Study on the Water Consumption of Walnut Trees using the Unit Dynamic Balance Method

Crop water consumption is an important data for the rational allocation of agricultural water resources and irrigation regime arrangement. Compared with the study of field crop water consumption, the measurement and calculation of orchard water consumption are not comprehensive. It is necessary to study the calculation method on a physical basis and discuss the existing method for improving the calculation accuracy of orchard water consumption. Walnut trees grown using drip irrigation in Aksu district, Xinjiang were used for this study. Soil hydrodynamic method was introduced to investigate the water consumption of fruit trees, water potential theory was used to analyze the moisture exchange in the root zone, the soil water balance was studied from a dynamic perspective, and the calculated water consumption was used to evaluate the irrigation regime. The results showed that the closer distance to the tree trunk, the greater was the water consumption of the soil decreases with a decrease in soil water content. The soil water content greatly varies within a depth of 0-60 cm. In all directions, the soil moisture exchange between the root zone and bottom layer is greater than the radial and axial exchange. The water exchange between the root zone and the bottom layer had the most obvious influence on the water consumption of walnut trees. The water consumption during the entire growth period was 829.08 mm. Water consumption of the hard-core period and oil conversion period was 70.37% during the entire growth period. The optimal irrigation quota of walnut tree is 450 m^3．hm^(-2), which meets the requirements of water-saving and high-yield. Preliminary studies showed that compared with the traditional water balance method, the unit dynamic balance method is more comprehensive and realistic. Therefore, it provides a theoretical basis for the scientific management of walnut orchards in arid regions of northwest China.

關鍵字

Walnut Tree ； Water Consumption ； Soil Water Content ； Balance Body ； Moisture exchange

並列摘要

作物耗水量是農業水資源合理配置和制定灌溉制度的重要數據。相對於大田作物的耗水研究，果園耗水量的測量與計算不太全面。因此具有物理基礎的計算方法的研究及現有方法的探討對於提高果園耗水量的計算精度是十分必要的。本研究以新疆阿克蘇地區滴灌核桃樹為研究對象，將土壤水動力學方法引入果樹耗水量的研究中，利用水勢理論分析根系區的水分交換，從動態角度研究土壤水量平衡，用計算得到的耗水量評價灌溉制度。結果表明，距離樹幹越近的土壤耗水量越大，耗水量隨土壤含水率的減小而減小，0-60 cm深度內土壤含水率變化幅度較大。各方向的土壤交換水量為根系層與底層間的交換＞徑向交換＞軸向交換。根系層與底層的水分交換對核桃樹耗水量的影響最為明顯。全生育期耗水量為829.08 mm。硬核期和油脂轉化期的耗水量占全生育期的70.37％。核桃樹最優灌水定額為450 m^3．hm^(-2)，滿足節水高產的要求。初步研究表明，相對於傳統水量平衡法，單元動態平衡法考慮的要素更加全面，計算結果更接近實際。為西北幹旱地區核桃園的科學管理提供理論依據。

並列關鍵字

核桃樹；耗水量；土壤含水率；平衡體；水分交換

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