摘要
滨海盐渍土盐度变化存在明显的季节性,地下水埋深浅、矿化度高是造成滨海地区冬-春季节土壤积盐的主要原因。台田-浅池农业生态系统的构建,既可抬高土壤耕作面,又能形成开阔的水体。利用冬季浅池中自然冻结形成的咸水冰覆盖台田,其融水可实现对台田土壤盐分的淋洗,防止返盐。台田覆冰后,又在冰面设置了无覆盖、芦苇秆覆盖和无纺布覆盖3种处理,以调节冰体融化速度。实验过程中监测冰体融化前后及融化过程中台田0～100 cm土层含水率与盐度变化。结果表明,冬季咸水冰覆盖不仅抑制了土壤的返盐,还能降低部分盐度,增加土壤含水率。冰面无覆盖条件下,覆冰融化迅速,土壤含水率在短时间内大量增加,洗盐效果明显,但持续时间较短。覆盖处理减少了蒸发,可延缓覆冰融化,延长脱盐时间。与芦苇秆覆盖相比,无纺布覆盖条件下,融冰速率适中,土壤脱盐效果最佳。3种处理方式下,覆冰融尽时0～20 cm土层含水率分别增加44.5%、42.8%和68.5%,土壤脱盐率分别为44.4%、47.0%和72.4%。土壤墒情的改善与盐度的降低为作物的种植创造了良好的条件,为后续改良方法的顺利实施提供了保障。
Seasonal variation of salinity is typical of coastal saline soils. High water table and high salinity of the groundwater are considered to be the main cause of salt accumulation in the soil in winter and spring. Fortunately, an agro-ecosystem consisting of raised-beds and shallow pools is expected to be able to solve this dilemma. Raised-beds are built to lower ground water table, and shallow pools provide in winter brackish ice that can be used to mulch the fields. The mulching of brackish ice melts, leaching salt off from raised-beds, thus preventing surfacing of salt. In the experiment, to control melting speed of the ice, three treatments were designed, i.e. no mulching over on the ice layer, mulching with reed straw and mulching with non-woven fabrics. Variations of water content and salinity in the soil of the raised-beds were monitored, before and after melting of the ice and during the process of melting in the experiment. Results show that mulching with brackish water can not only inhibit accumulation of salt, but also decrease salinity and increase water content of the soil. In the treatment of no mulching on ice, the ice melted quickly, raising soil water content quickly in a short time, so its desalinizing effect was notable but not lasting. The treatment of mulching the ice with reed straw reduced evaporation of ice water, and deferred ice melting, thus prolonging desalinizing time. Compared with the foregoing treatment, the treatment of mulching with non-woven fabrics displayed a proper ice melting rate and the best desalinizing effect. In the three treatments at the time the ice mulching completely melted, the water content in the 0～20 cm soil layer increased by 44.5%, 42.8% and 68.5%, respectively, as against that in the soil without ice mulching and the desalinization rate reached 44.4%, 47.0% and 72.4%, respectively. The improvements in soil moisture and soil salinity create a suitable soil environment for crops, and provide a guarantee for successful implementation of follow-up amelioration of coastal saline soils.
出处
《土壤学报》
CAS
CSCD
北大核心
2012年第1期18-25,共8页
Acta Pedologica Sinica
基金
国家"863计划"课题"精细地面灌溉技术与设备"与"海冰资源淡化与利用技术"资助
关键词
滨海盐渍土
咸水冰
台田
洗盐
Coastal saline soils Brackish ice Raised-beds Salt leaching
