Changes in salinity of a clay soil after a short-term salt water flood event

Abstract

The effects and subsequent recovery from a short-term salt water flood event were studied on a clay soil. Sea inundation of agricultural land caused marine salt water to pond on the soil surface for up to 144 h. The salinity of the soil, how deeply the salt water penetrated into the soil and how quickly salts washed out of the soil were assessed. Elevated salt content was seen most strongly in the top layer (0–2 cm) of the soil and salt concentrations increased with the length of inundation. Maize crops died if inundated for 24 h or more, while ryegrass pasture died after an inundation period of 36 h or more. Flushing of soil particles with fresh rainwater proved effective at lowering the salt content in the top 2 cm of soil. The salt content was considerably lower after one rainfall event of 35 mm and decreased only slightly more after another 165 mm of rain. The combined effect of sea level rise and land subsidence may enhance saltwater contamination and soil salinisation with potential serious environmental and socio-economic impacts, e.g. compromising agriculture. Using salt tolerant grasses as pasture species in these low-lying areas should be further investigated.