Effects of Biogas Slurry Irrigation on Accumulation and Leaching of Soil Carbon,Nitrogen and Phosphorus in Low Hilly Orchards in Southern China
To understand the impact of long-term irrigation with biogas slurry as a water source on soil nutrient accumulation and leaching in orchards of the southern low hills,three citrus orchards with a large-scale pig farms-biogas-orchard cycle system were selected,and their soil types were red sandstone soil,red soil and bole soil,respectively.Representative plots for each of the orchards with biogas slurry irrigation time of 0(control),2-3 and 5-7 years were selected,soil samples at different depths were collected from all selected plots for measuring soil quality indicators,including pH,bulk density,organic carbon,active organic carbon,total nitrogen,available nitrogen,total phosphorus,available phosphorus,and phosphorus saturation.The results showed that long-term biogas slurry irrigation could significantly increase the pH value and organic carbon of 0-30 cm soil in orchards,reduce the bulk density of corresponding soil layers,and increase the active organic carbon of 0-45 cm soil.Long term biogas slurry irrigation could significantly increase the accumulation of nitrogen and phosphorus in the soils,with total nitrogen mainly accumulating in the 0-30 cm soil layer,total phosphorus mainly accumulating in the 0-15 cm soil layer,and effective phosphorus accumulating in the 0-45 cm soil layer.The depth of effective nitrogen accumulation could reach over 60 cm depth.Research had shown that carbon,nitrogen and phosphorus introduced by biogas slurry mainly underwent leaching in their active forms(active organic carbon,NH4-N,NO3-N,available phosphorus)downwards,and the vertical leaching of nitrogen was significantly higher than that of phosphorus.The significant accumulation of available nitrogen and phosphorus in the surface soil and the vertical leaching of available nitrogen and phosphorus into deep soil indicate the risk of nitrogen and phosphorus loss in long-term biogas slurry irrigation.
万方数据
维普
