Within-Farm Variability in Soil Fertility Management in Smallholder Farms of Kirege Location, Central Highlands of Kenya

Abstract

Smallholder farms in Central Highlands of Kenya exhibit a high degree of heterogeneity, determined by a complex set of socio-economic and biophysical factors. The farms consist of multiple plots managed differently in terms of allocation of crops, nutrient inputs and labour resources, making within-farm soil fertility gradients caused by management strategies a common feature. In most cases, nutrient inputs are preferentially allocated to home fields, whilst outfields are neglected. A monitoring study involving nutrient inputs, flows and balances was conducted in Kirege location, where nine case study farms were used. The study was to compare the intensity of soil fertility management between home fields, mid-fields and outfields. It also compared soil fertility management practices between three different resources endowment classes to reveal important differences in patterns of fertility management. The farms were visited to record movement of nutrient-containing materials using a monitoring protocol covering household, crops, livestock, soil and socio-economic aspects of the farm. Data obtained was analyzed using IMPACT program version 2.0 to obtain total nutrient inputs and balances at field and farm levels and statistical analysis done using GenStat Discovery edition 2. Results revealed that mean N inputs over all resource endowment classes decreased with distance to the homestead (from 94 to 22.9 kg ha–1), as did P (from 54.6 to 15.6 kg ha–1) and K (from 193 to 34 kg ha–1). Due to this heterogeneity in smallholder farms, there is a need for a more targeted approach to soil fertility intervention that differentiates between farm fields, agro-ecological zone and resource endowment status. Keywords: Heterogeneity• Home fields• Nutrientinputs• Outfields• Soil fertility gradient