In this article we will discuss about how to fertilize the soil naturally by using organic manures.
Organic manures are natural products used by farmers to provide food (plant nutrients) for the crop plants. There are a number of organic manures like farmyard manure, green manures, compost prepared from crop residues and other farm wastes, vermicompost, oil cakes, and biological wastes – animal bones, slaughter house refuse.
Organic manures increase the organic matter in the soil. Organic matter in turn releases the plant food in available from for the use of crops. However, organic manures should not be seen only as carriers of plant food. These manures also enable a soil to hold more water and also help to improve the drainage in clay soils. They provide organic acids that help to dissolve soil nutrients and make them available for the plants.
Organic manures have low nutrient content and therefore need to be applied in larger quantities. For example, to get 25 kg of NPK, one will need 600 to 2000 kg of organic manure whereas the same amount of NPK can be given by 50 kg of an NPK complex fertilizer.
The nutrient content of organic manures is highly variable from place to place, lot to lot, and method of preparation. The composition of fertilizers is almost constant. For example, urea contains 46% N regardless of which factory makes it anywhere in the world.
Different fertilizers contain different amounts of plant nutrients; organic manures are also not alike. Average quality of farmyard manure provides 12 kg nutrients per ton and compost provides 40 kg per ton. Most of the legume green manures provide 20 kg of nitrogen per ton. Each ton of sorghum/rice/maize straw can be expected to add 26 kg of nutrients.
Green manuring is the practice of growing a short duration, succulent and leafy legume crop and ploughing the plants in the same field before they form seeds. Sesbania, Crotalaria, ‘Pillipesara’, Cowpea etc., are good for green manuring. Green leaf manuring refers to adding the loppings from legume plants or trees to a field and then incorporating them into the soil by ploughing. Glyricidia, Pongamia, Leucina are common green leaf manuring plants.
This is the method of manuring to the soil at the site.
On the basis of origin of manure there are two types of in-situ manuring:
i. Manuring by animals at site.
ii. Manuring with plant material grown at site, popularly known as green manuring.
Manure and compost have been the major traditional means sustaining plant nutrients in the soil throughout history, and they are equally as important today. However, in addition, the other methods of fertility maintenance are in-situ manuring, tapping flood water, cutting and carrying natural green manure species, slicing of weeds and soils from terrace risers, tree leaf litter decomposition in agroforestry and burying of crop residues on the land.
This is a widespread practice in areas where herders traditionally migrate their flocks each year for the search of better pastures. There is a mutual advantage to both herders – who need a place to settle their sheep each night and farmers, who get urine and manure right in their fields for a small fee. The manuring of fields by tethering the animals directly in the fields, is also an important strategy that farmers developed to suit their conditions.
There are three types of in-situ manuring- One is keeping of cattle and buffalos in the open lands (un-irrigated, un-bunded terraces) just after harvesting of the crops. This is commonly done in October-November (after the harvest of finger millet, and before planting winter crops, like wheat or barley).
The second period occurs in March-April after harvest of wheat or barley, and before planting maize or millet. Animals are moved from one peg to another after every 2-3 nights so as to completely manure the field. Certain pieces of lands are intensively manured, by keeping animals for a longer period where land is available, for about 2-3 month after the harvest of first crop.
This is done by constructing temporary sheds in the fallow lands, and the animals are kept in these sheds for a few weeks at a time. Such temporary sheds are moved from time to time so as to manure the complete follow area. In such intensively manured lands, nursery raising of finger millet and rice, and planting of maize or potatoes are the practices subsequently carried out.
Some farmers also keep animals under the canopy of fruit trees, in order manure the orchard. Generally, these animals are kept for a period of one to three nights at a site depending upon the number of animals, or the size or type of land. All these systems, assist the farmer to feed crop residues at the same spot, and at the same time reduces the transportation cost of manure from the cattle shed to the fields.
Depending on the season and location, some farmers provide temporary shade, but in most cases, animals are kept in the open overnight. Farmers have reported that urine and dung of a buffalo tethered for three days in one spot of land is equal to heavy application of compost.
The other system of in-situ manuring is carried out by using migratory flocks of sheep and goats kept under a transhumance system. In hilly areas, these flocks graze on the high hill alpine pasture (above 2500 m), where almost no crops are grown (from May to October/November) while in hot arid areas the time starts just after harvest in the one and only rainy season crop i.e., from November to June. The sheep and goats are kept overnight, preferably in dry lands.
When the flocks are kept overnight on a person’s land, other than the sheep owners, the land owner has to pay the Shepherd in cash or kind usually food grain, for every night of the stay on the land. There is a very high demand for such flocks.
One method of farm yard manure application is the herding of sheeps into the field (in some parts, donkeys are used). The sheeps are allowed to remain in the field overnight. Urine and excreta deposits are available right where they are needed.
The droppings are later ploughed directly into the soil. This practice is undertaken when there are no crops in the field.
(1) Useful to small and marginal farmers who do not own cattle and have limited land.
(2) Useful to farmers having limited farm yard manure.
(3) Transportation and labour charges are avoided.
(4) Pastorals can generate income by charging a fee for this service.
(5) Manure decomposes easily.
(6) Release nutrient into the soil through decomposition.
(7) Promotes easy infiltration in vertisols.
(8) Utilizes urine which is normally wasted,
(1) It is difficult for those areas where sheep population is low.
(2) Farmers have to depend on migratory practices of the herders.
The most common practice is used by large proportion of farmers in the hills and hot arid areas, and is a system which has been developed by the farmers through their ingenuity and has been sustained since long time. The system seems quite sustainable as it is a very old and traditional system developed by the farmers themselves. Farmers’ have already recognized its importance and value.
Labour is the key component for management of soil fertility. Limitations in the more widespread of compost and FYM are created because of labour constraints. The in-situ system is an efficient method of recycling organic residues, since crop(s) residues and animal waste are properly utilized directly into the soils, with no nutrient loss, and minimal involvement of human labour. Neither does the system involve any external inputs. Further, as a traditional practice, it does not suffer any communication barrier, as many new technologies does.
Green manuring can be defined as a practice of ploughing or turning into the soil un-decomposed green plant tissues for improving physical structure as well as soil fertility. From the time immemorial, the turning in a green crop for improvement of the conditions of the soil has been a popular farming practice. Green-manuring, wherever feasible, is the principal supplementary means of adding organic matter to the soil.
It consists in the growing of a quick-growing crop and ploughing it under to incorporate it into the soil. The green-manure crop supplies organic matter as well as additional nitrogen, particularly if it is a legume crop, which has the ability to fix nitrogen from the air with the help of its root nodule bacteria. The green-manure crops also exercise a protective action against erosion and leaching.
Growing a green manure is not the same as simply growing a legume crop, such as beans, in a rotation. Green manures are usually dug into the soil when the plants are still young, before they produce any crop and often before they flower. They are grown for their green leafy material, which is high in nutrients and protects the soil.
If food is in very short supply, it may be better to grow a legume from which a bean crop can be harvested and then dig the plant remains into the soil. These plant remains will not break down in to the soil so quickly and will not be as good for the soil as younger plants but they will still add some nutrients to the soil for the next crop.
It is possible that some green manures may grow too vigorously and become weedy. This is especially true for plants which are not found locally. They may grow among the following crop or spread into new areas. The green manure should be chosen carefully to avoid this. If a green manure is to be used for the first time in an area, it should be tried on a small plot and checked to see that it does not become a weed.
Things to check for are:
(1) Light seeds being blown about by the wind.
(2) The green manure plant growing in places where it was not planted.
(3) Long stems that grow from the plant and spread along the surface of the soil. New roots then grow at intervals along these stems.
Checks should be carried out for at least two years, if possible, before the green manure is accepted for general use. Growing perennial green manures as annuals, it will prevent them from taking over and growing in areas where they are not wanted.
For more than a decade it has been accepted that green manures and cover crops would only be accepted by small farmers if they could be grown on land that had no opportunity cost, could be intercropped with other produce, grown under tree crops or on fallow land and be cultivated in periods of expected drought or extreme cold. They would also be favoured if they involved no extra labour or out-of-pocket cash expense.
Ex-situ is literally out of place and the opposite of in situ (in place). Many a times in-situ manuring not able to fulfill the nutrient requirement of the soil on the other side plenty of organic waste from agriculture, animals and human being is available which is rich in nutrient and needs safe disposal and crop field are the best place for this.
In the organic farming the nutrient cycle has to be maintaining in which the nutrient taken out in terms of economic yield has to be returned to soil and use of agriculture waste is the appropriate solution for maintaining the cycle.
Organic manures from agriculture/animal/human waste, contain essential plant nutrients and other growth promoting agents like enzymes and hormones, while no synthetic chemical fertilizer can supply all together thus they are indispensable from the manural schedule for any crop production.
The organic manure through the process of decomposition and humification gives humus which helps to improve the physical, chemical and biological properties of soil. The organic acid released during decomposition of organic manure controls certain fungal pathogens and nematode infestations. Commonly available organic manures like FYM, crop residues, poultry and sheep manure, oil cakes and other farm wastes will effectively be utilized for nutrient supplement.
Agricultural wastes (animal manures and crop residues or mixtures of the two) are now considered quite an important component for horticultural crop production especially that based on organic systems. Agricultural wastes can now be considered to include crop after harvest and primary processing, tree residues organic/plant residues from social forestry, animal excreta and processing left-overs from the slaughter houses and agro-industrial wastes.
Thus, agricultural wastes comprise all organic wastes produced and disposed of or used in primary agricultural production. Of course, these materials are essentially byproducts of production rather than wastes in the strict sense of the word.
There are several types of material mainly form plant or animal origin which can be used for ex-situ manuring, directly or in decomposed form:
(1) Cattle-shed wastes such as cattle and buffalo dung, and urine.
(2) Other livestock and human excreta.
(3) Byproducts of slaughter-houses and animal carcasses (Blood and meat wastes, bones, horns and hooves, leather and hair wastes).
a. Beef Cattle-Feedlots:
Most of the beef cattle raised for meat production are produced in feedlots that are either paved or unpaved. In either case, the manure is allowed to accumulate over a period of time. During this time, the manure is exposed to wetting and drying action caused by the weather, microbial activity, and mixing and compaction due to the animal activity. The quantity and characteristics of the manure will vary significantly with the rations.
The studies conducted by Grub et al. (1969), cattle fed on three different diets consisting of a high concentrate ration, cottonseed hulls, and sweet sorghum silage produced 1.1, 3.0, and 0.73 kg of dry solids per day per animal, respectively. Cattle fed a predominantly high roughage diet will produce more waste than cattle on high concentrate rations.
Under these conditions, manure handling generally consists of periodic scraping and field spreading. Estimates by indicate that approximately 95% of the total waste produced is either removed by cleaning operations or decomposed on the feedlot surface. Potentially 5% of the total waste generated may leave the feedlot as surface runoff. A common method for treating the runoff is by use of aerobic or anaerobic lagoons.
b. Slotted Floors:
Some beef cattle are confined within building sufficiently insulated and ventilated. Under this management practice, the animals are placed on slotted floors and the manure is allowed to accumulate beneath the floor in manure pits. Using this system, a manager has two options. He may choose to let the manure in the pit accumulate and undergo anaerobic decomposition. Then when conditions permit, he can dispose of the waste by field spreading.
The other option may be to treat it beneath the floor aerobically and allow the excess to run into a polishing lagoon. In either case, the manure under this management practice will be different from that of feedlot operations. Work by McCalla and Viets (1969) indicates that the fertilizer value of manure slurry contains 2.64, 1.64, and 3.00 kg of nitrogen (N), phosphorus (P2O5), and potassium (K2O), respectively.
c. Dairy Cattle-Stanchions:
Dairy cattle are housed in buildings using either stanchions or free-stalls. Manure from stanchion barns is allowed to collect in gutters where it is manually or mechanically scraped and stacked in storage areas until it can be hauled to fields for spreading and utilization. Farmers employing stanchion barns generally use bedding such as sawdust, straw, or wood shavings for the animals.
While the manure and bedding are stacked, liquid wastes will seep from the stored manure. The seepage liquid has a high pollution potential and must be controlled in order to avoid contamination of surface waters.
The liquid wastes can be collected in storage tanks where they can be used as liquid fertilizer or they can be allowed to flow to a lagoon for subsequent treatment. Characteristics stacked stanchion barn manure depend upon the time of storage, environmental conditions, and the type and amount of bedding used.
Manure produced from dairy cows housed in free-stall barns can be scraped by a from-end loader and stacked in a storage area for later utilization. In many of the newer setups, the manure is flushed by large volumes of water discharged a few times a day. The liquid waste from the flushing aisle is discharged to a series of lagoons for treatment.
Normally the effluent from the lagoon is used as the flush water. In other setups, the liquid waste is passed through a separator where the majority of the solids are removed from the liquid waste. The solid portion is transported and stacked for further utilization while the liquid part is allowed to flow to a lagoon for treatment.
Fresh manure contains approximately 5.0 kg of nitrogen, 2.0 kg of phosphorus, and 4.5 kg of potassium per each 1000 kg fresh, wet manure. Much of this value is lost, however, due to seepage and the volatilization of nitrogen during decomposition.
Generally speaking, livestock wastes can be characterized as high strength, low volume wastes in contrast to municipal wastes that are low strength and high volume. Basically, livestock wastes are solids containing some water whereas municipal wastes are liquids containing some solids. Consequently, approaches different from those used by sanitary engineers must be employed for handling and treating livestock wastes.
Livestock waste can occur as solids, semisolids, or liquid depending upon the design and operation of the production unit. In solid floor buildings and paved feedlots where manure is allowed to accumulate, its moisture content and consistency at any given time are a function of the age of the manure and its exposure to environmental conditions.
If it is under, roof, the moisture of the manure will be dictated by the slope of the floor, ventilation rate, temperature, and relative humidity. Manure exposed to adequate drainage, good ventilation and a hot, dry solid that can be readily scraped, scooped, stacked and transported.
On the other hand, if the accumulated manure on a solid floor is exposed to poor drainage, moist conditions, and occasional rainfalls, the results will be entirely different. Under these conditions the manure will have a high moisture content and appear as a semisolid. In many cases, the excess moisture will leach out many of the solids and nutrients and drain from the solid floor as a liquid waste.
In some production units, the manure is allowed to drop through slotted floors or screened cages and accumulate in a pit of water beneath the animals. These units can be operated as either aerobic or anaerobic systems. In either case, the manure is mixed with a great deal of water and is treated as a liquid.
This is also the case for production units using flushing gutter systems that either continuously or periodically discharge large volumes of waste to flush the manures from the building. Thus, it is apparent that the final consistency of animal waste may appear either as a solid, a semisolid, or a liquid. Its final form is dependent upon the type of production unit chosen.
Species and Age of Animal:
The amount of manure produced along with its chemical and physical characteristics is dependent upon the age and species of the animal. For example, wastes from mature stock and milk animals will be digested to a greater degree than that from younger, growing livestock.
Waste from ruminants has a different composition than waste from simple-stomached species. Ruminants, because of the bacteria in their stomachs, and utilize feeds high in cellulose which are difficult to digest. Swine and poultry on the other hand consume diets that are highly digestible. As a result, the characteristic of waste from these two classifications of animals varies, requiring different design conditions for treatment.
Other factors that may affect the characteristics of waste are bedding materials and spilled feed. Bedding material may consist of straw, wood shavings, sawdust, or shredded paper. It may be used for the comfort of the animal or simply to absorb the excess moisture in the waste. In either case, it will affect the characteristics of the waste and must be taken into account in the design of the treatment facility.
Spilled feed can also alter the characteristics of livestock wastes. It is a good practice to eliminate this source of wastage. Not only does it increase production costs but it puts an additional load on treatment facilities.
Crop residues, tree wastes and aquatic weeds:
(1) Crop wastes of cereals, pulses and oilseeds (wheat, paddy, bajra, jowar, gram, moong, urad, cowpea, arhar, masoor, ground-nut, linseed, etc.).
(2) Stalks of corn, cotton, tobacco, sugar-cane trash, leaves of cotton, jute, tapioca, arecanut, tree leaves, water hyacinth, forest litter, etc.
Urban and Rural Wastes:
(1) Rural and urban solid wastes.
(2) Urban liquid wastes – sewage and sullage.
Agro-Industries by Products:
(2) Paddy husk and bran,
(3) Bagasse and pressmud,
(5) Fruit and vegetable wastes,
(6) Cotton, wool and silk wastes, and
(7) Tea and tobacco wastes.
3. Marine Wastes:
Fish meal and aquatic/seaweeds.
Residues left out after the harvest of the economic portions are called crop residues/straw. In the developing countries like India, they are mostly used as cattle feed. In the developed countries, harvesting is done using combine harvester and hence the straw cannot be used as cattle feed.
They are generally burnt in the field itself. Straw has good manurial value since it contains appreciable amount of plant nutrients. On an average, cereal straw and residues contain about 0.5 % N, 0.6 % P2O5 and 1.5 % K2O. The crop residues can be recycled by way of incorporation, compost making or mulch material.
4. Agro-Industrial Wastes:
Agro-industrial wastes are available in substantial quantities at processing sites and can be effectively utilized as manure.
i. Rice Husk:
It is the major by-product of the rice milling industry. Unhulled paddy grain constitutes 20-25 % of husk. It is a poor source of manure and the nutrient content is very low (0.3-0.4% N, 0.2-0.3% P2O5 and 0.3-0.5% K2O). Rice husk should be incorporated into the wet soil and can be used in saline and alkaline soils to improve the physical conditions. It can also be used as a bedding material for animals.
The most important by-product of sugar industry is bagasse. It is mainly used as fuel in boilers of sugar factories. It can be used as manure raw or after composting. It contains 0.25 % N and 0.12 % P2O5.
It is a by-product obtained during the process of sugar manufacturing. It contains about 1.25 % N, 2.0 % P2O5 and 20-25 % organic matter. Addition of pressmud is highly useful to acidic soils since it contains high amount of lime (upto 45 %)
iv. Tea Wastes:
In the tea industry, tea wastes are available during the course of tea production, processing and storage. Tea wastes are used for extraction of caffeine. The decaffeinated tea wastes can be used as a manure. Nutrient content of the spent tea waste is 0.3-0.35 % N, 0.4 % P2O5 and 1.5 % K2O.
v. Coir Waste:
It is a waste product from the coir industry and mostly dumped near the road sides. Coirpith contains high amount of lignin (30 %), cellulose (26 %) and wide C : N ratio (112:1). To reduce the bulk and C : N ratio, composting is recommended. The composted coirpith contains 1.26 % N, 0.06 % P, 1.20 % K with C/N ratio 24:1. The lignin content is reduced to 4.8 % due to composting.