Soil fertility management at Wulbareg-2022

Common bean is important cash crop and source of protein for farmers in Ethiopia. Low available phosphorus, total nitrogen, sulfur, and lack of selected varieties are major limiting factors for common bean production in the study area. Thus, the experiment was conducted at Wulbaregi District in 2022 main cropping season (July-October), to evaluate the effect of Blended NPS fertilizer rates and Rhizobium inoculation on the yield and yield components of common bean varieties to identify an economically appropriate combination of the factors that give maximum yield. Factors studied were four common bean varieties (HD, SER119, SER125 and Rori), three levels of blended NPS fertilizer rates (0, 100, 200 kg/ha) and two levels of Rhizobium (with and without). Randomized Complete Block Design in factorial arrangement with three replications was used. The Phenological, growth, yield and yield components data were collected and analyzed with SAS version 9.0 GLM model. The result revealed that the varieties had significant differences in days to physiological maturity, harvest stand count, pods per plant, seeds per pod, and harvest index. The NPS rates significantly influenced all studied parameters except stand count. The highest number of days to flowering (42), days to physiological maturity (90), hundred seeds weight (27.62g), above-ground biomass (7.76ton/ha) and grain yield (3.36ton/ha) were obtained from NPS 200kg/ha. Rhizobium inoculation significantly influenced the physiological maturity, nodulation, branch numbers, and harvest index of common bean. The interaction of NPS rates with varieties on nodulation, plant height, primary branch number, pods per plant, and harvest index was significant. The highest number of total nodule, effective nodule and dry weight for SER125and harvest index for HD were obtained from the combination of NPS 200kg/ha. Rhizobium inoculation with Varieties significantly influenced pods per plant and seeds per pod for variety HD with highest pods per plant (17.37) and seeds per pod (5.96). Significantly highest harvest index (44%) was obtained from the combination of Rhizobium with NPS rate of 200kg/ha. Rhizobium inoculation with NPS rate of 200kg/ha and variety HD produced the highest number of seeds per pod (6.8). The economic analysis showed the highest net returns from NPS rate of 100 kg/ha with a net benefit of 77,228ETB/ha and marginal rate of return of 422.3%. Thus, it can be recommended to enhance productivity in the study site and areas with similar agro-ecology. Since no significant difference was observed among the varieties any of them can serve as alternative choices based on preferences of the farmers. Moreover, inoculation did not enhance grain yield and as a result farmers can grow the bean crop without inoculation to avoid the extra expense. However, the result of the present study need to be evaluated and reconfirmed preferably in more sites and with quality check-up of the inoculant to reach a conclusive recommendation.普通菜豆是埃塞俄比亚农户重要的经济作物与蛋白质来源。本研究区域内，有效磷、全氮、硫素匮乏以及优良品种不足是普通菜豆生产的主要限制因素。为此，研究团队于2022年主作物季（7-10月）在乌勒巴雷吉（Wulbaregi）地区开展试验，旨在探究掺混型氮磷硫复合肥料（Blended NPS fertilizer）用量与根瘤菌接种（Rhizobium inoculation）对普通菜豆产量及产量构成性状的影响，筛选可实现最高产量的经济最优因子组合。 本试验的供试因子包括4个普通菜豆品种（HD、SER119、SER125和Rori）、3个掺混型氮磷硫复合肥料用量水平（0、100、200 kg/ha）以及2个根瘤菌处理（接种与不接种），采用因子型完全随机区组设计（Randomized Complete Block Design），设置3次重复。研究人员测定并收集了物候期、生长性状、产量及产量构成相关数据，采用SAS 9.0版本的广义线性模型（GLM）进行统计分析。 结果表明：不同菜豆品种在生理成熟天数、收获时田间株数、单株荚数、单荚粒数以及收获指数上存在显著差异；掺混型氮磷硫复合肥料用量对除田间株数外的所有供试性状均有显著影响。当肥料用量为200kg/ha时，菜豆的开花天数（42天）、生理成熟天数（90天）、百粒重（27.62g）、地上部生物量（7.76吨/公顷）以及籽粒产量（3.36吨/公顷）均达到最高值。 根瘤菌接种显著影响普通菜豆的生理成熟期、结瘤性状、分枝数以及收获指数。掺混型氮磷硫复合肥料用量与品种的交互作用对结瘤数、株高、一级分枝数、单株荚数以及收获指数存在显著影响：其中，SER125的总结瘤数、有效结瘤数和结瘤干重均达最高，HD品种的收获指数最优，二者均在肥料用量200kg/ha时实现该表现。 根瘤菌接种与品种的交互作用对HD品种的单株荚数和单荚粒数存在显著影响，HD品种的单株荚数（17.37）与单荚粒数（5.96）均达组内最高值。当根瘤菌接种配合200kg/ha的掺混型氮磷硫复合肥料用量时，试验组的收获指数最高，达44%。根瘤菌接种结合200kg/ha肥料用量与HD品种的组合，其单荚粒数最高，达6.8。 经济分析结果显示，当掺混型氮磷硫复合肥料用量为100kg/ha时，可获得最高净收益，净效益为77228埃塞俄比亚比尔（ETB）/公顷，边际收益率为422.3%。因此，该施肥方案可在本研究区域及相似农业生态区（agro-ecology）推广，以提升普通菜豆生产效益。 由于各供试品种间无显著差异，农户可根据自身偏好选择任意品种进行种植。此外，本试验中根瘤菌接种并未显著提升籽粒产量，农户可无需接种以避免额外的生产成本。但本研究结果需在更多试点区域开展验证，并对接种剂进行质量检测，方可得出更具说服力的推广建议。