In moist climates, soils may be adequate for cropping with the exception that they become waterlogged from from heavy rains for brief periods each year. Many soils have poor natural internal drainage and can remain waterlogged for several days after excess rain if there is no artificial drainage. This prolonged wetness prevents timely fieldwork and causes stress to growing crops because saturated soils do not provide sufficient ventilation for crop root development. The roots of most crops cannot tolerate excessively wet conditions for more than a couple of days. Soil conditions that make drainage a necessity for some agricultural lands include those with slow water permeability or dense soil layers that restrict water movement, flat or digressional topography and, in some areas, high levels of salts at the soil surface.
Other soils may have an impervious layer of mineralized soil, called a hardpan, or relatively impervious rock layers may underlie shallow soils. Drainage is especially important in tree fruit production. Soils that are otherwise excellent may be waterlogged for a week of the year, which is sufficient to kill fruit trees and cost the productivity of the land until replacements can be established. In each of these cases appropriate drainage carries off temporary flushes of water to prevent damage to annual or perennial crops.
An Agricultural Drainage System is one used in surface ditches, subsurface permeable pipes, or both, to remove standing or excess water from poorly drained lands. When installing a sub- surface drainage system, pipes are either strategically placed in a field to remove water from isolated wet areas or installed in a pattern to drain an entire field. In some areas, surface inlets or intakes (risers extended from underground pipes to the surface) remove excess surface water from low spots in fields.
The installation of an agricultural drainage system is a significant financial investment. The decision to make this investment was determined for two major reasons, which have improved agricultural production significantly:
Although large in scale, the implementation of the phases of the Mabouya Drainage Project did not take long. The workers’ operational hours were from 7am-10pm and monthly valuations were completed diligently. Works on site of Phase I were finished within a five (5) month time frame. The second phase of the project was completed in stages over a fourteen (14) month period, due to various unforeseeable delays, mainly adverse weather conditions.
Phase II of the project extended a little past October 2006 due to the late commencement. However, the works were an overall success celebrated by all involved. The maintenance of the systems where soil and trash deposits constantly need to be cleaned, have been sufficiently maintained by the IMU yielding the desired results for the farmers in the area, and the public in general.