基于CWSI和土壤水分修正系数的冬小麦田土壤含水量估算

2000年10月～2001年7月在西北农林科技大学灌溉实验站冬小麦田内,进行了利用作物冠层温度定量估算冬小麦田土壤含水量的试验研究。根据水分亏缺条件下作物蒸发蒸腾量计算公式及作物水分胁迫指标(CWSI)的定义,得到了基于CWSI和土壤水分修正系数Ks的不同生育阶段冬小麦田土壤含水量估算公式,其中Ks采用了康绍忠的幂函数形式(KM)及Dooreboos的线性公式(DM)。用该公式对冬小麦田土壤含水量在4个生育阶段进行了估算,并对估算值和实测值进行对比和误差分析。分析结果表明:在出苗越冬期和越冬返青期KM和DM模型对土壤水分的估算偏高,其原因是由于麦田土地裸露导致CWSI观测中出现了较大误差;在返青抽穗开花期和灌浆成熟期KM模型估算冬小麦根层土壤含水量较适宜,误差在15%以内,DM模型误差较大达到30%。

ESTIMATION OF SOIL MOISTURE OF WINTER WHEAT FIELD BASED ON CWSI AND SOIL WATER CORRECTION COEFFICIENT

Relationship between crop water stress index(CWSI) and soil water content in irrigated winter wheat field was investigated at the Irrigation Experiment Station of the Northwestern Science and Technical University of Agriculture and Forestry during the cropping season from October 2000 to July 2001. Based on the formula for calculation of evapotranspiration of a crop under water stress and the definition of CWSI, a CWSI- and SWCC-based equation for estimation of soil water content in the winter wheat field at different vegetative stages was worked out using the Dooreboos model (D-M) and Kang Shaozhong model (K-M). The experiment results show: the D-M and K-M both overestimated soil moisture during the seedling-regreening stages and the error ratio reached 70% and 50%, respectively; and the K-M was inclined to overestimate while D-M was inclined to downestimate soil moisture during the regreening-maturing stage and the error ratio could reach 15% and 30%, respectively.