基于水分胁迫系数的枣树园土壤含水率估算

为了实现黄土高原地区滴灌条件下枣树园土壤含水率的小范围快捷监测,根据FAO-56水分胁迫系数的定义和相关计算公式,得到了基于土壤水分胁迫系数的黄土高原地区滴灌条件下枣树根层土壤平均含水率估算公式．2009年4-9月将该公式应用于西北农林科技大学陕西米脂孟岔试验站的枣树试验园,配置了3种不同的土壤含水率控制下限,对枣树2个重要生育期的土壤含水率进行了估算,模拟了水分动态变化过程,并对估算值和实测值进行对比和误差分析．结果表明:采用基于FAO-56水分胁迫系数的计算公式对土壤含水率的动态模拟达到了较高的精度,估算值与实测值之间误差较小:其中开花坐果期各处理(灌水下限为60％,50％,40％的田间持水率)的估算值与实测值之间的相关系数分别为0828 0,0907 3,0935 1;标准误差分别为0055,0093,0068．果实膨大期各处理的相关系数分别为0777 2,0766 7,0905 5;标准误差分别为0057,0092,0079．估算值与实测值之间的相关系数随土壤含水率的增大而减小,随土壤水分胁迫程度的增大而增大,即土壤含水率较高时对公式精度有一定的影响．该方法较适用于黄土高原半干旱地区,对农业用水管理具有一定参考价值．

Estimation of soil moisture content of jujube orchard in loess plateau based on water stress coefficient from FAO-56

To quickly monitor the soil moisture content of drip irrigated jujubes in Loess Plateau, a new equation for estimating average soil moisture content in root zone has been deduced based on the fundamental concept of FAO-56 water stress coefficient and related formulas, the equation is applicable in different growth stages of jujube. In April-September 2009, the equation was used to estimate the soil moisture content in two important growth stages of jujube by allocating three different lowest limits of soil moisture content in Mizhi Experimental Station in loess Plateau, and the dynamic change in moisture content was simulated; additionally, the estimated and measured values were compared and the corresponding error analysis was conducted. The results indicated that the FAO-56 water stress coefficient formula has a high accuracy in the dynamic simulation of the soil moisture content, thus the error between the estimated and measured values is less. During flowering and fruit set stages the correlation coefficients are 0.828 0，0.907 3，0.935 1, the root mean square errors are 0.055, 0.093, 0068 in different treatments (lowest limit of irrigation: 60%, 50%, 40% of field capacity). During fruit development stage the correlation coefficients are 0.777 2, 0.766 7, 0.905 5, and the root mean square errors are 0.057, 0.092, 0.079 for those treatments. Moreover, the correlation coefficients are reduced with increasing soil moisture content, but rise with increasing water stress degree, suggesting for higher soil moisture contents the formula accuracy will get poor slightly. This formula is more sui table for the semi arid areas in Loess Plateau, and it may be useful for agricultural water management.