Is "no till" really the best way to grow plants?
I'm hearing of more and more growers moving to "no-till" setups for their greenhouses, raised beds, and indoor gardens. The concept is simple, by not disturbing the soil, we are allowing for the microbes to establish soil structure and improve soil quality over time. There are many benefits to "no till," but I don't think we are truly comparing apples to apples when discussing our raised beds and indoor gardens.
So for starters, let's differentiate between using an actual rototiller and just digging our indoor pots and beds. 2 totally different situations. Yes, tilling can be quite damaging to soil structure and change the microbial dominance of the soil. One of the biggest issues with tilling is you create a compaction zone at the depth of the tiller. Not something you have to worry about when double digging an indoor bed or re-mixing soil in a container. "No till" sounds way cooler, but is it the best? I think growers should try out a few different ways of amending and then compare their results by measuring plant growth and yield for themselves.
In the trials we've run, we've had better success with double digging the soil to fully mix nutrients at further depths than just topdressing. It's not really killing the worms or larger insects with that sort of disturbance. This allows us to get less mobile nutrients like phosphorus and potassium into the rhizosphere faster than just topdressing. We can mix nutrients more homogeneously deeper into the soil and by "resetting" the soil to maintain a bacterial dominance similar to agricultural land, you should be selecting for an annual crop like cannabis that prefers bacterial dominant soil.
Now having said all that, we have growers just topdressing in containers and beds and getting good results by just scratching nutrients into the surface. Tim Wilson and I have had multiple conversations on the subject and he would say don't till, but has no issues with disturbing the first couple inches of soil (this would occur in nature through animals, erosion, weather, etc...) and still considers that "no till" because you aren't going any deeper.
My suggestion is simple. Try it out. Run a few beds or containers using a "no till" system and fully dig the nutrients into others. Treat the beds exactly the same and then measure the growth and yield at the end of the cycle. You may find that taking the time to mix the nutrients further into the soil has benefit.
At the very least, I'm confident that lightly tilling the nutrients into the first few inches of the soil will outperform a true "no till" garden in an indoor environment with the same inputs.
Feel free to comment below with your own experiences!
Resources:
http://www.motherearthnews.com/homesteading-and-livestock/no-till-farming-zmaz84zloeck
http://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=1751&context=extension_curall
Image courtesy of: By KVDP - Own work, Public Domain, https://commons.wikimedia.org/w/index.php?curid=4307299