Adsorption And Fixation Of Nitrogen And Phosphorus In Soil By Tea Residue Biochar And Improvement Of Acidified Soil

As an efficient and low-cost soil conditioner,biochar has attracted extensive attention from scholars from all walks of life.Although there have been a lot of studies on environmental pollution control and soil improvement,there are few reports on the adsorption and fixation of soil nitrogen and phosphorus by biochar prepared from tea residue.Therefore,in this paper,the basic physical and chemical properties of tea residue biochar prepared at400?,500?and 600?were characterized by modern analytical technology.Through culture experiments and isothermal adsorption-desorption experiments,the effects of tea residue biochar prepared at different pyrolysis temperatures on the improvement of acidic soil and the adsorption-desorption characteristics of soil phosphorus and inorganic nitrogen were studied,and the optimal adsorption conditions and theoretical maximum removal rate were determined by response surface analysis.It provides a theoretical basis for the resource utilization of tea residue,improving the utilization rate of soil nutrients and improving soil acidification in tea garden.The main conclusions are as follows:(1)Through the preparation and characterization of tea residue biochar,the changing laws of various physicochemical properties and pyrolysis temperature of biochar were revealed.Tea residue biochar was prepared and characterized at three pyrolysis temperatures(400?,500?and 600?).The results show that the pyrolysis temperature will affect the physical and chemical properties of biochar.With the increase of pyrolysis temperature,p H,BET,TP and TOC of biochar increased,while the Yield,CEC and TN of biochar decreased.(2)Discussion on the improvement of acidified soil by tea residue biochar.The effects of tea residue biochar prepared at different temperatures(400?,500?and 600?)on soil acidification indexes and enzyme activities were studied by culture experiments.The results show that biochar can increase soil p H,CEC and exchangeable base saturation,and reduce soil exchangeable acid content.At the same time,biochar can also significantly promote the activities of soil urease,acid phosphatase and sucrase.(3)To investigate the adsorption-desorption mechanism of tea residue biochar on phosphorus(P)in soil.The effects of pyrolysis temperature(400?,500?and 600?)and biochar dosage(0.25%,0.50%,1.00%and 2.00%)on the adsorption-desorption process of phosphorus in soil were analyzed by fitting the adsorption isothermal model.The results show that the soil samples treated with 1.00%CZ400 had a maximum adsorption capacity of 1224.70mg·kg^-1for phosphorus.At the same time,biomass char reduced the desorption rate of phosphorus by soil to a certain extent,the phosphorus desorption rate of tea residue biochar prepared at low temperature(400?)was lower than that of high temperature(600?).(4)Study on the adsorption-desorption mechanism of tea residue biochar on inorganic nitrogen in soil.The effects of biochar dosage(0.25%,0.50%,1.00%and 2.00%)and pyrolysis temperature(400?,500?and 600?)on soil adsorption of inorganic nitrogen were investigated by adsorption-desorption experiments.The results show that with the decrease of pyrolysis temperature,the adsorption of ammonia nitrogen(NH₄⁺-N)in soil increased and the desorption rate decreased.Among them,the soil samples treated with 2.00%CZ400 had a maximum adsorption amount of NH₄⁺-N of 1028.01 mg·kg^-1,a minimum desorption rate of 11.67%.Tea residue biochar prepared at different temperatures did not adsorb nitrate nitrogen(NO₃^--N)in the solution,when it was input into the soil,it would reduce the soil's adsorption of nitrate nitrogen.(5)Exploring the influence of environmental factors on the adsorption process of nitrogen and phosphorus.Three variables(biochar dosage,p H and temperature)that have a significant impact on soil phosphorus and ammonia nitrogen adsorption rates were selected as the research objects,and the effects of a single variable on soil nitrogen and phosphorus adsorption were analyzed through batch experiments.Using the BBD method of RSM to design experiments,the optimal adsorption rate and optimal adsorption conditions were obtained.The results show that the influence of environmental factors on the adsorption rate of phosphorus and ammonia nitrogen is as follows:dosage>temperature>p H.When the dosage of biomass carbon is 1.00%,p H=10 and temperature is 35?,the adsorption effect of tea residue biomass carbon on phosphorus in soil is the best,and the best adsorption rate that can be achieved in theory is 81.54%.When the dosage of biomass carbon is 1.00%,p H=10 and temperature is 15?,the adsorption effect of tea residue biomass carbon on NH₄⁺-N in soil is the best,and the best adsorption rate that can be achieved in theory is 63.25%.Figure 25 table 16 reference 120...