Turning farm manure into black gold

If well-managed to prevent nutrient loss, farm manure can save a farmer lots of money spent on buying chemical fertilisers. FILE PHOTO | NATION MEDIA GROUP

What you need to know:

  • Manure is not garbage, it is black gold.
  • Manure is further a source of energy (carbon) for the soil organisms, which helps to sustain their population and activities.
  • On most farms, manure is stored next to the zero-grazing unit either in heaps or pits.
  • Apply (composted) farmyard manure as soon as it is ready, the more it stays, the more nutrient loss it undergoes.

Manure remains a useful resource on the farm despite extensive use of inorganic fertiliser.

However, on many farms, you will site the animal or crop manure heaped at one corner, sometimes emitting odour, which makes it unwanted.

This is because majority of livestock farmers lack skills on management, handling and storage of farmyard manure to preserve its nutrients.

To begin with, manure is not garbage, it is black gold. Therefore, if well-managed to prevent nutrient loss, a farmer can save lots of money spent on buying chemical fertilisers.

You see, adding useful amounts of organic matter on animal manure helps improve soil structure and condition, thereby stimulating biological activities and enhancing its physical properties.

Manure is further a source of energy (carbon) for the soil organisms, which helps to sustain their population and activities.

Farmyard manure normally loses essential nutrients when exposed to the sun or rain.

Majority of farmers store manure in open heaps for convenience but research estimates a fairly high nutrient loss of over 30 per cent of nitrogen when open-air storage duration exceeds three months.

This loss increases further with longer duration of poor storage. Areas prone to rainfall can expose manure to anaerobic conditions, for instance, when storage pits are water-logged, making it of inferior quality.

STORAGE PITS

For better storage, manure should be mixed with dry plant materials like straws, crop residues, leaves to absorb any liquids or alternatively composted.

On most farms, manure is stored next to the zero-grazing unit either in heaps or pits. That should not be the case, protect the manure from direct sunlight, wind and rain to reduce nutrients loss.

Use of storage pits is particularly suitable for dry areas, especially during dry seasons. This is the opposite in wetter areas as there is greater risk of waterlogging.

However, waterlogging should be controlled by digging trenches around the pit and erecting shades to protect it from rainfall.

To use pits for composting, dig 0.9–1m deep with a slight slope at the bottom. Compress the bottom and first cover with maize stover if available, but use straw as bedding material.

Fill with manure layers of about 30cm thick as you compress each and finally cover with a thin layer of earth to increase micro-organism population. Repeat the layering to the fill.

Then fill to 30cm above the brim until it is dome-shaped, and cover with soil layer of about 10cm. Turning this pile is not needed if optimum conditions such as moisture content are met.

APPLY FARMYARD MANURE AS SOON AS READY

Practically test this by squeezing the material in your hand and if it shines, with small moisture droplets, then the moisture content is sufficient.

If the pile is too moist, it means water is replacing the air, you have to turn it to reintroduce air.

If maize stover has been used, it may be necessary to turn the manure to give a uniform chance of micro-organisms reaching everywhere.

Conversely, if the pile is too dry, biological activities will reduce or stop, therefore, add little water to moisten it. It will take about three to four months for the manure to be ready for application.

Well-rotten farmyard manure contains considerable amounts of nitrogen, phosphate and potash. Ideally, it should be black to brown with an earthy smell. Unpleasant smell indicates problems with decomposition.

Apply (composted) farmyard manure as soon as it is ready, the more it stays, the more nutrient loss it undergoes.

If not immediately used, store in polythene bags. Odour from poorly stored farmyard manure can be a nuisance, therefore, siting of storage pits or heaps should always consider the position of your main house.

Opinya is based at the Department of Animal Science, Egerton University.

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Why Compost

  • Manure carry bacteria, and bugs, therefore, they need to be composted before they are used in a garden.
  • The pile should be composted for even up to six months.
  • This gives the pile enough time to heat up to above 130 degrees killing most of the bad organisms.