| The quality of cultivated land and soil fertility is the prerequisites for ensuring the yield and quality of agricultural products.For a long time,the traditional agricultural development model has resulted in the issue of land degradation and pollution which has seriously restricted the sustainable development of agriculture.The scientific rotation system can be an important way to realize high and stable crop yield through the effective plant protection and improving the utilization effectiveness of soil nutrients,reducing the intensity of land utilization.The rotation system of rice and rain-fed crops can be proved as an important farming model of rice production worldwide to impact on the quality of arable land,rice yield and quality positively.Rice is a global staple food.Due to the lower benefit,farmers are always unwilling to plant rice.This threatens social,national and human security.To meet the dual requirement of rice quantity and quality,it is necessary to study the supply side of rice production by ensuring rice production efficiency(ecological,social and economic benefits).Some relative data are collected in the design and implementation of field experiments to analyze.In this paper,the differences between the soil physical and chemical properties,soil heavy metals content and the effects of different crop rotation patterns(or fallow)on rice production efficiency(economic,social and ecological benefit)were studied by single factor analysis of variance(One Way ANOVA)method.Furthermore,the rice yield and soil physicochemical properties and rice biological traits are researched by the correlation analysis method.Based on the above research results,the quantitative evaluations of rice production benefit are conducted further by the analytic hierarchy process and comprehensive index method.The main conclusions are as followings:1)The rotation system between rice and potato can be promote in southern China due to the universal significance of high production,nutrient utilization efficiency and lower production costs for the two crops.Although not applying fertilizer in rice production after planting potatoes,melons,rape planting rice production is used in fertilizer,but the potato-after the first rice crop rotation all the output of rice is still higher than production of watermelon-after the rice crop rotation,and potato,rice crop rotation mode and DongXianTian-rice,watermelonrice crop rotation mode effects on rice yield significant differences are,it shows that the potato-rice crop rotation mode can significantly increase the rice yield,direct drive the growth of economic benefits,ensure food security,the social benefit,and the highest comprehensive benefits.Next year despite the comprehensive benefit of rice production is lower than rape-rice crop rotation,but potato-rice crop rotation after the comprehensive benefit is higher than DongXianTian-rice,due to its low economic value,rape and potato crop with high economic value,determines the potato-rice crop rotation have great potential application in the practical production.2)Fallow continuously can improve rice production efficiency in the long term,which is a result of improving cultivated soil quality.In the years of farming soil,fallow has significant effects on soil physical and chemical properties,determines the direction and degree of changes in soil quality,improve production,increase economic benefits,has certain reference value in practical production.First year of the best potato-rice crop rotation mode,in the second year of planting,found that the economic benefit index and economic benefit value of DongXianTian-rice crop rotation mode was higher than potatoes-rice crop rotation,rape-rice crop rotation mode,.Again after winter fallow planting rice,rice biomass,yield,production rate and the economic benefit was higher than potato-after the rice crop rotation mode,.First year DongXianTian or DongXianTian-soil nutrients were lower after rice crop rotation,but by the next year winter fallow planting again,all these nutrients content showed a trend of recovery increase.After winter fallow,the economic indicators were lower than the ms-rice rotation pattern in the first year,but still higher than the watermelon-rice rotation pattern.By the following winter,the economic index of rice production was highert than the potato and rice crop rotation and the rape of rice.DongXianTianrotation of rice and potato-rice crop rotation mode,rape-rice crop rotation had significant influence on rice yield,the average grain yield DongXianTian-the highest rice crop rotation.3)Planting rape can improve soil quality and reduce the content of soil heavy metals,which can be referred to study ecological remediation of soil heavy metal pollution.In the single year,the amount of heavy metal Cu and Zn in the soil can be reduced,especially in Zn.In the benefit evaluation,the oil and rice rotation is the best.The cost of cooking oil as a green crop is low.Alkali solution of rape planting,soil nitrogen,available phosphorus and available potassium content are obviously increased than DongXianTianrice crop rotation,potato-rice crop rotation,which may be due to the fact that rape straw is rich in NPK,can increase soil nutrients,after mixed with the soil and that is beneficial to the growth of late rice stalk,rape,rice crop rotation after the highest average plant height of rice.In the two years,watermelon-rice-cole-rice crop rotation mode can adjust the pH value of soil,stability of soil organic matter content,is helpful to increase soil NPK content,improve soil fertility and soil adsorption capacity of heavy metal,reduce fertilizer use,protect the farmland soil ecological environment and its comprehensive benefit performance is the best.That is beneficial to improve the benefit of the whole farm production system,and the rape planting may be important.4)The combination of various crops in the long term,especially the introduction of green manure crops,will increase the comprehensive benefits of rice production in the long term.In the three rotation mode,although watermelon-comprehensive benefit of rice crop rotation are poor in potato-rice,DongXianTian-after rice crop rotation in the first year,rapeseed were superior to potato-rice,DongXianTian-after the rice crop rotation in the second year.From two years in a row planting,although watermelon is high consumption of soil fertility and crop and every two years to multiple cropping,as a result of rape planting,the watermelon-rice-cole-the combination of the rice crop rotation model of comprehensive benefit performance or the best,so in the farmland cropping system,the different crops between combination of crop rotation,especially the participation of green manure crops in the year could help improve the long-term comprehensive benefits,and the choice of green manure may be the key. |
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