Ammoniated straw incorporation increases maize grain yield while decreasing net greenhouse gas budget on the Loess Plateau, China

Two major concerns of sustainable agriculture are safeguarding food security and attenuating climate warming. Straw incorporation is a widely used field management measure, but issues are associated with its high carbon: nitrogen (C:N) ratio. Ammoniated straw treatments aim to reduce straw C:N ratio; however, studies on the performances of long-term ammoniated straw incorporation on maize grain yield and net greenhouse gas (GHG) budget are still scarce. We conducted a long-term in situ trial (2012-2021) to estimate the performance of different straw utilization methods (CK, straw removal; CSI, conventional straw incorporation; ASI, ammoniated straw incorporation) on grain yield, GHG emissions, net ecosystem carbon budget (NECB), net greenhouse gas budget (NGB), and net greenhouse gas intensity (NGHGI) in maize fields. Grain yield was 8.3% and 24.7% greater with ASI than that with CSI and CK, respectively. And ASI had the lowest coefficient of variation for grain yield and the highest sustainable yield index. However, in comparison with CK, both straw incorporation methods significantly aggravated CO2 and N2O emissions, on average, by 101.0% and 107.5% (CSI) and 59.4% and 80.8% (ASI), respectively. The CK, CSI, and ASI obtained average NECB values of 38, 841, and 1556 kg C ha(-1), respectively. The amount of C in soil heterotrophic respiration, roots, extra-root material, and straw input significantly affected NECB. NGB and NGHGI were ranked ASI < CSI < CK, which was attributed primarily to significant changes in NECB, followed by N2O emissions. These results suggested that ASI can enhance maize yield and yield stability and reduce net GHG budget on the Loess Plateau.

Automated summary

The two major concerns of sustainable agriculture are food security and climate warming. Straw incorporation is a commonly used field management measure, but its high carbon: nitrogen ratio poses issues. Ammoniated straw treatments aim to reduce the ratio, but studies on their long-term effects on maize grain yield and net greenhouse gas budget are limited.