半干旱地区环境因素与表层土壤积盐关系的研究

RELATIONSHIP BETWEEN ENVIRONMENT FACTORS AND TOPSOIL SALT ACCUMULATION IN SEMI-ARID REGIONS IN CHINA

通过田间试验对半干旱地区甘肃省秦安县果园环境因素（蒸发量、降雨量、近地面空气温度和湿度、土温、土壤水分）与表层土壤的积盐关系进行了研究。结果表明：在综合环境因素的影响下，不同土层的全盐含量随着潜在累积蒸发量的增加而增大，表现为正相关。土壤温度升高，不同土层土壤均有积盐的趋势。土壤0-2cm、2-5cm、5-10cm土层随着水分含量的增加有积盐的趋势，而15-20cm和20-25cm土层随着水分含量的增加有脱盐的趋势。土壤积盐受多种因素综合作用的影响。在果树生育期4-8月，15-20cm土层土壤盐分含量和土壤水分、气温具有较好的耦合效应，其模型为γ（土壤盐分）：0.0027-0.0002X1（气温）＋0.0154X2（含水量），（P=0.0047）。因此，根据模型，在生育期4-8月，低气温和高土壤含水量正是该层土壤积盐期。根据气象因子对积盐的影响，科学地提出了15-20cm土层为盐分的“活动面”的概念。

Field experiments were carried out to study relationship between environment factors （evaporation, rainfall, near-ground air temperature and relative humidity of orchards, soil temperature and soil moisture） and salt aeeumulation in topsoil in semi-arid regions of Qin＇an County of Gansu. Results indicate that total salt contents in different soil layers increased with the increase in potential cumulative evaporation amount under the integrated effect of environmental factors, showing a positive relationship. With a rising soil temperature, salt accumulation in all the soil layers showed a rising trend. A similar trend was also observed when soil moisture increased in the soil layers of 0-2 cm, 2-5 cm, and 5-10 cm, but a reverse trend appeared with soil moisture rising in the soil layers of 15-20 cm and 20-25 cm. Soil salt accumulation was influenced by many factors. During the growth period of apple from April to August, the soil layer of 15-20 cm was prominent with a good coupling effect of air temperature, soil moisture content and soil salt content, which fits the model： Y（Sah） = 0. 0027-0.0002X1（ Air temperature） ＋ 0.0154X2（Soil moisture） , （p =0.047）. Therefore, according to this model, soil salt accumulates when air temperature is low and soil moisture content is high. And the concept “Salt Activity Surface” is thus brought forward.