The possibility of drought may or may not be of serious concern, for it depends on when it is most likely to occur.
Soybeans are pretty tough, and can take some weather abuse and still make a crop.
I cannot recall any of my associates doing work in Spain, so I can't name anyone to use as a local reference for problems that might be encountered with soybean in Spain. I will check with our international ag office, and if a reference person is on our campus, I will follow up this message with such information. Gary Pepper Crop Sciences Dept.