Evaluating the Effects of Cobalt/Molybdenum, Rhizobium Inoculants and Diammonium Phosphate Fertilizer on the Growth and Yield of Soya Beans in Kisii County

Abstract

Soya bean is an important crop grown globally. It is the main source of dietary protein and oil and is used commercially to produce livestock feed and food for humans as well. Soy farming is mostly practised in the western and central regions of Kenya but the yield is low compared to other countries. Production is low in Kisii yet the potential for optimum yield is documented. Poor soya bean yield is thought to be caused by infertile soils due to poor agronomic and management practices, acidified soil, deficient nutrients in the soil and use of unimproved seed varieties. The study evaluated the effects of cobalt/molybdenum, rhizobium inoculants and diammonium phosphate fertilizer on the growth and yield of soya beans in Kisii County. A randomised complete block design experiment replicated in four blocks was done at Kisii Agricultural Training Centre.Treatments used for seed dressing per kg/seed included: Rhizoliq Top Soya 3mls, Wuxal Extra CoMo15 at 1ml, Wuxal Extra CoMo 15 at 1.5 mls, (Wuxal Extra CoMo 15 at 1.5 mls / Rhilizic top 3mls) and (Waxul Extra15 CoMo1m/Rhizoliq top 3ml, Control (Without Treatments), DAP 125kg/ha-1, of soya seed. Analysis of variance was conducted using SPSS version 22 and any significant means were further analysed using DMRT all at 95% confidence level. Soil analysis revealed moderately acidic soil (pH 5.5) low nitrogen (0.12%), moderate Phosphorus (20ppm) and low potassium levels (40%). Cobalt was 54.6 and Mo 6.44 Mg/lg. On germination CoMo1ml+Rhizob yielded the highest percentage, followed by CoMo1.5ml, with a significant statistical difference between treatments (< 0.05). CoMo1ml+ Rhizobium had the highest flowering percentage. Above ground biomass was highest with the use of CoMo1.5ml/ Rhizobium. CoMo1ml/ Rhizobium treatment showed highest pod weight per plant and had a statistically significant difference (<0.05). On the six plants seed weight per plant, Rhizobium treatment exhibited highest weight whereas the least was CoMo1ml. CoMo1.5ml/Rhizob was shown to have the highest 100 seeds weight, with statistically significant difference among the treatments (<0.001). The highest yielding inoculant was CoMo1ml/Rhizob followed closely by Rhizob. ANOVA showed a strong significant difference among the treatment’s yield per ha (<0.006). Plant height was highest with CoMo1ml, ANOVA exhibited a significant difference among treatments (<0.001). CoMo1ml/Rhizob exhibited the heaviest weight of seeds with the least weight from the control and CoMo1ml respectively. Where the inoculants were combined at different graded levels, favourable effects on all growth and yield parameters were exhibited. CoMo 1ml+Rhizob exhibited most positive effects. The study concluded that low yield in Kisii and other soya bean growing zones in Kenya can be enhanced by use of combined selected inoculants.