Responses of leached nitrogen concentrations and soil health to winter rye cover crop under no-till corn-soybean rotation in the northern Great Plains

Winter rye (Secale cereale L.) is an important cover crop (CC) in the northern Great Plains (NGP), yet concerns over its establishment under the variable weather conditions of this region are an important limitation for its widespread adoption. This study evaluated the impacts of no-till corn (Zea mays L.)-soybean [Glycine max (L.) Merr.] rotation with winter rye CC established in 2017 on (a) water quality (nitrate-N [NO3--N], ammonia-N [NH4+-N], and total nitrogen [TN]) and (b) soil health parameters at the 0-to-15-cm depth. Data showed that rye CC biomass was 251 kg ha(-1) in 2018, 1,213 kg ha(-1) in 2019, and 147 kg ha(-1) in 2020, coinciding with contrasting growing degree days for rye CC (i.e., 1,458, 2,042, and 794, respectively), as a consequence of variable weather conditions. Water quality was not affected for the periods when rye growth was <300 kg ha(-1). In the season when rye CC had greater biomass (1,213 kg ha(-1)), significant reductions in leached NO3--N (19-20%) and TN (8.5-16%) concentrations were observed due to greater N uptake by rye CC (18.8 kg N ha(-1)). Rye CC showed significantly (p <= .05) higher microbially active carbon ( similar to 13%) and water-extractable organic N(similar to 11%) than the control treatment. Nonsignificant impacts on soil health indicators due to rye CC showed that the study duration (3 yr) may not be sufficient to see the beneficial impacts of CCs on soils. However, significant reductions in leached NO3--N and TN concentrations for one (2019) out of three study years suggest that rye with optimal growth has the potential of reducing N leaching and enhancing soil health for the NGP region.

Automated summary

Winter rye is an important cover crop in the northern Great Plains, but its establishment is limited by variable weather conditions. This study evaluated the impacts of no-till corn-soybean rotation with winter rye cover crop on water quality and soil health parameters. The results showed that winter rye cover crop had significant effects on reducing nitrate-N and total nitrogen concentrations in the soil, which can potentially improve water quality. Additionally, winter rye increased microbial activity and water-extractable organic nitrogen content in the soil, indicating potential improvements in soil health.