Abstract
The combined use of organic manure and chemical fertilizer (CF) is considered to be a good method for sustaining high crop yields and improving soil quality. We performed a field experiment in 2019 at the research station of Guanxi University, to investigate the effects of cattle manure (CM) and poultry manure (PM) combined with CF on soil physical and biochemical properties, rice dry matter (DM) and nitrogen (N) accumulation and grain yield. We also evaluated differences in pre-and post-anthesis DM and N accumulation and their contributions to grain yield. The experiment consisted of six treatments: no N fertilizer (T1), 100% CF (T2), 60% CM + 40% CF (T3), 30% CM + 70% CF (T4), 60% PM + 40% CF (T5), and 30% PM + 70% CF (T6). All CF and organic manure treatments provided a total N of 150 kg ha−1. Results showed that the treatment T6 increased leaf net photosynthetic rate (Pn) by 11% and 13%, chlorophyll content by 13% and 15%, total biomass by 9% and 11% and grain yield by 11% and 17% in the early and late season, respectively, compared with T2. Similarly, the integrated manure and CF treatments improved post-antheis DM accumulation and soil properties, such as bulk density, organic carbon, total N, microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN) relative to the CF-only treatments. Interestingly, increases in post-anthesis DM and N accumulation were further supported by enhanced leaf Pn and activity of N-metabolizing enzyme during the grain-filling period. Improvement in Pn and N-metabolizing enzyme activity were due to mainly improved soil quality in the combined manure and synthetic fertilizer treatments. Redundancy analysis (RDA) showed a strong relationship between grain yield and soil properties, and a stronger relationship was noted with soil MBC and MBN. Conclusively, a combination of 30% N from PM or CM with 70% N from CF is a promising option for improving soil quality and rice yield.
Highlights
The combined use of organic manure and chemical fertilizer (CF) is considered to be a good method for sustaining high crop yields and improving soil quality
Compared with T 2, the combined treatment T 3 increased soil pH by (4.5% and 7.2%), soil organic carbon (SOC) (13% and 19%), total nitrogen (TN) (14% and 25%), available nitrogen (AN) (11% and 18%), availible phosphorus (AP) (14% and 22%), and AK (22% and 33%) dur
Our findings indicated that the combination of organic manure and chemical fertilizer improved N accumulation in leaves more effectively than the traditional urea-only application, and this was necessary to provide adequate grain-filling substrate and promote superior grain yield[58]
Summary
The combined use of organic manure and chemical fertilizer (CF) is considered to be a good method for sustaining high crop yields and improving soil quality. The integrated manure and CF treatments improved post-antheis DM accumulation and soil properties, such as bulk density, organic carbon, total N, microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN) relative to the CF-only treatments. The slow and steady N release from organic fertilizers is a benefit to sole CF application in achieving higher N use efficiency , crop yield, and grain quality[19,20,21]. The combined application of organic manure and CF has proven to be a promising option in improving and maintaining soil fertility and crop production than the use of either amendments or alone[20,22]. The advantages of organic manure fertilization are generally recognized, its optimal application ratio with CF remains unclear
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