It's difficult to define what biosystems engineering is, or even what biosystems engineers actually do, except to say that we apply engineering principles to life. Our work is a mélange consisting of biology, chemistry, computer science, and engineering, which has both its positive and negative aspects depending on which way you want to look at it.
The Melting Pot
Within the department of agricultural and biosystems engineering  at McGill University, there is more diversity in scientific backgrounds than perhaps any other department I know of. There are analytical chemists, food engineers and scientists, soil scientists, computer programmers, microbiologists, post-harvest engineers, agricultural engineers, chemical engineers, and others, all working together in the field of biosystems engineering. Many of the scientists have studied internationally at other universities, bringing with them a wide range of approaches to research. And collaborative projects within the department extend to places as diverse as Egypt, India, Panama, and China.
It may not be the case everywhere, but our department is research based, and there are perhaps as many graduate students as there are undergrads. Not surprisingly, the research is diverse, with projects ranging from neural network-based modeling of various systems to pulsed electric field treatment of food products.
Bioremediation, for example, has become a major focus of late, mainly as a result of increased awareness of our environment--as well as stricter government regulations. Within a group like this, it wouldn't be uncommon to find analytical chemists, botanists, engineers, soil scientists, and a couple of computer simulation specialists, working on models of, say, leaching of phosphates in soils, or developing methods for removing heavy metal contamination.
Then there's post-harvest engineering. To preserve the products we eat on a daily basis in a premium state requires research. How do you get a guava from South America to Canada without it going bad? Controlled atmospheres are usually the answer, and any controlled environment requires engineering. Physiologists work side by side with control systems engineers to determine the necessary conditions for keeping fruits and vegetables in optimum shape from harvest to delivery. Obviously there are different levels of quality in fresh produce too, so how did you sort the produce out according to size and quality? It would be fine to do it by hand if you only had a couple of bushels to deal with, but most producers deal with tons. This makes hand-sorting operations virtually impossible, because the product must be stored in a controlled environment quickly to prevent losses. For this, mechanical sorters are needed that can sort according to various criteria such as color or shape. Enter another facet of biosystems engineering that requires software engineers: machine vision.
There are also food engineers in our department, working on such topics as inactivating microorganisms to prevent spoilage and food poisoning. They apply techniques such as pulsed electric fields to destroy harmful bugs without impacting too much on product quality. Microbiology, food science, and an understanding of engineering principles come into play here.
Degrees in science and engineering are obviously the most common backgrounds in the programme, but there are people with far more diverse backgrounds doing research that incorporates the social sciences. It's of no use to draw conclusions about inefficient agricultural practices in Panama, for example, if you cannot transfer the information gained from research to the local population that actually depends on that land for their livelihood. Using a combination of engineering and scientific knowledge gained from field studies, as well as interaction with communities in developing countries, some researchers in our department are developing methods to effectively communicate information about best practices to the farmers, as well as methods to train them by example.
My own field of research is fermentation engineering, a field that requires knowledge of engineering, microbiology, and more recently, genetics. An example of fermentation engineering is the development of a microbial culture-based treatment system to degrade a phenol, which is toxic and very stable, to a liquid that can be safely disposed. The field is becoming increasingly important, particularly in the biotech industry. For instance, liquid culture fermentation is used to produce large quantities of insulin and erythropoietin used to treat diabetes and anaemia, respectively (the latter has also found notoriety in distance sports, such as cycling and marathon running, for its endurance enhancing properties). Fermentation engineers are responsible for engineering the organism that produces the product of interest, developing large-scale production processes (which, by the way, is not as easy as you might think), and figuring out how to process large quantities of raw material.
I started out with a bachelor's degree in food science at Stellenbosch University in South Africa, taking biochemistry, food engineering, and food microbiology amongst other courses. My university was in the heart of the wine region of South Africa, and many of my friends were studying oenology and viticulture. Like food science, these areas fell under the faculty of agriculture, and some overlapping courses led me to become interested in fermentation processes. I decided that I wanted to pursue further studies in this field. I also thought that it would be a good career move to study abroad. So, I chose the program at McGill University for its location and worldwide reputation for academic excellence.
With an interest in beer production, I began a master's degree in biosystems engineering, studying the physical properties of brewing yeast. Beer is a fine example of an economically (and socially) important bioprocess. Annual production at one company alone can approach or even exceed 10 billion litres.
The more I studied, the more interested I became in the field and knowing that I did not want to become an academic, I started contacting companies with the hope of getting a start as a researcher in the brewing industry. The response was encouraging, but as I have a desire to be in Europe, I determined that a PhD would be the only way in due to EU job-market protection regulations. I had already started numerous projects outside of my degree that were not yet complete and when done, would be perfect CV building material. As a result of that, and the enriching learning experiences I have had at McGill, I decided to stay on to complete a PhD in the same department. That's where I am now, and I'm enjoying the challenge!
A Case of Misinterpretation
There are both positive and negative aspects to multidisciplinary nature of biosystems engineering. On the plus side, it promotes interaction with researchers in fields (and places) other than your own and stimulates interest in other topics. I, for one, prefer to be a generalist and know a lot about many things than everything about one thing, so the field suits me.
But the broad nature of biosystems engineering can pose problems when it comes to finding positions. The fact that the field overlaps with numerous others means that biosystems engineers are often competing for the same jobs with biological scientists, and so the competition is fierce, particularly when a company is looking to fill a niche position. It's my impression that the hiring individuals don't sufficiently understand or appreciate the skill set of a biosystems engineer and overlook them because they think that the degree doesn't sound specific enough, like 'food science' or 'mechanical engineering'. Sadly, the problem lies in misinterpretation, because biosystems engineers are equipped to deal with a wide range of issues.
Perhaps that will change in the future. In a world of ever increasing rationalization, employers will likely be leaning toward hiring people that can do multiple jobs. With more people getting postgraduate degrees and entering their respective professions as specialists, those who will have a competitive edge may well be the students who have ensured that their research touches on several fields. Biosystems engineering may well fit the bill in this regard. Regardless, it's certainly worth considering for those looking for a different kind of challenge.