Effects of reducing chemical fertilizers combined with applying biochar and straw on yield of rice and nutrient absorption and carbon in soil in lime concretion black soil areas
The reduction of chemical fertilizer combined with applying biochar and straw is an effec-tive way of realizing the green and sustainable development of agriculture in China.A field plot experiment was conducted to study the efficient management of nutrient resources and the utilization of straw resources in the lime concretion black soil areas.The effects of reducing chemical fertilizers combined with returning straw to the field and biochar on the yield of rice,nutrient absorption and carbon in soil in the region were investigated for 2 consecutive years.5 treatments including no fertilizer(CK),conventional application of chemical fertilizer(100%NPK),20%reduction of chemical fertilizer(80%NPK),20%reduction of chemical fertilizer plus straw returning(80%NPK+S),20%reduction of chemical fertilizer plus biochar(80%NPK+B)were set up.The yield and biomass aboveground of rice,the content of N,P and K in plant,the content of total organic carbon(TOC)and microbial biomass carbon(MBC)in soil were mea-sured and analyzed.The results showed that 80%NPK+S or 80%NPK+B was beneficial for increasing the yield and biomass aboveground of rice,with the effect of 80%NPK+B more significant than that of 80%NPK+S.The average yield and biomass aboveground of rice treated with 80%NPK+B was 5.2%and 4.7%higher than that with 100%NPK,and by 7.9%and 7.2%higher than that with 80%NPK,re-spectively.The average yield and biomass aboveground of rice treated with 80%NPK+S was 3.4%and 3.0%higher than that with 100%NPK,respectively.There was no significant difference in the average yield and biomass aboveground of rice between the 80%NPK treatment and the 100%NPK treatment.The accumulation of N,P2O5,and K2O nutrients in the aboveground parts of rice treated with 80%NPK+B significantly increased,10.4%,7.2%,and 20.0%higher than that with 100%NPK.80%NPK+S treatment significantly increased the accumulation of nitrogen and potassium in rice,but significantly re-duced the accumulation of phosphorus in rice at the same time.80%NPK+B treatment or 80%NPK+S treatment was beneficial for improving the accumulation of total organic carbon in soil and significantly in-creasing the content of microbial biomass carbon in soil.Among them,the effect of biochar on increasing the content of total organic carbon in soil was better than that of straw,while the effect of straw on increas-ing the content of microbial biomass carbon in soil was better than that of biochar.Overall,80%NPK+B treatment or 80%NPK+S treatment can increase or maintain the yield of rice,improve nutrient absorp-tion capacity of rice,and facilitate the fixation of organic carbon in soil in the lime concretion black soil ar-eas along the Huai River.
reduction of chemical fertilizerbiocharreturning straw to the fieldnutrient absorptioncarbon in soilrice
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