Abstract:
Standard soil survey was carried out in Western Kenya to establish representative research sites on
the basis of landforms and other physiographic attributes. Soil profiles were characterized at
Emalomba (Nambale District) designated (EMA-P1) and at Bukhalalire (Butula District) named
BUMA-P1. Both pedons formed from in-situ weathering of granitic rocks under ustic moisture and
iso-hyperthermic temperature regimes. Fourteen soil samples from genetic horizons were analyzed
for physico-chemical properties. Both pedons had dark brown sandy clay and sandy clay loam
topsoils overlying dominantly clayey subsoils. Both pedons indicate clay eluviation-illuviation as a dominant pedogenic process with strong acidic soil conditions and available phosphorus of < 7
mg/kg soil. Organic carbon (OC) is high in EMA-P1 and medium to very low in BUMA-P1 while total
nitrogen is medium and low to very low. EMA-P1 and BUMA-P1 have C/N ratios of 8.6 - 9.6 and
12.9 - 24.8 respectively. Both pedons have low to very low exchangeable bases with cation
exchange capacity (CEC) < 16 cmol(+)/kg soil. CEC clay values in both pedons are < 24 cmol(+)/kg
with BUMA-P1 having < 10 cmol(+)/kg. Both soils are highly weathered with BUMA-P1 depicting
more advanced stage of weathering. In the USDA Soil Taxonomy, EMA-P1 was classified as
Kanhaplic Haplustults and BUMA-P1 as Typic Kandiustults, both corresponding to Haplic Cutanic
Acrisols in WRB. As regards soil fertility trends, OC showed positive correlation with calcium and
magnesium indicating organic matter as the main source of plant nutrients. The two pedons differed
noticeably in terms of physico-chemical characteristics emphasizing the need to characterize soils
before fertilizer recommendations are made. Organic fertilizers are recommended to increase
organic matter content and intercropping of cereals with nitrogen fixing legumes to enhance
nitrogen in the soils. Use of non-acidifying inorganic fertilizers and lime as soil amendments should
also be considered to correct acidity.
