Plant nutrient contents of cattle manures from small-scale farms and experimental stations in the Ethiopian highlands

In most small-scale farms in sub-Saharan Africa, net negative balances of n utrients result when nutrients are removed from the farm by harvested crops , because farmers cannot afford inorganic fertilizers. A key resource that could be useful in reversing this trend is manure from livestock. The N, P, K, Ca, Mg, Fe, Mn, Cu and Zn contents of manures collected from six experi mental stations and twenty small-scale farms in the Ethiopian highlands wer e analysed. The manures contained, on average, 21.3 g K, 18.3 g N, 16.3 g C a, 5.6 g Mg, 4.5 g P, 10776 mg Fe, 777 mg Mn, 92 mg Zn and 24 mg Cu per kg. Manures from experimental stations contained significantly more N, P, K, M g, Cu acid Zn than the manures from smallholder farms, probably due to diff erences in feed availability and quality. Fresh manures and stored (dry) ma nures were not significantly different in nutrient concentrations although stored manures had slightly higher nutrient concentrations, probably as a c oncentration effect after loss of carbon. Manu;es collected from farms in D eneba area had significantly greater contents of P, K, Mg, and Cu than manu res collected in Ginchi area, but, due to scarcity of fuel wood, farmers in Deneba use manures for fuel for domestic cooking and heating instead of ap plying it to the soil. Afforestation programmes, or other programmes that w ould ease the energy problem for domestic use, may be necessary if manures are to be applied to soils. Whether the amount of manure in the livestock-d ense Ethiopian highlands is sufficient to support crop production is unknow n. Research in other parts of Africa indicates that, although adequate manu re may be applied to some fields, insufficient manure is available to suppo rt crop production at a wider scale. (C) 2000 Elsevier Science B.V. All rig hts reserved.