COVER CROPS AND NITROGEN RATES IMPACT ON SOIL CHEMICAL AND BIOLOGICAL
PROPERTIES IN LOUISIANA NO-TILL CORN PRODUCTION
Abstract
Use of cover cropping systems to improve soil health is still limited in
Louisiana. This study aimed to examine the interaction between cover
crops and nitrogen (N) fertilizers rates on crop yield, soil chemical
and biological properties. Winter cover crops, including legumes, a
grass & a brassica, and a fallow control, were combined with N
fertilizer application at four rates (0, 90, 179, 269 kg N ha-1) in
continuous corn production as part of a no-till system. Soil samples
were collected at 0-8 cm before and after cover crop termination in 2017
and 2018. Soil nutrients, organic matter, inorganic N, microbial
community composition, and soil enzymes were analyzed. Legumes increased
corn grain yield overall and maximized yield at 90 kg N ha-1 compared to
grass & brassica treatments which maximized corn grain yield at 179 kg
N ha-1. Regardless of cover crop type, nitrogen fertilizer applications
increased soil organic matter by 8% compared to no nitrogen
applications. The concentrations of soil phosphorous from legume was
19% higher than the grass & brassica treatment, while grass &
brassica had a greater soil potassium concentration than legume. Cover
crops and N applications improved soil enzymes for carbon and N cycling.
Nitrogen rates applied for the main crop promoted microbial biomass in
spring soil sampling. Arbuscular mycorrhizal fungi were greatest in the
grass & brassica treatment and when no N was applied. Overall, the
incorporation of winter legumes could reduce N fertilizer input, sustain
corn production, and benefit soil health.