| .Biochar is the product of thermal pyrolysis of biomass in the absence of oxygen. Biochar has been decribed as a possible means to improve soil fertility and sequester carbon, so it is of condersiable interest in the field of Sustainable Agriculture and Environment. In this dissertation, the bamboo biochar (BBC) was added to the pear orchard soil to improve its fertility status. The objectives of this study was to investigate 1) the effects of BBC on the mineralization of organic fertilizer and nutrients leaching by labotary static incubation experiment and soil column leaching experiment; 2) the effects of BBC addition on the runoff loss of nutrient, pear quality and yield by plot experiment. And then, the influence of BBC on soil microbial diversity in the above experiments in order to reveal the possible mechanism of the influence of BBC addition on the nutrient content and leaching of the pear orchard soil. Furthermore, it will provide a certain theoretical basis for the soil and the agricultural non-point pollution control, and also put forward a new method for the reusing of argricultural wastes. The main conclusions of the experiments are as follows:(1) BBC possessed a larger surface area (332.10 m2 g-1), special porous structure, and various O-containing functional groups at its surface. Furthermore, BBC itself may release a certain nutrient such as TOC (1.346 mg g-1), TN (0.043 mg g-1), and TP (0.072 mg g-1).(2) In the static incubation experiment, BBC addition to soil increased the content of TOC, TN, TP, microbial biomas C, N, and P and the activity of urease and acid phosphatase. Furthermore, their increase rates were positively correlated with the content of added BBC. Compared with the control,1.0% BBC addition to soil increased TN, microbial biomass C, N, and P content by 11.80,66.67,125.00, and 107.15%, respectively, meanwhile enhanced urease activity and acid phosphaase activity by 40.91 and 49.28%. In the soil column leaching experiment, the addition of BBC reduced cumulative TOC, TN, and TP leach-loss, and the reduction rates were positively correlated with the content of added BBC. Compared with the control, the addition of 1.0% BBC lowered cumulative TOC, TN, and TP leach-loss by 31.88, 43.90, and 57.58%, respectively. For the whole experiment of static incubation and soil column leaching, the results of soil C, N, and P mass balance suggested that BBC addition accelerated the mineralization of organic fertilizer and increased the retention capacity of soil C, N, and P. Compared with the control, soil TOC, TN, and TP retention contents were 2.61,0.42, and 0.086 mg g-1 in the 1.0% BBC addition treatment.(3) The results of field plot experiments from 2009 to 2011 shown that BBC addition inhibited runoff, the total loss of SS, TOC, and TN in the pear orchard by 13.21,12.55,17.71, and 19.95%, respectively. Moreover, BBC addition had the positive effect on pear yield. Additionally, the value of NO3-N/NH4-N and TDP/TP of runoff lowered a little in the BBC addition treatment, which indicated BBC addition may also affect the transformation of nitrogen and phosphorus.(4) Not only in the laboratory but also in the field, the addition of BBC enhanced soil microbial diversity which mainly embodied in the whole activity of microbial community utilization carbon sources, substrate richness index S, Shannon index H, Simpson index D, and Mclntosh index U. Furthrtmore,1.0% BBC addition increased soil microorganisms utilization of these special carbon sources such as Glucose-1-Phosphate, Glycyl-L-Glutamic acid, and D-Malic acid by 18,12 and 35 times, which may be the reason that BBC addition increased soil C, N, and P content in the static incubation experiment. |
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