不同土地利用方式下土壤水分动态及对降水的响应——以青海省互助县浅山旱地为例

摸清青海旱作农业区土壤水分动态变化对保障农作物产量形成和粮食生产安全具有重要意义。采用野外采样结合统计学方法,探究青海互助浅山旱地不同土地利用方式下土壤水分季节动态、垂直剖面特征及土壤水分对降水的响应。结果表明：（1）不同土地利用方式下耕作层(0~30 cm)土壤含水量季节动态存在明显的干湿周期变化,土地利用方式对土壤水分季节变化影响不显著(P>0.05),降水事件、降水量级是影响耕作层(0~30 cm)土壤含水量季节动态的主导驱动力;（2）0~30 cm土层是雨养耕作层,典型土壤含水期分为干旱期、湿润期、常态期和过渡期,土壤干旱发生一般由表层开始,随着土壤水分耗损加重土壤干旱逐渐向深层土壤延伸;（3）4种土地利用方式的土壤水分动态变化与前期累计降水量变化基本一致,亚表层(10~20 cm)和深层(20~30 cm)土壤含水量与前期累计降水量极显著相关性(P<0.01)。因此,在干旱事件频繁的青海旱作区发展“浅埋滴灌技术”是寻求土壤供水平衡的有效路径。

Soil Moisture Dynamics and Response to Precipitation Under Different Land Use Patterns: A Case Study of Shallow Mountain Dry Land in Huzhu,Qinghai

To find out the dynamic changes of soil moisture in the dry farming areas of Qinghai and to ensure the formation of crop yields and grain production safety, we studied the seasonal dynamics and vertical profile characteristics of soil moisture, and its responses to precipitation under different land use patterns in the shallow dry-land of Huzhu, Qinghai. The results showed that: (1) the soil moisture content of the tillage layer (0-30 cm) under different land use patterns had obviously dry-wet cycle changes, the land use pattern had no significant effect on the seasonal variation of soil moisture (P>0.05), but the precipitation events and precipitation levels were the dominant driving forces affecting the seasonal dynamics of soil moisture content in the tillage layer (0-30 cm); (2) 0-30 cm soil layer was the rain-fed layer, its soil moisture seasonal dynamics could be divided into dry period, wet period, normal period and transition period; the occurrence of soil drought generally began with the surface layer and gradually extended to the deep soil with the increase of the soil moisture loss; (3) the soil moisture dynamics of 4 land use types were basically consistent with the changes of the previous precipitation, and the soil water content of the subsurface (10-20 cm) and the deep (20-30 cm) were significantly correlated with the cumulative precipitation in the previous period (P<0.01). Therefore, the “shallow buried drip irrigation technology” is an effective way to seek the balance of soil water supply in the dry farming area of Qinghai with frequent drought events.