Effects of irrigation techniques on soil carbon sequestration and yield maintenance in non-rainfed croplands under...

Driven by policies promoting green agricultural development and straw resource utilization, straw return has become an important strategy for improving cropland quality and enhancing farmland carbon sequestration. However, in non-rainfed croplands, stable crop production still depends on appropriate irrigation. Under straw return, the effects of different irrigation techniques on soil carbon sequestration and crop yield remain unclear, limiting the optimization of irrigation regimes and the synergistic enhancement of farmland carbon sequestration and yield stability.

Based on this, the present study was conducted in a non-rainfed maize-growing region of Northeast China using high-throughput sequencing and statistical modeling. This study revealed how different irrigation techniques under straw return altered soil microbial communities, enzyme activities, and carbon components, thereby influencing crop yield.

Under the BICS treatment, microbial network structure and dissolved organic carbon were strongly associated with variations in maize yield. In contrast, the SDCS treatment increased particulate organic carbon content by 15.28% compared with BICS, and exhibited higher laccase activity (up to 2.38 nmol min^-1 g^-1), greater fungal richness, and a higher proportion of K-strategist microorganisms. Among these factors, particulate organic carbon accumulation and shifts in microbial life-history strategies may represent important drivers associated with yield improvement. The DPCS treatment exhibited the highest maize yield (14,011.90 kg hm^-2), soil carbon component contents, sucrase activity, and bacterial richness, among which bacterial richness, laccase activity, and easily oxidizable organic carbon showed strong correlations with yield variation.

This study contributes to a deeper understanding of how irrigation techniques under straw return regulate soil carbon sequestration and crop yield formation, and provides a theoretical basis for optimizing water management strategies that jointly promote carbon sequestration and stable production in non-rainfed croplands.