Water-logging and Salinization Adverse Effects on Agriculture
Water-logging and salinization continue to cause economic losses in many areas of the world, though farmers and scientists have been aware of these problems and potential technical solutions for thousands of years. In this research a model is suggested to study the effect of water-logging on the net profit from the crops farm yield. The duration of water-logging according to different irrigation systems, crop type and soil type by calculating water consumptive use for each crop using Blaney-Criddle method and calculating the amount of deep percolation that causes water table rising, the effect of salinity on crops yield only, the combined effect of water-logging and salinity on crops yield.
Water-logging and salinity problems often require some form of drainage to allow sustainable agriculture production. This must be an integral part of irrigation system investments. However, poor irrigation and agronomic practices have led salinity and water logging.
Wichelns D. examined farm-level and project-level models of crop production to identify policies that will encourage farmers to consider opportunity costs and the effects of irrigation and leaching on depth to regional water tables. Kotob described counter-measures taken by the government on a national and regional scale and farmers on a local or field scale.
McFarlane D and Williamson D identified three types of water logging. These were associated with perched aquifers in texture contrast soils, inundation of terraces and valleys, and saturation in surface soil due to the hydraulic pressure being above ground level in aquifers at the base of the regolith of highly weathered granites and gneisses or within channels in broad valley sediments.
The main objective of this study is estimating a model of the net profit from the farm according to the effect of both water-logging and salinity on different crops yield. The duration of water logging is calculated also according to crop type, soil type and irrigation method.
Methods of Measuring and Estimating Water-logging Intensity and Duration
The measurement of water logging intensity and duration is usually confined to experimental sites though they have application in farm management. The methods applied include: 1- The determination of the intensity and duration of saturation of the root zone using shallow dip wells inserted to the top of the perching layer. 2- Examination of historical crop or pasture yields and corresponding rainfall; 3- Estimation based on knowledge of soil hydraulic properties and climate data; 4- Inference of water logging intensity from soil morphology; 5- Mapping water logging damage in crops using satellite remote sensing.