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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Adaptive Cropping Systems Laboratory » Research » Publications at this Location » Publication #418762
Research Project: Developing Practices for Nutrient and Byproducts to Mitigate Climate Change, Improve Nutrient Utilization, and Reduce Effects on Environment (BRIDGE PROJECT)

Location: Adaptive Cropping Systems Laboratory

Title: The decomposition and nutrient release dynamics of mixed cover crops in a no-till row crop rotation

Author
item IAMJUD, KRITSANEE - Louisiana State University Agcenter
item Fultz, Lisa
item DICK, KATHLEEN - University Of Arkansas
item MUELA, P.CAROLINA - Louisiana State University
item CARRILLO, PEDRO - Louisiana State University Agcenter

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/6/2025
Publication Date: 12/27/2025
Citation: Iamjud, K., Fultz, L.M., Dick, K., Muela, P., Carrillo, P. 2025. The decomposition and nutrient release dynamics of mixed cover crops in a no-till row crop rotation. Agronomy Journal. https://doi.org/10.1002/agj2.70262.
DOI: https://doi.org/10.1002/agj2.70262

Interpretive Summary: To date, very little research has focused on multi-species cover crop mixes, their degradation, and the ultimate impacts on soil nutrient content cycling. This research demonstrated that multi-species mixes produced greater amounts of biomass and thus increased nutrient scavenging and release to subsequent nutrient release. On average, 50% of nutrients, particularly nitrogen, were released from biomass within 3 to 4 weeks of cover crop termination. However, only soil nitrogen concentrations reflected this release, with optimum soil inorganic nitrogen availability approximately 6 weeks post termination. Of the mixes included, crimson clover + hairy vetch + radish and cereal rye + hairy vetch resulted in greater soil nitrate-nitrogen concentrations compared to all others.

Technical Abstract: Impacts of cover crop mixtures on essential nutrient availability after termination is not well understood in the Mid-South. This study’s goal was to evaluate biomass degradation and nutrient turnover and availability in soil from cover crop biomass. Experiments were conducted at the Macon Ridge (MRRS) and Dean Lee (DLRS) Research Stations in northeast and central Louisiana, respectively. At MRRS, treatments included seven cover crop (including mono- and polycultures of legumes, grasses, and a brassica) and a fallow (control) as the main plot, and two nitrogen rates (0 and 179 kg N ha-1) as the subplot. This research was replicated at DLRS, with the number of cover crop treatments reduced to four. Cover crop biomass production was assessed at termination in mid-February and nylon bags containing collected biomass were placed on the soil surface. Soil samples and nylon bags were collected at intervals of 0, 1, 2, 3, 4, 6, and 8 weeks post-termination to determine the optimum time of nutrient availability after cover crop termination and degradation rates of cover crop biomass. The polyculture cover crop mixes tended to produce more biomass and N assimilation. The optimum timing of inorganic-N availability to cash crop was 6 weeks after cover crop termination which resulted in greater soil NO3--N, for synchronous release of N to meet the main crop N demand early in spring. However, soil P, K, and S were not significantly different among cover crop treatments. 3-species mix of grass-legume-brassica (BO+CC+RD) showed the most rapid N degradation rate while CC+HV+ RD had the greatest N released amount from biomass.