Nitrogen Mineralisation from Filtermud, Cattle Manure, Factory Ash and Nitrogen Uptake by Maize in a Glasshouse Experiment

In view of the world energy crisis and continuing rise in cost of mineral fertilisers and questions as to their future availability and safety to environment, there is renewed interest in organic matter recycling to improve soil fertility (Wccraratna, 1979; Warren, 1992). Filtermud (FM), a by-product of white sugar manufacture, is such an organic input. It is readily available from all sugar factories in Kenya with annual production for the 10 years (1982-1991) of 187,407 t (Anon., 1991). The decomposed filtcrmud (> 6 months) contains 1.44% nitrogen (Anyango 1984), 0.77% phosphorus and 0.36% potassium (Mutanda, 1978). This would give an estimated 2670, 1429 and 668 t annually of nitrogen, phosphorus and potassium respectively from FM which could be used to partially meet the need for inorganic fertilisers. Extensive and efficient utilisation of filtcrmud would save the country foreign exchange. Mutanda (1991) reported 50% saving if filtennud was used. Decomposed filtermud has a narrow carbon to nitrogen (C:N) ratio of 17.73 (Anyango, 1984) and would perhaps have positive effect on nitrogen release.