Investigation And Analysis Of The Current Situation Of Fertilization And Economic Benefits In Rice-crayfish

The integrated cultivation of rice and crayfish is a new rice production model that combines rice cultivation and crayfish farming.It realizes the dual use of one water and two harvests of one field,which is called"a revolution in modern agriculture"and has made important contributions to the increase of farmers’income,agricultural efficiency and rural revitalization.In 2020,the area of rice and crayfish cultivation and the yield of crayfish in Hubei ranked first in China,with 48,700 hm²and 982,000 t,respectively.Jianghan Plain is the main adoption area,accounting for77%of the planting area of the rice-crayfish system in Hubei Province,which is also a typical representative of the rice-crayfish system.Due to the introduction of crayfish（Procambarus clarkia.）,the nutrient budget pathway of rice-crayfish system became more abundant than that of rice mono cropping,especially the input of feed nutrients of crayfish and the output of drained nutrients of rice-crayfish system.Therefore,it is of great significance for scientific fertilization and sustainable development of rice-crayfish system to study the current situation of rice fertilization and its existing problems.In this paper,the sampling method of farmers was adopted to investigate and analyze the rice cultivation mode,yield level,fertilizer type,nutrient dosage,fertilization mode,fertilization frequency,base application ratio and comprehensive benefit of rice-crayfish system,so as to provide the basis for nutrient management of rice-crayfish system.The main research results are as follows:（1）Clarified the rice planting characteristics and yield level of the rice-crayfish system.The main cultivation method of rice was direct seeding,accounting for 69.4%;The average sowing amount was 63.6 kg/hm²,which was not significantly different from that of rice monoculture mode.The proportion of crayfish ditch area in rice-crayfish system was 9%-40%,with an average of 25%.The rice yield of rice-crayfish system was 3478.9 kg/hm²to 9959.5 kg/hm²,with an average of 7742.9 kg/hm²,which was 10.8%lower than that of rice mono-cropping system.（2）The main fertilizer types,nutrient dosage,fertilization times and fertilization methods of rice in the rice-crayfish system were clarified.Compound fertilizer and urea were the main fertilizers used in rice-crayfish system,accounting for 94.9%and85.5%respectively.Compound fertilizer formula is mainly 17-17-17 and 26-10-15.In the whole growth period of rice,the nutrient dosages of N,P₂O₅and K₂O were 0kg/hm²-164.8 kg/hm²,0 kg/hm²-170.1 kg/hm²and 0 kg/hm²-204.0 kg/hm²,and the average dosages were 164.8 kg/hm²,74.3 kg/hm²and 89.6 kg/hm²,respectively,which was reduced by 36.7 kg/hm²,25.6 kg/hm²and 13.3 kg/hm²,respectively,compared with rice mono cropping mode.The declines were 18.2%,25.6%and12.9%,respectively.Fertilization frequency was mainly twice（one base fertilizer and one top fertilizer）,accounting for 81.7%;The percentages of N,P₂O₅and K₂O were55.1%,86.8%and 83.2%,respectively,which were decreased by 0.9%,3.6%and2.5%,1.6%,4.0%and 2.9%,respectively,compared with rice mono-cropping mode.The main fertilization method was artificial fertilization,accounting for 96.3%.（3）Compared with rice monoculture mode,rice-crayfish system increased the economic benefits and energy sustainability index of the system,and reduced carbon emissions in rice season.The economic benefit of rice shrimp cultivation system was24,300 yuan/hm²,which was 1.2 times higher than that of rice monoculture mode.The carbon emission in rice season was 4.97 t CO₂-eq/hm²,which decreased by30.0%compared with rice monoculture mode.The sustainability index of the system was 29,an increase of 70.6%compared with the rice monoculture model.With the increase of rice-crayfish system field area,the economic benefit and energy sustainability index of the system showed an increasing trend,and the annual carbon emission and rice season carbon emission showed a decreasing trend.In conclusion,the rice yield of rice-crayfish system in Jianghan Plain showed a decreasing trend compared with that of rice monocultural mode,and there was a large variability.Therefore,it is necessary to further regulate the system to increase its ability to resist disasters.There are some problems in the rice-crayfish system,such as too high proportion of crayfish ditch area,non-standard fertilization during the growth period of rice,and unbalanced ratio of foundation and catchment.From the perspective of comprehensive benefits,there are some problems,such as too much investment in the early stage and difficult to maintain income in the later stage,so it is suggested to further standardize in the future.