Abstract
Rhizobia inoculation can increase soybean yield, but its performance is influenced by among others soybean genotype, rhizobia strains, environment, and crop management. The objective of the study was to assess soybean response to rhizobia inoculation when grown in soils amended with urea or vermicompost to improve nitrogen levels. Two greenhouse experiments and one field trial at two sites were carried out. The first greenhouse experiment included soils from sixty locations, sampled from smallholder farms in Western Kenya. The second greenhouse experiment consisted of one soil selected among soils used in the first experiment where inoculation response was poor. The soil was amended with vermicompost or urea. In the two greenhouse experiments, Legumefix (inoculant) + Sympal (legume fertilizer blend) were used as a standard package. Results from the second greenhouse experiment were then validated in the field. Analysis of variance was done using SAS statistical software and mean separation was done using standard error of the difference for shoot biomass, grain yield nodulation, nodule effectiveness and nutrient uptake. In the first greenhouse trial, soybean response to inoculation was significantly affected by soil fertility based on nodule fresh weight and shoot biomass. Soils with low nitrogen had low to no response to inoculation. After amendment, nodule fresh weight, nodule effectiveness, nodule occupancy, and shoot dry biomass were greater in the treatment amended with vermicompost than those amended with urea (Legumefix + Sympal + vermicompost and Legumefix + Sympal + urea) respectively. Under field conditions, trends were similar to the second experiment for nodulation, nodule occupancy and nitrogen uptake resulting in significantly greater grain yields (475, 709, 856, 880, 966 kg ha−1) after application of vermicompost at 0, 37, 74, 111, and 148 kg N ha−1 respectively. It was concluded that soybean nodulation and biological nitrogen fixation in low fertility soils would not be suppressed by organic amendments like vermicompost up to 148 kg N ha−1.
Highlights
The soils organic Carbon was determined by chromic acid digestion and spectrophotometric analysis (Heanes, 1984), total N (%) determined from a wet acid digest (Buondonno et al, 1995) and N analyzed by colorimetric analysis (Anderson and Ingram, 1993), soil texture was determined using the hydrometer method, soil pH in water determined in a 1:2.5 (w/v) soil:water suspension, available P using the Mehlich-3 procedure (Mehlich, 1984) and the resulting extracts analyzed using the molybdate blue procedure described by Murphy and Riley (1962), exchangeable cations (Ca, Mg, and K) extracted using the Mehlich-3 procedure and determined by atomic absorption spectrophotometry
A wide variation in soil properties was noted with coefficients of variance (CV) ranging from 11 to 208% with most of the parameters falling under what is considered low
Soybean response to inoculation was affected by the soil properties
Summary
In sub-Saharan Africa (SSA), where over 80% of the soil are nitrogen deficient (Liu et al, 2010), and over 39% of the children under 5 years are malnourined and stunted. This has been related to deficiency of essential nutrients in most of diets, proteins (Müller and Krawinkel, 2005), which has contributed to over one third of child deaths (Bain et al, 2013). Integration of soybean in the smallholder farming systems would improve human nutrition when the crop is included in the diet practices and soil productivity. Materialize when good agronomic practices, including integrated soil fertility management, are implemented in soybean production systems
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
