The practice of spreading liquid digested slurry also presents problems in that not only storage
tanks are needed, but transport vessels as well, and the amount of work involved depends in part
on how far the digested slurry has to be transported. For example, transporting 1 ton of dung a
distance of 500 m in an oxcart takes about 5 hours (200 kg per trip). Distributing the dung over the
fields requires another 3 hours or so.
If, for reasons of economy and efficiency, liquid fertilizing should appear impractical' the digested
slurry can be mixed with green material and composted. This would involve nitrogen losses
amounting to 30 - 70%. On the other hand, the finished compost would be soil-moist, compact
(spade able) and much easier to transport.
If irrigated fields are located nearby, the digested slurry could be introduced into the irrigating
system so that it is distributed periodically along with the irrigating water.
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)
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