| Poplar branch,corn straw and cow manure were selected from local site in order to study the effects of those amended materials on desertified soil in Ningxia,and the microcosm experiment was set up to test the effects of individual material or mixed materials on contents of carbon and nitrogen and enzymatic activity of desertified soil and alfalfa biomass.This study consists of 7 treatments:(1)control without any added organics(CK);(2)soil single application of 3%cow manure(CM);(3)the single application of 3%soil poplar branch(PB);(4)soil 3%single application of corn straw(CS);(5)soil fertilizer 1.5%Poplar branch +1.5%cow manure(PB+CM);(6)soil fertilizer 1.5%poplar branches +1.5%corn straw(PB+CS);(7)soil fertilizer 1.5%corn straw +1.5%cow manure(CS+CM);(8)soil fertilizer 1%poplar branches +1%cow manure +1%of corn straw(PB+CS+CM).CH4N2O 5 g and KH2PO4 2 g perbarrel.Each treatment consisted of 4 replicates/barrels,totaling 32 test barrels.The main results are as follows:(1)The decomposition rate of organic matter in soil is affected by the content of carbon and nitrogen in soil and the content of carbon and nitrogen in organic materials.In the early stage of culture,the decomposition rate of organic materials was CS>PB>CM,followed by PB>CS>CM.The application of poplar branch to soil was beneficial to the improvement of soil organic carbon content,and the application of cow manure to the soil was beneficial to the improvement of soil organic nitrogen content.Therefore,the application of mix organic materials may provide a continuous source of carbon and nitrogen,which is beneficial to the growth of plants.(2)The results of the simulation experiment in 2015-2016 showed that both individual(except cow manure)material and mixed materials increased all fractions content of carbon and nitrogen except inorganic nitrogen of soil compared with control.Cow manure increased inorganic nitrogen,and the organic carbon,oxidized organic carbon,total nitrogen and available nitrogen of soil with addition cow manure were the highest among the treatments.Mixed material with poplar branch,corn straw and cow manure was best in increasing microbial carbon and microbial nitrogen content,and also had best tendency on increasing enzymatic activity.Mixed material with poplar branch,corn straw and cow manure were also the best to increased alfalfa biomass among treatments,yet cow manure decreased alfalfa biomass compared with control.(3)Study on soil microbial functional diversity,the application of organic materials on soil microbial carbon source utilization increased,enhanced microbial activity,soil organic carbon content and soil fertility levels may also increase.Among them,the effect of single poplar branch on soil microbial metabolism was the strongest.Study on bacterial community structure of sandy soil poplar branches can promote the number of Proteobacteria,applying corn straw can promote the number of Ascomycota.In summary,the organic material is a good material for the improvement of Ningxia sandy soil,and determined poplar branches can improvement the sandy soil in Ningxia:applied poplar branches in soil promoting soil microbial carbon source utilization increased,also improve the number of Proteobacteria.Mixed material with poplar branch,corn straw and cow manure was best in increasing microbial carbon and microbial nitrogen content,and also had best tendency on increasing enzymatic activity.Mixed material with poplar branch,corn straw and cow manure were also the best to increased alfalfa biomass among treatments.Cow manure increased inorganic nitrogen,and the organic carbon,oxidized organic carbon,total nitrogen and available nitrogen of soil with addition cow manure were the highest among the treatments.Applying corn straw can promote Ascomycota number.We also need to know that organic material will incur the imbalance of ratio of carbon and nitrogen,and lead to microorganism to fix nitrogen.So,it necessary to adjust ratio of carbon and nitrogen when use those organic materials to amend soil. |
