不同灌水深度条件下南疆枣树根系吸水模型研究

Study on Water Absorption Model of Southern Xinjiang Jujube Tree Under Different Irrigation Depth Conditions

为探究不同灌水深度条件下,南疆枣树根系分布特征及吸水机理。以枣树为研究对象,试验导水装置设置3个深埋水平,分别为20 cm(T1)、35 cm(T2)和55 cm(T3),以地表滴灌(T0)为对照组;结合土壤水分运动基本方程建立枣树根系一维吸水模型,并利用实测数据对吸水模型进行验证。研究结果表明,各处理下枣树根系随土层的增加呈负指数趋势分布,相比于T0,T1、T2和T3处理下出水口范围内枣树有效根长分别增长18.2%、15.3%和10.9%,即深层灌水处理促进了枣树深层扎根;不同灌水深度处理下,各土层含水率大小为T2>T3>T1>T0,同一灌水深度处理下,各土层土壤含水率随土壤深度的增加呈现先变大后变小的趋势;通过建立的根系吸水模型模拟土壤含水率,计算值和测量值差异性在允许范围内,满足枣树根系吸水模型对土壤含水率预测的精度要求。综上可得,当灌水深度设置为35 cm左右时,利于枣树根系充分吸收水分和提高水分利用效率。

In order to investigate the root distribution characteristics and water absorption mechanism of jujube in southern Xinjiang under different irrigation depths,taking jujube as the research object,the experimental water diversion device was set at three deep burial levels,which were 20 cm(T1),35 cm(T2)and 55 cm(T3)respectively.Surface drip irrigation(T0)was used as the control group.Based on the basic equation of soil water movement,a one-dimensional water absorption model of jujube root was established,and the water absorption model was verified by the measured data.The results showed that the root system of jujube tree under each treatment showed a negative exponential distribution with the increase of soil layer.Compared with T0 treatment,the effective root length of jujube tree under T1,T2 and T3 treatments increased by 18.2%,15.3%and 10.9%respectively,that is,deep irrigation treatment promoted the deep rooting of jujube tree.Under different irrigation depth treatments,the soil moisture content of each soil layer was in the order of T2>T3>T1>T0.Under the same irrigation depth treatment,the soil moisture content of each soil layer first increased and then decreased with the increase of soil depth.The soil moisture content was simulated by the established root water absorption model and the difference between the calculated value and the measured value was within the allowed range,which met the accuracy requirements of the jujube root water absorption model for the prediction of soil moisture content.To sum up,when the irrigation depth is set at about 35 cm,it is conducive to the jujube root system to fully absorb water and improve water use efficiency.