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In drainage research the collection and analysis of field data is important. [5] In dealing with field data one must expect considerable random variation owing to the large number of natural processes involved and the large variability of plant and soil properties and hydrological conditions.
Practically, wheat does not require irrigation because it develops deeper roots while during the maturing period a dry soil is favorable. The analysis of cumulative frequency [6] of climatic data plays an important role in the determination of the irrigation and drainage needs in the long run.
Drainage design procedures. When the land needs a subsurface drainage system, but saline groundwater is present at great depth, it is better to employ a shallow, closely spaced system of pipes or ditches instead of a deep, widely spaced system. The reason is that the deeper systems produce a more salty effluent than the shallow systems.
Improving soil drainage is a balancing act requiring consideration of soil composition and compaction, and may take a number of approaches to improve.
Subsurface (groundwater) drainage for water table and soil salinity in agricultural land can be done by horizontal and vertical drainage systems. Horizontal drainage systems are drainage systems using open ditches or buried pipe drains. Vertical drainage systems are drainage systems using pumped wells, either open dug wells or tube wells.
The soil's hydraulic conductivity plays an important role in drainage design. The development of agricultural drainage criteria [3] is required to give the designer and manager of the drainage system a target to achieve in terms of maintenance of an optimum depth of the water table. Figure 3. Positive and negative effects of land drainage
Agricultural soil science studies the chemical, physical, biological, and mineralogical composition of soils as they relate to agriculture. Agricultural soil scientists develop methods that will improve the use of soil and increase the production of food and fiber crops. Emphasis continues to grow on the importance of soil sustainability.
the permissible long term average depth of the water table (Dw) on the basis of agricultural drainage criteria; the soil's hydraulic conductivity (Ka and Kb) by measurements; the depth of the bottom of the aquifer (Di) the design drain spacing (L) can be found from the equation in dependence of the drain depth (Dd) and drain radius (r ...