IMPACT OF SOIL AMENDMENTS ON INTERMITTENT EVAPORATION, MOISTURE DISTRIBUTION AND SALT REDISTRIBUTION IN SALINE-SODIC CLAY SOIL COLUMNS

Naturally occurring organic amendments and inorganic compounds are use d as additives to improve soil physical conditions. This study was con ducted to determine the effects of some organic and inorganic soil ame ndments on cumulative evaporation, moisture distribution, and salt lea ching through saline-sodic clay soil columns. Organic amendments were mixed with the top 5 cm in 60-cm soil columns at the rate of 22 ton/ha for farmyard manure and water hyacinth and 44 ton/ha for chicken manu re and dry sludge. The 1:2 sand-soil mixture was applied to the top 20 cm of the columns at a rate of 800 ton/ha, whereas gypsum was adminis tered as a saturated solution with the irrigation water. In accordance with previous findings, the cumulative evaporation, E, was found to b e a linear function of the square root of time (E C root t), where C, was determined largely by the type of amendment added. Sand increased soil water penetrability, lambda, and markedly reduced E by 32% over t he control. Chicken manure,gypsum, water hyacinth, farmyard manure, an d dry sludge reduced evaporation by 23, 17, 15, 10, and 6%, respective ly. The soil moisture distribution was governed by the amount of water conserved. Sand and chicken manure additions increased the amount of water conserved by 72% and 52% respectively, compared with the control . The depth of the wetting front advanced deeper and the transmission zone of the moisture distribution lengthened as time progressed. Desal inization and dealkalization were governed largely by lambda. Sand add ition was more effective in increasing the desalinized zone from 28.5 cm at the end of the first 30 days to 40.0 cm at the end of the experi ment. Chicken manure was the most effective organic amendment, increas ing the desalinized zone from 17.5 cm to 37.5 cm during the same two p eriods. Sand additions also increased the dealkanized zone from 18.7 c m to 33.5 cm, whereas, gypsum, which was more effective than the organ ic amendments on SAR redistribution, increased the dealkanized depth f rom 12.5 cm to 32.5 cm during the same two periods. Organic and inorga nic amendments increased soil water penetrability into clay soils and enhanced salt leaching. This research which was conducted to acquire i nformation relevant to the possible remediation of saline-sodic soils, used organic and inorganic amendments, which are both available and i nexpensive.