Characterizing farming systems around Kakamega Forest, Western Kenya, for targeting soil fertility–enhancing technologies

Abstract

Kakamega district in Western Kenya represents the smallholder farming systems typical for much of the densely populated humid highlands in East Africa. A specific feature, however, is the presence of a protected forest reserve (Kakamega Forest National Park), covering some 20% of the district area. Year-round crop production with little use of external inputs is resulting in declining soil fertility and crop yields. Technologies to counteract fertility constraints are rarely implemented, as they do not consider system diversity or farm-specific characteristics. We surmised that farm type-specific targeting of technology options to address soil fertility-related production constraints would reduce the anthropogenic pressure on the resources of the adjacent Kakamega rainforest reserve. Based on Kenyan national census data, we selected 168 farms in physical proximity of the Kakamega forest and characterized them regarding production system and soil attributes. Cluster and principal component analyses identified five distinct farm categories. Three representative farms from each cluster group were subsequently selected to establish labor-use patterns, draw resource-flow maps, and determine NPK balances. Small subsistence-oriented farms were most common (> 50%), with maize yields of 0.9 t ha -1 (Cluster 1). Most farmers relied on the forest to provide fire wood, animal feed, and medicinal plants. Mixed farms, combining subsistence maize with industrial crops, were differentiated by soil type, with tea being grown on Ferralsol (Cluster 3), and sugar cane being grown on Acrisol (cluster 4). The dependence on forest resources was limited to animal grazing and the collection of feed stuff (Cluster 3), or the extraction of medicinal plants (Cluster 4). Only few farms showed a high degree of market orientation of the food-crop production. These comprised either small farms with high investments in fertilizer and maize yields close to 2 t ha -1 (Cluster 2), or larger farms (1.6-3.9 ha) with low fertilizer but high hired-labor use (Cluster 5). Their reliance on forest resources was generally low. Resource flows showed mainly patterns of nutrient export in subsistence farms, and more complex flow patterns, involving several farm compartments, in the diversified farms. Partial nutrient balances were strongly negative for N and K, irrespective of soil or farm type. Soil-fertility characteristics reflected the nutrient balances with generally low C and N in all farms on Acrisol, and low P in farms not applying mineral fertilizers or farmyard manure. The proposed typology is expected to improve the targeting of technologies addressing soil fertility-related production constraints, and to reduce the pressure on forest resources. This is of particular importance in the case of small-scale subsistence and mixed farms close to the forest margin.

Do livelihood typologies influence local perceptions of forest cover change? Evidence from a tropical forested and non-forested rural landscape in western Uganda

“…In comparison to much published literature (e.g. Bidogeza et al 2009;Costard et al 2009;Diwani et al 2013;Chilongo 2014), this constitutes a large amount of data, for which variable dimensional reduction is desirable prior to further analysis, but for which the total size of the data matrix provides confidence in the analytical outcomes. Dimension reduction was achieved using Principal Components Analysis (PCA) (using SPSS version 22) (see details in Supplment3).…”

Live fences – a hidden resource of soil fertility in West Kenya

“…Annual rainfall varies between 1000 mm in the South, following a bimodal distribution pattern and 2100 mm in the North, following a monomodal distribution pattern. The main soil types are classified as orthic Acrisol in the South and as ferralo‐chromic Ferralsol in the northern part of the District ( Diwani et al, 2013).…”

“…The resulting soil fertility decline has led to a decrease in maize yields ( Ngome et al, 2011) and aggravated food insecurity, rural poverty and low livelihood levels ( Rietdorf , 2008; Rufino et al, 2009). This holds true for both the sub‐humid bimodal rainfall zone with sandy Acrisols in the North, and the humid monomodal rainfall zone with clay Ferralsols in the South of the district ( Diwani et al, 2013).…”

“…The introduction of N 2 ‐fixing perennial legumes could further improve the quality of fences and contribute to both soil fertility enhancement in field cropland and the provision of animal feed. However, the livestock densities in most farms of Kakamega are extremely low ( Diwani et al, 2013), and the low concentration of plant available soil P may limit possible benefits arising from biological N fixation ( Vance , 2001). In any case, the introduction of alternative fencing species and the partial substitution of currently prevailing low‐value by economic or multiple use species benefitting from improved soil fertility within the fence must take into account: (1) the provision of rapid benefits needed in smallholder and largely subsistence‐oriented systems ( Kiptot et al, 2007); (2) the maintenance of current fencing functions (boundary demarcation, prevention of trespassing); (3) the minimization of resource competition between fences and adjacent field crops; and (4) the social acceptability of commonly used fencing resources by neighbouring farmers (conflicts, use strategies).…”

Influence of biophysical aspects on the performance of sustainable land management measures in the Usambara highlands of Tanzania

“…In Sub-Saharan Africa, one region that is particularly known for land degradation problems is the humid highlands of East Africa (Diwani et al, 2013). These Highlands are defined as areas above 1,200 meters above sea level.…”