Influence of two glomus species on the fertilizer efficiency of sokoto phosphate rock in soybean production and the residual soil
A screenhouse experiment was carried out at the University of Agriculture, Abeokuta, to investigate the influence of two species of Glomus (G. mosseae and G. deserticola) on the fertilizer efficiency of Sokoto phosphate rock in promoting soybean production and the impact on the residual soil. The experiment was arranged in randomized block design with four replicates. The treatments consisted of sole inoculations of G. mosseae and G. deserticola and their combinations with phosphate rock (PR), sole application of PR, SSP and a no-inoculation, no-fertilizer control. Results obtained revealed that the percent colonization rate of arbuscular mycorrhiza fungi (AMF) was significantly higher in treatments with combinations of PR and Glomus than the sole AMF treatments and least in non mycorrhizal fungi treatments at 3 and 9 Weeks after sowing (WAS). Also, sole inoculation of G. deserticola caused significantly higher P uptake than treatments with combination of PR and Glomus as well as SSP application and least in control, N uptake was however similar in all the treatments. Consequently, growth parameters such as, plant height, numbers of leaves and branches, canopy diameter as well as leaf area significantly increased between 2-6WAS due to inoculation of G. mosseae or G. deserticola and their combinations with PR. Furthermore, shoot biomass significantly increased at 3, 6 and 9 WAS with G mosseae and PR combination similarly, root biomass significantly increased at 3 WAS due to application of PR and at 6 and 9 WAS, combination of G. deserticola and PR increased root biomass. Nodule weight increased significantly with combinations of PR with G. deserticola at 6, 8 and 9 WAS and PR with G. mosseae at 9 WAS while nodule number increased significantly with combination of PR and the two species of Glomus at 6, 8 and 9WAS. Sole inoculation of G. deserticola and SSP caused the plants to flower significantly earlier than other treatments and yield was significantly higher in sole G. mosseae and PR treatments than in SSP and control. At the end of soybean cropping, treatments with PR/Glomus combination and sole G. mosseae produced significantly higher N in the residual soil while sole application ofPRproduced the least. Application of SSPgave the highestP, whilePRas well as control gave the least and soil organic matter was highest with sole inoculation of G. deserticola and least inPRapplication.
Keywords: Phosphate Rock, Glomus mosseae, Glomus deserticola, soybean, Residual soil