Enhancing the coupling coordination of soil–crop systems by optimising soil properties and crop production via subsoiling

Abstract

Subsoiling is a well-known practice for improving soil structure, increasing soil nutrient content and enhancing crop growth. However, studies applying the coupling coordination analysis (CCA) model to reflect the coupling coordination between soil properties and crop production via subsoiling are still scarce. This study used the CCA to analyse the coupling coordination between soil properties and yield based on a long-term tillage positioning experiment. Tillage treatments included subsoiling (SS35 and SS40—subsoiling shovel) and rotary tillage (RT15—harrow blade, control). Soil pore structure was analysed using X-ray computed tomography and mercury injection tests. Results showed that SS35 and SS40 increased the macropore area by 82.0 %–130.7 % and the cumulative pore volume by 47.8 %–62.1 % in the 20–40 cm soil layer compared to RT15. This led to a 1.3 %–1.8 % increase in soil macro-aggregates, 9.0 %–14.5 % increase in mean weight diameter and 6.9 %–12.1 % increase in geometric mean diameter in case of SS35 and SS40 compared to RT15. These results indicated that subsoiling significantly enhanced the pore characteristics and aggregate stability in the 20–40 cm soil layer. The impact of SS40 on soil pore properties and aggregate stability surpassed that of SS35. As a result, SS35 and SS40 significantly increased carbon sequestration by 2.4 %–14.5 % and maize yield by 8.9 %–11.9 % compared to RT15. The CCA model analysis showed that SS35 and SS40 increased the coupling coordination (D) between soil properties and crop production compared to RT15, especially in the 30–40 cm soil layer. The D value was 0.617–0.899 for SS35 and 0.631–0.817 for SS40. This study provides new insights into quantifying the role of tillage for multi-indicators in the soil–crop system. The findings will guide policymakers in formulating for more sustainable tillage to improve crop production and ensure carbon mitigation.