秸秆覆盖增强滩涂重盐土雨水脱盐的效果

Desalinization Effectiveness of Straw Mulching on Heavy Saline Soil in Jiangsu Coastal Area

为促进沿海滩涂盐碱地脱盐和开发利用,研究了三个秸秆覆盖水平——0、1.5和3 kg m^(-2)下滨海重盐土(EC1:5=4.18 dS m^(-1))土壤盐分的动态变化规律。结果表明2种秸秆覆盖量对0~40 cm表土均具有较好的快速脱盐效果,处理后3个半月0~20 cm和20~40 cm的土壤盐分分别降至0.18/0.15和0.80/0.41 dS m^(-1),0~40 cm土层脱盐率达90%以上。回归分析表明土壤盐分含量与累积降雨量、淋洗方程(ECa/ECi与Dw/Ds间的关系)均表现为指数函数关系,模拟的效果均较好(P <0.01)。1.5 kgm^(-2)秸秆覆盖条件下0~20 cm和0~40 cm土壤剖面脱盐80%需要142 mm和324 mm的累积降雨量,而3 kg m^(-2)秸秆覆盖条件下0~20 cm和0~40 cm土壤剖面脱盐80%需要186 mm和316 mm的累积降雨量。两种覆盖量脱盐效果的差别主要体现在1m剖面的60~100 cm。秸秆覆盖增加了雨季滨海重盐土的淋洗效果,秸秆覆盖条件下滨海重滩涂脱盐80%需要320 mm的累积降雨量,江苏沿海地区雨季(6~8月)的常年雨量可满足这一要求。

In order to desalinize coastal tidal flats and utilize coastal land, the dynamic changes of soil salinity in coastal heavy saline soil （ECI：5 = 4.18 dS m-t） were investigated under three levels of straw mulching. Both levels of the straw mulching had good desalinization effects in soil of 0 - 40 cm after 3.5-month straw mulching. Soil salinity in 0 - 20 cm and 20 - 40 cm soil under straw mulching of 1.5 kg m-2 decreased to 0.18 and 0.80 dS m-1, while it decreased to 0.15 and 0.41 dS m-1 under 3 kg m-2 straw mulching. Desalinization rates in the soil of 0 - 40 cm reached above 90% under two levels of straw mulching. The relationship between soil salinity and cumulative rainfall and leaching equation （the relationship between EC~/ECi and Dw/Ds） showed a negative exponential function （P 〈 0.01）. About 142 mm and 324 mm of accumulative rainfall were required for removing 80% salt from 0 - 20 cm and 0 - 40 cm soil layers under 1.5 kg m-2 straw mulching, while 186 mm and 316 mm were needed under 3 kg m-2 straw mulching. The difference in the desalinization effects between two straw mulching levelswas mainly found in the 60 - 100 cm soil. The straw mulching enhanced the leaching effects incoastal heavy saline soil duringthe rainy season, and 320 mm of accumulative rainfall was required for removing 80% salt from 0 - 40 cm soil under straw mulching. The rainfall during the rainy season in Jiangsu coastal areas could meet this requirements. Increasing straw mulching levels enhanced the desalinization effects at 60 - 100 cm soil.