Soil may be defined as the upper thin layer of earth’s crust, which serves as a natural medium for the growth of plants. Soil is formed by slow weathering of parent rocks under the combined effect of physical, chemical and biological factors. Soil differs from the parent material in the morphological, physical, chemical and biological properties. Top soil is a precious resource. If it is lost through wind or water erosion it would take very long time for the ground lying below it to become suitable for plant growth.
The components of soils are mineral material, water, air and organic matter. The proportions of these components vary from one oil sample to another. The various components of soil together from a system for plant growth.
Soil performs the following functions in the cultivation of crops.
1. The soil serves as a reservoir of different nutrients required for the growth of plants.
2. The soil provides water to the plants.
3. The soil provides oxygen to the roots of the plants through aeration.
4. The soil provides mechanical anchorage.
5. The soil provides organic matter called humus to the plants, which helps in their growth.
6. The soil also contains microorganisms, which protect plants.
Preparation of Soil
Preparation of soil is the first step in cultivating a crop for food production. The soil is prepared for sowing the seeds of the crop, by ploughing, leveling and manuring. Let us now discuss these steps in detail.
The process of loosening and upturning the soil is called ploughing. Ploughing is done by using a plough, which is made of either wood or iron. The ploughing of small fields is done with the help of animal which large fields are ploughed using a tractor. Ploughed soil becomes soft and porous. Ploughing helps in the following ways:
1. Ploughing breaks the large lumps of clay into smaller particles.
2. Roots of plants can penetrate the loose soil easily.
3. It leads to aeration of the soil.
4. Ploughing uproots the unwanted plants already growing in the field.
5. Ploughing facilitates uniform mixing of fertilizers with soil.
The ploughed soil is then leveled to ensure uniform irrigation. The leveling is done with the help of a soil leveler which is wooden plank or an iron plank. The soil leveler can be driven by bullocks or tractors. Leveling also prevents loss of fertile top layer of soil with wind or washed away with water. This loss of top layer of soil by wind or water is called soil erosion. Thus, leveling prevents soil erosion.
Finally, manure or chemical fertilizers are added to the soil so that it can supply all the nutrients to the plants required for their growth. Before adding the fertilizer, the soil must be analysed to find out which nutrient it is lacking.