Study On The Improvement Of Soil Quality And Economic Benefit Under Rice-Crayfish-Duck Ecological Complex Cultivation Model

Paddy field ecological agriculture is a new agricultural production mode which combines planting and aquaculture.It can improve the quality of paddy field land and the efficiency of space use,and buffer the pollution brought by the outside world.It can not only maintain the stability of paddy field ecological environment structure,but also promote the function of material circulation in situ.Nowadays,most studies only focus on the effects of single ecological cultivation mode on water quality,soil,pests and diseases,and less on the effects of paddy field combined cultivation mode on soil physical structure,nutrients and economic benefits.Therefore,the paddy field soil in the polder area of Hangbu River basin of Chaohu Lake in Hefei was taken as the object of this study.Two years of field experiments were conducted to combine the two techniques of rice-crayfish rotation and rice-duck co-cultivation to form an ecological compound cultivation model.By studying the change characteristics of soil physical and chemical properties,humus and economic benefits under rice-crayfish-duck ecological compound cultivation mode,the effects of rice-crayfish-duck ecological compound cultivation mode on soil physical structure,fertility change characteristics and productivity of paddy field were clarified.In order to implement the ecological compound cultivation mode of paddy field with reduced input of chemical fertilizer and pesticide,the non-point source pollution of agriculture was reduced and the soil was improved.Soil provides theoretical reference.The main research results are as follows:(1)After two-years field trials,CDR mode increased the sum of soil texture powders and sands(p<0.05)compared with others.Compared with modes of SSR and DSR,0-10cm-soil-layer CDR mode reduced bulk density obviously and improved the total porosity of soil significantly;CDR mode significantly improved the soil saturated moisture content and field moisture capacity of paddy field compared with DSR mode;Improvement of the soil texture mode was remarkable compared with the SSR;The bulk density of soil(0-10 cm)decreased by 0.06 g·cm-3.CDR of 10-20cm soil layer showed no difference in the improvement of soil physical structure.(2)In terms of soil chemical properties,CDR mode significantly improved the contents of total nitrogen,available nitrogen and available phosphorus in 0-20cm soil and the content of available potassium in 0-10 cm soil layer compared with CK mode.After harvesting of rice,the CDR mode stabilized the total nitrogen content in the soil with a reduced amount of fertilizer.Compared with CK modes in different soil layers(0-10cm and 10-20cm),the organic matter of CDR mode increased by 8.77 g·kg-1 and 6.04 g·kg-1,the content of total nitrogen increased by 0.38 g·kg-1 and 0.35 g·kg-1,and the full phosphorous increased by 46.36%and 38.49%respectively.And available nutrients increased significantly as well.(3)Compared with four models,it was found that the soil organic and inorganic recombination increased in the CDR mode,but the recombination degree decreased.Although the application of fertilizer can improve the humus compound quantity in soil,the DSR mode was still lower the CDR mode.The effects of different planting modes on different conjugated humus were different.The carbon content of recombinant humus and loose soil in different soil layers was the highest in CDR model.The compact state and the stable state are on the contrary,CK,SSR and DSR modes were high.Loose/tight values are also highest in CDR mode.CDR mode can significantly increase soil humus content.Compared with CK mode,the content of humus and humic acid in the soil layer of 0-20 cm CDR mode increased significantly,and the ratio of HA/FA and PQ was also increased,CDR mode significantly improved the HA-?log k and HA-E4/E6,and the trend of optical properties of the four modes was SSR<DSR<CK<CDR.(4)The soil heavy metal contents in the test area was low,but it turned out that the CDR mode can reduce the amount of heavy metal contents in the soil.Compared with the DSR mode,the strain of the rice,the number of grain and the percentage of the rice in the CDR mode were increased by 4.83%,5.28%,and 2.84%,and the yield per area of rice was increased by 5.67%.Compared with SSR and DSR,CDR mode increased by 5.4%and 2.82%,respectively.Its gross output value and profit have significant difference with DSR mode.