Abstract
Background: Rice yields increased in the first decade of this century with 25% for boro, 50% for aus and aman rice. The yields increase in the eight years of the second decade with 15% for boro, 20% for aus and 10% for aman rice. In 1999 around half of the Bengali soils were deficient in soil organic matter, phosphor, potassium and sulphur. The further mining for plant nutrients of the Bengali soils will ultimately result in lower rice yields.
Respirable airborne particle concentrations in kitchens are five to ten times higher than the recommended safe concentrations due to the traditional stoves and solid fuels used for cooking in nearly all rural households.
Method: A literature study was made and two experimental biogas plants were build and tested.
Results: Biomass from straw, weeds, leaves and twigs should not be used as fuel for cooking, but converted into biogas. The effluent of the biogas plant (Bio-slurry) should be used as organic fertiliser together with chemical fertiliser. A design of a biogas plant is proposed with a high biogas yield and low emissions of greenhouse gases.
Conclusion: Bio-slurry returns macro and micro nutrients to the soil. Cooking on biogas will reduce the number of fatalities due to respirable airborne particles.
Keywords: Fuels for cooking, biogas, soil fertility, Bangladesh, airborne particles, greenhouse gases.
Graphical Abstract
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