Should I be rototilling?
I have a 40 foot by 40 foot vegetable garden with raised beds. Every year in the spring I put a layer of manure and compost on top and till it into the soil before planting. In the fall I do the same for my garlic planting and in the summer after harvesting the garlic beds I do it in those beds before planting other crops. I usually have earthworms but this year I have especially many of them, particularly in beds that I had covered with hay mulch. Now I am wondering if rototilling is causing more harm than good, killing the earthworms. Looking at various sites I see that some say one should never till, others say not too often or deeply. I have a small tiller (Mantis) and do not till more frequently than mentioned above. Should I continue doing this or stop or reduce? If I stop, how do I mix the manure and compost into the soil, or does that even need to be done? I have been doing this more or less continuously since 1985, and think that my soil is very good. But I don't like to kill worms if there is any workable alternative.
Thank you for your question. You are very observant, and must have healthy soil to have so many worms! Worms actually will do the tilling for you, as they aerate the soil by moving through it. And they take the manure and other organic material further down, adding their own ‘touch’ to it in their excrement. Here is a blog from a professor at Cornell with a modified approach: http://blogs.cornell.edu/ccesuffolkligardening/tag/rototilling/ You might find, however, that all you will need is a trowel for seed/transplants if the worms and organic material keep the texture of the soil workable. Many Extension sources recommend against tilling because it destroys that texture. Adding a layer of manure or clippings—or a cover crop of legumes—will protect the soil over the winter, and add nutrients, to boot. Good luck!
When I put the manure on top of a bed I worry that it is too strong (even though I get aged horse manure) to plant into directly, so I mix it in with the existing soil. Which is why I've been tilling. Should I just leave it on top, or maybe mix it lightly in with a shovel or hoe? Or if I put it in at the end of the season instead of before planting will it winter over enough to be left alone when I plant in spring?
I’m not sure what animal’s manure you are using, or whether it is your own animal(s) or purchased commercially. If it it is the latter, it probably is aged enough that the nitrogen content is not too high (‘hot’) that it burns the roots. Here is an OSU short article on the use of manure in vegetable gardens: https://extension.oregonstate.edu/news/turn-manure-compost-your-garden Leaving it above ground will allow weather to age it further, and soil microbes will be composting it at soil level. And, as I mentioned earlier, putting it on in the fall will protect the soil from compaction.