Soil Fertility I : Organic Manures - Form 1 Agriculture Note

• Organic Manures
  • Importance of Organic Matter in the Soil
  • Limitations in the Use of Manure
  • Types of Organic Manures
• Green Manure
  • Characteristics of Plants Used for Preparation for Green Manure
  • Preparation of Green Manure
  • Reasons why Green Manure is not Commonly Used/Limitations:
• Farm Yard Manure (FYM)
  • Factors that Determine the Quality of FYM
  • Preparation of FYM
• Compost Manure
  • Factors to consider in Selecting Site for Making Compost Manure:
  • Preparation of Compost Manure
  • Advantages of Compost Manure
  • Limitations of Compost Manure

Organic Manures

- Manures are derived from plants and animal remains.

- They supply organic matter to the soil which after decomposition releases plant nutrients.

- The end product of this decomposition is known as humus.

- It influences soil chemical properties and soil temperature.

- Manures supply a wide range of essential plant nutrients. 

Importance of Organic Matter in the Soil

• Increases the soil water holding capacity of the soil.
• Improves soil fertility by releasing a wide range of nutrients into the soil.
• Provides food and shelter for soil micro-organisms.
• Improves the soil structure.
• Buffers soil pH/moderates soil pH.
• Reduces the toxicity of plant poisons in the soil.
• Moderates soil temperature by its dark colour.

Limitations in the Use of Manure

• They are bulky - low nutritive value per unit volume.
• Laborious in application and transport.
• They spread diseases, pests and weeds.
• Loss of nutrients if poorly stored.
• If not fully decomposed crops may not benefit from them.

Types of Organic Manures

• Green manure.
• Farm yard manure.
• Compost manure

Green Manure

- Made from green plants which are grown for the purpose of incorporating into the soil.

Characteristics of plants used for preparation for green manure:

• Have fast growth rates.
• Have high nitrogen content.
• Capable of rotting quickly.
• Capable of growing in poor conditions.

Preparation of Green Manure

• Plant the green manure crop in the field.
• Allow the crop to grow up to flowering stage.
• Incorporate it into the soil through ploughing.
• Allow the crop to decompose for two weeks.
• Prepare the field for planting the major crop.

Reasons why Green Manure is not Commonly Used/Limitations:

• Most of the plants used as green manure are food crops.
• Green manure crops may use most of the soil moisture.
• Most of the nutrients are used up by soil micro-organisms in the process of decomposing the green manure.
• Planting of the major crop is delayed.

Farm Yard Manure (FYM)

- Is a mixture of animal waste and crop residues used as beddings in animal houses.

Factors that Determine the Quality of FYM

• The types of the animals used.
• Types of food eaten
• Types of litter used.
• Method of storage.
• Age of farmyard manure.
• Age of the animals used.

Preparation of FYM

• Provide beddings in the houses of farm animals.
• Animals deposit their droppings and urine on the beddings.
• Animals mix them through trampling.
• The beddings together with dung are removed and heaped under shed to decompose.
• After sometime, the materials decompose and FYM is formed.
• It can then be used in the farm

Compost Manure

- Is manure prepared from heaped (composted) organic materials.

Factors To Consider In Selecting Site For Making Compost Manure:

• A well drained place.
• Direction of the prevailing wind.
• Size of the farm.
• Accessibility.

Preparation of Compost Manure

Two methods:

• Four heaps method
• Indore Method (Pit Method)

Indore Method (Pit Method)

Procedure ;

• Select a sheltered place with a shade and near the field.
• Dig a pit with the dimension 1.2m x 1.2m x 1.2m.
• Place the materials in the following order:
  • Hedge cuttings or maize stalks to a depth of 30cm as a foundation
  • A layer of grass, green weeds or leaves and kitchen wastes to 30cm.
  • A well rotten manure/poultry droppings.
  • Wood ash and phosphatic fertilizers.
  • A layer of topsoil to introduce micro¬organism for the decomposition of organic remains.
  • Note: Some water should be sprinkled to the materials to initiate the decomposition process and regulate temperatures.

Four heaps method:

Procedure

• Clear the site.
• Level the site
• Four posts 2m high are fixed 1.2m apart from four corners of the heap.
• Fix wood planks on the sides.
• Materials are placed in two heaps as in the pit method,
• The two heaps make up heap 1.
• After 3-4 weeks, the decomposed material from heap 1 is transferred to heap II.
• After another 3 - 4 weeks the material is transferred to heap III.
• After 3-4 weeks it is ready for use in the farm.

Indicators of well decomposed manure

• Absence of bad odour.
• Materials are lighter.
• Manure is brown in colour.

Advantages of Compost Manure

• One does not have to own livestock in order to prepare it.
• A lot of manure can be produced within a short time.
• A variety of materials can be used in its preparation.
• Uses locally available materials thus cheaper than the artificial fertilizers.
• Improves the soil structure.

Limitations of Compost Manure

• It releases nutrients slowly into the soil.
• Large quantities of compost manure are required to supply enough plant nutrients.
• Its preparation is labour intensive.
• It may induce soil-borne pests and diseases.