Integrated Effects of Rhizobium Inoculation and Phosphorus Application on Tissue Content, Rhizobium and Phosphorus Use Efficiency in Soybean Production

Abstract

A field experiment was conducted at Chuka University farm to determine the effect of integration of rhizobium inoculation (R) and triple superphosphate (TSP) on tissue content (TC), rhizobium and phosphorus use efficiency (PUE) in soybean production in Meru South Sub County. Two trials were done between MarchAugust 2018. The objective was to determine the effect of integrating effect of R and TSP on TC, symbiotic efficiency and PUE in soybean production. Treatments included; three concentrations of TSP (0, 20 and 30 kg- ha-1), and concentrations of rhizobia (0, 100 and 200 g ha-1) either applied alone or in combination and soybean genotypes (SB19 and SB24). Trials were laid out in an RCBD in split-split plot arrangement and each treatment replicated thrice with genotypes assigned main plot, R and TSP in split plots. Data collected was subjected to analysis of variance using the Scientific Analysis System and significantly different means separated using Tukeys test at P≤0.05. Results showed significant difference in nitrogen and phosphorus content, rhizobia and PUE in SB19 and SB24 in both trials at P≤0.05. The highest nitrogen TC of between 1.73% and 9.10% was observed when R and P was applied at concentrations of 200 g and 30 ha -1 kg in both trials. R and TSP at concentrations of 200 g and 30 kg per ha resulted in highest phosphorus content of between 849.6 and 955.0 ppm in both trials. The SB24 had the highest symbiotic efficiency of 207 and 261 ppm compared to SB19 of 201 and 227 ppm in both trials. The PUE was highest when R and P was applied at concentrations of 200 g and 20 kg and 200 g and 30 kg per ha for SB19 and SB24 soybean in trials I and II respectively. Co-application of R and P at concentrations of 200 g and 30 kg P/ha and adoption of SB24 showed potential of enhancing soybean productivity.