The most important quality criteria for soybean are protein and fat contents.
Climatic and local conditions can influence the quality.
- Extreme weather. Anything that in any way removes leaves from the soybean plants like wind, heavy rain or hail, will affect protein and oil contents. This also goes for leaf-eating insects.
- Water and drought. Drought early in the season can reduce the protein content, but drought late in the season will increase this content. The late season drought reduces oil content, and this has an inverse effect on the protein content.
- Temperature. The effect of temperature is quite complicated and not well understood. However, it is known that general high temperatures reduce the overall yield, and higher temperatures at the end of the season have a tendency to increase oil and not protein.
It is important to select the right variety of soybean in order to get plants suited for the local climate. Once having the correct variety, the best way to influence the quality of soybeans is through proper and well planned nutrition.
The nutrients availability has influence on seeds chemical composition and affects its metabolism and strength. Fertilizer management and soil acidity alleviation can affect oil and protein levels of soybean seeds.