels in Long-Term Dryland Cropping Systems in Montana.

Adoption of diversified no-till and organic cropping systems in semiarid regions of Montana has increased due to potential for soil quality, pest control, and economic benefits; however, relatively little research has been conducted to quantify these potential benefits in long-term experiments.�Our current study objective was to evaluate the effects of crop diversification and nitrogen (N) fertilizer rate (full vs � rate) on soil nutrient test levels in a long-term dryland cropping system.�The field plot study was conducted at the 12-yr crop diversification rotation study located at the Post Agronomy Farm near Bozeman, Montana.�Soil was collected at four-year intervals beginning in 2004. Soil samples were separated into depth segments of 0-15, 15-30, and 30-60-cm and each depth composited from four subsamples per plot. Soils were analyzed for a suite of parameters including ammonium, nitrate, total N, Olsen phosphorus, exchangeable potassium, sulfate, and organic carbon.�Study results are pending as spring 2012 samples continue to be processed, but will be completed in time for the annual meeting.