Effect of Bone Char on Nodulation Capacity, growth and yield Soybean (Glycine Max L. Merr.) Grown in High P-Fixing Acidic Soils

Abstract

Soil acidity is one of the major obstacles to soybean production in south western Ethiopia, reducing availability of phosphorus (P) which plays a crucial role in the energy-intensive process of nitrogen fixation. Increased Nodulation efficiency and N2- fixation can be achieved with optimum P application. However, Ethiopian farmers have limited capacity to purchase and apply commercial P fertilizers. The potential of animal bone- char as P fertilizer in agricultural fields has been recently recognized and yet it is not fully utilized and its role in combination with Bradyrhizobium inoculation in soybean production is poorly understood. Therefore an experiment was conducted to evaluate how bone- char application influences nodulation efficiency, nitrogen fixation and yield of soybean in P fixing acid soil. The experiment was conducted during 2023 main cropping season at Mizan Agricultural, Technical and Vocational Education Training College demonstration site. The experiment had eight treatments including bone-char, Triple super Phosphate (TSP), TSP + lime applied with and without Rhizobium inoculation (MAR 1495) which were laid out in a randomized complete block design (RCBD ) with three replications. The P sources were applied to supply 20 Kg/ha P. Data on phenological parameters, nodulation, growth and yield traits were measured and subjected to analysis of variance (ANOVA) using SAS version 9.3. Results revealed that application of Lime + TSP and bone-char with rhizobium inoculation significantly (P<0.01) influenced most of the phenological, nodulation, growth and yield parameters. As compared to the control and other treatment the tallest plant height (61.2 cm), highest number of primary b ranches per plant (11.7), highest total nodule counts per plant (47. 86 plant–1, highest effective nodules (43.5 plant-1) and highest nodule dry weight (0.76 g plant-1) was recorded from the application of Lime + TSP with inoculation and statistically similar with bone-char with rhizobium inoculation. Application of lime + TSP without inoculation resulted in reduced number of days to reach 50% flowering (55.3) and 90% physiological maturity (117.3) as compared to rhizobium treated plot. While prolonged days to attain 50% flowering (61.7) and 90% physiological maturity (125) was recorded from treatments with rhizobium inoculation. The highest grain yield (2756.33 kg ha−1), highest aboveground biomass (3985 kg ha−1), highest number of pods (40), 100 seed weight (16.23 g) and highest harvest index of soybean (0.69) were recorded from application of TSP + Lime with rhizobium inoculation which was statistically similar with bone-char application with inoculation. Partial budget analysis revealed that, the highest net benefit of (157,661.6 Birr ha-1) was obtained from the application of Bone-char with Rhizobium inoculant followed by (154,901 Birr ha-1) from application of TSP + Lime with inoculation. MRR (511.87 %) obtained from the application of bone-char with inoculation. Therefore, the overall analysis revealed that application of bone-char with rhizobium inoculation resulted in highest yield and economic benefit. For sound recommendation the experiment should be repeated at different location, over years and seasons.