water Quality Effects on Capillary Rise in Soils of different Textures

摘要

Sustainability of irrigated agriculture in major and medium irrigation projects in India is threatened due to development of waterlogging and secondary soil salinisation. Understanding of the process of capillary rise is, therefore, of utrmost importance. As large spatial and temporal variation occur in water quality, its effect on capillary rise in soils of differnet texture need to be evalauted. The maximum height of capillary rise was 286 cm in the case of chromustert l (A heavy texture soil) when distilled water was used. it was half of this value when the water was of poor quality with an EC of 16 dS/m and SAR of 40. It was minimum of 61 cm in the case of Typic Ustorthent (a light texture soil) with a water of EC 16 dS/m and SAR 40 while the naximum value was 81 cm with the distilled water. Both the increasing electrolyte conductivity and the sodium adsorption ratio (SAR) depressed the maximum height to which capillary rise occurred. The effect was more in the case of fine than the light textured soils. Hagen- Poseuille equations were evaauted for their applicability in predicting the maximum height of capillary rise. The excellent match etween the observed and predicted values encourages us to recommend their use as more sophisticated tools may not find applicatiosn for want of appropriate parameters for the soils investigated. Practical applications of the findings are that in case shallow drains are adopted (this view is gainign acceptance) to reclaim saline lands and to improve soil aeration of the root zone, cropping pattern should be so designed such that water flux at critical times is maintained downward. Ample amount of water commensurate with these requirements be arranged.