What are agriculture residues?

Agriculture residues directly burnt as fuel in developing world include crop residues, forest litter, and also grass and animal garbage. Crop residues are more widely burnt than animal waste and forest litter.
Image
Eucalyptus Litter

Crop residues encompasses all agricultural wastes such as straw, stem, stalk, leaves, husk, shell, peel, lint, stones, pulp, stubble, etc. which come from cereals (rice, wheat, maize or corn, sorghum, barley, millet), cotton, groundnut, jute, legumes (tomato, bean, soy) coffee, cacao, olive, tea, fruits (banana, mango, coco, cashew) and palm oil.
CropsCrop wastesResidues production
RiceStraw, husk, bran1.5t of straw and 0.2t of husk from 1t of rice
WheatStraw, husk, bran2t of residues from 1t of wheat seed
MaizeStalk, leaves6t of waste from 1t of maize (leaves + stalks 4t)
SorghumStraw, bran2.5t of residues from 1t of sorghum seed
BarleyStraw, bran1.5t of straw from 1t of barley
MilletStraw, bran2t of residue from 1t of millet produced
CottonStalk, lint, hull0.2t of waste from 1t of cotton seed
GroundnutShell, stalk, leaves25% of shell weight from non husked
JuteStemna
TomatoStemna
CoffeePulp, husk3.6t of waste from 1t of green coffee
Olive
na
Banana
na
CocoHull, fibre0.9t of waste from 1t of coconut
Palm oilShell, fibre, fruit bunches75% waste from weight of fruit bunch
MangoPeel


Sources: (1) Memento de l’agronome : quatrième edition 1640 pages (2) J lamptey and al – 1990- bioenergy – IDRC/UNU - 210 page (3) CowiConsult – 1984 – Etude d’une utilisation efficace des déchets agricoles comme fuel domestiques au Sénégal 250 pages

Forest litter is mainly constituted of dry fallen leaves. Plantations of those species widely used for reforestation or soil conservation/sand fixation such as Eucalyptus and Casuarina equisetifolia, provide an important biomass litter yearly.

Image
Eucalyptus Litter
. Animal garbage is livestock manure. Generally dry animal wastes directly used as fuel are cow and camel dung, and sometimes that of horse and sheep. The quantity of manure produced depends on the amount of fodder eaten, the quality of fodder and the liveweight of the animal. The excrement-yield values vary among the species.

SPECIESDaily manure yield as % of liveweightAnimal liveweight (Kg)Animal liveweight (Kg)Dung yield (Kg/day)Dung yield (Kg/day)
Cattle 51358006.840.0
Buffalo534042017.021.0
Pigs230750.61.5
Sheep/goats3301000.93.0
Chickens4.51.530.10.1

Source: (1) Memento de l’agronome : quatrième edition (2) GTZ – 1989 – biogas plants in animal husbandry – 134 pages
Image
Filao Litter

Agricultural residues characteristics

In the developing world, most agricultural residues burnt as fuel are used in their natural state with some pre-treatment like drying, and cutting, and compacting in rare occasions. Crop residues are characterized by its seasonal availability and have characteristics that differ from other solid fuels such as wood, charcoal, char briquette. The main differences are the high content of volatile matter and lower density and burning time.

Agricultural residues Volatiles (%)Fixed carbon (%)Ash (%)HHV (Kj/kg)LHV (Kj/kg)Density (%)
Arhar stalk83.4714.761.7715.0014.85
Bagasse75.1016.878.0319.5019.3740 - 60
Bamboo dust75.3215.599.0916.0215.87
Cotton stalk70.8922.436.6818.2617.8510 - 20
Coconut coir70.3026.772.9318.2017.797 - 8
Corn cob80.2016.203.6015.5815.2310 - 20
Dhaincha stalk80.3217.012.6719.6319.43
Groundnut shell68.1224.976.9117.2017.06
Jute stick75.3319.005.6719.4519.01
Mustard shell70.0914.4815.4317.6117.47
Pine needle72.3826.121.5020.1219.97
Rice husk60.6419.9019.4813.3813.249
Sal seed leaves60.0320.2219.7518.5718.42
Sal seed husk62.5428.069.4020.6020.13
Coffee husk
16.00
10



Concerning animal waste, the calorific values of cow dung and chicken droppings are respectively 16 – 19 Mj/kg and 14 - 16 Mj/kg. Cow dung calorific value is more important than the one of wood.
Image
Filao Litter
The large potentials of agro-industrial residues like bagasse, groundnut shell, palm oil residues are mainly used to meet the energy need of the factories.

Who uses them?

The rural families in the villages who own agricultural land use their own agricultural residues which varies throughout the year as per the crop planted. They use it as a household fuel for cooking, heating water and for space heating in colder climates.

Agricultural wastes are directly burnt to meet the need of cooking. Crop residues are yet used to light wood and charcoal.

West African potters burn a large amount of agricultural residues in their traditional pottery pit in order to produce their canaris, earthenware jars, ceramic stoves and other pottery.

In the part of the world faced by the scarcity of woodfuel and the cost-effective fuel substitutes, agricultural waste (owing to its high potentiality) may play a major role on sustainable energy. However the traditional use of crop residues and the lack of information on modern technologies such as briquetting, pelleting, and bioconversion, limit the development of large scale use which leads to increase the value of agricultural output.

Agriculture as a biomass supplier is yet affected by soil quality. Agricultural wastes can be used as either fuel or fertilizer. So the bio digestion of agricultural residues leads to provide both energy (biogas) and upgraded fertilizer than raw waste.

Agricultural residues potentiality in developing world

Agricultural wastes potentiality can be estimated by the following formulae:
Image
Formula to estimate agricultural wastes

Where:
Image means the potentiality of crop residues where “a” represents the crop production; “b” designs the crop residue yield production, and “i” the type of crop. when the calorific value of each type of crop is used the potentiality can be calculated in TOE (ton crude oil equivalent).

Image means the potentiality manure production where “alpha” represents the number of animal head; “b” designs the garbage yield production, and “i” the animal species.

Image means the potentiality of crop residues where “S” represents the area of plantation; “R” designs the residue yield production per unit of surface, and “i” the type of crop.

The statistical data about agricultures production are available for any country in the FAO website.



Example: the Senegal crop residues production
Crop productions
CROP'CROP PRODUCTION ( tonnes ) 1999''CROP PRODUCTION ( tonnes ) 2000''CROP PRODUCTION ( tonnes ) 2001''CROP PRODUCTION ( tonnes ) 2002''CROP PRODUCTION ( tonnes ) 2003''CROP PRODUCTION ( tonnes ) annual production'
Groundnut1 014 250 1 061 540 943 837 501 298 900 000 884 185
Sugarcane 889000 850000 890000 890000 890000 881 800
Oil palm 64000 65000 65000 65000 70000 65 800
Cotton 14 649 20 411 34 237 33 913 34 000 27 442
Millet 675000 600221 470105 414687 450000 522 003
Maize 66132 78593 106444 97858 103000 90 405
Sorgho 147444 143750 140297 143892 154000 145 877
Rice 239 786 202 293 243 907 177 756 177 756 208 300
Coco 4 700 4 700 4 700 4 700 4 700 4 700



Crop residues productions
Crop Residues Calorific value (KJ/Kg) Annual crop production (tonnes) Waste yield (%) Annual residues production (tonnes) Energy (TOE)
GroundnutShell 17 884185 25.0% 221 046 89.5
Sugarcane Bagasse 19.37 881800 30.0% 264 540 122.0
Oil palm Wastes 16 65800 72.5% 47 705 18.2
Cotton Stem 18.3 27442 20.0% 5 488 2.4
Millet Wastes 18 522002.6 200.0% 1 044 005 447.4
Maize Wastes 18 90405.4 600.0% 542 432 232.5
Sorghum Wastes 18 145876.6 250.0% 364 692 156.3
Rice Wastes 12 208299.6 170.0% 354 109 101.2
Coco Wastes 17.9 4700 87.0% 4 089 1.7
TOTAL
2830511.2 2 848 107 1171.2


In Senegal the total of annual crop wastes equals 2 848 107 tonnes or 1171.2 TOE, which represents the amount of imported oil consumed. However the quantity available and exploited is low, under 40%. Bagasse and groundnut shell are widely burnt by industries to meet their energy need in the factories.

Advantages

  • Agricultural residue is a fuel which is available free of cost to the poor rural families.
  • It is also a useful way to dispose of the crop residues in the field, instead of burning them in situ.
  • Agricultural wastes remain safer than LPG which poses some safety concerns in local transport and use;
  • It is easy to handle and transport;
  • Low impact on women’s time for harvesting
  • Agricultural wastes are much easier to light than wood and charcoal.

Disadvantages

  • It is responsible for extreme cases of air pollution when it is burned in open fires? or traditional or Improved stoves?.
  • It is very bulky and has to be carried to the homes.
  • The seasonal availability of crop residues can be limit for its use.
  • Its burning time is worse.
  • Its storage requires more space in house.

Devices


Although the world rice production is important, particularly in developing countries, where it is cropped by family exploitation, its residue is widely used as fuel for cooking. In countries where rice production is important, such as Thailand and the Philippines, improved cooking stoves are made.

Improved cooking stoves used in Thailand : the Meechai, improved rice-husk stove without chimney.
Image
The Meechai

Image
The Meechai

Image
The Meechai


The mayon turbo stove disseminated by REAP Canada
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Mayon turbo stove (Photo: REAP Canada)
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Mayon turbo stove (Diagram: REAP Canada)

Contributors

Grant Ballard-Tremeer 1 September 2003
Dr Karabi Dutta 11 September 2003
Mamadou Fall 12 July 2007





Last edited by Miriam Hansen , based on work by Grant Ballard-Tremeer .
Page last modified on Tuesday 28 of September, 2010 14:21:50 GMT. @HEDON: CACB

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