Effects Of Biochar On Soil Physical-chemical Properties And Nitrogen Use Efficiency

In this study,long-term positioning fertilization trial of post-mountain brown soil are used in Shenyang Agricultural University,Liaoning province,China.Discuss the effects of different dosages of biochar on soil physic-chemical properties,corn yield and fertilizer use efficiency.The tests aim to confirm impacts of biochar application on fertilization,soil improvement and fertilizer use efficiency,to provide scientific basis for the research and development of soil conditioner and new type of fertilizer.The positioning experiment began in 2013.Ten treatments are designed:(1)CK(no fertilizer);(2)C1(low biochar);(3)C2(moderate biochar);(4)C3(high biochar);(5)NPK(mineral nitrogen,phosphate and potassic fertilizer);(6)C1NPK(low biochar,mineral nitrogen,phosphate and potassic fertilizer);(7)C2NPK(moderate biochar,mineral nitrogen,phosphate and potassic fertilizer);(8)C3NPK(high biochar,mineral nitrogen,phosphate and potassic fertilizer);(9)PK(phosphate and potassic fertilizer);(10)C1PK(low biochar,phosphate and potassic fertilizer).In this study,the changes of soil physic-chemical properties,soil enzyme activities and microbial biomass C and N during the growth period of maize are analyed in 2015,and the changes of maize yield and nitrogen use efficiency are compared.The results are as follows:(1)Continuous addition of biochar to the soil reduces soil bulk density,soil bulk density of biochar is 6.27%lower than that of CK,and soil bulk density of combined with NPK is 6.02%lower than that of NPK.The effect of biochar on the soil water content of maize seedling stage is not significant.And the water retention performance is showed gradually with the growth period.(2)Biochar can significantly improve the soil pH and alleviate the soil acidification.The addition of biochar could significantly increase soil organic matter and total nitrogen content,and has no significant effect on soil total phosphorus and total potassium.With the combination of nitrogen,phosphorus and potassium,it can promote the slow release of ammonium and nitrate nitrogen in soil,significantly increase soil available phosphorus,available potassium content,reduce nutrient leaching loss and improve soil fertility,and the higher the application rate,the more obvious of fertilizer efficiency.(3)The addition of biochar could significantly increase soil urease and sucrase activity,And there is no significant correlation between soil enzyme activity and the dosages of biochar.Soil urease activity changes significantly at different growth stages of maize,and shows a trend of increasing first and then slowing down,reaching the peak of activity at jointing stage.The soil sucrose activity fluctuates little with the growth stages.(4)The addition of biochar could significantly increase the soil microbial biomass C and N,regardless of whether the biochar is applied with N,P and K fertilizers.But individual biochar treatment has no effect on soil microbial biomass N.During the whole growth period,the soil microbial biomass C and N shows the trend of increasing first and then decreasing,reaching the maximum at jointing stage,and there is a good correlation with the application amount of biochar.(5)Biochar combined with N,P,K can improve chlorophyll SPAD,improve photosynthetic efficiency and promote the growth and development of maize.The biochar treatment significantly increases the yield of maize,thus improves the utilization rate of nitrogen fertilizer,partial productivity and agronomic efficiency.(6)The correlation analysis shows that there is significant positive correlation between dosages of biochar application and the soil pH,organic matter and total nitrogen content.But there is significant negative correlation between soil bulk density and dosages of biochar application.And there is significant positive correlation between urease and NH4+-N,NO3--N,SMBN,the soil water content.There is significant positive correlation between sucrose and SMBC,the soil water content.In summary,addition of biochar to the soil reduces soil bulk density,improves the soil water content.With the combination of nitrogen,phosphorus and potassium,it can promote the slow release of nutrients and improve the soil water retention and fertilizer ability.Therefore,biochar can improve the physic-chemical environment and increase soil enzyme activity and microbial biomass.So biochar promotes the growth of maize and improves maize yield and nitrogen use efficiency.