不同配置农田防护林对田间土壤水分空间变异的影响

Effects of Different Configurations of Farmland Shelterbelt System on Spatital Variation of Soil Moisture Content

河套灌区是我国最大的引黄灌区,区内水资源匮乏,农田防护林系统在灌区土壤水分调控中发挥着重要作用。为明确防护林对农田土壤水分的影响,采用传统统计学方法综合分析了防护林网内土壤蒸发、风速、光照强度、气温、空气相对湿度、细根生物量密度及土壤容重等因素对土壤含水量的影响。结果表明:不同配置的农田防护林网内田间土壤水分具有明显的空间异质性,水平方向上土壤含水量与林带距离呈正向关系,主要影响因子为风速、土壤蒸发和1 H(H为防护林树高)范围内的细根生物量密度;垂直方向上0-80 cm土壤水分从表层向下逐渐增加,主要影响因子为20-80 cm土层的细根生物量密度、土壤容重和表层土壤蒸发。不同配置农田防护林系统对田间土壤水分影响差异明显,2行小美旱杨+2行二白杨疏透度为45%的防护林的防护效益最好,田间土壤含水量最高。研究结果明确了不同配置防护林的农田土壤水分特征以及主要影响因子,可以为合理的防护林规划提供理论依据。

The Hetao Irrigation Area is the largest irrigation area of the Yellow River region.Water scarcity is severe,and farmland shelterbelt is playing an important role in the soil water and salt regulation.In order to determine the effect of shelterbelt on soil moisture in farmland,this paper used traditional statistical methods to investigate the variation of soil moisture in four different configurations of farmland shelterbelt systems in early May 2019.The effects of soil evaporation,wind speed,light intensity,air relative humidity,fine root biomass and soil physical and chemical properties on soil moisture content were analyzed.The results showed that the soil water had obvious spatial structure characteristics.Soil moisture in different configurations of farmland shelterbelt system had obvious spatial heterogeneity.In the horizontal direction,soil moisture in farmland at different distances from the main forest belt increased first and then decreased,and the main influencing factors were wind speed,soil evaporation and the distribution of fine-root biomass density with in 1 H(H is the height of shelter forest).In the vertical direction,soil moisture increased with the increase of soil depth,and the main influencing factors were fine-root biomass density in 20-80 cm soil layer,soil bulk density and soil evaporation.soil moisture in different configurations of farmland shelterbelt system had an obvious difference,shelterbelt with a permeability of 40%(1 lines of Populus popular’s+2 lines of Populus gansuensis+1 lines of Populus popular’s)had the best protection effect and the highest soil moisture content.This study basically analyzed the soil moisture of different farmland shelterbelts and provided a theoretical basis for rational shelterbelts and farmland construction.