Integrated nutrient management approach
By Atiq-ur-Rehman, Dr Ehsanullah & Dr Riaz Ahmad
PLANTS like animals require food for their growth. Soil is the medium from where plants derive these essential elements of food. Soil has a limited ability to cope with the nutritional requirement of plants. For healthy growth and optimal yield, nutrients must be available to plants in correct quantity, proportion and in a usable form at right time. To fulfil these requirements chemical fertiliser or natural manures are needed.
Application of chemical fertilisers makes the soil fertile and increases productivity of plants, but also has an adverse effect on soil and environment. Therefore, it is needed that fertility and productivity of the soil be restored by using organic fertilisers.
There is a need to organise the supply of nutrients to crop through organic and renewable sources and strengthen the idea of Integrated Nutrient Management (INM). Use of organic manures, apart from improving physical and biological properties of soil, helps in improving the use of efficiency of chemical fertilisers.
Decreasing soil fertility has also raised concerns about the sustainability of agricultural production at current levels. Future strategies for increasing agricultural productivity will have to focus on using available nutrient resources more efficiently, effectively than in the past. Integrated management of the nutrients is needed for proper plant growth, together with effective crop, water, soil, and land management.
The categories considered in the INM are:
Compost: It is an organic manure artificially prepared from plant residues and animal waste products. It is largely a biological process in which aerobic and anaerobic micro-organism decompose organic matter and lower the carbon-nitrogen ratio of the refuse. It is prepared from waste vegetables and other refuse mixed with animal excreta and also from town waste and night-soil. It may be rural compost prepared from farm waste products, e.g. wheat and rice straw, crop stubbles, crop residues such as sugarcane trash, groundnut husks and leaves, cotton stalks etc., weeds, waste fodder, litter from cowshed and hedge clippings.
Urban compost is prepared from town waste and night soil. Since compost is made of plant refuses, all nutrients needed by plants are made available to plants, when compost is added to soils. The nutrients lost from the soils are restored for future use. Compost along with improving the physical structure of soil also adds millions of organisms already present in soil. Compost is supposed to contain small amount of growth promoting substances.
Farmyard manure: The farmyard manure is a mixture of solid and liquid excreta of farm animals along with litter and left over material from cattle fodder. Farmyard manure is one of the most commonly used organic manure. Cow dung is a valuable manure rich in nitrogen, phosphorus and potassium.
Poultry manure is also an extremely rich source of nitrogen and organic matter. Poultry manure contains 1.0-1.8 per cent nitrogen, 1.4-1.8 per cent phosphorous and 0.8-0.9 per cent potassium.
Green manure: The practice of ploughing or turning into the soil un-decomposed plant tissues for the purpose of improving physical condition as well as fertility of the soil is referred to green manure. The green manure crop supplies organic matter as well as additional nitrogen particularly if it is a legume crop which has ability to acquire nitrogen from the air with the help of its root nodule bacteria.
Manure of gobar gas Plant: Gobar gas plant is a system comprising a gas holder and a digestion chamber, in which cow dung can be treated anaerobically to produce two important and useful items, namely, fuel gas and organic manure. The manure coming out from bio-gas plant is rich in nitrogen, phosphorous and potassium and humus.
Oil cakes: Oil cakes are the by-products of oil seed crops. Oil cakes are important and quick acting organic nitrogenous manures. It also contains small amounts of phosphorous and potassium. All oil cakes give result with almost every crop and on all types of soil. They can be applied a few days prior to sowing or at sowing or as a top dressing after the crop has made a certain amount of growth.
Blood meal: Dried blood or blood meal is a by- product of slaughter house. It contains 10 to 12 per cent nitrogen and 1 to 1.5 percent phosphorous and 1.0 per cent potassium. It is a quick acting manure and is effective for all crops and all types of soils.
Fish manure: Non-edible fish carcasses and offal are used to prepare fish meal. It is available either as dried fish meal or powder. In those parts of country where fish oil is extracted, the residues can be used as manure. It contains four to ten per cent of organic nitrogen, three to nine per cent phosphorous and 0.3 to 1.5 per cent potassium. It is quick acting organic manure and is suitable for application to all crops and on all soils. Fish meal is used as an ingredient of poultry feed.
Steamed bone meal: This manure is obtained by treating bones with steam under pressure using an autoclave resulting in the increased percentage of phosphoric acid and the subsequent reduction of nitrogen content. Steaming also removes fat and greasy substances enabling the powdering of bones. Further advantages of steaming are that the bone meal decomposes more rapidly in the soil compared to raw bone meal.
Wood ash: Wood ash, cattle dung ash etc. are the indigenous sources of potassium. Wood ashes contain a very small percentage of nitrogen, 1.0 to 5.0 per cent phosphorous and 0.5 to 36.0 percent potassium. Out of various ashes, ash of tobacco stem contains 36 per cent potassium. Un-leached wood ash contains 5 to 6 percent potassium in the form of potassium carbonate, 1.0 to 2.0 percent phosphorous and 25 to 30 percent lime.
Wood ashes are mainly applied to fruit crops and root vegetable crops. Cow dung alone or mixing with kerosene oil are dusted on vegetable crops such as brinjal or lady finger to prevent insect attack. This material acts as a repellent for the insect.
Sewage and sludge: Sewage and sludge is the product of sewage system of sanitation, a modern system of sanitation commonly adopted in cities. On an average, sludge contains 1.5-3.5 per cent of nitrogen, 0.75- 4.0 per cent of phosphorous and 0.3-0.6 per cent of potassium. Sewage and sludge can be used profitably as organic manure for producing crops. These also can be used as starter in the compost making by activated compost process.
Night soil is the human excrement: It is rich in nutrient content. On an average it contains 1.0 to 1.6 per cent nitrogen, 0.8 to 1.2 per cent phosphorous and 0.2 to0.6 per cent potassium on oven dry basis. It is a good manure for the production of crop.
Biological sources: Bio-sources are the specific micro-organisms derived either from the nodules of plant roots or from the soil of root zone (rhizosphere). These micro-organisms have the ability to fix atmospheric nitrogen either by living symbiotically with the roots of leguminous plants or non-symbiotically (free living) to transform atmospheric or nutrients from non usable to usable form through biological processes. There is a lot of potential of this source to supplement inorganic fertilisers for productive agriculture.
Sugarcane press mud: Sugarcane is used in the preparation of jiggery. The spent material after processing is known as press mud. It contains high amounts of cellulose and hemicelluloses which needs to be broken down into simpler constituents. Also press mud harbours pathogenic micro-organisms which are spore formers and heat resistant. Hence, the raw material needs to be properly digested and composted before it is applied to the soil.
Coir pith: This is the raw material obtained from coconut. It is available in plenty and also the cost is reasonable. Acts as excellent mulch in young plantations and conserves moisture during the drought months. It has the capacity to absorb moisture many times over its weight and is used in composting and nursery preparation. It has high amounts of silica and hence should be sparingly applied.
Bio-fertilisers: These are biologically active inputs and contain one or more types of beneficial micro-organisms such as bacteria, algae or fungi. Every micro-organism has a specific capability and function. There are broadly seven types of bio-fertilisers.