Stress
Farm research science isn't particularly stressful. You'll spend most of your time researching and testing, not doing the physical harvesting or worrying about the cost versus profit of this year's crop.
Sure, it can be frustrating when something you try fails to produce the results you hoped for. But, as a trained scientist, you know it's not about what you want, it's about the data. As long as you respect that, this job should stay pretty stress-free.
The main stress you'll deal with is crunch-time—finishing a big project, or scheduling your research so your vacation time doesn't overlap with the critical stage of an experiment.
The best thing for stress is to go away and plant yourself on a beach, or a mountain hiking trail, and to do it a couple of times per year. Get out and in touch with the nature that you study every day, or get away from it to the sights and sounds of a big city. Either way, stow away some vacation time and you'll be doing just fine with the stress.