Soil is the topmost layer of the earth's surface. It consists of a mixture of minute particles of disintegrated rocks, minerals, organic matter and bacteria. Soil is formed when forces of nature such as temperature, rain, wind, waves, animals and plants act on rocks and break them into tiny pieces over a long period of time. The depth of soil is not the same in all parts of the country. Soil may be only a few centimeters deep in some places while in others it may extend to as much as 30 meters.

Soil consists of four layers. The first or topmost layer of soil is made up of minute soil particles and decayed plant and animal matter. This layer is vital for the cultivation of crops. The second layer is made up of fine particles like clay; the third layer is a combination of weathered basic rock materials and soil while the fourth layer consists of un-weathered hard rocks.

India has various types of soil ranging from the fertile alluvial of the Indo-Gangetic plains to the black and red soils of the Deccan Plateau. For example, if one is traveling through the State of Tamil Nadu, one may observe that the ploughed fields in the districts of Salem and Periyar are red while those in Coimbatore and Ramanathapuram are black.

Each type of soil benefits different types of crops through their unique physical, chemical and biological properties. Alluvial soil is a fertile soil rich in potassium. It is highly suitable for agriculture, especially for crops such as paddy, sugarcane and plantain. Red soil has high iron content and is fit for crops like red gram, Bengal gram, green gram, groundnut and castor seed. Black soil is rich in calcium, potassium and magnesium but has poor nitrogen content. Crops like cotton, tobacco, chilly, oil seeds, jowar, ragi and maize grow well in it. Sandy soil is low in nutrient content but is useful for growing trees such as coconut, cashew and casuarinas in areas with high rainfall.

Soil may sometimes get eroded through factors such as wind, running water, overgrazing of animals and human activities such as construction. In addition, soil may also be depleted of its fertility if a particular crop is cultivated repeatedly in the area. This is when soil testing is vital. The quality of soil available in an agricultural area may be tested at soil testing laboratories. Here, the sample of soil is analysed and recommendations are made about what elements are needed to optimize it. Quality soil is one of the most important farming inputs. High yields and good produce can be achieved only when the right type of soil is used for a certain crop. For areas in which suitable soil is not available, one may add nutrients in the form of fertilizers to enrich it. Keeping this in mind, the government has set up a large number of soil testing labs all over the country. For more details, one may visit the links mentioned below.

Soil Testing

Soil testing is the base for management decisions about fertilizer requirements. It involves the estimation and evaluation of the available nutrient status and acidic reaction of a sample of soil. After testing, a fertility map is prepared where the available nitrogen, phosphorous and potassium is marked as low, medium or high. Areas of sufficient and insufficient nutrients are marked out and nutritional requirements are determined. Fertilizers such as NPK, lime or gypsum are recommended to improve soil fertility. Fertilizer addition, which is based on soil testing, usually leads to an increase in yields and profits by providing the correct amounts of needed nutrients. It also leads to uniform application of nutrients in a field. As nutrient availability becomes less variable, the crop growth is more uniform. Regular soil testing also contributes to environmental sustainability as the use of excess fertilizers can be avoided.

Soil Fertility fertility takes into account the presence of minerals like nitrogen, potassium and phosphorous. This helps in procuring the right fertilizers and choosing a suitable variety of seed in order to get the highest possible crop productivity.

Fertile Soil Fertility has the following characteristics:

• It is rich in nutrients necessary for basic plant nourishment. This includes nitrogen, phosphorus and potassium.
• It consists of adequate minerals such as boron, chlorine, cobalt, copper, iron, manganese, magnesium, molybdenum, sulphur and zinc. These minerals promote plant nutrition.
• It contains Soil Fertility organic matter that improves the structure of the Soil Fertility. This enables the Soil Fertility to retain more moisture.
• The Soil Fertility pH is in the range 6.0 to 6.8.
• It has a good Soil Fertility structure which results in well-drained Soil Fertility.
• It consists of a variety of micro-organisms that support plant growth.
• It often contains large amounts of topsoil Fertility.

Source: National Portal Content Management Team

The following factors are the prime consideration for planet earth programme:-

1. Soil and Land quality
2. Soil and Land quality indicators
3. Physical Chemical and Biological characteristics of soil
4. Soil temperature and plant growth
5. Soil water
6. Soil pollution
7. Organic Farming
8. Watershed Management
9. Land Management
10. Soil fertility
11. Soil erosion and conservation

1. To create awareness about soil health, pollution, fertility, erosion and conservation of soil.
2. Optimum utilizations of chemical fertilizers, pesticides.
3. Promoting organic manure like compost, vermicompost etc.
4. Motivation of students/teachers to chose soil management as profession.

1. Training and workshop for students, teachers and farmers.
2. Visit of students to laboratories working on soil management.
3. Vad-Vivad series on soil.
4. Invited lectures on soil science by eminent scientist.
5. Field level experiments with existing soil kits by Vigyan/Eco clubs.
6. Quiz and art competitions, essay writing on soil.
7. Radio serials.
8. TV series on evolution of soil.

Methodology-

The programme will be of three years duration. The resource persons will be trained on various important  components of soil, who in turn make awareness amongst target groups. The activities will be monitored by the experts in the field of soil and its management.