Question

The waterlogged soils are rendered infertile because of

(i) Lack of aeration

(ii) Reduced soil temperature

(iii) Weed growth 

(iv) Enhanced soil erosion

1. Only (i)
2. (i) & (ii)
3. (iii) & (iv)
4.  (i), (ii), (iii) & (iv)

Answer 1

Correct Answer - Option 2 : (i) & (ii)

Concept:-

When pH = 7 to 8.5 normal yields. (Best suited pH for maximum yields)

When pH = 8.0 to 9.0 yield decreases and partially infertile

When pH = 11 soil becomes more alkaline and infertile

Note: -

Waterlogging may be defined as the increase in water-table which leads to decreased productivity of the land. Whenever there is water-logging, there will always be salinity. And hence soil becomes alkaline.

Causes of waterlogging: -

1. Over and intensive irrigation
2. Seepage of water from adjoining high lands
3. Seepage of water through canals.
4. Inadequate natural drainage.
5. Excessive rainfall
6. Submergence due to floods.

Effects of Waterlogging

1. Poor aeration - The pores of soil are filled with water and hence there is no effective circulation of air 
2. Reduced soil temperature - A waterlogged soil warms up slowly and due to low temperature action of soil bacteria is inhibited and plant food available is less. It lowers the rate of nitrogen fixation.
3. Alters pH
4. Retard cultivation.
5. Affects soil nutrients.
6. Affects human health due to mosquito breeding and disease vectors.
7. Inhibiting activity of soil bacteria
8. Decrease in available capillary water