What are organic materials and manures?
Organic material and
manures are those materials that come from
plant or animal waste or by-
products such as cattle
or poultry manure, composted rice straw or other crop residues,
sewage sludge, oil cakes, green manures, and legume clippings.
How to use organic materials and manures?
Organic material or manure is normally applied uniformly across
the field, two or more weeks before being incorporated
into the soil during land preparation.
Sometimes rice straw is directly composted in the field.
Why use organic materials and manures?
Manures and other organic sources are used to improve soil
fertility and soil organic matter content and to provide micronutrients and other growth factors not normally supplied by inorganic fertilizers. Application of these materials may also enhance microbial growth and nutrient turnover in soil.
Applications of organic material can be difficult as it:
1. can be bulky, with high handling and transport costs.
2. may have high costs per unit of nutrient.
3. is not always available.
4. has to be applied at the beginning of the crop (thus early applications
may not meet later crop demand for nutrients).
5. can have an unpleasant odor, making it undesirable for farmers and others.
Combining organic manure and fertilizer
It is advisable to combine the use organic manures with the application of inorganic nutrient sources as needed.
This allows farmers to use organic materials or manure available on-farm at low cost to supply a portion of the crop’s demand for nutrients and improve soil fertility where required.
The use of organic manures available on-farm can return high yields and profit when combined with inorganic fertilizer, particularly on upland or poor lowland soils.
However, it is often not profitable to buy organic fertilizers even if they are sold as fortified organic fertilizers, which is a ready mix of organic and inorganic fertilizers.
