Manure application mitigates soil organic carbon loss from decade-long stover removal in no-till continuous corn

Abstract

Soil organic carbon (SOC) is essential for maintaining soil fertility, agronomic productivity, and overall soil health. However, the maximum removal of crop residues, such as corn stover, can deplete SOC and soil essential nutrients, necessitating the need for effective mitigation strategies. In this study, we investigated the impacts of various agricultural management practices (residue management, animal manure application, winter rye cover cropping, inorganic nitrogen fertilizer application, and irrigation) on SOC stocks in no-till continuous corn production systems in south-central Nebraska. Over 10 years, manure increased SOC stocks by 6.00% ± 2.04%, whereas residue removal decreased SOC stocks by 2.61% ± 1.81% at the 0- to 150-cm depth. The cumulative SOC at the 0- to 150-cm depth was significantly higher with manure application compared to no amelioration (126 ± 1.5 vs. 116 ± 2.2 Mg ha⁻¹, p < 0.05). This improvement is attributed to reductions in bulk density, increases in soil pH, and increases in soil total nitrogen. Winter rye cover cropping partially offset SOC losses, though its effectiveness was limited by the short growing period and the resulting low biomass production in our study. Inorganic nitrogen fertilizer had minimal long-term impacts on SOC due to its high bioavailability and rapid loss. Irrigation facilitated deeper SOC accumulation via the movement of dissolved OC through the soil profile. Manure application, cover cropping, and the optimization of fertilizer and irrigation rates offer effective strategies for sustainable soil management, enhancing SOC storage, maintaining soil fertility, and supporting long-term agricultural productivity.