Effect of water and salt regulations under drip irrigation on soil hydraulic properties in local coastal saline soil

In order to study the impact of filter and soil matric potential (-5, -10, -15, -20, -25 kPa) treatments on soil hydraulic conductivity K, Gardner α, and the contribution of pore size classes to flow in coastal saline soil, disc infiltration experiments at pressure heads of -15, -6, -3, and 0 cm were implemented. The results showed that, after local soil salt-water regulation, the hydraulic conductivity Ks and Gardner α were higher than that of the control (CK), and the K6, K15 were smaller than that of the CK, and K3 had no obviously changes. Through the tests of between-subjects effects with two factors of filter and soil matric potential treatments, filter treatment was the main factor to the hydraulic conductivity K, Gardner α, the Ksand K6, Gardner α of filter treatment was significantly larger than non-filter treatment. Contribution of macropores (>0.5 mm) to flow of filter and soil matric potential treatments was higher than CK, and the contribution of mesopores2 (0.25-0.1 mm) and micropores (<0.1 mm) to flow was less than CK, respectively. After the tests of between-subjects effects with two factors of filter and soil matric potential treatments, filter treatment was the main factor to the contribution of pore fraction to water flow. The contribution of macropores (>0.5 mm) and mesopores1 (0.5-0.25 mm) to flow under filter treatment had a significantly difference to the non-filter treatment (sig: 0.038, 0.014, respectively). The soil hydraulic conductivity Ks, K6 and Gardener α had a significantly increase, the contribution of large pore classes to flow increased too. The contributions of small pore classes to flow decreased after local soil salt-water regulation, so it was concluded that the soil structure was getting better after salt-water regulation.