Drainage of Waterlogged Soils - 2 | Agriculture Optional Notes for UPSC PDF Download

Effects of Water Logging

Poor Soil Aeration

• Waterlogging leads to the displacement of air within the soil, which is replaced by water.
• Inadequate oxygen supply hinders plant growth, while accumulated carbon dioxide negatively affects root development.
• Poor aeration also fosters the production of toxins and harmful chemicals.
• Microbial activity essential for synthesizing plant nutrients is reduced in waterlogged soil.

Change in Soil pH

• Waterlogged soils become more acidic, reducing their alkalinity, making plant growth challenging.
• Plants struggle to survive in increasingly acidic soil conditions.

Change in Soil Temperatures

• Waterlogging results in a drop in soil temperature, affecting microbial activity and nitrogen fixation rate.

Affecting Soil Nutrients

• Nitrogen and other essential minerals like sulphur, zinc, iron, manganese, phosphorus, and potassium are deficient in waterlogged soils.
• Some minerals become excessive, leading to plant toxicity and hindered plant growth.

Retard Cultivation

• Cultivating in waterlogged soils is difficult, leading to crop failure and losses.
• Only rice can thrive in such conditions.

Harmful Salt Accumulation

• Waterlogging transports harmful salts to the root zone, increasing soil alkalinity and limiting crop growth.

Expansion of Water-loving Wild Plants

• Waterlogging promotes the growth of weeds that thrive in wet environments, competing with crops.
• Removing these weeds is an additional cost for farmers, especially in severe waterlogged conditions.

Loss of Cash Crops

• Most cash crops cannot survive or be cultivated in waterlogged soils, leading to financial losses for farmers.
• Farmers may need to switch to rice, which is tolerant to such conditions.

Effects on Human Health

• Waterlogging creates an environment favorable for disease vectors like mosquitoes, slugs, and snails.
• These vectors transmit diseases such as malaria, bilharzia, typhoid, affecting human and animal populations and disrupting the ecosystem.

Preventive Methods of Water Logging

• Implementing artificial open and underground drainage systems is a viable option. Similarly, enhancing the flow conditions of existing natural waterways can be beneficial.
• Swiftly removing rainwater from the surface of the soil is essential to prevent an increase in the water table level and subsequent waterlogging.
• Preventing percolation loss can be achieved through efficient water utilization and maintaining low irrigation intensity. This ensures that only a small portion of arable land becomes inundated, limiting percolation losses and keeping the water table at an appropriate level.
• The use of alkaline water for irrigation can adversely affect the soil, making it more susceptible to future waterlogging. Therefore, it is advisable to avoid using alkaline water for irrigation.
• Alkali salts may accumulate on the soil surface, forming a crust that hinders the proper drainage of surface water.
• Drainage encompasses the removal of both surface and subsurface waters in a controlled and expeditious manner.
• When draining water, it is important to be cautious not to cause severe environmental damage or negatively impact adjacent fields that may also be affected by waterlogging.
• Implementing drainage is not a preventative measure but a remedial action that can support plant growth in waterlogged soil.
• Mulching involves the application of either organic or inorganic materials on the soil surface to cover and reduce evaporation losses in affected areas.

Waterlogging in India

• In India, waterlogging poses a significant concern, affecting a total of 86.92 lakh hectares of land. 
• This issue encompasses both areas within irrigation systems and those outside of them. 
• Land within irrigation systems becomes waterlogged primarily due to a rising water table caused by inadequate drainage, while other areas experience waterlogging due to prolonged flooding events.

Conclusion

Waterlogging occurs when an excess of water in the soil profile prevents plant roots from accessing oxygen. It's important to note that waterlogging may not always be visibly apparent on the surface, yet it remains a problem. Enhancing drainage in flooded fields can reduce the duration during which crop roots are exposed to oxygen-deprived conditions. Among the various solutions, raised beds require the most attention but are also the most effective in improving drainage. Additionally, it's worth noting that waterlogged soils release higher levels of nitrous oxide (N₂O), a particularly harmful greenhouse gas.