Effects of different farmland shelterbelts on soil water and nutrient storage in the Hetao Irrigation District

Abstract

<p>As an effective agricultural management method for improving ecological and environmental benefits, the farmland shelterbelt system is crucial in improving soil physical and chemical properties, the ecological environment, and crop yield. This study clarifies the effects of this system on ecosystem functions and provides a guide for the ecological restoration of fragile ecosystems. In the Hetao Irrigation District, three typical farmland shelterbelts (four-, five-, and eight-line patterns) were selected to measure soil properties at a 0-100 cm depth and vegetation properties of shelterbelts and farmland at different distances (0.3 H, 0.7 H, 1 H, 2 H, 3 H, and 4 H) from the shelterbelts during the growing seasons from 2019 to 2021. Soil moisture storage (SMS) and soil nutrient storage [soil carbon storage (SCS), soil nitrogen storage (SNS), and soil phosphorus storage (SPS)] were measured. The results showed that (1) the soil bulk density and clay content of different shelterbelts differed significantly in the horizontal direction, while the soil properties differed significantly in the vertical direction. (2) The shelterbelts had enhanced water retention and nutrient supply functions, and the soil water and nutrient reserves of the four-line pattern were higher than those of the five- and eight-line patterns (SMS = 237.44 mm; SCS = 544.93 g·m−2; SNS = 953.72 g·m−2; SPS = 859.04 g·m−2). (3) The average tree height and DBH of the four- row shelterbelt were 30.06 m and 0.41 m, respectively. Additionally, the four- row shelterbelt had the maximum crop yield of 15.75 t·hm−2. (4) Redundancy analysis showed that a close relationship existed between environmental factors and ecosystem functions in the different shelterbelts, soil characteristics were closely related to soil water and nutrient reserves, and vegetation attributes were negatively correlated with SNS and SPS. In conclusion, the four-line pattern demonstrated the strongest capacity for water and nutrient supply. The results of this study provide a sufficient theoretical basis for shelterbelt construction and ecological restoration in ecologically fragile areas.</p>

农田防护林作为提高生态环境效益的有效农业管理方式，对改善土壤理化性质、改善生态环境，提高作物产量具有重要意义。在河套灌区选择三种典型农田防护林（4行林带、5行林带和8行林带）测量了2019—2021年生长季农田内距防护林0.3 H、0.7 H、1 H、2 H、3 H和4 H处0～100 cm的土壤性质和防护林与农田的植被属性，测算了土壤水分储量（SMS）和土壤养分储量[碳储量(SCS)、氮储量(SNS)和磷储量(SPS)]。结果表明：（1）不同防护林系统水平方向上的土壤容重和土壤黏粒含量差异显著，在垂直方向上土壤属性均有显著差异。（2）防护林具有较好的保水性和养分供应功能，其中4行林带的土壤水分储量和养分储量高于其他林带，分别为SMS 237.44 mm、SCS 544.93 g·m-2、SNS 953.72 g·m-2和SPS 859.04 g·m-2。（3）4行林带的整体长势比较好，其平均树高为30.06 m，胸径为0.41 m，且4行防护林的作物产量最高，为15.75 t·hm-2。（4）冗余分析结果显示，不同防护林系统中，环境因子与生态系统功能之间存在密切关系，土壤特性与土壤水分和养分储量关系密切，另外，植被属性与SNS和SPS基本呈负相关。综上所述，4行林带的水分养分供给能力最强，本研究结果可为生态脆弱地区的防护林建设和生态修复提供有效的理论依据。