Effect of Aeration and Soil Water Redistribution on the Air Permeability under Subsurface Drip Irrigation

Abstract

While subsurface drip irrigation supplies water to meet crop needs with high water use efficiency, it might cause low O2 levels around crop roots and affect plant growth and yield. A modified flow apparatus was used in the laboratory to investigate the impact of aeration following subsurface drip irrigation on transient air permeability. Disturbed samples from two soils from China, a Brown Forest soil (sandy loam) and Lou soil (silty clay loam), were repacked to construct soil columns with various bulk densities (1.3, 1.35, 1.4, 1.45, 1.5, and 1.55 g cm−3). Subsurface drip irrigation (350 mL) was performed at the 17‐cm soil depth. Aeration (1050 mL) was conducted through the emitter of the subsurface drip irrigation system for 5 min. The results showed that air permeability was affected by soil texture and bulk density. The measured air permeability from the modified apparatus was comparable to that from the classical apparatus. Soil air permeability after irrigation was reduced by 88.2, 70.1, and 42.5% for the Brown Forest soil with a bulk density of 1.3, 1.4, and 1.5 g cm−3, respectively, and 71.2, 65.4, and 54.3%, respectively, for the Lou soil. A short‐period aeration following irrigation quickly improved soil air permeability, however. The air permeability level within 10 min after aeration was 3.7, 2.0, and 1.5 times that before aeration for the Brown Forest soil with a bulk density of 1.3, 1.4, and 1.5 g cm−3, respectively, and 3.0, 2.5 and 2.0 times, respectively, for the Lou soil. It seems a feasible and economical approach to improve soil air permeability by aerating the soil through a subsurface irrigation system following irrigation.