Nutrient management

 

 

 

 

 

Organic materials and manures as fertilizer

 

 

 

 

 

 

Describe the advantages and disadvantages of using organic materials and manures as fertilizer

 

 

 

 

 

What are organic materials and manures?

 

Organic material and manures are materials that come from plant or animal waste or by-products, for example:

  • cattle or poultry manure

  • compost

  • rice straw or other crop residues

  • sewage sludge

  • oil cakes

  • green manures (plant material incorporated into the soil while green)

 

 

 

 

 

 

 

 

 

Why should you use organic materials and manures?

 

Manure and other organic materials are used to improve soil fertility and soil organic matter content. These organic materials also provide micronutrients and other growth factors not normally supplied by inorganic fertilizers!

Applying organic materials and manures may also enhance microbial growth and nutrient turnover in soil.

 

Gathering rice straw in Bangladesh

 

 

 

 

 

N is the symbol for Nitrogen

 

How to use organic materials and manures?

 

Organic materials or manure are evenly spread on the field. This happens usually 2 or more weeks before the material gets incorporated into the soil during land preparation. Sometimes rice straw is directly composted in the field.

 

Spread the material evenly in the field and apply before land preparation

 

 

How much organic material or manure do you have to apply?

To get 100 kg of nitrogen(N) per hectare, you need:

217 kg of Urea (46% of N)

 

or

5 000 kg of Poultry manure (2% of N)

 

 

or

10 000 kg of Cattle manure (1% of N)

 

 

or

20 000 kg of Rice straw (0.5% of N)

 

Note the big amount of manure or crop residues needed to get sufficient N into the soil! From 5 tons up to 20 tons.

 

 

 

 

What are possible  problems with organic material?

 

 

 

 

A combination of manure and fertilizer gives most profits

 

Combine organic and inorganic fertilizer to increase yield!

 

Usually the recommended fertilization method is to combine organic manures with inorganic nutrient sources as needed.

 

Farmers should use on-farm, low-cost organic materials or manure to supply at least a portion of the crop’s required nutrients and improve soil fertility. Inorganic fertilizer should be added to reach the amount of nutrients necessary for the yield target.

 

Combining on-farm organic manures with inorganic fertilizer, particularly on upland or poor lowland soils,will help increase yields and profit!

 

 

 

 

 

NOTE: organic fertilizers can be expensive to buy (even if they are sold as fortified organic fertilizers, which is a ready mix of organic and inorganic fertilizers).

 

 

 

 

 

More information

 

Click on the icon to open a fact sheet about organic materials and manure.

Next lesson

 

In the next lesson we will discuss how you to manage nutrients in general.