Precision Manure Management Conservation Practices: Surface Soil Quality and Environmental Impact.

Maintenance and improvement of soil quality across spatially variable soils in continuous cropping systems are critical to sustaining agricultural productivity. The objectives of this project were to study the effects of variable rate application (VRA) of animal manure on selected surface soil quality parameters across site-specific management zones (MZs). This study was conducted in northeastern Colorado under continuous and furrow irrigated maize. Experimental strips, 4.5 m wide and 540 m long, spanned across all MZs with treatments nested within MZs in the field. Variable rate of manure applied ranged from 0 to 67 Mg ha^-1. Our results indicate that animal manure application of 44 and 67 Mg ha^-1 significantly (P≤0.05) increased soil organic matter (SOM) and decreased bulk density of low and medium MZs and had no significant impact on surface SOM and bulk density of the high zone. Overall results suggest that variable rate application of animal manure across management zones has potential to improve or maintain soil quality parameters over time.