Green manuring:

Green manuring is the practice of enriching the soil by turning under undecomposed plant material (except crop residues), either in place or brought from a distance. In various localities, green manuring is practiced differently. These include:

1) Green leaves are collected from forest areas and leguminous trees are grown on the boarder of the fields and other vacant places of the farm to provide green leaf and twigs for manuring paddy crops.

2) Legumes are grown to maturity and either cut close to the ground and laid on the soil or is simply allowed to dry. Litter – fall from drying plants is decomposed and contributes nutrients to soil.

3) Other scheme involves growing leguminous tree species such as ipil-ipil (Leuceana leucocephala) along the slope contours or farm boarders. The trees are trimmed periodically to prevent crop shedding. The cut branches and leaves are placed on the ground as green manures.

Types of green manuring

a. Green manuring in situ

The practice of ploughing or turning soil in the same field where the crop is grown. E.g. sunhemp, dhaicha, cowpea etc.

b. Green leaf manuring

The practice of turning gree leaves and tender twigs collected from shrubs and trees grown in bunds, wasteland and nearby forest area. E.g., Titepati, Asuro, Banmara, Khirro Etc.

Quality of good green manure crop

A good quality green manure crop must:

1) Be able to grow well quickly under local conditions, especially initially, so that weed growth is suppressed.

2) Be able to yield more leafy and succulent materials than woody or fibrous ones so that the decomposition will be fast.

3) Be leguminous as far as possible and be able to produce high amount of biomass with high N content so that nitrogen mineralized will be rapid and consequently there will be no N starvation of the succeeding crop.

4) Have deep and fibrous root system to penetrate lower horizons and to extract nutrients to bring to the

surface for the use of the succeeding crops.

5) They must have ability to grow in different soil condition.

6) It should contain large quantities of non-fibrous tissues for rapid decomposition and containing fair amount of moisture.

Advantages of green manuring

❖ It adds OM to the soil, conserve the soil nutrients.

❖ The green manure crops return to the upper soil plant nutrients taken up by the crop from deeper layers.

❖ Improves physical properties of soil.

❖ Helps to penetrate of rain water, decreasing runoff and erosion.

❖ The green manuring crops hold plant nutrients that would otherwise be lost by leaching.

❖ They add N to the soil for succeeding crop.

❖ It stimulates the activity of soil micro-organisms.

❖ It increases the availability of plant nutrients such as P2O5, Ca, K, Mg, & Fe.

Disadvantages of green manuring

❖ Improper decomposition of green manuring crops due to lack of water.

❖ Loss of one crop due to green manuring.

❖ The cost of green manuring crops may be more than the cost of commercial N-fertilizer.

❖ An increase of diseases, insect pests & nematode is possible. If the green manure crop is not well decomposed, the chances of white ant attack are more.

❖ Green manuring crops stand may not be satisfactory if rainfall is low.