Investigating the Influence of Fertilizer Application Rates on Soybean Yield Across Diverse Locations

This study investigated the impact of varying fertilizer application rates on soybean yield and agronomic characteristics in three distinct locations within Lao PDR (Laos People’s Democratic Republic-Lao PDR): the Rice and Cash Crop Research Center (RCCRC), the Faculty of Agriculture Nabong Campus (National University of Laos, NUoL), and the Faculty of Agriculture and Environment Nongpheu Campus (Savannakhet University, SKU). The field experiment was conducted during the 2022 growing season (August to December) using a randomized complete block design (RCBD) with three replications. Five fertilizer treatments were applied to a total of 15 experimental units, encompassing varying combinations and rates of organic and inorganic fertilizers. Agronomic traits, including plant height, number of branches, pods per plant, individual plant weight, 100-seed weight, and grain yield, were measured at maturity. Data analysis was performed using Statistix 10.0 software with a significance level of 95% (P < 0.05). Significant differences (P < 0.01) were observed among the fertilizer treatments for the number of branches, pods per plant, individual plant weight, and ultimately, grain yield. However, plant height and 100-seed weight were not significantly affected by the different fertilizer applications (P > 0.05). The highest grain yields were achieved with the application of organic fertilizer at a rate of 2,000 kg/ha (2.48 t/ha) and a combination of organic fertilizer at 1,000 kg/ha with inorganic fertilizer at 100 kg/ha (2.57 t/ha). Conversely, the control treatment, which received no fertilizer, resulted in the lowest grain yield. These results highlight the importance of fertilizer management strategies in optimizing soybean production in Lao PDR. Further research is needed to assess the long-term effects of these fertilizer regimes on soil health and environmental sustainability.