滴灌灌溉计划制定中毛管埋深对负压计布置方式的影响

为了为采用负压计拟定滴灌灌溉计划提供充分依据，对不同毛管埋深条件下滴灌番茄根区土壤基质势的时空分布进行监测，以探讨采用负压计拟定滴灌番茄灌溉计划的适宜布置方式。试验于2006和2007年在日光温室内的砂质壤土上进行，滴灌毛管设0、15和30 cm 3个埋深，监测距毛管水平距离0、15和30 cm 3个剖面上10、20、30、50、70和90 cm深度的土壤基质势。对番茄根区土壤基质势时空分布和番茄耗水量与土壤基质势变化的相关性分析表明，水平距毛管0、15和30 cm 3个剖面间土壤基质势差异较小，负压计距毛管的水平距离对耗水量与土壤基质势变化的相关程度影响不大；毛管埋深对20～70 cm土层土壤基质势影响显著，负压计埋置深度对耗水量与土壤基质势变化的相关性影响显著，应依据毛管埋深确定负压计适宜埋置深度。建议采用负压计制定灌溉计划时在毛管所在垂直剖面上安装1支即可，该研究条件下，毛管埋深0、15和30 cm时，用于制定灌溉计划的负压计宜分别埋置在毛管所在剖面上30、50和70 cm深度。

Effects of lateral depths on alternative placements of tensiometers used for drip irrigation scheduling

The temporal and spatial distribution of soil matrix potential (SMP) in the root zone of drip irrigated tomato was measured to investigate the optimal placements of tensiometers used for scheduling drip irrigation under various lateral depths. The experiments were conducted on a sandy loam soil in a solar-heated greenhouse during the growing seasons of 2006 and 2007. Three lateral depths of 0, 15 and 30 cm were used. The observations of SMP were conducted in the soil profiles of 0, 15 and 30 cm from the drip tape at depths of 10, 20, 30, 50, 70 and 90 cm. The temporal and spatial distribution of SMP in tomato root zone and the correlation between tomato evaportranspiration (ETa) and SMP variations were analyzed. The results showed that the variation of SMP among the soil profiles of 0, 15 and 30 cm from drip tape was insignificant, and the horizontal distance of tensiometers to drip tape had little effect on the correlation between tomato ETa and SMP variations. Lateral depths significantly influenced SMP from 20 to 70 cm soil layer and there were obvious effects of tensiometer depth on the correlation between tomato ETa and SMP variations. The suitable buried depths of tensiometers used for drip irrigation scheduling of tomato should be determined based on the buried depth of drip tape. The experiments recommended that one tensiometer should be installed just below a drip tape at depth of 30, 50 and 70 cm for the lateral depth of 0, 15 and 30 cm, respectively.