Moisture and Salinity Distribution around the Root of Drip-tape-irrigated Maize Cultivated in Heavy Soil of Khuzestan Province of Iran

Limited water resources have increased the need for optimal use of water in agriculture. One solution in this regard is to employ modern irrigation methods, including drip tape irrigation. In this study, furrow surface irrigation (the standard method used in the local area) was compared with a drip tape irrigation system under three irrigation regimes (two-, three-, and four-day regimes). Soil moisture and salinity during every stage of plant development (primary, middle, and final) were monitored by collecting soil samples from 0-25, 25-50, and 50-75 cm depths before and after irrigation. Similar moisture distribution was achieved in the 2 consecutive crop years. Under the 2 day irrigation regime, the most substantial moisture changes were observed in the 0-25 cm deep layer and under 3 and 4-day irrigation regimes in the 0-50 cm depth. Soil moisture content before irrigation was around 16 wt.%, reaching 18% after the 2 day irrigation treatment and 23% after 3 and 4 day irrigation treatments. Salinity in the 2-day EC irrigation regime, the soil salinity has decreased from 9 to 5 dS/m in the first year and from 11.5 to 2.8 dS/m in the second year, and in 3- and 4-day irrigation regimes, soil EC has increased from 9 to 10 ds/m in the first year and from 11.5 to 4.5 dS/m in the second year. The study of salinity distribution at different depths of plant roots introduces the best soil depth to 0 to 25 cm with the lowest salinity in all three irrigation regimes. In contrast, by the end of the second crop year, salinity dropped to a quarter, which was primarily due to the better water quality of The Karun River compared to the previous year. A similar outcome was achieved with surface irrigation. The results show that replacing tape strip irrigation with surface irrigation, in addition to saving on the amount of irrigation water consumption, also controls the soil salinization process by applying irrigation management and choosing the best irrigation regime.