Effects Of Straw And Biogas Slurry Returning On Soil Quality And Crop Yield

Crop straw and biogas slury with abundant mineral elements and organic nutrients are the two sources of fertilizer.In order to find an applicable straw and biogas slury returning back to field,a two-year experiment was conducted in Fengxian(Shanghai)and Dafeng(Jiangsu).Effects of different straw-back and biogas slury-back quantities on soil environment and crop yield were investigated.Soi physicochemical characteristics,soil heavy metal,crop yield,crop economic benefit and crop grain heavy metal were dectected.While ensuring the yield and the farmers economic benefits,relative better solutions for straw back and biogas slurry back could be chosen by synthesized comparision.Afterwards,the environmental pollution would be reduced.Through this research,it is hoped to provide some scientific basis and data support for recycling of agricultural wastes.The major results were as follows:(1)Effects of straw back on soil environment and crop yield of wheat.The experiment was carried out with of six treatments:control with no straw back and chemical fertilizer,chemical fertilizer treatment,quarter straw back,half straw back,full straw back and two-third straw back.The results showed that there was no significant difference in soil bulk density and soil water content under different treatments of straw returning after two years of straw returning.However,compared with the conventional fertilization treatment,the soil total nitrogen content of CFS3/2 treatment was the highest,1.00 g/kg,which was 11.10%higher than that of the conventional fertilization treatment under different straw treatments.The soil total carbon content of the treatment was also the highest,at 16.8 g/kg,5.66%higher than that of conventional fertilization treatments.The contents of lead,cadmium and chromium decreased by 8.96%,11.08%and 9.20%on average in all treatments.The average yield of two years of straw returning was 5769kg/hm~2,Of which,the highest yield of CFS was 6823.50 kg/hm~2.Compared with conventional fertilization,the content of lead in wheat decreased by34.96%,the content of cadmium decreased by 13.37%,the content of chromium decreased by 8.86%.(2)Effects of straw back on soil environment and crop yield of rice.A total of six treatments(the same above).The results showed that after two years of straw returning,different treatments of straw returning had little effect on soil bulk density and soil moisture,no significant difference.However,compared with the conventional fertilization treatment,the soil total nitrogen content of CFS3/2 treatment was the highest,1.03 g/kg,which was 11.96%higher than that of the conventional fertilization treatment under different straw returning treatments.The soil total carbon content was the highest 17.1 g/kg,increased by 7.55%compared with the conventional fertilization treatment.The contents of lead,cadmium and chromium decreased by 8.97%,11.13%and 10.42%respectively on average.The average yield of two-year straw-returning rice was 9104.13 kg/hm~2,of which the CFS-treated rice had the highest yield of 9370.5 kg/hm~2.Compared with the conventional fertilization treatment,the lead content of rice straw decreased by 14.96%;Cadmium content decreased 5.42%;chromium content decreased 7.42%.(3)Effects of biogas slurry back on soil environment and crop yield of rice.The experiment was consisted of five treatments:control with no slurry back and chemical fertilizer,chemical fertilizer,biogas slurry instead of 1/2fertilizer treatment,full biogas slurry back and biogas slurry instead of 3/2fertilizer treatment.The results showed that after two years of biogas slurry treatment,different biogas slurry treatments had little effect on soil bulk density and soil moisture,and there was no significant difference.However,compared with the conventional fertilization treatment,the total nitrogen content of BL3/2 treated soil was 1.47 g/kg,which was 14.84%higher than that of conventional fertilization treatment under different treatments of biogas slurry treatment.The soil total carbon content was the highest 18.1g/kg,which was increased by 7.10%compared with the conventional fertilization treatments.The contents of lead,cadmium and chromium in the treated soils increased by 10.24%,16.60%and 12.57%respectively.The average yield of two-year biogas slurry treatment was 9768.50 kg/hm~2,of which the BL treatment was the highest,which was 10238 kg/hm~2.However,compared with the conventional fertilization treatment,12.00%;the content of cadmium increased by 13.01%;the content of chromium increased by12.89%.On the whole,reasonable straw returning can increase soil carbon and nitrogen,crop yield and peasant income,meanwhile,reduce the accumulation and accumulation of heavy metals in grain and soil.With the increase of the straw planting years,the contents of lead,cadmium and chromium in the soil showed a decreasing trend.Based on the assurance of environmental benefits and stable economic benefits,this study recommended the selection of the full amount of straw in the actual production of local crops.However,excessive biogas slurry will cause accumulation and enrichment of heavy metals in grain and soil,and the content of heavy metals will also increase with the increase of biogas slurry life,so the amount of biogas slurry should be reduced in crop production as much as possible And control the years of continuous return.