Monitoring nutrient flows and economic performance in African farming systems (NUTMON) - IV. Linking nutrient balances and economic performance in three districts in Kenya

At the national level, agricultural production in Kenya is characterized by a negative nutrient balance and a downward trend in food production per capita and can therefore be classified as unsustainable. However, little information is available concerning ecological and economic sustainability of the various production systems at farm level. A one year monthly monitoring activity was conducted in the season 1995/1996 in three districts with the participation of 26 farm households covering the major existing fanning systems in these districts, in which data were collected on agronomic and economic aspects of the farm management. The average N-balance at farm level is -71 kg ha(-1) yr(-1) with large variations among farms ranging from -240 kg ha(-1) yr(-1) to +135 kg ha(-1) yr(-1); the average K- balance is slightly negative, the P-balance slightly positive. Net farm income shows no relation with the nutrient balance. A high market orientation on the other hand correlates with a more negative N- and K-balance. The market-oriented farms located in the highly populated areas are characterized by intensive crop and livestock activities, import nutrients through fertilizers and/or animal feeds, but insufficient to compensate the outflow through marketed products, leaching and erosion. The average annual net farm income amounts to US$ 1490 per farm, with large variations among farms. Average returns to family labour (US$ 2.2 per day(1)) and returns to land (US$ 91 per ha(-1)) are comparable or higher than unskilled wage rates and annual land rent respectively, but 50% of the farms perform below these rates. Market oriented farms have an economic performance that is similar to subsistence oriented farms. Off-farm income, however, is essential for large groups of small-scale farm households to achieve economic viability: without additional off-farm income, 54% of the farms in the sample are estimated to be below the poverty line. The replacement costs of mined nutrients amounts to 32% of the average net farm income. At crop level the cash crops tea and coffee realise higher gross margins and considerably lower nutrient mining levels than the major food crops maize and maize-beans. It is concluded that a multi-disciplinary monitoring activity at farm level, contributes to targeting and prioritization of development options aimed at optimization of soil nutrient management. (C) 1998 Elsevier Science B.V. All rights reserved.