NABARD Grade-A Exam : Notes on Agriculture & Rural Development | Major Soil Types, Soil Fertility, Fertilizers

The upcoming important exams are NABARD grade A and grade B, in which there is a section Agriculture & Rural Development (with a focus on Rural India) having high weightage of 40 marks. So, for the same, it becomes really important to have an in-depth knowledge of the various terminologies and practices involved in agriculture. Further its imperative to be aware of the present scenario of Indian Agriculture and the state of Rural Development in India. To help you with this, today, we are providing you with all necessary information related to the mentioned field which will help you to fetch some good marks.

Soil Types in India

Soil Fertility

“The capability of the soil to provide all the essential plant nutrients in available form is called as soil fertility”.

Soils are composed of five main components:

a) mineral particles derived from rocks by weathering;

b) organic materials – humus from dead and decaying plant material;

c) soil water – in which nutrient elements are dissolved;

d) soil air – both carbon dioxide and oxygen;

e) Living organisms including bacteria that help plant decomposition.

Types of Soil Fertility:

(i) Inherent or Natural Fertility:

(a) The soil, as nature contains some nutrients, which is known as inherent fertility.

(b) Among plant nutrients nitrogen, phosphorus and potassium is essential for the normal growth and yield of crop. The inherent fertility has a limiting factor from which the fertility is not decreased.

(ii) Acquired Fertility:

(a) The fertility developed by application of manures and fertilizers, tillage, irrigation, etc., is known as acquired fertility.

(b) The acquired fertility has also a limiting factor. It is found by experiment that the yield does not increase remarkably by application of additional quantity of fertilizers.

Methods of Soil Fertility Evaluation

Different Methods of Soil Fertility Evaluation are:

1. Biological Method: a. Field trials b. Pot culture c. Neubauer seedling method d. Aspergillus niger method.

2. Use of visual symptoms of nutrient deficiency or toxicity method.

3. Plant Analysis Method: a. Total elemental analysis b. Plant tissue tests 4. Soil Analysis Method: Soil testing has been used by soil scientist as an aid in determining soil fertility level.

Causes of Decline in Soil Fertility

1) Nutrient mining

2) Physical degradation of soil (poor structure, compaction, crusting and waterlogging etc.)

3) Decrease in organic matter content and soil bioactivity

4) Loss of nutrients through various routes

5) Soil acidification, salinization and alkalization

6) Inefficient soil management

7) Soil pollution

8) Loss of top soil by erosion

Managing Decline in Soil Fertility

Fertility management aims to maintain soil organic matter, soil structure, soil nutrient status and satisfactory soil pH.

This can be achieved in cropping systems by:

1) including pasture phases and leguminous crops

2) including the addition of soil amendments or fertilizers

3) employing a reduced tillage system

4) Retaining crop residues on site.

Fertilizers

Fertilizer, natural or artificial substance containing the chemical elements that improve growth and productiveness of plants. Fertilizers enhance the natural fertility of the soil or replace the chemical elements taken from the soil by previous crops. 

Fertilizers enhance the growth of plants. This goal is met in two ways, the traditional one being additives that provide nutrients. The second mode by which some fertilisers act is to enhance the effectiveness of the soil by modifying its water retention and aeration.

Fertilizers typically provide, in varying proportions three main macronutrients: 

Nitrogen (N): leaf growth

Phosphorus (P): Development of roots, flowers, seeds, fruit

Potassium (K): Strong stem growth, movement of water in plants, promotion of flowering and fruiting

Three secondary Macronutrients: calcium (Ca), magnesium (Mg), and sulphur (S)

Micronutrients: copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), zinc (Zn), boron (B), and of occasional significance there are silicon (Si), cobalt (Co), and vanadium (V) plus rare mineral catalysts.

Types of Fertilizers 

1. Nitrogenous Fertilizers: The nitrogenous fertilizers are divided into four groups — nitrate, ammonia and ammonium salts, chemical compounds containing nitrogen in the amide form, and plant and animal byproducts. Major varieties are Sodium Nitrate, Ammonium Sulphate, Ammonium Nitrate, Ammonium Sulphate Nitrate, Ammonium Chloride, Urea, Calcium Ammonium Sulphate 

2. Organic Nitrogenous Fertilizers: These fertilizers include plant and animal by-products, such as oil cakes, fish manure etc.. Before use by the crops these materials are converted by bacterial fermentation into utilizable ammonium-nitrogen and nitrate-nitrogen.

3. Phosphate Fertilizers: Phosphate fertilizers are classified as natural phosphates, treated phosphates, by-product phosphates and chemical phosphates. Major varieties are Rock Phosphate, Super Phosphate, Basic Slag, Bone-Meal 

4. Potassic Fertilizers: In India most of the soils contain sufficient amount of potash. Potassic fertilizers are used as muriate of potash (potassium chloride)and sulphate of potash (potassium sulphate). 

5. Compound  Fertilizers: These fertilizers contain two or three plant nutrients simultaneously. When both nitrogen and phosphorus are deficient in soil, a compound fertilizer, e.g., amorphous, can be used.

6. Complete Fertilizers (NPK): mixtures containing all the three principal nutrients (N, P and K) are called complete fertilizers as most soils usually remain deficient in these three elements.