| Upland red soil is an important agricultural production resource in Jiangxi Province.The rich water and heat resources make the agricultural production and economic development potential of the region huge,and play an important role in the sustainable development of agriculture in China.However,the low fertility of upland red soil has seriously restricted the sustainable development of agriculture in Jiangxi red soil region.Based on this,this study selected peanut shells and biochar prepared from dry land crops as the research materials,and set up seven treatments:(1)CK:routine management,(2)S1:peanut shell(3000 kg/hm~2),(3)S2:peanut shell(4500 kg/hm~2),(4)S3:peanut shell(6000kg/hm~2),(5)BC1:peanut shell biochar(1000 kg/hm~2),(6)BC2:peanut shell biochar(1500 kg/hm~2),(7)BC3:peanut shell biochar(2000 kg/hm~2).Through the method of field experiment,the effects of peanut hull and its biochar on physical and chemical properties,microbial activity,microbial community structure and sweet potato yield of upland red soil were studied.The main factors affecting the quality of upland red soil were discussed,which provided scientific basis for the improvement of upland red soil fertility and theoretical and practical guidance for the comprehensive utilization of crop straw and the implementation of circular agriculture in upland red soil area.The main results are as follows:(1)The application of peanut shell and its biochar could reduce soil bulk density,and the largest reduction of soil bulk density was found in the 15-30 cm soil layer of S3 treatment,reaching 1.24%;The largest decrease in bulk density of biomass carbon is in the 0-15 cm soil layer treated by BC3,up to 3.01%.The application of peanut shell and its biochar could increase soil organic carbon content,and peanut shell and its biochar had the largest increase in soil organic carbon content at the initial stage of root tuber formation.The 0-15 cm soil layer of S3 and BC3 treatments reached 3.11%and 3.84%respectively.The results showed that the application of peanut hull and biochar could increase the total nitrogen content of soil,among which S2 and BC2 treatments had the most significant effect,but increased first and then decreased with the increase of application amount.The application of peanut hull and its biochar could increase the total phosphorus content of soil,and it increased with the increase of application rate,and the effect of S3 and BC3 on soil total phosphorus content was the best.Peanut shell and its biochar could increase the content of soil hydrolyzed nitrogen,and peanut shell and biochar increased the content of soil hydrolyzed nitrogen most in the initial stage of root formation.The 15-30 cm soil layer of S3 and BC2 treatment reached 47.36%and 57.23%respectively.The effect of peanut shell and biochar application on soil available phosphorus content had no significant change.(2)The results showed that the application of peanut shell and its biochar could increase soil respiration intensity and microbial biomass carbon content.The increase of soil respiration intensity of peanut shell was the largest at seedling stage,which reached 152.20%in 0-15 cm soil layer of S3 treatment;the largest increase of soil microbial biomass carbon content of peanut shell was in the root harvest period,and reached 183.56%in 0-15 cm soil layer of S3 treatment;The increase of soil respiration intensity by biochar was the largest in the period of root tuber harvest,which was 242.47%in the 15-30 cm soil layer of BC2treatment;The maximum increase of microbial biomass carbon content in peanut hull was at the initial stage of tuberous root formation,and the 15-30 cm soil layer treated by BC2reached 251.15%.The application of peanut hull and its biochar increased the activities of FDA hydrolase and dehydrogenase in soil to a certain extent,among which the treatment of S2 and BC2 had the most significant promotion effect on the activities of soil FDA hydrolase and dehydrogenase,and more application(treatment of S3 and BC3)could inhibit the activities of FDA hydrolase and dehydrogenase.The application of peanut hull and its biochar promoted the activities of catalase and sucrase in soil to a certain extent,among which S3 and BC2 had the most significant effect on catalase and sucrase activities.Peanut hull and its low-dose biochar(BC1 treatment)could improve soil urease activity.Peanut shell had the largest increase in soil urease activity at seedling stage,which was 45.70%in15-30 cm soil layer of S3 treatment,and the largest increase of soil urease activity was in seedling stage,which reached 47.79%in 15-30 cm soil layer of BC1 treatment.(3)The application of peanut hull and its biochar increased the total PLFAs content and PLFAs content of each microbial community to a certain extent.Among them,peanut shell and biochar increased the total PLFAs content of soil microorganism in the early stage of tuberous root formation.The 0-15 cm soil layer treated by S2 and BC2 reached 106.64%and 112.16%respectively.Peanut shell and its biochar increased the content of PLFAs of Gram-positive bacteria in soil at the initial stage of root tuber formation.In the 0-15 cm soil layer treated with S2 and BC2,the content of PLFAs increased by 95.33%and 102.52%respectively;The increase of PLFAs content of soil Gram-negative bacteria by peanut shell and biochar was the largest in the early stage of tuberous root formation,and the 0-15 cm soil layer treated by S2 and BC2 reached 108.72%and 115.64%respectively.Peanut shell and its biochar increased the contents of PLFAs,actinomycetes,arbuscular mycorrhizal fungi and fungi PLFAs to a certain extent,and S2 and BC2 treatments had the most significant effect on the PLFAs content of each flora.Excessive application(S3,BC3treatment)could reduce the total PLFAs content and PLFAs content of each microbial community,thus changing the structure of soil microbial community.(4)The application of peanut shell and biochar could increase the yield of sweet potato in upland red soil.The yield of sweet potato increased first and then decreased with the increase of peanut shell and biochar application,but it was higher than CK treatment in general,S2 treatment had the largest increase in sweet potato yield,which reached 13.00%,and BC2 treatment had the largest increase in sweet potato yield,reaching 20.72%.In conclusion,appropriate application of peanut shell and its biochar can effectively improve soil physical and chemical properties,soil microbial activity and microbial community structure,and increase crop yield.In general,the effect of biochar on improving the quality of upland red soil is better than that of peanut shell,and BC2 treatment has the best effect on soil quality.Therefore,the application of peanut shell and its biochar combined with the actual planting situation of upland red soil has certain feasibility in improving soil microbial environment,reducing soil nutrient loss,improving soil fertility and promoting soil remediation. |
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