אסיף מאגר המחקר החקלאי

Prewetting rate and sodicity effects on soil permeability and surface sealing

Year:

2002

Source of publication :

Authors :

Volume :

573

Co-Authors:

Shainberg, I., Volcani Center, ARO, Institute of Soil, Water and Environmental Sciences, Bet Dagan, 50250, Israel
Levy, G.J., Volcani Center, ARO, Institute of Soil, Water and Environmental Sciences, Bet Dagan, 50250, Israel
Mamedov, A.I., Volcani Center, ARO, Institute of Soil, Water and Environmental Sciences, Bet Dagan, 50250, Israel

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Abstract:

Irrigation with saline water may introduce sodium into the exchange complex of soils. Exchangeable sodium deteriorates soils' structure and permeability. The susceptibility of soils to sodicity depends on 1) soil permanent properties (such as texture and mineralogy) and 2) time dependent variables such as cultivation (and time since cultivation), irrigation methods and wetting rates. Whereas the effect of inherent soil properties on soil response to sodicity has been studied extensively, the effect of management on the response of soils to sodicity has received little attention. The objective of this presentation is to demonstrate the effect of prewetting rate (PWR) on the permeability and surface sealing of soils. Six Mediterranean soils, ranging in their clay content between 90 and 680 g kg-1 and their exchangeable sodium percentage (ESP) level between 0.9 and 10.2 were studied. Air-dried soil samples were packed in columns (permeability studies) or trays (sealing studies) and were prewetted from below with three PWRs (2, 4-8, 50-60 mm h-1). Thereafter the soils were either leached or rained upon with distilled water. The effect of ESP and PWR depended on soil texture. In soils with low clay content (9%), the effect of PWR on soil permeability was negligible, whereas the effect of ESP was significant. The permeability of the soils with >9% clay increased with a decrease in PWR, and the effect increased with increase in clay content. High PWR caused aggregate slaking, lower permeability, more sealing and higher susceptibility to sodicity. In the clay soils PWR had a predominant effect on permeability and runoff, while the effect of ESP on these properties was small. It is concluded that no-till conditions and irrigation with slow application rates maintain stable aggregates and decrease the susceptibility of soils to sodicity and seal formation.

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