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

摘要

Naturally occurring organic amendments and inorganic compounds are used as additives to improve soil physical conditions. This study was conducted to determine the effects of some organic and inorganic soil amendments on cumulative evaporation, moisture distribution, and salt leaching 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 manure 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 administered as a saturated solution with the irrigation water. In accordance with previous findings, the cumulative evaporation, E, was found to be 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 the control. Chicken manure,gypsum, water hyacinth, farmyard manure, and dry sludge reduced evaporation by 23, 17, 15, 10, and 6%, respectively. 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. Desalinization and dealkalization were governed largely by lambda. Sand addition 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 experiment. Chicken manure was the most effective organic amendment, increasing the desalinized zone from 17.5 cm to 37.5 cm during the same two periods. Sand additions also increased the dealkanized zone from 18.7 cm to 33.5 cm, whereas, gypsum, which was more effective than the organic amendments on SAR redistribution, increased the dealkanized depth from 12.5 cm to 32.5 cm during the same two periods. Organic and inorganic amendments increased soil water penetrability into clay soils and enhanced salt leaching. This research which was conducted to acquire information relevant to the possible remediation of saline-sodic soils, used organic and inorganic amendments, which are both available and inexpensive.