No abstract

the manure produced further enhances the soil. Green manure straw is good chicken feed as it has high protein. With moderate chicken intensity, the green manure continued to grow after the chicken were sold. And finial the mixture with chicken manure and straw enhances the soil. This system of cover crop planting and chicken grazing was relatively simple to maintain, reducing labor costs. The free-range chickens are then sold before the main crops are planted, thus increasing the economic outputs. In this study, using a symbiotic farming practice with cover crops with chicken grazing in a winter fallow field, we aim to (i) improve soil carbon and nitrogen availability, (ii) increase rice grain yield, and (iii) reduce CH 4 emissions in the rice growing season. Results Soil organic carbon and nitrogen. The soil organic carbon content in the plot with cover crops was significantly higher than that in the bare fallow field (CK, Table 1). The soil organic carbon in the cover crop and chicken grazing (+ C) treatment was 5.2% (3 ~ 8%) higher than that in the treatment with cover crops and no chicken grazing (− C). Similarly, the soil total nitrogen content in the plot with cover crops was significantly higher than that in the CK plot (Table 1). The soil total nitrogen in the + C treatment was 26.6% (18 ~ 41%) higher than that in the − C treatment. The C:N ratio of the CK was significantly higher than that of the plot with cover crops, and the C:N ratio in the + C treatment was 16.5% (11 ~ 23%) lower than that in the − C treatment, while no significant difference was observed between the + C and − C treatments in the rice planting seasons. Therefore, chicken grazing in the cover crop plots increased the soil organic carbon and total nitrogen. Soil microbial carbon and nitrogen. The soil microbial carbon and nitrogen contents in the plot with cover crops were higher than those in the bare fallow field (CK, Fig. 1a,b). The peak of the soil microbial carbon and nitrogen contents occurred 120 days after chicken grazing, reaching 478.6 and 19.1 mg kg −1 in the + C treatment and 433.9 and 23.5 mg kg −1 , in the − C treatment, respectively. There was a significant difference among the + C, − C, and CK treatments. In addition, the soil microbial C:N ratio in the cover crop plot was not higher than that in the CK plot, while in the late rice harvesting stage (347 days after chicken grazing), the soil microbial carbon and nitrogen in the + C and − C treatments were higher than that in the CK plot (Fig. 1c). The results suggest that in situ chicken manure input to the plots with cover crops and chickens increases the carbon and nitrogen sources available to the soil microorganisms, which may also stimulate cover crop growth and development, and further increase root exudates for the soil microorganisms.