目前我国各灌溉试验站大都以“测坑”做为观测旱作物需水量的主要工具。测坑是把田间的一部分土体隔绝起来,通过测量和计算测坑内土体的水量平衡各要素,从而推算出作物需水量。“测坑”实际上是国际上通用的“非称重式蒸渗器”(Non—Weighing Lysimeter)。为了使测坑内测算出来的需 At present, most irrigation experimental stations in our country use “measuring pit” as the main tool for observing the water demand of dry crops. The test pit isolates a part of the soil in the field, and calculates the crop water demand by measuring and calculating the water balance of the soil in the test pit and balancing each element. “Test pit” is actually the internationally accepted “non-Weighing Lysimeter” (Non-Weighing Lysimeter). In order to measure the measured needs within the pit