Sterile Organics? Pitfalls of "Organic" Greenhouse Research

The "biodiverse" pots in my failed organic fertility greenhouse experiment

I’ll admit it. My first attempt at designing an “organic” fertility experiment was a complete failure. When I started my forages class at Ohio State in the fall of 2015, the teacher told us that we could design our own fertility-related forages experiment for our class project. I had a great plan—comparing the yields of biodiverse and monoculture forage plantings under an organic management system.

But I started to run into problems as soon as the experiment started. We trooped down as a class into the Kottman Hall greenhouse, where the teacher gave us pots, seeds for lots of different kinds of grasses and legumes, a nutrient-deficient sterile potting mix, and granular nitrogen, phosphorus, and potassium chemical fertilizers to add as we desired. Disdaining those, I came up with my own plan for a liquid organic fertilizer—making up a “manure tea” by running water through some goat manure on my next trip home. I figured that would work great.

But it didn’t. I dumped lots of my “manure tea” on my potted plants, but after seven weeks it was pretty obvious that they looked worse than anyone else’s. Since I was getting graded on the plant yields, not just completing the experiment, I finally ended up having to add urea—a chemical nitrogen fertilizer—to my pots. The effect on the grass was amazing—it suddenly turned green and doubled in size overnight. The legumes were mostly dead by that point and never recovered, and I ended up having no difference between my “biodiverse” and “monoculture” pots. But at least I made the yield goal by the end of the semester and got an A for the project.

What I really learned from this experiment is that organic farming is not simply a matter of replacing chemical fertilizers with “organic” ones using the same methods. Organic farming is, first and foremost, about having a living soil, full of microorganisms. The potting medium we used for this experiment wasn’t soil at all; it was a sterile, dead combination of peat moss and vermiculite. I realize now that any attempt to make an “organic” system starting with sterile potting mix was doomed from the start.

The implications of this for organic farming are huge, because a large percentage of agronomy and horticulture research relies on greenhouse pot experiments. The main reason for this is that everything can be controlled in a greenhouse—light, temperature, humidity, fertility, etc. But it is pretty much impossible to simulate the diverse soil and aboveground ecosystems of an organic farm in a greenhouse. Even if researchers use a soluble organic fertilizer that can keep plants alive and growing, they can never re-create the true complexity of a real organic field. The results from the thousands of greenhouse-based experiments that are conducted every year are pretty much useless for organic farmers, because they do not reflect real-world conditions.

Perhaps this is one reason why the majority of university agronomists have historically been opposed to organic farming. Truly organic researchers would have little use for their expensive and complex system of greenhouses and growth chambers. They could use them to start transplants, like most organic vegetable growers do, but that would be all. Growing plants for their whole lifecycle under artificial conditions wouldn’t be a good research design. The only valid research would be long-term studies on organically managed land—a type of research that has been notoriously hard to get funding for.