滴灌下生物质改良材料对盐渍土水盐氮运移的调控效应

Regulation Effect of Biomass Improved Materials on Migration of Soil Water,Salt and Nitrogen in Salt-affected Soil under Drip Irrigation

为探究生物质改良材料对滴灌盐渍土水、盐、肥运移过程的调控效应,采用土箱模拟试验,研究了水肥一体化滴灌条件下,生物炭和腐殖酸两种改良材料对盐渍土水、盐、氮运移和再分布过程及其时空分布特征的影响规律。结果表明:在滴灌条件下,盐渍土壤水盐的时空动态变化表现出明显的水分入渗驱动的盐分运移过程和蒸发扩散驱动的水盐再分布过程;铵态氮含量在时间上表现出先增大、后减小的变化趋势,在空间上的运移再分布特征较弱;硝态氮含量初始时空分布表现出与水盐相似的运移特征,受铵态氮硝化作用的多重影响,后期空间分布与铵态氮空间分布相似;生物炭通过提高土壤饱和导水率,增大了入渗阶段土壤水、盐、氮的运移速率和分布范围;腐殖酸通过提高土壤田间持水率增大了再分布过程土壤水、盐、氮的分布范围和强度,同时其对尿素的水解和硝化过程表现出更强的抑制效果。应用生物质改良材料在改变土壤物理性状进而调控滴灌土壤水盐运移的同时,还影响土壤氮素转化运移过程及其分布,这为水肥一体化滴灌盐渍农田的节水、控盐、减肥治理提供了理论基础。

Aiming to explore the regulation effect of biomass materials on water,salt and fertilizer transport in salt-affected soil under drip irrigation,an indoor soil tank experiment was carried out to investigate the influential law of two biomass materials,including biochar and humic acid,on the migration,redistribution and spatio-temporal characters of soil water,salt and nitrogen under the conditions of water-fertilizer integration and drip irrigation.The results showed that under drip irrigation,the spatial and temporal dynamics of soil water and salts consisted of two obvious processes:the transport process of soluble salts driven by water infiltration,and the redistribution process of soil water and salts induced by evaporation and diffusion.Ammonium nitrogen content showed temporal changes of first increasing and then decreasing,and the migration and redistribution characteristics were not obvious in space.Nitrate nitrogen exhibited similar migration and spatio-temporal distribution characteristics to those of soil water and salts,and it was also influenced by the nitrification of ammonium nitrogen.Biochar greatly improved the migration rate and distribution range of soil water,salts and nitrogen in the infiltration stage by significantly increasing the soil saturated hydraulic conductivity.Humic acid enhanced the range and intensity of soil water,salts and nitrogen in the redistribution stage by increasing the soil water holding capacity.Meanwhile,humic acid showed stronger inhibitory effect on the hydrolysis and nitrification process of urea.It was concluded that the application of biomass materials could not only regulate the soil water and salts transport by improving soil physical properties,but also affect the transformation,migration and distribution of nitrogen in salt-affected soil.The research result provided a theoretical basis for water-saving,salt-control and fertilizer-reduction management in saline farmland under water-fertilizer integration and drip irrigation.