STUDY OF SOIL AND CLIMATE
Soil is an important matter for cultivation of crops. Soil supplies all the important factors for the growth of the crop plants. The yielding potential is largely dependent on the soil in which the crops are grown. The type and properties of soil directly affect the crop growth and yield, hence management and conservation of soil should be done with interest.
Climate also is a factor that affects the crop growth and productivity. As we all know Indian agriculture is largely dependent on climatic conditions. The changing weather scenario affect the yield and quality of crop plants and one should find the ways to tackle the problem of such weather effects.
After reading this lesson you will be able to:-
• learn the importance of soil and climate in crop production.
• know the methods of soil improvement and conservation.
• understand climatic parameters and their effect on crop plants.
We can define the soil as the topmost layer of surface of the earth in which the crops grow.
The upper layer of the earth crust on which crops are dependent for
support and nutrition is called soil.
Functions of soil
Here we will discuss about the functions of soil:-
1) Provision of support- Soil helps the crop to stand erect by providing
support to the roots.
2) Supply of water- Roots take the water from soil which is utilized in photosynthetic activities.
3) Supply of Nutrients- All the important nutrients (13) are taken from the soil.
4) Function of soil organisms- Micro organisms in soil performs different functions like Nitrogen fixation, phosphate and sulphur solubilisation, decomposition of organic matter etc.
Characteristics of an ideal soil for crop production
We have read the functions of soil but it is essential to know the characteristics of an ideal soil. These characterstics are as follows:
1) The soil should be well aerated.
2) pH of soil should be 6 to 8.
3) Good water holding capacity.
4) Well drainage of excess water.
5) Good amount of organic matter.
6) Good amount of available nutrients.
7) Free from soil borne diseases and pests.
8) Deep, friable and well textured.
Formation of soil
Lets us see how the soils form—
Soil is formed from the rocks by the process called weathering of rocks and by different pedogenic processes. The properties of a soil are dependent on the rock from which it is formed, climatic conditions, organisms and time. The study of soil profile gives us knowledge about its formation and quality.
A simple formula for soil formation is as follows:
Intext questions 1.1
a) Fill in the blanks:-
1. Soil supplies nutrients to crop plants.
2. An ideal soil should have pH between & .
3. Soil is formed form by the process called of rocks.
4. The study of soil gives us knowledge about formation and quality of soil.
1.4 Types of soils
Soil types are classified according to many more factors. They are classified on the basis of colour, depth, pH, productivity, texture and process of formation.
Soil types according to depth are as follows:
1) Shallow Soil - Soil depth less than 22.5cm. Only shallow rooted crops are grown in such soil, e.g. Paddy, Nagli.
2) Medium deep soil - Soil depth is 22.5 to 45cm. Crops with medium deep roots are grown in this type of soil e.g. Sugar cane, Banana, Gram.
3) Deep soil - Soil depth is more than 45cm. Crops with long and deep roots are grown in this type a soil e.g. Mango, coconut
Major soil types in India
The main types of soil in India are as follows:
1) Red soils
2) Laterites and lateritic soil
3) Black soil
4) Alluvial soils
5) Forest & hill soils
6) Peaty and marshy soils
1) Red soils: Red soils have two broad classes:
a) Red loam with cloddy structure and allow content of concretionary
b) Red earths with loose, Permeable top soil and a high content of secondary concretions. Generally these soils are light textured with porous and friable structure and there is absence of lime Kankar and free carbonates. They have neutral to acidic reaction and are deficient in nitrogen humus, phosphoric acid and lime.
2) Laterites and Lateritic soils
These soils are red to reddish yellow in colour and low in N, P, K, lime and magnesia. These soils are formed in-situ under conditions of high rainfall with alternation dry and wet periods. On account of heavy rainfall there is an excessive leaching of soil colloids and silica hence the soils are porous.
3) Black soils
These are mostly clay soils and form deep cracks during dry season. An accumulation of lime is generally noticed of varying depths. They are popularly known as “Black cotton soils” because of their dark brown colour and suitability for growing cotton. These are also known as
Indian regurs.These soils are deficient in nitrogen, phosphoric acid and organic
matter but rich in calcium, potash and magnesium.
4) Alluvial soils
These soils occur along rivers and represent the soil materials that have been deposited by the rivers duing flood. Usually they are very productive soils but many are deficient in nitrogen, humus and phosphorus.
5) Forest and hill soils
These soils occur at high elevations as well as at low elevations, where the rainfall is sufficient to support trees. These soils are very shallow, steep, stony, and infertile for the production of field crops. However, they serve a very useful purpose by supplying forest product such as timber and fuel.
6) Desert soils
These are mostly sandy soils that occur in the low rainfall track. They are well supplied with soluble salts but are low in nitrogen and organic matter and have a high pH value. These are quite productive. These are often subjected to wind erosion.
7) Saline & Alkaline soils
These soils occur in areas having a little more rainfall than the areas of desert soils. They show white incrustation of salts of calcium & Magne
sium and sodium on the surface. These are poor in drainage and are infertile.
8) Peaty and Marshy soils
These types of soils are found in Kerala, coastal track of Orissa, Sunderban area of W.B. When the vegetation growing in such wet places dies, it decomposes very slowly dues to excessive wetness of soils and after several hundreds of year a layer of partly decayed organic matter accumulates on the surface, giving rise to such peaty and marshy soils. These are black coloured, heavy and highly acidic soils. When properly drained and fertilized, these soils produce good crops of rice.
Intext questions 1.2
A. Fill in the blanks:
1. Shallow soils have less than depth.
2. Lateritic soils are in colour.
3. Black soils are known as .
4. Desert soils are mostly soils which occur in low rainfall track.
1.5 Soil improvement
We have already learned characteristics of an ideal soil but we could not find such soil all the time. There are many types of problem soils and we have to improve those soils.
Problem soils: The soils with acidic or basic reaction, soils with poor drainage, soil with low water holding capacity, salt affected soils, and soils with pathogen are known as problem soils. Such soils have bad effect on crop growth and plants show deficiencies of different nutrients.
Steps for improvement of problem soils:
1. Bunding and leveling: The soil should be leveled properly and provided with strong bunds along with field boundary.
2. Provision of irrigation water: Sufficient salt free water should be made
3. Drainage: Provision of adequate drainage is essential. Proper surface and subsurface drainage is important factor in soil improvement.
4. Application of amendments: Gypsum is the standard amendment for
alkaline soils. For acid soils calcium carbonate is applied as amendment.
5. Leaching: Leaching means removal of soluble salts from the root zone.
6. Cropping: Grow the crops which tolerate particular problem soil. For
example salt tolerant crops like sugarcane, barley, and oats.
7. Addition of organic manure: Addition of organic manure in sufficient amount will provide drainage in heavy soils and improves water holding capacity of poor soils.
Intext Questions 1.3
A) Match the followings:
|| 1. Removal of soluble salts
| 2. Leaching
|| 2. Gypsum
| 3. Problem soil
||3. Calcium carbonate
| 4. Acid soil
|| 4. Water holding capacity
| 5. Organic manure
||5. Poor drainage
Different parameters of climate have direct and indirect effect on growth and yield of crop plants. Especially in India, climate plays an important role in
Climate – Long term average condition of climatic factors of a particular place is known as climate. E.g. Hot and dry or Hot and humid.
Weather – The condition of climatic factors of the particular place at a
particular time is weather.
Parameters of climate are as follows:
1) Temperature – It is one of the important factors limiting the growth of crops. Each crop has its own range of temperature i.e. its minimum, maximum and optimum temperature for growth. Crops either die or cease their growth when the temperature is very high or very low. On the basis of temperature, the world is divided in six temperature zones.
3) Micro thermal
6) Perpetual frost
Crops are classified broadly as warm or cool weather crops.