Spatio-Temporal Distribution of Topsoil Nitrogen As Influenced By Cover Crops and Manure.

Green and animal manures provide a low-cost nutrient supply in annual cropping systems and contribute to improved soil quality. However, legume cover crops often do not supply enough nitrogen (N) to fully meet in-season corn demands, while animal manures tend to oversupply phosphorus (P). Integrating cover crops with animal manures applied at P-based rates may allow for improved N supply while avoiding excess P. The recent development of an implement to apply dry manure below the soil surface in a band offers a more efficient delivery method for poultry litter. However, little is known about the distribution of soil inorganic N from manure applied in this method, especially where N is also released from cover crop residues. The objective of this study was to model the spatio-temporal dynamics of soil inorganic N in a no-till corn system receiving both cover crop and animal manure amendments. The study tested three cover crop treatments – hairy vetch monoculture, cereal rye monoculture and hairy vetch/cereal rye biculture; and three manure treatments – 0 Mg ha^-1, 3.6 Mg ha^-1 pelleted poultry litter broadcast at planting, 3.6 Mg ha^-1 pelleted poultry litter subsurface banded, in a factorial design. Conventional tillage treatments were also included, wherein the cover crop residues and 3.6 Mg ha^-1 pelleted poultry litter were incorporated just prior to planting. Soil samples were collected at discrete soil profile locations between corn rows at five corn growth stages. The spatial distribution of soil moisture and inorganic N were modeled at each corn growth stage.