Influence of drip irrigation level on salt leaching and vegetation growth during reclamation of coastal saline soil having an imbedded gravel–sand layer

Abstract

Water resources are very scarce in coastal saline areas; as such, water-saving irrigation regimes are needed. Drip irrigation combined with an imbedded gravel–sand layer has been proved to be a good method for constructing ecological landscapes in coastal saline soils. A 3-yr experiment (2009–2011) was conducted to evaluate the effects of different drip irrigation amounts controlled by soil matric potentials (SMP) (−5, −10, −15, −20, and −25kPa) on soil salinity and landscape species growth in coastal saline soils with an imbedded gravel–sand layer in Northeast China. The mean electrical conductivity of the saturated paste extract (ECe) of the soil profile significantly decreased to less than 4dSm−1 for SMP treatments higher than −20kPa after two months, then remained at the low level. No significant differences in the extent of desalinization occurred among the drip irrigation treatments based on −5, −10, −15, and −20kPa SMP. The −20kPa treatment could reduce irrigation water usage by 150–610mm in the first three years of reclamation compared with higher SMPs (−5, −10, and −15kPa). Variations of pH of the saturated paste extract (pHe) in the soil profile were relatively moderate. After the 3-yr experiment, the landscape species that are moderately sensitive or sensitive to salt grew well, with an average survival rate of 72%. To balance salt leaching and water saving, a SMP of −20kPa could be used to guide landscape construction in the first three years of reclamation.