Here is a list of organic manures that helps in improving the fertility and productivity of soils.
i. Farm Yard Manure (FYM):
This is traditional and the most commonly used organic manure. It is a decomposed mixture of cattle dung and urine with bedding materials and residues of fodder fed to the cattle. The nutrient content of FYM depends upon the type of animals and nature of feed. On an average, well rottened farm yard manure contains 0.4 to 1.5 per cent N, 0.3-0.9 % P2Os and 0.3-1.9% K2O.
Composition of Dung:
a. Moisture – 75 to 80%
b. Insoluble materials of fodder or food – 20 to 25%
Chief components of insoluble materials – woody fibre, starch, fats, bile pigments, mucus, skatole and Indole (by product derived from the digestion of food material) fatty acids, Ca, Mg PO4, alkaline soap etc.
Nutrient Content of Dung (%):
Composition of Urine:
a. Water – 96 %
e. Uric Acid
f. Hyppuric Acid
g. Sodium Chloride
h. Sodium Hydrogen PO4
i. Ca and Mg PO4
j. K and Na SO4
Nutrient Content of Urine (%):
Composting is a biological process in which microorganisms decompose waste materials like weeds, straw of different crops, vegetable refuse, and animal wastes. This process of decomposition reduces the C: N ratio of waste materials. The final product of well rottened manure is known as compost, which contains higher quantity of macro and micro nutrients than that of FYM.
iii. Sheep and Goat Manure:
It is a valuable organic manure and contains higher percentage of nutrients than FYM and compost. This is effective to all types of crops. On an average, the manure contains 2-3% N, 0.7-1% P2O5 and 1- 2% K2O. Penning is quite common in certain areas, where sheep and goats are kept overnight in the field. The urine and droppings of sheep and goats are added and incorporated to the soil insitu by working with blade harrow or cultivator.
iv. Poultry Manure:
This manure contains higher nitrogen and phosphorous than other bulky organic manures. It is recommended at 5t/ha for obtaining higher yields of crops. The average nutrient content is 2-3 % N, 1.5 – 2.5% P2O5 and 1-1.5% K2O.
v. Sewage and Sludge:
Sewage is a liquid waste containing large quantities of plant nutrients used for growing sugarcane, vegetables and fodder crops near large towns .The sewage is subjected to undergo preliminary fermentation in the tank and it is aerated. The solid portion settles at the bottom is called as ‘activated sludge’. It contains about 3.0 to 6.0 % N, 2.0% P2O5 and 1.0% K2O.
The average nutrient content of different bulky organic manures is given below:
Nutrient Content of Different Manures:
2. Concentrated Organic Manures:
i. Oil Cakes:
Oil cakes are valuable organic manures containing higher percentage of nitrogen with lower percentage of phosphorus and potash. The N, P and K contents vary with different oil cakes which are presented in the table. They are insoluble in water and should be well powdered before application. The nitrogen in the oilcakes is made available to crops only after 7 – 10 days of application.
ii. Blood Meal:
It is a by-product of slaughter house containing 10 to 12% available nitrogen, 1 to 1.5% phosphorus and 1.0 % potassium. It is highly effective on all types of soil thus favouring yield of all crops.
iii. Fish Meal:
Non edible fish, carcasses of fish and wastes from fish industry are used to prepare fish meal, which is available either as dried fish or as powder. It contains 4 to 10% nitrogen, 3 to 9% phosphorus and 0.3 to 1.5% potassium. This organic manure is suitable for application to all crops and on all soils.
iv. Bone Meal:
It is prepared by utilizing the wastes of meat industry, slaughter houses and carcasses of all animals. Raw bone meal is prepared from bones of slaughter houses. These are dried and powdered without any treatment. It contains 20.0 to 25.0 % P2O5. Steamed bone meal is prepared from bones of slaughter houses after soaking with water and caustic soda. It is a rich source of phosphorus (27.0% P2O5). This is suitable for acidic soil and also for long duration crops.
Nutrient Content of Concentrated Organic Manures:
3. Green Manures:
Green manuring is the practice of growing lush plants and plough in situ when succulent to improve the soil properties. Green manures when it is incorporated into the soil, not only supply the nutrients, it improves the crop yield by enhancing soil fertility, improving soil structure, preventing soil erosion, and also improves the microbial activity. The green manure crops are incorporated directly into the soil during flowering stage (45-60 days) by using a mould board or country plough or burmese setturn.
Methodology of Green Manuring:
Green manures can be sown in different combinations and configurations in time and space.
i. Improved Fallow:
Natural fallow vegetation in several areas can be sown with green manure seeds to rejuvenate the land into green vegetation.
ii. Alley Cropping:
Quick growing trees or shrubs usually legumes are planted in rows and are regularly pruned. The primings are incorporated into the soil in the alleys between the rows.
iii. Agro Forestry:
It is an alternate land use system in which woody perennials usually leguminous tree species grown in combination with annual crops. The tree loppings nourish the soil.
Suitability of Green Manures:
Green manures require water for their decomposition, which releases nutrients thereby improving fertility status of soil. So, these green manures are suitable for wet lands and garden lands. However, proper distribution of rainfall and required quantity coinciding with date of incorporation permits growing of green manure (Kohngi-Tephrosia purpurea) under dryland conditions.
The suitability of green manures for different crops is presented hereunder:
4. Green Leaf Manures:
Green leaf manuring is the practice of collecting green leaves and tender green twigs from shrubs and trees grown on bunds and waste lands and applying to the main fields for improving the fertility status of soil.
Nutrient Content of Green Manures and Green Leaf Manures:
Beneficial effects of green manuring and green leaf manuring:
i. Leguminous green manure crops fix atmospheric N, which enriches the soil.
ii. When the green manure crop is ploughed in, it decomposes easily without leaving much residue in the soil.
iii. The green manures and green leaf manures added to soil promote the activity of soil microbes, which aid in the release of nutrients to crops.
iv. Organic acids produced during decomposition of green manure and green leaf manure help to release phosphorous and make them available for the next crop.
v. Improve the structure of the soil.
vi. The green manure crop withdraws the plant nutrients from the lower layers and concentrates them in the surface soil for use of the succeeding crops.