1. What are 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.
2. How are organic manures beneficial in the cultivation of crops?
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.
3. How are organic manures differing from fertilizers?
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 where as 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 contain 46% N regardless of which factory makes it any where in the world.
4. How much of plant nutrients are provided by organic manures?
Just as 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.
5. What is green manuring?
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.
6. What is green leaf 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.
7. What green manure crops are beneficial?
Sesbania, Crotalaria, ‘Pillipesara’, Cowpea etc are good for green manuring.
8. What are the popular green leaf manuring plants?
Glyricidia, Pongamia, Leucina are common green leaf manuring plants.
9. What is compost?
Compost is well decomposed organic wastes like plant residues, animal dung, and urine earth from cattle sheds, waste fodder etc.
10. How good compost is prepared?
Compost making is the process of decomposing organic wastes in a pit. Site for compost making is selected should be at a high level and water should not pond during monsoon season. Pit should be of 3’ depth and 6’ to 8’ width. Length may be of any convenient size. The process is as follows:
- Make slurry of the cattle dung with water.
- Prepare 6” layer of organic wastes – plant residues, sweepings from the cattle shed, waste fodder, dried plants stalks and leaves etc. and sprinkle water to just moisten it. (Over watering should be avoided)
- Cover with the layer with urine earth and cattle dung slurry.
- Add 5 to 10 kg of super phosphate for every 10 tons of organic wastes.
- Repeat the process of putting such layers till the pit is full.
- Close the pit with urine earth, waste fodder and then heap the soil till it gets convex shape (about 1 to 1.5’ above the ground) so that the rainwater rolls away.
- After six months compost is ready to apply to the fields.
The pit can be filled up if sufficient organic wastes are available. Otherwise a temporary partition can be made in the pit with bamboos or stalks and the pit can be filled up over time filling each partitioned area as and when the material is available for composting.
11. Why super phosphate is added in compost making?
Due to quick heating and drying during the decomposition of organic wastes, nitrogen in the organic wastes will be lost due to volatilization. Addition of super phosphate decreases such nitrogen losses. It will also increase the phosphate content of compost.
12. What is vermicomposting?
Vermicomposting is a type of compost making in which earthworms are used to convert organic wastes into valuable material to supply nutrients for crops.
Where can I get more information on vermicomposting?
Please click on the following Internet site for more details on vermicomposting.