秸秆覆盖条件下滨海盐渍土蒸发对近地层微气候变化影响的模拟研究

为明确秸秆覆盖后微气候对盐渍土水盐运动的调控机理,通过室内土柱试验,模拟研究了盐渍土蒸发过程(0～17 717 min)中不同秸秆覆盖量(0、0.3、0.6、0.9 kg·m~(-2)和1.2 kg·m~(-2),分别以CK、A、B、C和D表示)对近地层微气象因素(地表土壤温度、空气温度、相对湿度)、湍流热通量、蒸发强度及水盐运动的影响。结果表明,秸秆覆盖可有效提高近地层土壤温度和近地层空气温度,A、B、C和D处理的地表土壤温度比CK分别增加了21.9%、27.4%、27.2%和33.5%,地表上方15 cm处空气温度比CK分别增加了1.02%、0.59%、0.95%和1.54%;无外热源补给条件下,A、B、C和D处理的湍流交换系数比CK分别低了73.3%、62.8%、29.9%和51.7%,湍流热通量分别增加了80.2%、70.6%、52.8%和69.6%,潜热通量分别低了84.9%、79.4%、57.6%和69.8%,差异显著;秸秆覆盖对土壤蒸发强度的抑制作用主要在蒸发前期(0～10 000 min),且A、B、C和D处理的蒸发强度比CK处理分别降低了12.4%、52.5%、26.7%和60.3%(p0.05),随着秸秆覆盖量的增加表层0～1 cm土层土壤电导率呈降低趋势,表明秸秆覆盖在一定程度上可以抑制土壤盐分向地表积聚。

Simulation of the effects of straw mulching on the micro-climate and soil evaporation of coastal saline soil

In order to clarify the regulation mechanism of micro-climate on the movement of water and salt in saline soil with straw covering, different straw mulching (0, 0.3, 0.6, 0.9 kg·m^-2 and 1.2 kg·m^-2, denoted by CK, A, B, C, and D, respectively) were simulated through indoor soil column experiments during the evaporation process (0~17 717 min.) for saline soil, and the effects of near-surface micro-meteorological factors (surface soil temperature, air temperature, and relative humidity), turbulent heat exchange, evaporation rate, and water and salt movement were analyzed. The results showed that straw mulching effectively increased the surface soil temperature and the near-surface air temperature. The surface temperature of A, B, C, and D increased by 21.9%, 27.4%, 27.2%, and 33.5%, respectively, over CK. The air temperature at 15 cm above the surface increased by 1.02%, 0.59%, 0.95%, and 1.54% compared to CK; without external heat source replenishment, the turbulence exchange coefficients of A, B, C, and D treatment were 73.3%, 62.8%, 29.9%, and 51.7% lower, the turbulent heat flux was 80.2%, 70.6%, 52.8%, and 69.6% higher, and the latent heat flux was 84.9%, 79.4%, 57.6%, and 69.8% lower than those of CK, respectively, with significant difference. The inhibitory effect of soil evaporation rate was mainly in the early stage of evaporation, 0~10 000 min, evaporation rate of CK was 12.4%, 52.5%, 26.7%, and 60.3% lower than that of A, B, C, and D, respectively. To a certain extent, straw mulching could suppress the accumulation of soil salt to the surface, and with the increase of straw coverage, the salt content of the surface layer 0~1 cm soil layer showed a decreasing trend.