Drip versus surface irrigation in long term environmental modelling of soil-water-plant exposed to saline water

Abstract

A physically based soil-water storage model with two surface and drip irrigation scenarios in response to saline water was used in the semi-arid Gordonia district in South Africa. The model (CoupModel) consists of several different modules that couples mass and energy flow models with dynamic biotic models of plant and its environment. The simulation period accounted for non-productive water losses, salt accumulation in root zone, and salt transport to below aquifer via deep percolation. The monitoring of biomass production with respect to water consumption and soil osmotic pressure indicted a decline in crop yield due to the water and salt stresses. The drip scenario had a better functionality in terms of the water wastage as the soil evaporation decreased by 40%. However, the productive water consumption decreased by 20% due to insufficient leaching fraction while salt accumulation increased drastically in the entire root zone. We found that salt could be flushed out from the root zone by more leaching but the water wastage increases as well as increasing the possibility of salinization beneath aquifer. The soil-water and plant ecosystem responds differently to salinity in different water management practices. Salt as a source of pollution can either stabilizes the soil by accumulation in the root zone causing anthropogenic soil desertification or can percolate it to beneath the aquifer resulting to long-term salinization. The findings of our study could sever to improve different management schemes in similar semi-arid regions. © 2012 WIT Press.