不同水头和土壤容重下微润灌湿润体内水盐分布特性

为探明微润灌溉施肥的湿润体内水盐分布规律,开展不同压力水头和土壤容重下室内微润灌溉入渗试验。设置3个水头(H1.0:1.0 m、H1.5:1.5 m和H2.0:2.0 m)和3个土壤容重(D1.00:1.00 g/cm~3、D1.15:1.15 g/cm~3和D1.30:1.30 g/cm~3),以质量分数0.3%的硝酸钾溶液为入渗溶液,研究微润灌湿润体内水盐空间分布规律和变异特征。结果表明:微润管入口水头和土壤容重对湿润体内含水率、NO_3~--N与K~+含量均值影响显著。同一土壤容重下,H1.5和H2.0与H1.0相比,湿润体剖面面积增大13.50%~21.61%,湿润体内含水率、NO_3~--N与K~+含量均值分别增大3.69%~10.71%、7.80%~10.95%和7.29%~17.49%,均匀系数分别增大7.65%~18.63%、5.22%~13.63%和9.34%~21.89%;同一水头下,D1.15和D1.30与D1.00相比,湿润体剖面面积减小5.76%~9.21%,含水率、NO_3~--N含量均值分别减小15.73%~21.54%、8.08%~10.97%,而K~+含量均值增大34.89%~64.79%,三者均匀系数分别减小9.02%~11.45%、4.04%~7.25%和7.09%~11.54%。K~+在微润管周围分布较集中,K~+聚集分布面积约占湿润体剖面面积的40.80%~61.41%。微润灌湿润体内含水率、NO_3~--N和K~+含量均值与至微润管的水平距离符合四参数Log-logistic模型。

Water-Salinity Distribution Characteristics in Wetted Soil of Moistube Irrigation under Different Pressure Heads and Soil Bulk Densities

In order to investigate water-salinity distribution characteristics in wetted soil of moistube fertigation, the infiltration experiment of moistube irrigation was carried out under different pressure heads and soil bulk densities, the 0.3% potassium nitrate solution was used in infiltration experiment, and three pressure heads (H1.0:1.0m, H1.5:1.5m and H2.0:2.0m) and three soil bulk densities (D1.00:1.00g/cm3, D1.15:1.15g/cm3 and D1.30:1.30g/cm3) were designed to study the water-salinity distribution and spatial variation traits in wetted soil of moistube irrigation. The results showed that pressure heads and soil bulk densities had significant effect on average contents of moisture, NO-3N and K+ in wetted soil. Under the same soil bulk density, compared with H1.0, the sectional area of wetted soil of H1.5 and H2.0 was increased by 13.50%~21.61%, average contents of moisture, NO-3N and K+ were increased by 3.69%~10.71%, 7.80%~10.95% and 7.29%~17.49%, respectively, and uniformity coefficients were increased by 7.65%~18.63%, 5.22%~13.63% and 9.34%~21.89%, respectively. Under the same pressure head, compared with D1.00, the sectional area of wetted soil of D1.15 and D1.30 was decreased by 5.76%~9.21%, average contents of moisture and NO-3N were decreased by 15.73%~21.54% and 8.08%~10.97%, but average content of K+ was increased by 34.89%~64.79%, and uniformity coefficients of moisture, NO-3N and K+ contents in wetted soil were decreased by 9.02%~11.45%, 4.04%~7.25% and 7.09%~11.54%, respectively. K+ distributed intensively around moistube and accounted for 40.80%~61.41% of distribution area of wetted soil. Average contents of the moisture, NO-3N and K+ in wetted soil of moistube irrigation and the horizontal distance from moistube conformed to the four-parameter Log-logistic model. The research results can provide theoretical basis and practical reference for moistube fertigation.