Molecular Soil Biology 2024, Vol.15, No.5, 236-246 http://bioscipublisher.com/index.php/msb 242 6 Case Study 6.1 Effects of straw incorporation and potassium fertilization on soil stability in rice-oilseed rape rotation In the rice-oilseed rape rotation system of southern China, soil structure stability and fertility directly impact agricultural productivity and ecological sustainability. However, due to a lack of organic matter and inadequate fertilizer management, soil structure degradation has become a significant issue. Consequently, straw incorporation and appropriate potassium fertilization have been widely adopted as effective measures to improve soil quality (Hagos et al., 2020). A multi-year field study analyzed the effects of straw incorporation and potassium fertilization on soil aggregate stability and nutrient content (Xue et al., 2022). The results indicated that straw incorporation significantly increased soil organic carbon (SOC) levels and iron oxide concentrations, especially in soil aggregates larger than 0.25 mm, which contribute to enhanced soil aggregate stability. This practice effectively reduced SOC loss in rice-oilseed rape rotation, showing higher aggregate stability after the harvest of oilseed rape. In contrast, the direct impact of potassium fertilization was limited, mainly influencing processes related to SOC transformation and microbial activity. Scanning electron microscopy further demonstrated the improvement in soil structure under straw incorporation treatment, showing a rougher surface with increased porosity (Figure 4), enhancing soil’s water retention and nutrient-holding capacity. The study concluded that straw incorporation, as a soil improvement measure, offers significant advantages for boosting soil fertility and promoting sustainable agriculture. Figure 4 Scanning electron micrograph showing the structure and morphology of aggregates under no straw returned and straw returning treatments. F2, mineral nitrogen, phosphorus and potassium; F4, mineral nitrogen, phosphorus and potassium with straw returning (Adopted from Xue et al., 2022) Image caption: The figure shows that in the treatment without straw returning (F2), soil aggregates have smaller particles, fewer pores, and a more compact arrangement; whereas in the straw-returning treatment (F4), aggregates have larger particles, significantly more pores, smoother surfaces, and contain some undecomposed straw residues. The results indicate that straw returning improves the structure and stability of soil aggregates by increasing organic matter and promoting microbial activity (Adapted from Xue et al., 2022)
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