Question

Soil fertility is reduced by
A. Crop rotation
B. Nitrogen fixing bacteria
C. Decaying organic matter
D. Intensive agriculture

Answer 1

Hint: Soil fertility refers to the ability of soil to grow the various types of crops. A fertile soil is able to provide better and proper nutrients to the growing crops and plants. It is reduced by various natural and artificial means. Maintaining proper soil fertility is very important for the plants.

Complete Answer:
Soil fertility can be defined as the natural ability of the soil to provide nutrients in the right amount and at the right time and without toxic chemicals. Soil production is the ability of the soil to produce crops in each area.

Some of the factors which affects soil fertility are:
- Type of soil
- Climatic conditions
- Vegetation
- Topography of soil
- Physical conditions of soil
- Age of soil
- Fertilizing capacity of soil
- Composition of soil
- Availability of nutrients
- Soil erosion
- Agriculture patterns
- Environmental conditions

- Crop rotation is an agricultural method of planting different crops sequentially on the same land to improve the soil conditions. It increases the fertility of soil as the soil is exposed to different nutrients according to the type of crops sown.
- Nitrogen fixing bacteria such as Rhizobium and Azospirillum help in the nitrogen fixing in the soil. This increases the nitrogen content of the soil and leads to increase in soil fertility.
- Decaying organic matter also enriches the soil with the nutrients and thus increases the soil fertility. Intensive agriculture is a method by which soil gets harmed and the nutrient content as well as the fertility is reduced.

The correct answer is option (D).

Additional information:
Types of fertility
1. Natural fertility: Soil, as its kind, contains certain nutrients known as ‘inherent fertility’. Among plant nutrients, nitrogen, phosphorus and potassium are essential for normal growth and crop yield. Indian soil contains 0.3 to 0.2 percent nitrogen, 0.03 to 0.3 percent phosphorus and 0.4 to 0.5% percent potassium.

2. Acquired fertility: Fertility done by using fertilizers, plowing, irrigation etc. Acquired fertility also has a limiting factor. It is obtained by trying to ensure that yields increase dramatically with the use of additional fertilizers. It is therefore necessary to fertilize on the basis of soil nutrient content and to be measured by soil testing.

Note: Fertility is decreased by intensive agricultural practices. This does not allow the soil to hold the nutrients for a longer period of time and thus resulting in loss of nutrients. The dead and decaying matter in the soil provides the remaining in organic nutrients after decomposition.