Effects of quantity of biochar on nitrogen leaching in simulated soil columns and soil moisture parameters in field

Using the simulation experiment in soil columns and field experiment, the different quantity of biochar prepared by the fruit tree branches as 0,20,40,60 t·hm-2 and 80t·hm-2 was applied to soil to search the impacts of different quantity of biochar on the nitrate nitrogen leaching and soil moisture. The results showed that after the biochar applied, the accumulative leaching amount of NH4+-N and NO3--N in soil can be effectively reduced.Among them the treatment of 80 t·hm-2 compared with the control, the NH4+-N and NO3--N leaching was decreased 41% and 18.6%(P0.05), respectively. The leaching loss of NO3--Nmajor occurred in the first three times, the leaching amount of NO3--N was accounted for 97.3% to 98.8% of the total leaching volume.The biochar can increase the retention time of NO3--Nin soil, retard the leaching loss. In whole leaching process, the main form of nitrogen leaching loss was the NO3--N. Its accumulative leaching amount accounted for 97.3% to 98.14% of the total NO3--N and NH4+-N leaching losses.After application of biochar to plant the spring maize, the increase of soil water content and soil total porosity was not notable.