Studies On The Effect Of Corn Straw And Biochar On Soil Properties And N₂O Emissions In Latosol Soil

Nitrous oxide is not only a powerful greenhouse gas,but also can destruct the ozone layer.Nitrification and denitrification are the main microbial processes that produce N2O in soils.Straw and biochar amendment to soils improved soil properties,and may accordingly influence N2O emissions.Hainan with abundant water and heat resources formed the poor fertilizer supply and retention capacity of typical soil which was needed to improve.However,there is little published information about effects of biochar or straw on soil physical properties and N20 emissions from latosol soil in Hainan.In the study,an incubation experiment under 30? and 75%field water holding capacity and a field experiment were conducted to investigate the effect of straw and biochar on the soil properties and N2O emissions and compare the effects between straw and biochar.In the field experiment,six treatments including no organic material and N fertilizer addition,no organic material addition,biochar addition at dose of 20t·ha-1 and 40t-ha-1,straw addition at 40.23t·ha-1and a combination of biochar at 10t ha-1and straw at 20.12t-ha-1 were arranged to.In the incubation experiment,four treatments including no organic material addition as control(CK),two addition rates of biochar(1g and 2g biochar·100g-1 dry soil)and straw addition were arranged to.The main research results are as follows:1.Both biochar and straw additions can significantly improve soil properties.At the end of the incubation experiment,both biochar and straw additions can significantly increase soil pH,organic C,available P and available K contents,more obviously for straw addition.And biochar and straw also increased soil organic C,available K,exchangeable Ca and exchangeable Mg contents in the field.2.Biochar additions can reduce N2O emissions.In the incubation experiment,compared to CK(1657.12±165.89?gN20-N·kg-1),biochar addition at rates of 1%and 2%significantly reduced cumulative N20 emissions by 53.9%and 70.1%,respectively,and the reduction mechanism of N2O emission was probably due to the decreased N2O production ratio from nitrification.In the field experiment,biochar applications at 20t·ha-1 and 40t·ha-1 only reduced cumulative N2O emissions by 6.8%and 5.6%compared to control,respectively.3.Both straw additions and combination of biochar and straw additions can increase N2O emissions.At initial incubation(1?60d),compared to CK,straw addition reduced significantly cumulative N20 emissions by 58.0%,which was attributed to decrease in the nitrification of NH4+ pool caused by increased NH4+ immobilization,but the N2O emissions of straw-treated were dramatically increased in the late of incubation(180?225d).Compared to CK,straw addition significantly increased total N2O emissions by 349.8%.In the field experiment,the cumulative N2O emissions of straw treatment and combination of biochar and straw treatment were 14.81±1.29kgN2O-N·ha-1 and 14.15±1.24kgN20-N·ha-1,and significantly increased 45.5%and 39.0%compared to control,respectively,but on significantly difference between them.4.In the field,N2O emission was not correlated with soil water content(WFPS),but negatively correlated with soil temperature.There were significantly positive correlations between N20 emissions and the content of soil NH4+ and NO3-in the control treatment.