Integrated nutrient management (INM) is an approach to soil fertility management that combines organic and mineral methods of soil fertilization with physical and biological measures for soil and water conservation. INM adopts a holistic view of plant nutrient management by considering the totality of the farm resources that can be used as plant nutrients.
Integrated nutrient management is based on three fundamental principles:
- maximize the use of organic material
- ensure access to inorganic fertilizer and improve the efficiency of its use
- minimize losses of plant nutrients
Research gaps in integrated nutrient management
The research gaps include:
- Mismatching of INM practices developed at research stations with the farmers resources and their practices
- INM recommendations for different crops are not based on soil testing and nutrient release behaviour of the manures
- Nutrient balance/flow analysis vis-a-vis soil fertility management practices with special reference to INM at farm level needs to be worked out
- Nutrient release characteristics of farm residues in relation to their quality to develop decision support systems
- Biofertilizers were not included as component of INM in many cases; and
- Integrated Farming Systems approach needs to be encouraged for sustaining livelihood in rural areas particularly for small and marginal farmers.
Role of biofertilizers in INM
Different types of biofertilizers available at present among that Rhizobium is relatively more effective and widely used. Considering an average N fixation rate of 25 kg N/ha per 500 g application of Rhizobium, it is expected that 1 tonne of Rhizobium inoculants will be equivalent to 50 tonnes of nitrogen. On the other hand, Azotobacter, which is used in non legume crops, has given inconclusive results. Similarly, Blue Green Algae (BGA) and Azolla have been reported to be effective in certain growing areas in the country. Meanwhile if BGA applied at 10 kg/ha fixes 20 kg N/ha, then 1 tonne of BGA has an equivalent fertilizer value of 2 tonnes of nitrogen. Another important role of biofertilizers is liberation of growth substances, which promote germination and plant growth. Against the total anticipated biofertilizers demand of 1 million tonne in the country, the current supply position is very low (<10 000 tonnes). There are several constraints to effectively utilize and popularize the use of biofertilizers. Some of these constraints are:
- Unlike mineral fertilizers, use of the biofertilizers is crop and location specific. A strain found ideal at one location may be ineffective at another location due to competition of native soil microbes, poor aeration, high temperature, soil moisture, acidity, salinity and alkalinity, presence of toxic elements etc.
- Low shelf life of the microorganisms
- Unlike mineral fertilizers, biofertilizers need careful handling and storage
- Lack of suitable carrier material, for restoration and longevity in actual field conditions
In order to overcome the above constraints and make biofertilizers an effective supplementary source of mineral fertilizers, these aspects need to be critically attended.
Basic components of Integrated Nutrient Management
Different components of INM
There are various components of plant nutrients for INM which can be applied in an integrated way. Besides inorganic fertilizers as the major component, others include farmyard
Manure (FYM), composts, green manure crops, crop residues, crop rotation and bio fertilizers. Fertilization in a balanced way, improved crop nutrition maintain the soil fertility and of plant nutrient supply to an optimum level for sustaining the desired crop productivity through optimization of various plant nutrients in an integrated manner.
i) Chemical fertilizers: Chemical fertilizers are rich in nutrients. They are required in less quantity to supply nutrients as compared to organic manures. But continuous use of chemical fertilizers deteriorates the soil conditions. Therefore, chemical fertilizers should be accompanied by organic / biofertilizers.
ii) Organic manures like FYM in situ, Vermicompost: It improves the bulk density of soil up to a layer of 25 cm. It reduces resistance to penetration and Supplements N up to 50% of the nitrogenous requirement of the crop. Increases available N and P use efficiency when combined with 100% of the recommended quantity of NPK and Biofertilizers.
iii) Industrial waste various practices can be adopted to convert wastes into suitable products Convert all available biomass on the farm into compost instead of burning or wasting it.
iv) Inclusion of legume crops in cropping system to fix the atmospheric nitrogen in the soil.
v) Use of Biofertilizers like azolla, blue green algae, and rhizobium etc.
vi) Crop residues and Make use of cattle excreta as manure rather than as fuel
vii) Green manuring either growing in the same field or incorporating of leguminous plant or leaves.
ix) Crop rotations:It is most important INM strategy which is ignored by the growers that is crop rotation is a very important tool in sustaining nutrient supply. Legumes in rotation restore soil fertility in more than one way viz, some of the N fixed is left in the soil after harvest, improvement in soil properties, lesser disease and pest problem and better weed control.
Green manure improves nutrient use efficiency in various ways:
Using Green Manure and the cover crops which are incorporated into the soil when they are still green are called as green manures. Cover crop are also grown but are grown to protect soil from erosion when the vegetable grower not growing the crop. Because upper layer of soil is rich in organic matter and nutrient content, controlling erosion is an important method of conserving soil nutrients. Green manures and cover crops are both used to supply nitrogen and increase soil organic matter. Legumes crops such as alfalfa and Beans can fix between 45 kg and 91 kg of nitrogen per acre in one year. The grasses like rye without a legume will not increase the nitrogen content of the soil. These crops are used for increasing soil organic matter content. They can also retain the residual nitrogen from the previous crop and keep it from being lost by leaching. A mixture of both grasses and legumes can be used to obtain the advantages of each. Improved soil tilth from added organic matter improves root growth, which increases the capacity of a crop to take up available soil nutrients. The decision to plant a green manure should take into account the cost of cultural practices and seed, as well as the lost opportunity cost if the green manure is grown instead of a cash crop. Some green manure crops accumulate high levels of phosphorus and are thought to increase phosphorus availability to subsequent crops by returning it to the soil in organic form. Green manuring through Sesbania aculeate (dhaincha) is equivalent to 60 kg inorganic Nitrogen per hactore. Incorporation of mungbean after picking pods results in savings of 60 kg inorganic Nitrogen per hactore. Alley cropping to Leucaena leucocephala,(ku-Babul) Gliricidia sepium and Acacia mangium can provide 100-300 kg N/ha per year. Pruning of Sesbania rostrata planted as hedgerows provides 3-4 t/ha dry matter after decomposition, it releases an average of 70 kg N/ha.
Besides above, green manure helps in
- Increasing apparent use efficiency of K when combined with 50% of the recommended NPK.
- Having residual effect on the next crop.
- Minimizing the adverse effects of Fe in acidic lateritic soils.
Goals of INM
- To maintain soil productivity.
- To ensure productive and sustainable agriculture.
- To reduce expenditure on costs of purchased inputs by using farm manure and crop residue etc.
- To utilize the potential benefits of green manures, leguminous crops and biofertilizers.
- To prevent degradation of the environment.
- To meet the social and economic aspirations of the farmers without harming the natural resource base of the agricultural production
- To maintain or enhance soil productivity through balanced use of mineral fertilizers combined with organic and biological sources of plant nutrients
- To improve the efficiency of plant nutrients, thus limiting losses to the environment
- To improve physical conditions of soils
Common constraints encountered by the farmers in adoption of INM technology are as follows:
- Non-availability of FYM
- Difficulties in growing green manure crops
- Non-availability of biofertilizers
- Non-availability of soil testing facilities
- High cost of chemical fertilizers
- Non-availability of water
- Lack of knowledge and poor advisory services
- Non-availability of improved seeds
- Soil conditions
- Non-availability of credit facilities
How this INM technology different from conventional way of farming?
Integrated nutrient management differs from conventional nutrient management in that it considers nutrients from different sources, notably organic materials, nutrients carried over from previous cropping seasons, transformation of nutrients in soil, In conventional farming, people gave more emphasis on yield through use of chemical fertilizers, use of high yielding varieties and chemical pesticides along with irrigation facilities.
In INM it integrates/combines the objectives of production with ecology and environment, that is, optimum crop nutrition, optimum functioning of the soil health, and minimum nutrient losses or other adverse effect on the environment. Integrated Nutrient Management (INM) has to be considered an integral part of any sustainable agricultural system.
- Enhances the availability of applied as well as native soil nutrients
- Synchronizes the nutrient demand of the crop with nutrient supply from native and applied sources.
- Provides balanced nutrition to crops and minimizes the antagonistic effects resulting from hidden deficiencies and nutrient imbalance.
- Improves and sustains the physical, chemical and biological functioning of soil.
- Minimizes the deterioration of soil, water and ecosystem by promoting carbon sequestration, reducing nutrient losses to ground and surface water bodies and to atmosphere.
Chandanshive Aniket V.
PhD Scholar, Department of vegetable science,
College of Agriculture, CCS, Haryana Agricultural University, Hisar (Haryana) 125004