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Organic manures (benefits & preperation)

Written by Dr. Shaun Murphy

Here is some information about manure and its type. I will also talk about its preparation and benefits.


Manures are substances that are organic in nature, capable of supplying plant nutrients in available form, bulky in nature having low analytical value, and having no definite composition, and most of them are obtained from animal and plant waste products.

Bulky Organic Manures

Bulky organic manures contain a small percentage of nutrients and they are applied in large quantities. which are very beneficial for the plants.

1. Compost manure

A mass of rotted organic matter made from waste is called compost. It contains 0.5 percent N, 0.15 percent P2O5, and 0.5 percent K2O.

Preparation of good compost

Most people think composting is as simple as throwing all food and garden waste into a container and leaving it there for a couple of years.

While you will get compost that way, you can produce much better compost and get it much more quickly if you follow these simple guidelines for the perfect recipe.

There are 4 ingredients for good compost: greens, browns, air, and moisture. These 4 need to be balanced correctly for the best results.

C: N Ratio

The ingredients you add to a compost heap contain carbon and nitrogen. The ratio of carbon to nitrogen determines whether we label it a ‘green’ or a ‘brown’.

Ingredients that have are latively high nitrogen content and a carbon-to-nitrogen ratio below 30:1 are called ‘greens’. Ingredients with a lower nitrogen content (in other words a higher carbo

n-to-nitrogen ratio) are called ‘browns’.

Color isn’t always a reliable indicator of what is a ‘green’ or ‘brown’ material. For example, fresh grass clippings when spread out and left to dry are still considered a ‘green’ ingredient even though they’ve turned a brownish color because really all they’ve lost is water.

Compost manure

Components that are used

On the other hand, straw is always considered a ‘brown’ because before it was cut, the main stems had died and much of the plant’s nitrogen had gone into the seeds as protein.

Good examples of greens to add to your compost pile are grass clippings (which haven’t been sprayed with weedkiller), vegetable waste, fruit peels, annual weeds before they’ve developed seeds, and old bedding plants.

Don’t compost animal products such as meat, and try to avoid adding diseased plant material, or fats and oils. Good examples of browns include sawdust, straw, wood chippings, shredded brown cardboard, and fallen leaves.

Bedding from herbivorous pets such as guinea pigs is ideal, as their manure adds a bit of extra nitrogen into the mix.

Compost decomposes much faster if you chop the ingredients up, so shredding woody materials and tearing up cardboard speeds up the process because there is then more surface area exposed to the microbes that decompose the compost.

However, avoid shredded evergreen trees such as Leylandii because they don’t compost well and the pine resin can inhibit seed growth.

When making compost you want to aim for 2-3 times more brown materials than greens, at least initially, although some more greens can be added as the compost cooks.

For most gardeners, the biggest challenge therefore collecting enough brown materials and not just piling in loads of greens which will result in a soggy, smelly mess.

Never add lots of grass clippings in one go as they will just form a slimy matted layer. Air is vital to the composting process so it’s important to mix the ingredients together, and never squash them down.

By turning or remixing the compost more air is introduced, which speeds up decomposition.

Moisture in compost

The fourth vital ingredient is water. If like me you stockpile brown materials, you’ll need to water the pile to get things going when first mixing it.

Build the compost pile up with layers of browns and greens, watering it was necessary to produce a moist (but not soggy) mixture. A good compost heap has a slightly sweet composty smell.

If it smells sour or rotten then it either has too many greens or is too wet.

In either case, the remedy is to mix more brown materials in to compensate.

By getting the right balance of 2 or 3 parts browns to 1 part greens with moisture and air, you’re giving the microbes that decompose the materials the best conditions to work in.

As they break the organic matter down they give off heat, which in turn speeds up the decomposition.

In a well-mixed heap, temperatures reach over 150 degrees Fahrenheit, or 65 degrees Celsius.

Last stage

This heap for example was mixed several days ago and it’s already been cooking nicely, although it’s starting to cool a little now.

After a few more days I will remix it to introduce more air and to bring materials from the edges into the center.

Several weeks later the heap will cool, and worms can move in to finish the process. If you follow this recipe you should get a fine, crumbly-textured compost.

Any remaining large bits can be sieved out and put into the next compost heap you build, leaving you with the very best food for your plants.

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2. Green Manure

Crops grown for the purpose of restoring or increasing the organic matter content in the soil are called green manure crops while their green undecomposed plant material used as manure is called green manure.

Their use in cropping systems is generally referred to as green manuring. It is obtained in two ways either by grown in situ or brought from our site.

  1. In situ green manuring: Growing green manure crops in the field and incorporating it in its green stage in the same field (i.e. in situ) is termed as green manuring.
  2. Green leaf manuring is the application of green leaves and twigs of trees, shrubs, and herbs collected from nearby locations and adding into the soil. Forest tree leaves are the main source of green leaf manuring.

Green Manure

Advantage of green manuring: –

  1. It has a positive influence on the physical and chemical properties of soil.
  2. Helps to maintain the organic matter status of arable soil.
  3. All green manures supply extra organic matter to feed and breed beneficial soil organisms for soil fertility and soil health.
  4. Increases the water holding capacity of light soils.
  5. It facilities the penetration of rainwater, thus decreasing runoff and soil erosion.
  6. The green manure crops hold plant nutrients that would otherwise be lost by leaching (e.g. Nitrogen)
  7. When leguminous plants like sunn hemp and dhaincha are used as green manure crops, they add nitrogen to the soil for the succeeding crops.
  8. Green manuring crops help in the reclamation of saline and alkaline soils by the release of organic acids.

Limitations of green manuring: –

(1) Under rainfed conditions it is feared that proper decomposition of the green manure crop may not take place if sufficient rainfall is not received after burying the green manure crop.

(2) Since green manuring for wheat loss of Kharif crops, the practice of green manuring may not be always economical.

(3) Sometimes the cost of green manure crops may more than the cost of commercial fertilizers.

(4) Sometimes it increases termite problem.

(5) The green manure crop may be failed if sufficient rainfall is not available.

Characteristics of green manure crops: – An ideal green manure crop should have the following characteristics.

(1) It should be preferably from a leguminous family so that atmospheric nitrogen can be fixed.

(2) It should have quick initial growth so as to suppress the weed growth.

(3) It should have more leafy growth than woody so that its decomposition will be rapid.

(4) It should yield a large quantity of green material in a short period.

(5) It should have a deep-rooted system so that it would penetrate deep layers of the soil and thus aid in creating a goodwill structure.



Nutrient content (%) on an air-dry basis
N P2O5 K2O.

Green manure crops

Sunn hemp 2.30 0.50 1.80
Dhaincha 3.50 0.60 1.20
Sesbania 2.71 0.53 2.21

About the author

Dr. Shaun Murphy