Laboratory experiment study on the effects of water quality and emitter discharge on wetted soil geometry and volume

A series of laboratory experiments were conducted to quantify the influences of irrigating water salinity, emitter discharge rate on the patterns of the wetted soil column and the wetting front dynamics. An alkaline silt clayey loamy soil, three discharge rates(2, 3.4, 8 L/h), five saline levels of irrigating water(four different combinations of SAR=20 and 2 and C=80, 20 mmol/L, as well as distilled water, DW), were used in the experiments. A 15° wedge-shaped plexiglass container was used to represent one twenty-fourth of the complete cylinder. The results indicated that drip irrigation of different discharge rates with different quality of irrigating water had its significant influences on the wetted patterns. Higher discharge rate produced higher lateral or horizontal movement of soil water under the same water quality. The increase of emitter discharge is the advantage of horizontal movement of soil water, while disadvantage of lateral movement of soil water under the same water application; Irrigation with DW yielded very lower vertical infiltration and the horizontal water advance was much faster, which is not good for salt leaching and may cause surface runoff. Irrigation with saline water produced faster horizontal water movement initially and with irrigation going on, vertical infiltration tended to increase as compared with the lateral movement.