(a) (i) Define the term drainage. (ii) State four reasons why waterlogged agricultural land should be drained. (b)List six factors affecting nutrient availa...

(a) (i) Define the term drainage.
(ii) State four reasons why waterlogged agricultural land should be drained. 

(b)List six factors affecting nutrient availability in the soil.

(c) Complete the table below on the causative organisms of crop diseases.

Answer Details

(a)

(i) Drainage refers to the process of removing excess water from a land or soil through artificial means such as ditches, pipes, or channels to ensure proper moisture levels for plant growth.

(ii) Four reasons why waterlogged agricultural land should be drained are:

1. To prevent oxygen deprivation in plant roots, which can lead to plant death or stunted growth.
2. To prevent the accumulation of harmful salts in the soil, which can negatively affect plant growth and yield.
3. To prevent soil erosion caused by runoff from waterlogged land.
4. To reduce the incidence of plant diseases caused by water-loving organisms.

(b)

Six factors affecting nutrient availability in the soil are:

1. Soil pH: Nutrient availability is affected by soil pH levels. Some nutrients are only available within certain pH ranges.
2. Soil organic matter: Soil organic matter plays an essential role in nutrient cycling and availability in the soil.
3. Soil texture: Soil texture influences nutrient availability by affecting water-holding capacity and nutrient retention in the soil.
4. Soil temperature: Soil temperature affects nutrient availability by influencing the rate of nutrient release from organic matter and the activity of soil microorganisms.
5. Soil moisture: Soil moisture affects nutrient availability by influencing the solubility and mobility of nutrients in the soil.
6. Soil aeration: Soil aeration affects nutrient availability by influencing the rate of microbial activity and the oxidation of organic matter.

(c)

Completing the table on the causative organisms of crop diseases:

Explanation: - Rice blast is caused by a fungus called Magnaporthe oryzae. - Groundnut rosette is caused by a virus. - Cassava mosaic is caused by a virus. - Root knot of tomato is caused by a nematode, a type of microscopic worm. - Maize rust is caused by a fungus called Puccinia polysora. - Tristeza is caused by a virus.