| In recent years,the planting area and soil quality of double cropping rice have declined,and the overall benefit of sustainable development of green agriculture is urgent to be improved.Jiangxi province is a typical double-season production area in the middle and lower reaches of the Yangtze River.In line with the development requirements of the National Planting Structure Adjustment plan（2016-2020）and the national"Thirteenth Five-Year plan",Jiangxi province stabilizes the Planting area of double cropping rice in the middle and lower reaches of the Yangtze River,steadily increases the rice yield,improves rice quality and improves grain Production efficiency,thus playing an important role in ensuring China’s food security and rice green development.This localization trial began in April 2012.Based on different winter crops（winter fallow,Chinese milk vetch,rape,garlic,and winter crop rotation）,five treatments were set up.On condition that winter crops and rice straw are returned to the field,the impact of different cropping patterns in the double cropping paddy fields in southern China on the environmental quality of paddy soil,rice yield and quality was discussed in depth,and the soil quality of paddy field ecosystems was comprehensively evaluated from the soil’s physical,chemical and biological aspects in hopes of understanding the effect of different paddy fields winter planting patterns and techniques on improving soil environmental quality of Paddy fields,thus providing a strong support for the rational application of green and efficient cropping rotation modes and technologies in the area of South China.The main research conclusions are:1)Compared with the winter fallow treatment from 2016 to 2017,different planting patterns of winter paddy fields has increased rice spike length,effective panicle number and seed setting rate to a certain extent.The early and late rice yields with the winter planting treatments increased respectively from 0.91%to 4.51%and from 1.01%to 6.33%.among which the total output of double-season rice has raised from 15630 to 15955 kg·hm-2 and the rate of increase from 0.77%to 4.79%.As for the treatments,winter croprotation,rapeseed and garlic treatments performed better.As for annual rice yield（2012-2017）,during 6 years’ winter crops planting,the yield difference of the 4th year has amounted to the largest,then followed by a trend of decrease in the output growth rate.Compared with the winter fallow treatment,the accumulation of rice dry matter under the winter planting treatments during the tillering and maturation periods of early and late rice increased by 1.06%～21.81%and 1.13%～16.85%respectively,but during the booting and panical stage,their performance varied.In terms of rice soil nutrients,total nitrogen,available potassium,available phosphorus and alkali-hydrolyzed nitrogen in Paddy soil were improved to a certain extent,but the difference was not significant（P<0.05）.In terms of rice soil nutrients,total nitrogen,available potassium,available phosphorus and alkali-hydrolyzed nitrogen in paddy soil were improved to a certain extent,but the difference was not significant（P>0.05）.In terms of plant nutrients accumulation,during the main growth period of rice,although the accumulation of N,P,and K varied among the treatments,the accumulation of nutrients mainly happened in the tillering and maturation periods,and the cumulative accumulated amount in the two periods was 101.13～142.28 kg·hm-2、32.32～56.46 kg·hm-2 and 112.61～139.37 kg·hm-2.The accumulated nutrient amount of winter planting crops of every treatment was higher than that of winter leisure treatment.After planting different crops for 6 years in the winter,the processing quality（milled rice rate and whole polished rice rate）,appearance quality（chalkiness rate and chalkiness）,and cooking and eating quality（amylose and gel consistency）of the early and late rice have been improved,in which the late rice is more obvious than that of early rice.2)The test of different soil layers in 2017 showed that the soil water stability aggregates were mainly 0.25-0.5 mm,and the size of soil particles were smaller aggregates（less than<0.25 mm）.During the growth season of early and late rice,the "smaller"contents of each treatment ranged from 78.1%to 84.8%and 85.6%to 91.1%.The amount of "larger" soil Particle（1-2 mm and 0.5-1 mm）was less,and the "larger" content of each treatment ranged from 13.1%to 21.9%and 8.9%to 14.4%respectively.At the same time,compared with the winter leisure treatment,the contents of"smaller" aggregates in the soil of early and late rice in different planting treatments in winter were significantly different,and the content of soil aggregates（<0.5 mm）decreased,and "larger" aggregate content（>0.5 mm）increased,while the early rice season performed more significantly than the late rice season（P<0.05）.The study also showed that there was a significant correlation among MWD,GMD,and R0.25 indicators（P<0.05）,and all three indicators were significantly negatively correlated with the fractal dimension D index（P<0.05）.The MWD and GMD of the water-stable aggregates in the 0-50 cm soil layers of early and late rice soils increased significantly,and the fractal dimension decreased significantly.This indicates that different planting patterns in winter in paddy fields are conducive to improving the stability of soil aggregates in early and late rice.3)In the 0-15 cm and 15-30 cm soil layers in 2017,the soil carbon stock management index during the early rice harvest period increased by 18.85%～49.77%and 3.17%～43.11%respectively,compared with the winter leisure treatment.The increase range of late rice was 14.52%～43.95%and 13.94%～40.40%,respectively.The soil carbon pool management index amplitude and organic carbon content were significantly greater in the 0-15 cm soil layer than that in the 15-30 cm soil layer（P<0.05）.Except for the significant positive correlation between carbon,microbial biomass carbon and particulate carbon,and between the easily oxidized state and microbial biomass carbon,there was no significant correlation between the other active organic carbons（P>0.05）.4)Compared with the winter treatments,from 2016 to 2017,the amount of bacteria,azotobacteria,and bacteria/fungi ratio in the soils during the early and late rice harvest period in different winter crops increased in different degrees.The microbial biomass carbon in rice fields and the nitrogen content increased,and the rang of early rice change was higher than that of late rice.Among them,the treatment of vetch in the winter and rotation（between potato,garlic,rapeseed and milk vetch）and rapeseed performed better.At the same time,soil invertase activity,invertase activity,urease activity and alkaline phosphatase activity were also significantly improved in different winter planting treatments.The early rice soil enzyme activity was higher than that of late rice.5)Compared with the winter fallow treatment,the types of weeds in the main growth stages of the early and late rice in the winter rice fields in 2017 were reduced,among which the garlic treatment was the best.The weeds as well as density of the treatments in the late rice season were lower than those in the early rice and the former decreased 35.7%～69.8%correspondingly.In terms of dry matter weight of weeds,the trends of early and late rice were basically the same,and the total dry matter weight of wet weeds was much greater than that of floating weeds,and there was a certain relationship between them.The total dry matter mass of weeds was positively correlated with alkali-hydrolyzable N while significantly and negatively correlated with soil pH and available K（P<0.05）.The effect of soil alkalized N on the dry matter quality of Paddy weeds was the largest and most direct;direct effects of available Potassium,pH,and available phosphorus were negative,and the effects were reduced in turn,but they indirectly Played a positive effect through the influence of other factors.6)Factor analysis of 26 indicators of paddy soil was conducted by means of principal component analysis and minimum data set（MDS）method was used to determine 9 soil quality indicators such as bulk density,pH,organic matter,MBN,alkaline nitrogen,available K,phosphatase AP,bacteria and 0.5 mm aggregates to reflect soil quality.After 6 years of planting different crops in winter,compared with the winter leisure treatment,the soil quality of all other treatments has increased significantly except winter garlic cultivation,which was followed by winter planting rotation in descending order（0.726）>planting rapeseed in winter（0.723）>planting milk vetch in winter（0.712）>Winter recreation（0.643）>Garlic treatment in winter（0.638）.Winter planting crop rotation,winter planting rapeseed,and winter planting of milk vetch have increased by 10.73%～12.91%.7)The light utilization efficiency of each winter treatment was significantly higher than that of winter fallow treatment,and the total light utilization rate of B and E treatment was relatively high,reaching 68.74%and 51.32%respectively.ComPared with winter crops such as milk vetch,rapeseed and potato,garlic planting in winter can make more effective use of the effective accumulated temperature of winter growing season and obtain higher production efficiency of temperature.Compared with the winter fallow treatment,the winter planting mode has increased the growth period of crops,so from the annual perspective,it can make more effective use of the temperature resources of winter cropping season and obtain higher croP yield.The results showed that the resource utilization efficiency of double cropping rice field could be improved by replanting different winter crops.（8）Among the total value of service functions of the dual cropping rice field ecosystem,supply function value of primary product,accumulation function value of soil nutrient and gas regulation function play dominant roles.Compared with the winter fallow treatment,the total value of service function of rice field ecosystem can be improved under different winter seed replanting methods in 2016 and 2017,with the increase range of 1.71%～6.31%and 3.09%～9.92%,respectively.Among them,winter garlic and winter compound seed rotation treatment is better.In terms of production and investment ratio,the results of this experiment show that the annual production and investment ratio of A is the highest from 2016 to 2017（only taking the output value of primary products into account）,which is 22.42%to 37.12%higher than that of winter planting treatment.However,if the total value of service function of dual cropping field ecosystem is taken into account,compared with winter leisure treatment,the value of other service functions of winter crops is higher except primary products. |
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