Productivity dynamics of agroecosystems under prevailing and alternative management practices across the United States

Industrialized agriculture has dramatically increased crop yields over the last century, but this has led to soil erosion and reductions in soil organic matter, raising concerns about the long-term sustainability of agroecosystems under weather variability. The first step towards restoring soil organic matter in agroecosystems is achieving sustained net ecosystem carbon uptake, as reflected in positive net ecosystem productivity (NEP). Thus, we evaluated how prevailing and potentially more sustainable, alternative management practices influenced NEP across a range of agroecosystems in the United States. Specifically, we analyzed eddy covariance data from eleven Long-Term Agroecosystem Research cropland locations to compare gross primary productivity (GPP) and NEP dynamics in the two systems. At seven locations spanning diverse environments, mean annual NEP was higher under the alternative management. Five of these sites with cover crops exhibited longer carbon uptake period (CUP) than their prevailing management counterparts. Importantly, a longer CUP was associated with increases in both annual sum of GPP and NEP and their peak values. Increased precipitation at the alternative sites enhanced CUP length, which contributed to higher overall productivity while prevailing systems showed no sensitivity to precipitation. The relationship between annual NEP and CUP showed steeper slopes at drier sites, indicating potential benefits for NEP gains associated with extended CUP. Our findings demonstrate that sustainable management practices can strengthen carbon uptake capacity, highlighting their importance for maintaining agroecosystem productivity.