Bulky Vs Concentrated Organic Manure
Organic manures are derived from biological sources like a plant, animal, and human residues. These organic manures contain low amounts of plant nutrients but organic matter, other than nutrients, present in large quantities hence called bulky organic manures. Among various bulky organic manures, farmyard manure, compost, green manures, concentrated manures, oil cakes are most widely used.
A. Bulky Organic Manures
1. Farmyard manure
Farmyard manure is a decomposed mixture of cattle dung and urine with straw and litter used as bedding material and residues from the fodder fed to cattle.
The waste material of cattle sheds consisting of dung and urine-soaked in the refuse of the shed is collected daily and placed in trenches about 6 meters long, 2 meters wide, and 1 meter deep. Each trench is filled up to a height of about 0.5 meters above the ground level and plastered over with a slurry of cow dung and earth. The material is allowed to decompose undisturbed 3-4 months for anaerobic microorganisms to completion of fermentation.
Farmyard manures become ready to apply after 3-4 months. It is spread evenly over the field 4-6 weeks before the sowing, mixed with the soil by hand hoe or cultivator. Well rotted farmyard manure contains 0.5% N, 0.2% P205, and 0.5% K2O. Animal and cow dung from biogas plants are also utilized in a similar manner.
Large quantities of waste material are available as vegetable refuse, farm litter such as weeds, stubble, bhusa, sugarcane trash, sewage sludge and animal wastes in houses and of areas like human and industrial refuse, town refuse, excreta can be converted into useful compost manure by conserving and subjecting them to a controlled process of anaerobic decomposition
3. Green manures
Green manuring is another useful method of adding organic matter to the soil. Legume crops usually sunn hemp, dhaincha, berseem, Kudzu vine, cowpea, leaves of bushes and trees are buried in the soil and allowed to decompose in the field. The green manure crop supplies organic matter, improves the physical structure of the soil, and maintains the fertility of the soil. On average, a leguminous crop-producing 10 tonnes of green matter per hectare will add about 35 kg of nitrogen when ploughed under. While decomposition numerous macro and micro organism act upon the organic material and develop a well-balanced soil biota which not only supplies the plant nutrients but also releases many fixed minerals (solubilised) in soil solution. It increases water holding capacity and organic colloids in the soil so that nutrient adsorption surfaces are increased and their loss is minimized.
B. Concentrated organic Manures
Concentrated organic manures are the byproduct of animal or plant industry which are organic in nature and contain a higher percentage of major plant nutrients, N, P, and K compared to bully organic manures.
The common concentrated organic manures are oil cakes, bone meal, blood meal, fish manures, meat meal, etc. The oil cakes are a byproduct of oil industries that are used as concentrated organic manures to a large extent. These have comparatively high nutrient content e.g. groundnut cake, til cake, mustard cake, castor cake, Neem, and Mahuwa cakes. They are fairly quick-acting manures which is applied well before a crop is sown.
A variety of products of animal origin are used for concentrated organic manures. The most common ones are derived from animal carcasses or products of slaughter-house viz: dried blood, meat meal, horn and hoof meal, etc. It is used in the same way as oil cakes are used.