Soil is a living medium which serves as a natural nutrient source for growth of plants. The components of soils are mineral, organic matter, water and air, the proportions of which vary and together form a system for plant growth. Soils are studied and classified according to their use. Soil surveys are made for Natural Resource Management and soil testing is conducted as part of Fertilizer Use and Management.
Nutrient Status of Soils
- In India, intensive agriculture has resulted in impressive growth in food grain production powered by improved varieties of seeds, application of fertilizers and assured irrigation. A great variability is observed in fertiliser consumption among States from 250 kg / ha in Punjab, 212 kg / ha in Bihar, 207 kg / ha in Haryana to 4.8 kg / ha in Nagaland and 2 kg / ha in Arunachal Pradesh in nutrient form during 2012-13. However, imbalanced application of fertilisers have caused deficiency of primary nutrients (i.e. NPK), secondary nutrients (such as sulphur), and micronutrients (boron, zinc, copper etc.), in most parts of country.
- Site specific nutrient management involving soil test based application of fertilizers is critical to enhance fertilizer use efficiency. A fertilizer not suitable to a soil type can be called as an incorrect fertilizer used for that soil, and in such case, fertilizer consumption ceases to be efficient to increase Different types of fertilizers are required to be used in acidic/ alkaline soils. Fertigation involving the use of water soluble fertilizers through drip and sprinkler irrigation is expected to give better use efficiency for water and fertilizers. Therefore, it is necessary to promote use of required sources of plant available forms of nutrients coupled with use of soil amendments in acidic/ alkaline soils so as to enhance soil nutrient availability. In India, in general, blanket fertilizer recommendations are followed for N, P & K which rarely matches soil fertility need, and often ignoring secondary and micro nutrients, in various cropping systems followed by small and marginal farmers. Keeping in view the above facts, Government of India is promoting integrated nutrient management (INM) i.e. balanced and judicious use of chemical fertilizers, along with bio fertilizers and locally available organic manures based on soil testing to maintain soil health and crop productivity.
Soil Testing Programme
- Soil testing programme was started in India in the year 1955-56 with the setting up of 16 Soil Testing Laboratories (STLs) under "Determination of Soil Fertility and Fertilizer Use" programme. Total nutrient content varies from soil to soil, and plant available forms of nutrients are chemically determined in soil testing laboratories. Till 1980, the laboratories generally used to analyze for pH, texture, electrical conductivity, organic carbon (as an index of available N), and available P and K.
- The process of setting-up of soil testing laboratories has continued with financial support from Government of India, year after year. In 2012-13, the soil analyzing capacity in the country was 31 lakh soil samples per annum. The soil testing facility is provided by State Governments to the farmers free of cost or with some nominal fee.
- In view of the critical role played by soil testing in ensuring balanced and efficient use of fertilizers, states have been advised from time to time to enhance and improve their soil testing programme. The State Governments are preparing district wise and also block wise fertility maps. Computerization of soil test data, which the farmers can access online, is also making available.
- As seen from above, no uniform norms are followed in the country for soil analysis and distribution of Soil Health Cards. There is also a need to devise a mechanism to issue soil health cards every 2 years in respect of all landholdings in order to capture the soil fertility changes occurring due to plant uptake or other natural causes. More attention is required on the follow up measures on the soil nutrient deficiency identified in soil health cards. Along with soil health cards that diagnose fertility related constraints small and marginal farmers need technical support to apply site specific fertilizer recommendations. Therefore, Soil Health Card scheme is proposed for periodic testing of soil and to recommend nutrient management. The scheme is implemented in all the States to promote the soil testing services, issue of Soil Health Cards and development of Nutrient Management Practices. The scheme on Soil Health is implemented in accordance with the guidelines provide by Govt. of India. Cost of the interventions proposed under the scheme is shared in the ratio of 90:10 between the Central and the State
