滴灌施肥条件下土壤水分运移规律研究

Study on Soil Water Movement under the Condition of Drip Irrigation and Fertilization

为了更加精准确定宁夏中部干旱区作物水肥管理方案,利用点源入渗的方式,设置灌水量(3、5 L)、滴头流量(0.5、0.75、1 L/h)和氮肥浓度(0、200、500 mg/L)3个因素开展同一滴头流量,不同再分布时间和不同氮肥浓度下土壤水分运移规律的研究。结果表明:(1)同一滴头流量不同再分布时间下,当再分布时间较短时(t<3 d),土壤含水率随纵向土层深度的增大呈递减的趋势;同一滴头流量不同再分布时间下,土壤含水率随水平径向距离的增大呈递减的趋势;纵向土层深度或水平径向距离超过25 cm时,土壤含水率减小得更快。(2)再分布时间与纵向土壤含水率、径向土壤含水率均呈极显著相关,但相关性F1=66.889>F2=53.152,拟合优度R2^1=0.660>R2^2=0.607。(3)在同一滴头流量不同氮肥浓度下,土壤含水率随纵向土层深度或水平径向距离的增大呈递减的趋势。纵向土层深度在0~25 cm范围内,θF2均为最大值;水平径向距离在0~30 cm范围内,θF1皆为最大值;纵向土层深度或水平径向距离大于25 cm时,θFi减小得更快。综上所述,在0~30 cm范围内,纵向土层深度或水平径向距离为25 cm是土壤含水率变化的关键节点,该研究结果可为宁夏中部干旱区枸杞滴灌种植提供可靠的技术支撑。

In order to more accurately determine the water and fertilizer management program for crops in the central arid region of Ningxia,using the way of point source infiltration,three factors,namely irrigation amount(3,5 L),droplet flow rate(0.5,0.75,1 L/h)and nitrogen concentration(0,200,500 mg/L),were set to carry out the study of soil water transport law under the condition of same droplet flow rate,different redistribution time and different nitrogen concentration.The results showed that:①Under different redistribution time of the same droplet flow,when the redistribution time was shorter(t was smaller than 3 days),the soil moisture content showed a decreasing trend with the increase of longitudinal soil depth.The soil moisture content decreased with the increase of horizontal radial distance under different redistribution time of the same droplet discharge.When the depth or horizontal radial distance of longitudinal soil layer exceeded 25 cm,the soil moisture content decreased faster.②The redistribution time was significantly correlated with the longitudinal and radial soil moisture content,but the correlation of F1(66.889)was larger than F2(53.152),and the goodness of fit R21(0.660)was larger than R22(0.607).③Under the same droplet flow and different nitrogen fertilizer concentration,the soil moisture content showed a decreasing trend with the increase of longitudinal soil depth or horizontal radial distance.When the depth of longitudinal soil layer was within the range of 0~25 cm,θF2 was the maximum value.In the range of 0~30 cm,θF1 was the maximum value.When the depth or horizontal radial distance of the longitudinal soil layer was greater than 25 cm,θFi decreased faster.In summary,within the range of 0~30 cm,the depth or horizontal radial distance of the longitudinal soil layer is 25 cm,which is the key node for the change of soil water content.This research result can provide technical support for the drip irrigation planting of Lycium barbarum in the arid region of central Ningxia.