Abstract:
In pursuit of higher yields by increasing farm chemical fertilizer inputs, farmland soil harden, soil available nutrients and organic matter content, soil acidification, the phenomenon such as fertilizer use efficiency decline. To explore the effects of comprehensive fertilizer optimization on soil nutrients and crop yield in rapeseed-rice multi cropping fields in the middle reaches of the Yangtze River. The main plot consisted of conventional fertilization (CK), Nitrogen reduction fertilization treatment (KF) and comprehensive optimization treatment (BMP). Ecological stoichiometry was used to investigate the changes of nitrogen, phosphorus and potassium content and crop yield in soil of rapeseed-rice multi cropping field under the under comprehensive fertilizer optimization. The results showed that compared with CK, the contents of BMP soil organic carbon, total nitrogen and total phosphorus were increased by 5.77%-16.81%, 1.73%-6.36% and 1.08%-6.84% (P<0.05), respectively, during 2018 to 2022. The soil C∶N ranged from 10.12 to 22.21, C∶P ranged from 12.47 to 22.45, and N∶P ranged from 1.01 to 1.39 under different treatments. Compared with CK, BMP treatment increase soil C∶N, decrease soil N∶P, and KF treatment decreased soil C∶N and N∶P. The C∶N was the highest, and the difference between BMP and CK was smaller With the passage of time. Compared with CK treatment, the BMP treatment rapeseed yield increased by 4.49%-26.78% and the rapeseed yield of BMP treatment increased year by year, while CK and KF treatment decreased first and then increased. Rice yield under CK and BMP treatment increased year by year from 2018 to 2022, while rice yield under KF treatment decreased slightly from 2020 to 2021. The marginal yield of N, P and K of rape and rice increased with the passage of time, and the yield of rape was better than that of rice. The correlation analysis showed that the yield of rape and rice was positively correlated with soil total nitrogen and total phosphorus content (
P<0.05), the most of the soil nutrients and stoichiometric characteristics were significantly correlated, and the average annual temperature was significantly correlated with soil nutrients and stoichiometric characteristics. In this study, long-term positioning monitoring was adopted to explore the dynamic changes of soil nutrients through the combination of organic fertilizer and weight-loss fertilization. In summary, the concluded that,after the organic and inorganic fertilizers are returned to the field, enhance the capacity of soil to maintain fertilizer, supply fertilizer and buffer fertilizer, and the nutrients required for crop growth are continuously supplied, which improves the soil structure and increases the crop yield. Therefore, the results of this study indicate that integrated optimization treatment is the best fertilization mode to optimize regional farmland nutrient management.