Organic Manure: Role, Use and Disadvantages

After reading this article you will learn about Organic Manure:- 1. Role of Organic Manure 2. Uses of Organic Matter 3. Disadvantages.

Role of Organic Manure:

Organic manure or organic matter charging the soil properties.

Function of organic manure is given below:

1. Organic manure binds soil particles into structural units called aggregates. These aggregates help to maintain a loose, open, granular condition. Water infiltrates and percolates more readily. The granular condition of soil maintains favourable condition of aeration and permeability.

2. Water-holding capacity is increased by organic matter. Organic matter definitely increases the amount of available water in sandy and loamy soils. Further, the granular soil resulting from organic matter additions, supplies more water than sticky and impervious soil.

3. Surface run off and erosion are reduced by organic matter as there is good infiltration.

4. Organic matter or organic manure on the soil surface reduces losses of soil by wind erosion.

5. Surface mulching with coarse organic matter lowers soil temperatures in the summer and keeps soil warmer in winter.

6. The organic matter serves as a source of energy for the growth of soil microorganisms.

7. Organic matter serves as a reservoir of chemical elements that are essential for plant growth. Most of the soil nitrogen occurs in organic combination. Also a considerable quantity of phosphorus and sulphur exist in organic forms upon decomposition, organic matter supplies the nutrients needed by growing plants, as well as many hormones and antibiotics.

8. Fresh organic matter has a special function in making soil phosphorus more readily available in acid soils.

9. Organic acids released from decomposing organic matter help to reduce alkalinity in soils.

10. Fresh organic matter supplies food for such soil life as earthworms, ants and rodents. These macro-organism improves drainage and aeration. Earthworms can flourish only in soils that are well provided with organic matter.

11. Organic matter upon decomposition produces organic acids and carbon dioxide which help to dissolve minerals such as potassium and make them more available to growing plants.

12. Humus (highly decomposed organic matter) provides a storehouse for the exchangeable and available cations—potassium, calcium and magnesium. Ammonium fertilizers are also prevented from leaching because humus holds ammonium in an exchangeable and available form.

13. It acts as a buffering agent. Buffering checks rapid chemical changes in pH and in soil reaction.

Uses of Organic Matter:

1. Retention of soil water:

Water-holding capacity is increased by organic matter. Organic matter increases the amount of available water in sandy and loamy soils. Water is held in the capillary pores or micro pores. Organic matter helps to increase the capillary pores in a soil. Organic matter itself has a great capillary capacity.

Under-composed organic matter is generally porous having a large surface area which helps to hold more capillary water. The humus that is formed on decomposition has a great capacity for absorbing and holding water. Hence, the presence of organic matter in soil controls the amount of capillary water.

2. Movement of soil water:

In saturated flow or gravitational flow, water percolates down (vertically) into the lower layers. Organic matter helps to maintain a high proportion of macro pores, larger the pore space, greater the flow. In capillary movement or unsaturated movement water moves from lower level (thick moisture level) to upward level (thin moisture level). Upward rise of water is higher in micro pores or capillary pores. The humus helps to increase the capillary pores.

3. Availability of soil water:

Organic matter binds soil particles into structural units called aggregates. These aggregates help to maintain a loose, open, granular condition. Water infiltrates and percolates more readily. Thus, organic matter reduces surface run off and makes soil water more available to plants.

4. Special use of organic manures:

There are a number of special uses of manures.

Firstly, application of soil areas denuded by erosion or land leveling for irrigation.

Secondly, special cases of micronutrient deficiency can be ameliorated with manure application.

Thirdly, the water holding capacity of very sandy soils are increased with heavy manure applications. Manure application also increases tilth of heavy-textured clay soils. Fourthly, manures are also applied to the trees and shrubs.

Long-Term Effect of Manures:

Manures have very long term effect on the soil because nutrients are released very slowly. Only one-fifth of the nutrients supplied by animal manures are recovered by the first-crop following the application. Much of the remainder is held in humus-like compounds subject to very slow decomposition.

In these forms, the elements are released only very slowly, rates of 2-4% per year being common. Thus, the humus-like compounds in manure will have continuing effects on soils years after their.

Disadvantages of Organic Manure:

1. Nutrients are so low that a huge quantity of manure has to be added for the desired dose of nutrients.

2. Transport of a huge quantity of manure to the site of application is difficult.

3. It increases the cost also.

4. The rate of mineralization and the rate of release of nutrients, particularly of the nitrogen, is slow.