Effects Of Biochar Addition On Humification And Application Of Pig Manure Compost

With the development of breeding industry,the natural degradation of livestock manure exceeds the environmental carrying capacity,and the pollution caused by it has become an urgent problem to be solved.Aerobic composting is the optimal way to realize the harmless treatment of livestock manure.In this study,8%（T1）,10%（T2）,12%（T3）jujube branch biochar was added into the compost with pig manure and straw as raw materials as the treatment group,and the control group without biochar was set up（CK）.The effects of adding biochar on the temperature,p H,electrical conductivity,water content,nutrients（total nitrogen,total phosphorus,total potassium）,humus and its component contents of the compost were studied by self-made box compost.The rot grade of the compost was evaluated by fuzzy comprehensive evaluation method and grey correlation analysis method,and the compost products were applied to lettuce cultivation.The effects of biochar fertilizer on soil physicochemical properties,growth and quality of lettuce were studied,in order to provide theoretical reference for manure manure manure processing.The main research results of this paper are as follows:（1）The temperature,p H and electrical conductivity（EC）of the reactor increased first and then decreased.The high temperature period in the treatment group was 5～8 days longer than that in the control group,and the p H and EC of the treatment group were lower when the composting was completed.The contents of nitrogen,phosphorus and potassium showed an increasing trend,and the contents of nitrogen,phosphorus and potassium were 12.52%～20.90%higher,3.56%～7.93%lower and 1.71%～4.72%higher in the biochar added reactor than in the control group.Humus organic carbon content in the reactor decreased first and then increased.Humus organic carbon content in the treatment group increased by 0.96%～2.62%compared with the control group,humic acid organic carbon content increased by 4.94%～14.58%,and fulvic acid organic carbon content decreased by 4.68%-14.38%.The nutrient content of the compost in the biochar treatment group was higher.（2）The seed germination index（GI）of the T3 group was 6.67%～11.67%at the initial stage,and increased to 86.67%～96.67%at the end of composting,and it reached 80%14 days earlier than that of the CK group.After composting,the percentage of humic acid organic carbon in total organic matter（HI）increased by 40.00%～88.00%,and the percentage of humic acid organic carbon in humus organic carbon（PHA）increased by 29.26%～53.50%,with the growth rates of T3>T2>T1>CK.After composting,the degree of humus polymerization（DP）of CK to T3 groups were 1.42,1.93,1.81 and 1.90,respectively,which reached the maturity standard.Humic acid E4/E6 decreased;The absorption peak intensity of infrared spectra increased at 3400 cm^-1,2900 cm^-1,2800 cm^-1,1450 cm^-1,1400 cm^-1,732 cm^-1,679 cm^-1and 520cm^-1,indicating that macromolecular materials were decomposed into small molecules,and the aromatization and unsaturation of the reactor increased.Fuzzy comprehensive evaluation method was used to evaluate the grade of reactor maturation:CK and T1 were"better maturation";T2 and T3 were"complete maturation",and T3 group had the highest degree of maturation.Grey correlation analysis was used to evaluate the grade of reactor maturation:CK was"basic maturation";The results of T1,T2 and T3were"complete maturation".Grey correlation analysis was more suitable for evaluating compost maturity.Adding biochar can improve the maturity of reactor.（3）The compost products T1,T2,T3 and CK were mixed according to the ratio of compost:garden soil（m:m）1:15,and then the planting soil F1,F2,F3 and CK were obtained respectively,which were used for planting lettuce experiment.Compared with the changes of soil physical and chemical properties before and after planting and the differences of growth and quality of lettuce at harvest,the application of biochar compost products enhanced soil breathability and water retention,and the nutrient content was higher than that of the control group.The plant height,root length,leaf number and weight of lettuce in F1,F2 and F3groups were 2.98%～14.12%,2.77%～11.52%,4.88%～14.63%and 56.29%～84.90%higher than those in CK group,respectively.The SPAD value,vitamin C,soluble sugar and crude fiber of lettuce leaves were168.05%～219.69%,17.30%～29.26%,32.43%～35.54%and 7.60%～59.55%higher than those of the control group,respectively.The application of biochar compost products can increase the yield and improve the quality of lettuce.