Long-term application of sewage sludge compost in large amount increases crop yield and soil carbon storage of North China
[Objectives]This study investigated the effects of long-term application of varying doses of sewage sludge compost(SW,comply with quality standard)on crop yield and topsoil organic carbon storage(SOCS)and total nutrient contents in a winter wheat-summer maize rotation system in North China.The result will provide reference for the efficient utilization of sewage sludge compost in agriculture.[Methods]A field experiment was conducted from 2008 to 2020 in Changping District of Beijing.The treatments included 100%urea(N),50%SW+50%urea(0.5SW+0.5N),100%SW+50%urea(SW+0.5N),200%SW+50%urea(2SW+0.5N),and 400%SW+50%urea(4SW+0.5N).Wheat and maize yield,as well as SOCS,total nitrogen(TN),total phosphorus(TP),and total potassium(TK)contents in 0-20 cm soil layer were measured each year.The soil carbon sequestration efficiency was also calculated.[Results]With the increasing of sewage sludge compost input,wheat and maize grain and straw yields increased.The multi-year average yields of wheat and maize grains and straw in 0.5SW+0.5N treatment were not significantly different from that in N treatment,while those in SW+0.5N,2SW+0.5N,and 4SW+0.5N were significantly increased,with the increment in wheat grain yields by 6.97%,14.88%,and 17.94%,and in maize grain yields by 8.43%,11.77%,and 15.38%,respectively.The SOCS,TN,TP,and TK kept enhanced with the increase of sewage sludge compost input amounts(P<0.05).The multi-year average TN in treatment N,0.5SW+0.5N,SW+0.5N,2SW+0.5N,and 4SW+0.5N were 1.07,1.26,1.56,1.93,and 2.73 g/kg;the multi-year average TP were 1.19,1.67,2.37,3.27,4.11 g/kg;and the multi-year average TK were 18.60,19.06,19.85,20.07,21.19 g/kg,respectively.[Conclusions]Replacing 50%of urea N with sewage sludge compost will not impact the wheat and maize yield,but increase soil fertility significantly.Under half of conventional urea N input rate,increasing the application rate of sewage sludge compost could significantly elevate the wheat and maize grain yields,especially when the application rate is 4 times of the urea N input,the grain yield will be increased by 15%-18%,and the soil organic carbon and nutrient storage increased greatly,which boosts the sustainability of grain yields and the carbon sink effect of soil.
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