itrogen availability and early corn growth on plowed and no-till soils amended with different types of cover crops
Ladan, S. and P.A. Jacinthe. 2017.
Abstract
Heavy application of nitrogen (N) fertilizers to agroecosystems contributes to water pollution and emission of
nitrous oxide (N2O), an atmospheric constituent implicated in the greenhouse effect and stratospheric ozone
depletion. The incorporation of cover crops biomass into agricultural soil is a practice that could provide a
portion of the N needed by growing crops, and thereby could help reduce N fertilizer input and N loss from
agroecosystems. Although the cover crop composition and the tillage management history of receiving soils
could affect the pattern of mineral N release and its fates, these questions have not been addressed in previous research. A greenhouse experiment (85 d) was conducted to investigate the effects of two cover crops,
hairy vetch (Vicia villosa, C/N: 11) and rye (Secale cereale, C/N: 82) on mineral N flux, N2O emission, and
corn growth in soils under no-till (NT, 11 years) and plow-till (PT). Overall, tillage practice had only a marginal
influence on N dynamics. Although NO3
- flux was enhanced by both cover crops, the NO3
- released was more
efficiently utilized in the rye treatment. Corn growth and N uptake were significantly greater (P<0.02; 1.5 times)
with rye compared to the vetch treatment. Conversely, N2O emission was significantly (P<0.03) higher with
vetch than rye addition, with cumulative emission (across PT and NT) averaging 2.45 kg N ha-1 with vetch and
1.28 kg N ha-1 with rye addition. Positive relationships were found between NO3
- flux and N2O emission, with
the slopes of the regression lines suggesting a greater propensity of NO3
- released from vetch to be converted
into N2O. By leading to less N2O emission and better corn N uptake, the study results indicate that rye is a better
cover crop option than vetch, regardless of tillage practice.
Key Words
Tillage practices, cover crop, nitrogen management, nitrous oxide
