EVALUATION OF YIELD POTENTIAL AND MANAGEMENT PRACTICES AFFECTING SOYBEAN PRODUCTION IN WESTERN KENYA

Abstract

Soybean production in Western Kenya is low despite its yield potential. This is due to poor soil fertility, spacing and genotypes among others. Eleven soybean genotypes were evaluated for two seasons in three agro ecological zones in Western Kenya to evaluate the influence of inter-row spacing and genotype on growth and yield performance of soybean under optimum rates of P and K fertilizer application. Four best performing and most preferred genotypes were then assessed on the contribution of legume fertilizer blend and organic inputs. The two experiments were laid in a randomized complete block design (RCBD) and replicated three times. Grain yield and yield component data were subjected to ANOVA using SAS. Genotype x Environmental x management interaction means were separated using LSD (α =0.05). Inter-row spacing of 45cm was significantly different from inter-row spacing of 75 cm on growth and yield performance of soybean genotypes. Soybean genotypes also performed better in long rains than short rain. Nyabeda-in Siaya County out-yielded Ekitale in Bungoma County and Kambare in Kisumu County in that order. The highest mean grain yield was obtained from Sc Squire (3200 kg ha-1), while TGx 1987-62F recorded the highest mean biomass. Simple linear correlation coefficient for grain yield showed positive association with above ground biomass, Nodule mean score, and plant height, Number of pods per plant and 100-seed weight. Application of Sympal, manure, scum or combination, out-performed treatments with inoculation alone in biomass and grain yield. Combination of manure or scum with Sympal fertilizer gave higher overall yields. The best inter-row spacing across seasons and sites is 45cm. Sc Squire is the best genotype for grain yield across seasons, spacing and sites while TGx 1987-62F is the best genotype for biomass production and nitrogen fixation. Therefore achieving high yields would require combination of mineral fertilizer, with manure or scum, adaptable genotype and inter-row spacing of 45 cm