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close this bookBiogas Plants in Animal Husbandry (GTZ, 1989)
close this folder3. The agricultural setting
View the document3.1 Natural parameters for biogas plants of simple design
View the document3.2 Suitable types of biomass and their characteristics
View the document3.3 Agricultural/operational prerequisites and stock-farming requirements
View the document3.4 Fertilizing with digested slurry
View the document3.5 Integral agriculture

3.5 Integral agriculture

Integral agriculture, also referred to as biological or ecological farming, aims to achieve effective, low-cost production within a system of integrated cycles. Here, biogas technology can provide the link between animal husbandry and crop farming.


Fig. 3.8: Flow diagram for integral farming with a biogas plant (Source: GTZ 1985)


Fig. 3.9: Site plan of the Bouaké Ecofarm in Côte d'lvoire. 1 Impounding reservoir for rainwater, 2 Fallow land, 3 Manioc (1st year), 4 Yams and Manioc (2nd year), 5 Farmhouse, 6 Stables, 7 Biogas plant, 8 Sugar cane, 9 Water reservoir, 10 Fishpond, 11 Vegetable garden, 12 Various food plants (Source: GTZ 1985)

Consider, for example, the planning of a GTZ project in Cote d'Ivoire. The project included the development of a model farm intended to exploit as efficiently as possible the natural resources soil, water, solar energy and airborne nitrogen.

The integral agricultural system "Eco-ferme" (ecofarm) comprises the production elements gardening, crop farming (for food and animal fodder), stock farming (for meat and milk) and a fishpond. A central component of such closed-loop agricultural production is the biogas plant, which produces both household energy and digested slurry for use in the fishpond and as a fertilizer.

The average family-size "eco-ferme" has 3 ha of farmland with the following crops:

Fodder plants


Panicum (for the rainy season)

0.15 ha

Sugar cane (for the dry season)

0.50 ha

Leucaena and brachiaria (mixed culture)

0.50 ha

Panicum, brachiaria and centrosema (mixed culture)

0.50 ha

Food plants


Manioc

0.20 ha

Corn

0.40 ha

Yams

0.10 ha

Potatoes - beans

0.10 ha

Vegetables

0.20 ha

Rice and miscellaneous crops

0.17 ha

Four milk cows and three calves are kept year-round in stables. The cattle dung flows via collecting channels directly into a 13 m³ biogas plant. The biogas plant produces 3.5-4 m³ biogas daily for cooking and lighting. Part of the digested slurry is allowed to flow down the natural gradient into an 800 m² fishpond in order to promote the growth of algae, which serves as fish food. The remaining digested slurry is used as crop fertilizer.


Agitating rods