彭曼模型在给定土壤含水率条件下预测玉米腾发量研究

Prediction of Corn Evapotranspiration by Penman-Monteith Model under Given Soil Moisture Condition

为了检验彭曼模型在给定土壤含水率条件下对玉米腾发量的预测精度。以沈阳地区为例,基于实测数据利用水量平衡原理推求得玉米实际腾发量,进而利用彭曼模型计算其理论预测值,并利用误差分析法分析不同土壤水分处理条件腾发量的实测计算值和理论预测值之间的误差。结果表明:利用彭曼模型计算作物腾发量时,对土壤含水率变化的影响考虑的不足;不同水分处理的实测值与理论预测值的回归系数(b)、决定系数(R2)在0.75~1.25之间有3个处理,6个处理的误差方差Var(ER)均大于0.1,6个处理的平均绝对误差(AAE)均超过0.25,平均相对误差(ARE)超过25%的有4个处理。说明在给定土壤含水率控制范围的精准灌溉中,利用彭曼公式推求作物腾发量以指导灌溉,存在一定的误差。

Based on the measured data in Shenyang area, corn actual evapotranspiration was obtained by using the principle of water balance, and theoretical prediction of corn evapotranspiration was calculated by Penman-Monteith model. The error between measured calculation values and theoretical prediction values of crop evapotranspiration was analyzed with different soil water conditions. The results showed that Penmen model for calculating crop evapotranspiration did not directly consider the effect of soil moisture change. Comparison of the measured values with the theoretical prediction values under different water treatment situations, the regression coefficients(b) and coefficient of determination(R2) between 0.75 to 1.25 were three treatments, error variance Var(ER) of 6 treatments were greater than 0.1, the mean absolute error(AAE) were more than 0.25. The mean relative error(ARE) of 4 treatments were more than 25%.With a given range of soil moisture content for precision irrigation agriculture,crop evapotranspiration calculated by Penman-Monteith model are used to guide the irrigation which will exsist a certain error.