Indigenous Farmers' Knowledge in Soil Fertility Indicators and Its Scientific Verification In Embu District, Kenya

Abstract

Smallholder farmers possess indigenous knowledge that could be an invaluable source of information in assessing, monitoring and evaluating changes that occur in soil quality. This study aimed at comparing the scientific soil quality indicators with the local farmers’ knowledge-based indicators. A total of 134 small-scale farmers from five major agro-ecological zones of a 30 km transect were interviewed in Embu District, Kenya. Major fertility indicators from farmers perspective included presence of some weeds, soil colour and soil structure. The most pronounced and elaborate local indicator seemed to be the dominance of certain weeds. These included Commelina benghalensis, Bidens pilosa, Galinsoga parviflora, Commelina diffusa and Amaranthus spp as indicators of high fertility. On the other hand Rhynchelytrum repens, Richardia scabra, Alternanthera philoxeroides and Pteridium equilinum were the most prevalent low soil fertility indicator weed species. Soil samples were collected from ‘fertile’ and ‘infertile’ sections of the farms and analyzed for soil pH, exchangeable bases (Ca and Mg), total K, extractable P, organic carbon, and total N. The pH of soils collected from ‘infertile’ and ‘fertile’ sections were 4.8 and 5.4, respectively, in the cooler, wetter agro-ecological zones while that of the lower, warmer zones was 6.0 and 6.9 for ‘fertile’ and ‘infertile’ sections, respectively. Results indicated that soil pH and exchangeable bases were the most sensitive parameters that corroborated farmers’ perceptions and knowledge of soil fertility indicators across the study area. The concentration of exchangeable bases in the ‘fertile’ fields was 5-9 times higher than that of the infertile fields. The information obtained in this study can be used to develop a simple low-cost tool for use by both farmers and researchers where laboratory soil analysis is not accessible or is not economically feasible.