Objectives We compared the change in rice yield, quality, and soil fertility under three conventional rice-rotation patterns to set up a green cultivation mode in the study area.
Methods Field experiments were conducted for two years consecutively in the Han Tang experimental base of Hanzhong Institute of Agricultural Science from 2018 to 2020. Indica hybrid rice cultivar ‘Quanxiangyou 1521’ was used as test material in 2019 and conventional indica rice cultivar 'Huanghuazhan' in 2020. There were six crop rotation patterns and straw incorporation treatments: rape-rice rotation (R–R) with or without straw incorporation, Astragalus sinicus–rice rotation (G–R) with the incorporation of A. sinicus straw only, with the incorporation of A. sinicus and rice straws, winter fallow–rice rotation (F–R) with or without rice straw incorporation. After rice harvest, soil samples in 0–20 cm soil layer were collected to determine the soil nutrient contents, rice yield, yield components, and rice quality.
Results Compared with the no straw incorporation treatment, returning straw to the soil (P < 0.05) increased active organic carbon by 4.09%–18.89%, organic carbon by 6.84%–24.06%, available N by 9.63%–17.43%, available P by 9.10%–41.05%, and readily available K by 3.72%–17.36%. Rotation patterns improved soil fertility in the order R–R > W–R > G–R. Rotation mode had a (P < 0.05) effect on grain number per spike. Returning straw to the soil (P < 0.05) affected grain number per spike and the effective panicle of rice. Compared to G–R and W–R, R–R treatment (P < 0.05) increased the rice yield of ‘Quanxiangyou 1521’ by 1.71%, 8.95% and ‘Huanghuazhan’ by 5.51%, 6.41%, respectively. Rotation patterns did not affect rice appearance quality. However, it affected head rice rate, rice taste, protein, and amylose content. G–R treatment (P < 0.05) increased the protein content and gel consistency by 11.01% and 4.69% and decreased amylose content by 2.56%, compared to R–R and W–R. Returning straw to the soil increased rice heading rate by 0.48%–3.12% and taste value by 0.45%–4.79%.
Conclusions Returning straw to the soil annually under all the three rotation patterns can improve soil fertility, grain number per panicle, effective panicle, rice yield and appearance, processing quality, nutritional quality, and steaming quality of rice. Returning rice straw and Astragalus sinicus to the soil can improve indica rice yield and quality, and is a green cultivation mode suitable for high-quality agricultural development in Hanzhong region.
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