Effects Of Fertilizer And Biochar Addition On Soil Physicochemical Properties And Respiration

Global climate change is one of the most important environmental issues at present.Biochar addition to farmland is an effective measure to alleviate the climate warming.However,the study on the influence mechanism of biochar addition on soil respiration is still scarce.In this study,an experiment was carried out at Dongyang Experimental Demonstration Base in Shanxi Academy of Agricultural Sciences,in which different treatments with different gradients of inorganic fertilizer and biochar in a sorghum soil were selected.Based on the field measurement data of soil respiration?R_s?we analysed the relationship between soil respirtion and the environments and the effects of fertilizer and biochar addition on soil physicochemical properties.The treatment begon in 2011 and the measuremnet of soil respiration begon between 2016-2017.The five treatments were:Blank Control?CK?,Biochar only?CK+B??4500 kg/ha/a?,Chemical Fertilizers?OPT??3375 kg CO?NH₂?₂+900 kgCaP₂H₄O₈+900 kg K₂SO₄?ha/a??,Chemical Fertilizers and half biochar?OPT+1/2B??2250 kg/ha/a?and Chemical fertilizers and Biochar?OPT+B??4500 kg/ha/a?.The results are as follows:?1?At daily scale the fertilizer and biochar addition had significantly affected the daily mean value of R_s?P<0.05?and had no effect on the daily variation trend of R_s.But these treatments changed the time of extreme value.And the time of extreme value of CK and OPT+1/2B were 12:00 and 14:00,respectively.The CV value of the daily variation of R_s for CK was 4.5%higher than that of OPT+1/2B.?2?Generally,the fertilizer and biochar addition could increase soil respiration rate,but did not reach the significant level?P>0.05?.The mean value of soil respiration under CK+B was 21.4%,9.1%,33.8%,12.1%and6.8%higher than that under CK in the seedling stage,jointing stage,heading stage and filling stage of the sorghum growing season,respectively.However,the mean value of soil respiration under CK+B in mature period was 6.8%lower than that in CK treatment.In the sorghum growing season,the soil respiration under OPT+B was lower than that under OPT,which stated that the combined application of fertilizer and biochar could mediate the promoting effect of biochar on R_s.?3?The relationship between the R_s in the 5 treatments and soil temperature(T₁₀)in 0-10 cm depth could be fitted in an exponential model,in which the interpretation degree was between 24.4⁴1.3%.The biochar addition increased the interpretation degree.Except for CK,the relationship between R_sof the other four treatments and the soil moisture(W₁₀)of soil 10cm depth could be fitted in a linear equation,with negative correlation,and the explanation degree was 17.3³8.1%.Compared with the single factor model,the soil water heat factor bivariate model could better explain the variance of R_s,and the interpretation degree of each treatment was between29.8⁵1.8%.?4?In general,soil pH,soil organic matter content and soil bulk density did not reach a significant difference?P>0.05?.However,biochar addition increased the soil pH and soil organic matter content,and decreased soil bulk density.The biochar addition decreased the activity of invertase.Compared with CK+B and OPT+B,the activity of invertase under CK and OPT decreased by 34.3%and 81.6%,respectively.And the biochar addition slightly increased the activity of catalase,whereas had no significant effect on the activity of phosphatase.