[Objective]Soil salinization is the major cause of reduction of agricultural production in Dongying of Shandong Province,China,where shallow groundwater table,high evaporation and low precipitation cause soil salt to move upwards and accumulate on the surface soil of farmlands,so that yields of the crops therein are often quite low. In the study,an indoor simulation experiment was carried out using soil columns to explore effect of the farming practice of simultaneous straw mulching and straw incorporation on soil water evaporation,salt movement and soil water and salt distribution in farmland,in an attempt to provide a theoretical basis for amelioration and utilization of the coastal saline soil in Dongying.[Method] The in-lab simulation experiment was designed to have six treatment i.e. T1(Straw mulching),T2(Straw incorporation into the 35~40 cm soil layer),T3(With the ratio of straw in mulching and incorporation set at 1:1),T4(With the ratio set at 2:1),T5(With the ratio set at 1:2)and CK(No straw mulching or incorporation). Soil water evaporation and soil salt content was monitored during the experiment.[Result] It was found that:(1)The treatments varied sharply in effect on daily soil water evaporation and exhibited an order of T4< T5< T3< T1< T2< CK. Under the same atmospheric condition,either mulching or incorporation or both reduced cumulative soil water evaporation and Treatment T4 was the most obvious in the effect,cutting the cumulative evaporation by 76.13% as compared with CK by retarding the upward movement of soil water from the bottom soil layer,thus greatly reducing soil water loss. The evaporation inhibition rate of Treatment T4 reached 65.89%,being the highest among those of the treatments,so the treatment was the best in the experiment in inhibiting soil water loss through evaporation;(2)During the phase of water leaching and infiltration in the experiment,the treatments also varied significantly in effect on salt leaching. Treatment T3 was the best,with the soil desalination rate in the 0~40cm soil layer reaching up to 14.83%, while all the other treatments,except Treatment T2,were also found higher than CK in soil desalinization rate. During the phase of of water evaporation,all the treatments were found to have salt accumulated on the surface by a varying degree,and Treatment T4 treatment was the lowest in soil resalinization rate,and much lower than CK;(3)Treatments T3,T4 and T5 were obviously higher than Treatments T1 and T2 in effect of inhibiting soil water evaporation and soil resalinization,with Treatment T4 in particular;and(4) Correlation analysis of cumulative soil water evaporation and cumulative soil salt accumulation shows that the two were positively related,that is,the higher the cumulative soil water evaporation,the higher the soil salt accumulation.[Conclusion]Through the in-lab simulation experiment,it is found that the practice of either mulching or incorporation or both can inhibite soil water evaporation and soil resalinization to a varying extent and the practice of mulching and incorporating straw simultaneously at a ratio of 2:1 in quantity is the best in controlling soil water evaporation and soil resalinization,so it is a good option for amelioration of salt-affected soils.%采用室内土柱模拟的方式,研究了秸秆双层覆盖对盐碱土的改良效应及机制,以期对盐碱地的改良提供理论依据.结果表明:1)与对照相比,不同的秸秆覆盖模式均能降低土壤水分的累积蒸发量,T4处理(土表与土表下35~40 cm处覆盖秸秆量之比为2:1)在45 d内土壤水分累积蒸发量较CK(无秸秆覆盖的对照)低36.73 mm,抑蒸率为65.89%,抑蒸率最大,对土壤水分蒸发的抑制效果最好.2)秸秆处理均在不同程度上抑制了土壤返盐,其中T4处理返盐率最小,远低于对照处理.3)土壤水分累积蒸发量与土壤累积含盐量存在高度正相关关系.4)秸秆双层覆盖对土壤水分蒸发和土壤返盐的抑制效果大于秸秆表层覆盖和秸秆深层覆盖,并且,在不同的秸秆双层覆盖的处理中,T4处理的控盐保水效果最好,是一种较好的改良盐碱土的方法.
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