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Huang-Huai-Hai region is the major superiority area of planting industry and breeding industry in China. With the increasing attention to the rural environment problems caused by crop straw and livestock manures, it is important to analyze “raising by planting” in Huang-Huai-Hai region, realize agricultural waste comprehensive utilization, and implement green development. “Raising by planting” was the core idea of this paper. The “raising by planting” calculation methods were as follow. First, technical regulations for production of wheat-corn and field research results in Hebei, Henan and Shandong provinces were used to summarize production model of wheat-corn in Huang-Huai-Hai region. So the conventional fertilization could be defined. According to test results of researches, this paper determined the amount of partial replacement of chemical fertilizer by organic manures. At the same time, thermophilic aerobic composting was chosen as techniques of livestock manure comprehensive utilization. The untreated amount of livestock manures was calculated. Then, the quantities of different species of livestock and poultry were calculated. According to the technical regulations, the amount of nitrogenous fertilizer were 532.5, 562.5 and 575 kg/hm2 in Hebei, Henan and Shandong provinces. The ratio of partial replacement of chemical fertilizer by organic manures was 30%. So the amount of replacement were 159.75, 168.75 and 172.5 kg/hm2. At the same time, there were no influence on grain security after the replacement of chemical fertilizer by organic manures. Due to the additional application of organic manures promoted soil nitrogen leaching risk, the environmental risk assessment of nitrogen in arable farmland was used. Nitrogen input mainly consisted of nitrogenous fertilizer, organic manure converted from livestock manures, seed, straw returning, atmospheric dry and wet deposition and irrigation water. Nitrogen output mainly consisted of grain and straw. Grade of environment risk in farmland in Hebei, Henan and Shandong provinces were all medium risk. Nitrogen loss rate of thermophilic aerobic composting fromlivestock and poultry manures was 42.26%. Other calculation parameters of livestock and poultry production, such as feeding period, population structure, were defined by many research papers. So in production model of wheat-corn in Huang-Huai-Hai Region, 6 dairy cows, or 18 beef cattle, or 47 to 51 swine, 731 to 789 laying hens or 8062 to 8705 broilers per hectare were land carrying capacity. Besides, at the field scale, various factors, such as soil fertility and soil microbial, might affect the ratio of partial replacement of chemical fertilizer by organic manures. So more researches were needed in the amount of replacement. On account of medium environment risk in farmland, lowering the risks was necessary. Nitrogen input structure: 46.3% chemical fertilizer, 27.5% straw returning, 19.8% organic manure, 4.0% atmospheric dry and wet deposition, 2.0% irrigation water and 0.4% seed. So reducing straw returning was one of risk solutions. In simulation results, reducing corn stalk or wheat straw both lowered environment risk effectively. The results provide a reference for planting and raising combination in Huang-Huai-Hai region. [ABSTRACT FROM AUTHOR]

Warming climate has been a global concern. Methane is an important greenhouse gas. Double rice cropping system in Hunan province contributes a large proportion of the national rice production. In this study, we studied the effect of agricultural managements of rice on methane emissions from double cropping paddy fields in Hunan Province, China based on Meta-analysis method. Only studies designed as side-by-side paired field experiments were included in this study. Field management practices, treatments, and controls were described in detail in each study, and the location of the experiment was provided. If seasonal accumulative CH4 emission fluxes were not directly provided, these values were calculated by multiplying time and mean CH4 emissions by the measurement period. A total of 53 published peer-reviewed papers published before 2018were obtained by reference retrieval. From them, 840 groups of data were drawn. The management measures included crop rotation, symbiosis ecosystem, tillage, nitrogen fertilizer input, organic manure and residue retention. The control and treatment groups were fallow versus winter crops, paddy-rice system versus rice-duck and rice-fish systems, conventional versus no tillage, no fertilizer-N input versus fertilizer-N input, no manure input versus fertilizer-N and manure input, and fertilizer-N input versus residue retention. Natural log of response ratio was used as the effect size in the random effect meta-analysis. Results showed that CH4 emissions from both early and late rice accounted for 97.9% of annual CH4 emissions, and more CH4 emissions from late rice was observed than that for early rice. In the double rice cropping system, adding winter crops could significantly increase CH4 emissions from double rice season by 43.88% (P < 0.05) compared to winter fallow. Moreover, the increase in methane emissions from early rice was significantly higher than that from late rice. Symbiosis ecosystem of rice (i.e., with ducks or fishes) and adopting no-till significantly decreased CH4 emissions by 37.02% and 26.84% (P < 0.05), respectively. The decrease in the emission from early rice field was much higher than that from late rice field. As for yield-scaled emission, application of N fertilizer decreased yield-scaled CH4 emissions by 40.01% (P < 0.05) mainly due to the yields increased by 73.87% (P < 0.05). Additionally, organic fertilizer application and residue retention increased 68.11% and 71.80% (P < 0.05) of yield-scaled CH4 emissions without impacting the rice yield. The results suggested adopting symbiosis ecosystem rice production or no-till along with optimized N input is conducive to balancing rice yield and CH4 emissions from fields with double rice cropping system in Hunan province. [ABSTRACT FROM AUTHOR]