Abstract:
Soil fertility depletion in smallholder farms is the fundamental biophysical root cause for
declining per capita food production in Sub-Saharan Africa. Climate change exacerbates the
problem of poor soil health. The combined use of mineral and organic fertilizers in ways that
are adaptable to local conditions has the potential to achieve efficient nutrient use and result
in improved yields for staple food crops. Despite multiple efforts made by the government of
Kenya and international partners, soil health continues to deteriorate in the central
highlands. This study was conducted in Sportee village of Laikipia East sub-County, Kenya,
to investigate the effects of croton compost on selected physicochemical properties of soil,
principally soil moisture retention capacity and the yield and yield components of French
beans (Phaseolus vulgaris L) crop during the short rains season of 2021. Six treatments
including, Control; Eco Planting Mix 2t/ha; Eco Top Dress 2t/ha; Eco Planting Mix 2t/ha +
Eco Top Dress 2t/ha; Eco Planting Mix 2t/ha + Calcium Ammonium Nitrate 75Kg/ha and
Di-ammonium Phosphate 100Kg/ha + ETD 2t/ha, were laid out in randomised complete
block design in three replications. The study found that croton compost had a significant
improvement (P ≤ 0.05) on pH, total N, organic carbon, available P, Mg, Mn and Fe in
various treatments. It also showed that croton compost relatively increased moisture
retention capacity of soil in the ETD 2t/ha and DAP 100Kg/ha + ETD 2t/ha treatments at
17.02% and 17.21% respectively. Highest leaf area index was observed in EPM 2t/ha + CAN
75Kg/ha treatment (31.66 mm2) while control recorded the lowest (24.44 mm2) at (P ≤ 0.05).
The treatments EPM 2t/ha, ETD 2t/ha and DAP 100Kg/ha + ETD 2t/ha had significant
increase in yield of 46, 26 and 17% respectively (22.75 t/ha, 19.74 t/ha and 18.26 t/ha)
against control (15.63 t/ha) at (P ≤ 0.05). The study concludes that compost addition likely
improved French beans root growth and thus indirectly improved nutrient uptake by the
plants with consequent marginal increases in leaf area development and crop yield. Further
study is recommended over longer periods of time to exhaustively determine the long term
effects croton compost would have on some physiochemical properties such as hydraulic
conductivity, organic carbon and micronutrients. It would also aid in recommending the best
treatment combination with the highest marginal rate of return over time since in this study
all the treatments had a positive cost benefit ratio thus all were profitable
