Molecular Soil Biology 2024, Vol.15, No.5, 236-246 http://bioscipublisher.com/index.php/msb 243 6.2 Enhancing crop yield through straw incorporation and phosphorus fertilization In the rapeseed-rice rotation system widely cultivated in the Yangtze River basin, the low utilization efficiency of phosphorus fertilizer has led to insufficient soil nutrient accumulation or phosphorus runoff, impacting both crop growth and environmental quality. With the promotion of straw incorporation techniques, combining this approach with appropriate phosphorus application has become a viable method to enhance soil fertility and boost crop yields (Yang et al., 2020; Zhang et al., 2023). In a three-year experiment, Zhang et al. (2023) investigated the effects of combining straw incorporation with various phosphorus fertilization strategies on crop yield and soil health in a rapeseed-rice rotation system. The results indicated that alternating the incorporation of rice and rapeseed straw and applying 120 kg/ha of phosphorus fertilizer during the rapeseed season (T2P3 treatment) significantly improved crop yields, with a 15% increase in rapeseed yield and a 17% increase in rice yield. Additionally, the T2P3 treatment markedly enhanced the available phosphorus content in the soil and optimized the soil microbial community structure, particularly promoting the growth of phosphate-solubilizing bacteria such as Pseudomonas and Bacillus subtilis. Compared to traditional seasonal fertilization (T2P2), the T2P3 treatment improved soil fertility and biodiversity while reducing phosphorus fertilizer usage, demonstrating the feasibility of this optimized strategy. This study provides scientific evidence for phosphorus management and straw utilization in the region. 7 Challenges and Limitations 7.1 Decomposition rate and nutrient release The decomposition rate of rapeseed straw and the subsequent release of nutrients are critical factors influencing its effectiveness in improving soil fertility and crop productivity. The presence of arbuscular mycorrhizal fungi (AMF) has been shown to significantly promote the degradation of rapeseed straw and enhance the release of essential nutrients such as nitrogen, phosphorus, and potassium (Guo et al., 2023). However, the rate of decomposition can vary significantly depending on environmental conditions and the presence of microbial communities. For instance, the application of decomposition agents can alter the fungal community structure, thereby affecting the rate of straw decomposition and nutrient release (Wang et al., 2022). Additionally, long-term studies have shown that the effects of straw return on soil organic carbon (SOC) storage can be inconsistent, with some soils showing greater increases in SOC stocks than others (Hagos et al., 2020). This variability poses a challenge in predicting the exact benefits of rapeseed straw incorporation in different soil types and climatic conditions. 7.2 Potential negative effects While rapeseed straw can improve soil fertility, it may also have potential negative effects, such as allelopathy, which can inhibit the growth of subsequent crops. Studies have found that aqueous extracts of rapeseed straw significantly affect the seed germination and seedling growth of crops such as oats, maize, and sunflowers. However, higher concentrations of the extract inhibit root and stem growth in sunflowers, while lower concentrations have a promoting effect on maize. This allelopathic inhibitory effect is most pronounced in sunflowers, with relatively lesser effects on maize and oats (Gao et al., 2020). The incorporation of rapeseed straw has been associated with changes in soil microbial communities, which can lead to the production of allelopathic compounds that negatively affect plant growth (Jin et al., 2021). Additionally, the application of straw can result in increased greenhouse gas emissions, including methane and nitrous oxide, which contribute to global warming (Li et al., 2023). These emissions are particularly concerning in paddy-upland cropping systems, where the combination of straw and high moisture levels can exacerbate the release of these gases (Salam et al., 2019). Therefore, careful management practices are required to mitigate these potential negative effects and ensure the sustainable use of rapeseed straw in agriculture. 7.3 Practical challenges in large-scale application The large-scale application of rapeseed straw in agricultural systems presents several practical challenges. One major issue is the logistics of collecting, transporting, and evenly distributing the straw across large fields. This process can be labor-intensive and costly, particularly in regions with limited mechanization (Song et al., 2023).
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