The adoption of drainage techniques to remove excess water and allow free circulation of air is the most important management measure to make waterlogged or poorly drained soils agriculturally productive. Some drainage devices include:
Surface drainage involves the construction of ditches to convey water away.
Ridging to raise the seedbed above the surrounding topography.
Molding: Also, farmers make big heaps (mold) whereby the top of the mold is kept above water all year round.
In certain countries such as Japan, paddy soils are filled to grow sugarcane and some water-loving crops.
The maintenance of good soil structure and aggregate stability through the use of organic matter, farm manure, and the growth of legumes enhance optimum soil aeration.
Probably one of the most viable options in the management of paddy soils is the cultivation of crops (Such as paddy rice) adapted to conditions of poor soil aeration.
These crops develop a system of interconnected internal air spaces through which atmospheric oxygen diffuses down into the root, and out of the root into the soil immediately outside the root, thus permitting the actual uptake of ions by the root to take place as an aerobic process.
Furthermore, some plants such as mangroves and rice are adapted for growing in water and have a high tolerance to Mn and Fe.
In some parts of Japan, “tile drainage” is practiced so as to maintain an adequate rate of percolation of water. Green manuring and the use of composts also help to maintain a good enough soil structure in the initial stages of flooding to allow adequate percolation.
Over drainage of calcareous or alkaline soils can be undesirable; for by lowering the CO2 concentration in the soil water, the pH may rise sufficiently to cause loss of yield through too low availability and uptake of ferrous iron.
Nitrate-nitrogen (NO – N) fertilizer should not be applied to paddy (Swamp) rice to avoid loss of nitrogen through DE nitrification. In areas where swamp rice is grown extensively, nitrogen is added in ammonium, NH4, and urea, (NH2)2 CO forms.
Read also: Soil Aeration on Biological Activities and Plant Growth