A. de Jager

Attaining Sustainable Farm Management Systems in Semi-Arid Areas in Kenya: Few Technical Options, Many Policy Challenges

Soils in arid and semi-arid lands (ASAL) are fragile, low in fertility and susceptible to erosion and leaching. To address these problems, activities were implemented in 1998–2003 to identify current problems, and design, test, implement, demonstrate and disseminate improved, integrated soil fertility management techniques. Current soil fertility management results in slightly negative nutrient balances, especially for phosphorus and potassium. Recycling of nutrients through crop residues and animal manure is inefficient, with evidently high losses. Due to the relatively high price of fertilisers and the high risks of crop failure, use of mineral fertilisers is restricted to market-oriented farms with access to irrigation facilities. Of the total farm household population, 35–85% lives below the poverty line. Applying higher rates of Farm Yard Manure (FYM) and/or fertilisers is unattractive and risky. Combinations of FYM and fertilisers give better financial returns than either of the two alone. Where irrigation is available, farmers adopt innovative farming systems that include higher application of mineral and organic fertilisers, and result in higher and more stable yields and higher financial returns. A set of specific policy measures for the semi-arid areas were identified to arrive at necessary changes in the economic environment, leading to a wider range of financially attractive technology options for smallholders.

Soil Quality and Agricultural Sustainability of Dryland Tropical Farming Systems: A Case Study in Mbeere District, Eastern Kenya

Abstract A study was carried out to investigate soil quality of dryland farming systems of Mbeere District, Eastern Kenya and its implications on agricultural sustainability. Soil sampling was done in years 2002 and 2004 from 30 study farms and same sampling sites and from paired adjacent land-use systems (bush fallow and cultivated fields). Physical, chemical and biological laboratory analyses were carried out. Factor analysis showed that the main soil quality indicators for evaluating sustainability of the dryland farming systems of the district were texture; organic matter, exchangeable bases (Ca, Mg, K, and Na); extractable nutrients (P and Zn); and acidity (pH). Cultivated soils were characterised by low pH, nutrient deficiencies (N, P, Cu, and Zn) and low organic matter and a decline in organic C, total N, exchangeable K and extractable P across time. They were also lower in exchangeable bases and microbial biomass C than adjacent bush fallow soils. We conclude that the soils are degraded and farming systems are partially unsustainable and may increasingly be so in the near future if declining soil quality is not addressed.