POWON M.P., AGUYOH J.N., MWAJA V.
Abstract
Arable land in Kenya is decreasing as a result of population pressure, therefore there is need to increase production
per unit area. Potato (Solanum tuberosum L.) being a heavy feeder of plant nutrients in the soil requires high supply
of external mineral nutrients in the form of inorganic fertilisers or organic manure. Decline in soil fertility
and high cost of inorganic fertilisers are limitations to potato yield improvement in Kenya. Potato (Variety 'Asante')
was planted for 2 seasons at National Agricultural Research Center - Kitale and one season at Psigirio village
(West Pokot District) during 2002 and 2003. The experimental design was Randomized Complete Block (RCB) laid in a
Split-plot arrangement with three replications. The potassium levels (0, 83 and 166 K kg ha-1) formed the main plots,
while phosphorus (0, 52 and 100 P kg ha-1) and farmyard manure (0, 10 and 20MT FYM ha-1) combinations formed the sub
plots. Cost-Benefit-Ratios (CBR) was computed to assess the profitability of treatments. The highest CBR was realized
in the application of 100 P kg ha-1 at NARC - Kitale season 1, 50 Kg P ha-1 + 20 t FYM ha-1 at NARC - Kitale season 2
and the application of 83 kg K ha-1 + 50 kg P ha-1 at the Psigirio site. Results indicated that the combined use of
inorganic fertiliser and manure is feasible option for soil fertility improvement for potato production. The main
objective of the study was to assess the potential for producing high potato yields through use of farmyard manure
with reduced quantities of phosphorus and potassium fertilizers..
Key words:
potato Solanum tuberosum, farmyard manure, inorganic fertilizers, benefit cost ratio