Soybean (Glycine max [L.] Merr) is an important crop, as both food for humans and feed for livestock in Cambodia, but the yields are low, due to use of low yielding genotypes and limited use of inputs. This study aimed to investigate the effects of different genotypes and different N and P fertilizer sources on growth, seed yield, and seed protein of soybean. Five genotypes (Sbung, Hongry, 98C81, ACS1, and Kaiabi) were grown under different N (90 kg N ha⁻¹ from urea, nano-n, Nitroplus, and without N application as control) and P fertilizers (50 kg P ha⁻¹ from Inorganic P, nano-p, Mykovam, and without P application as control) in two screenhouse experiments. Shoot, root, and nodulation traits, as well as seed yield and protein, were significantly affected by genotypes and different N and/or P fertilizer sources. Notably, while genotypes Sbung and 98C81 showed the highest yields among the genotypes, regardless of different N and P fertilizers, only Sbung had the highest seed protein. The application of different N and/or P sources significantly increased seed yield, compared to non-N and -P application. Specifically, seed yield and seed protein were higher when treated with nano-n or urea, and number of nodules, root biomass, and nodule dry weight was increased with Nitroplus, whereas seed yield and protein were higher with nano-p, Mykovam, and inorganic P. Application rate of 90 kg N ha⁻¹ and 50 kg P ha⁻¹ produced higher seed yield and its components and seed protein. We conclude that N and P application as well as Nitroplus inoculation can help increase seed yield of soybean in Cambodia.

A study was undertaken in Koun Mom district of Ratanakiri province in Cambodia to analyze the perceptions of the current status and constraints to soybean production and identify solutions to improve production and the management practices. Primary data were collected by personal interviews at field level of 130 producers. Most respondents were in the medium age category, Grade 4 education, with an average land holding of 2.96 ha and annual income of KHR 6,195,548 Riels (about 1548 USD). In terms of economic and production constraints, the high cost of fertilizers, severe insect and disease infestation, were identified as most important. Association with independent characteristics and scientific orientation were not significant, but education, land holding, annual income, socioeconomic status, and risk preference were significantly associated with constraints to soybean production. Within the context of sustainable agricultural production practices, it is suggested to improve high-yielding genotypes, ensure timely availability of high-quality seeds, and identify appropriate crop management practices (planting dates, planting density, nutrient and water management practices) and find ways to efficiently and effectively disseminate information to farmers to enhance soybean production in the region. In addition, extension agents and other agencies should provide soybean farmers marketing information, establish viable links between farmers and relevant stakeholders and private sector to improve access to inputs and modern technologies while the local and state governments should establish rural markets with good market infrastructure to enable farmers have high returns from soybean production.