Mitigation of harmful effects of flooded soils

How is are the flooded soils formed and ways to mitigate them

1. FLOODED SOILS MOHAN RAJ V 2019045030

2. Flooded soils or swamp soils are  a condition in which an area of soil is oversaturated with water

3. PHYSICAL CHANGES The pore spaces in the soil gets saturated with water leading to swelling of soil and softening and breaking of hard clods. Puddling of soil further breaks the soil structural aggregates and soil becomes a sludgy or soapy mixture. The exchange of air between soil and atmosphere is impeded, so it slows down the drying of soil. Water particles are held by soil particles, so they are prevented from percolating downwards.

4. CHEMICAL CHANGES Development of two distinct chemical zones – oxidized and reduced zones. Oxidized zone is the thin upper zone, 1-10 mm in thickness. It absorbs O 2 from water and turns brown. Reduced zone is a lower layer, extremely low in available O 2 . It is dark blue or gray in color.

5. N 2 in incorporated plant and animal residues are converted into NH 4 during flooded conditions. When the flooded soil is drained for ploughing, the microbial activity changes the NH 4 into NO 3 . Again when the soil is re-flooded, NO 3 in the soil is converted into N 2 & N 2 O and escapes into air. Nearly 20 – 700 kg/ha of N 2 is lost in this process.

6. BIOLOGICAL CHANGES Only microbes which can live without air (especially without O 2 ) are found in these soils. They decompose the organic matter much slow. Some end products of decomposition are toxic to rice crops which stunt the growth of rice crop.

7. Thank you