Influence of three biochars produced by three leguminosae plants on Hainan latosol properties and N2O emission

ObjectiveThe effects of biochar prepared by different leguminosae plants under different temperatures on the properties of latosol and N2O emission were studied to select the suitable raw leguminosae materials which could con-tribute to N2O emission reduction and soil improvement,and provide theoretical basis for rational utilization of legumino-sae plants in Hainan.MethodThree common leguminosae plants in Hainan(peanut,soybean and stylosanthes)were sam-pled,and were produced into nine biochars under pyrolysis temperature 300,500 and 700℃. Indoor cultivation experi-ment was conducted with application of these biochars. During the experiment,the air was collected to measure N2O emis-sion from soil,mineral nitrogen content variation and soil physicochemical properties. Cultivation without biochar was set as control(CK).ResultDifferent biochar treatments could significantly increase soil pH and available potassium(P<0.05,the same below),and enhanced soil organic carbon and total nitrogen contents. The biochar made by soybean straw could largely increase soil pH,organic carbon,available phosphorus and available potassium contents. Biochar produced at 300 ℃ effectively stimulated soil N2O emission. Effects of biochar produced at 500 and 700 ℃ on soil N2O emission varied as the materials differed. With culture time prolonged,ammonium nitrogen(NH4+-N)content in soil under different treatments decreased while nitrate nitrogen(NO3--N)content increased on the contrary. At the end of the culture,NH4+-N content in soil treated by biochars was close to 0 mg/kg,and NO3--N content in soil was 71.06-93.09 mg/kg. In terms of biochar made by the same materials,as the temperature rose,soil nitrification rate increased. At the end of culture,soil ni-trification rate in biochar treated groups was close to 100.00%,but that of CK was 90.57%which was lower than biochar treatments.ConclusionTaking the effects of different biochars on soil properties and N2O emission into consideration, biochar produced by soybean straw at 500℃was recommended to improve latosol in tropical region.