Based on an intern project by Rachel Vecchio, Certified Master Gardener
THE MYTH: Till vegetable gardens every year.
THE REALITY: For hundreds of years, an annual rite of spring has been to till the garden to get it ready for planting. However, current evidence indicates that annual tilling really isn’t necessary, and may actually harm the garden instead of helping it.
One of the most common reasons to till the garden is to loosen compacted soil while also introducing air and oxygen to stimulate microbial activity. While these things are accomplished by tilling, there are also negative effects from the tilling process. The additional burst of nutrients provided by the increased microbial activity soon dissipates, leaving the soil in worse condition and not providing ongoing nutrients for plant growth. Tilling also disrupts nature’s workers, i.e. worms, and churns up the natural drainage flow created by their tunnels. If left undisturbed, the worms can work unharmed, providing aeration channels and leaving behind beneficial castings.
Another common reason to till the garden is to reduce weeds. However, tilling can actually increase the proliferation of weeds in the garden by bringing dormant weed seeds closer to the surface, providing them with better conditions to germinate.
Tilling is also a popular method for incorporating fertilizer and organic material at a deeper level in the soil. This isn’t necessary, though, as a majority of a plant’s feeder roots are closer to surface level. The nutrients they need to be healthy and grow should be kept at a higher level in the soil, not at a deeper level.
Instead of tilling, the “no-till” (or “no-dig”) approach has recently gained traction in the home garden. For years, farmers have utilized the no-till method for crops. With this approach, soil is tilled only to initially get the garden started, and then the soil is amended annually by adding significant amounts of organic material, such as compost or mulch, on the surface of the garden soil. The organic material breaks down slowly over time, providing an ongoing source of nutrients. By providing these nutrients the garden will be less likely to need supplemental nutrients, thereby saving time and money. The deep layers of organic material also keep weeds at bay by not providing the conditions needed for growth.
While tilling has its place in soil management, especially to prepare soil for the first-time garden, the conclusion is it is not necessary to till the garden every year. The no-till method should be considered as a viable approach instead of annual tilling.
SOURCES/REFERENCES:
Finneran, R. (2015, February 11). Preparing the smart vegetable garden. Retrieved April 17, 2018, from
http://msue.anr.msu.edu/news/preparing_the_smart_vegetable_garden
University of Maryland Extension, Home and Garden Information Center. No Till Gardening. (2013, May 23). Retrieved April 17, 2018, from https://www.youtube.com/watch?v=Kt9yEbcTUfw
Wolf, K. (2012, November 9). To Till or Not to Till [PDF]. Pullman, WA: Washington State University.
Woods, T. (2012, September 7). Mulch is a key to no-till gardens. Retrieved April 17, 2018, from http://extension.oregonstate.edu/gardening/mulch-key-no-till-gardens