Conservation management improves agroecosystem function and resilience of soil nitrogen cycling in response to seasonal changes in climate

Authors: LI, LIDONG; KONKEL, JULIE - TENNESSEE DEPARTMENT OF AGRICULTURE; Jin, Virginia; SCHAEFFER, SEAN - UNIVERSITY OF TENNESSEE

Submitted to: Science of the Total Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/10/2021
Publication Date: 3/15/2021
Publication URL: https://handle.nal.usda.gov/10113/7313646
Citation: Li, L., Konkel, J., Jin, V.L., Schaeffer, S.M. 2021. Conservation management improves agroecosystem function and resilience of soil nitrogen cycling in response to seasonal changes in climate. Science of the Total Environment. 779. https://doi.org/10.1016/j.scitotenv.2021.146457.
DOI: https://doi.org/10.1016/j.scitotenv.2021.146457

Interpretive Summary: Climate change involves increased temperature and intensified precipitation. Increased temperature and intensified precipitation can potentially cause soil nitrogen loss from agroecosystems, posing risks to the environment. Conservation agricultural management, such as vetch cover crops, reduced tillage, and reduced inorganic fertilizer application, can reduce the soil nitrogen loss caused by climate change.

Technical Abstract: Understanding how conservation agricultural management improve soil nitrogen (N) stability in the face of climate change can help increase agroecosystem productivity and mitigate nutrient-impaired waters in west Tennessee and the downstream water quality of the Mississippi River Basin. We conducted a 2-year field study in a 36-year rain-fed cotton production system to evaluate the impacts of changing climatic factors (temperature and precipitation) on soil N under conservation management, including moderate inorganic N fertilizer application (0 and 67 kg N ha-1), winter cover crops (fallow; winter wheat, Triticum aestivum L.; hairy vetch, Vicia villosa Roth), and reduced tillage (no-till; disk tillage). Structural equation modeling (SEM) was used to quantify and compare the effects of conservation management and climatic factors on soil N concentrations. Fertilizer and vetch cover crops increased soil total N concentration by 16% and 18%, respectively, and also increased microbial N transformation rate by 41% and 168%. In addition, vetch cover crops also increased soil labile N concentrations by 57%, 21%, and 79%, i.e., extractable organic N, ammonium, and nitrate, respectively. The SEM showed positive effects of temperature and precipitation on labile N concentrations, suggesting destabilization of soil N and potential of soil N loss under increased temperature and intensified precipitation. Fertilizer and vetch might mitigate some of the effects of temperature by accelerating microbial N transformation, with vetch having a larger effect than fertilizer (0.35 vs. 0.15). No-till can reduce some of the effects of precipitation on soil labile N by maintaining soil structure. Our study suggests that fertilizer, vetch cover crop, and no-till might help improve function and resilience of agroecosystems in relation to soil N cycling. Soil N stabilization in cropping systems can be enhanced by adjusting agricultural management in the face of climate change.