Response of canning navy bean to application of fertilizers and pesticides

Abstract

Low soil fertility, insect pests and diseases are the major constraints to improvement of canning navy bean productivity in Kenya. A study was conducted at the University of Nairobi's Kabete Field Station during 2010 short and long rains to determine the effect of fertilizers and pesticides on growth, yield and quality of canning navy beans. The fertilizer treatments were full dose farmyard manure (8 tonnes/ha), half dose farmyard manure (4 t/ha) + half dose NPK (100 kg/ha), Full dose NPK (200 kg/ha), Rhizobium inoculation, control (no fertilizer) while the pesticide treatments were fungicide spray (Ortiva), insecticide spray (Actara), fungicide spray (Ortiva) plus pesticide spray (Actara) and Control (No spray). The experimental design was a randomized complete block design laid out in a split plot arrangement with three replications. The variety used was Mexican 142. Results demonstrated that pesticide sprayed and fertilizer supplied plots had significantly(p:50.05) higher plant count than non-treated control plots Organic fertilizers significantly (ps 0.05) increased the number of nodules but pesticide application had no effect. Pesticide application significantly ((P:50.05) improved grain yield and quality only in fertilizer supplied plots, while fertilizer treatments had no yield-effect in unsprayed crops. Partial cost analysis demonstrated that application of half dose farmyard manure (4 t/ha) plus half dose NPK (100 Kg/ha) in combination with insecticide or insecticide+fungicide sprays was the most cost-effective treatment regime. Pesticide sprays, Rhizobium inoculation and combined moderate doses of organic and inorganic fertilizers have the potential to improve navy bean productivity.