To till or not to till... that is the question

I had an interesting question from a friend INRE putting in a new vegetable garden. He wanted to know, after getting rid of the indigenous blackberries, should he (roto)till or not?

Not being a garden expert myself... and being one upped by my tomato plants more than I'd care to admit... I set to researching the opinions of experts. I actually landed upon several good sites that I'd like to share.

First, about tilling. The most common thread I've seen is that the usual practice of tilling annually is not necessarily beneficial. Per Master Gardener, Cisco Morris, in his article last February, it all depends on the soil status.

In the old days the recommendation was to rototill your vegetable garden every spring to incorporate organic compost to improve the soil. If you're breaking ground for a new garden, it might be a good idea to rototill in amendments, but if your soil is loose, open and fluffy, rototilling could destroy the soil pores that enable water and oxygen to pass through, and could harm millions of microorganisms that help feed the soil and prevent soil-borne diseases.

If your soil is reasonably good, simply mulch with an organic compost or well-composted manure. The soil-building humus and microorganisms will be washed in by rain and worked in by worms. You'll improve soil structure and continue to feed the web of life in your soil without causing a major disturbance.

The College of Agriculture at the University of Arizona says much the same INRE tilling annually. But they also offer an alternative for the home gardener - chisel plowing. They do say rototilling can work, but with some caveats.

From their Reference Manual in regards to soil preparation for vegetable gardens:

While garden plowing is still a common practice, turning the soil completely over has been found to be detrimental in some cases, causing soil compaction, upsetting balances of microorganisms, and often causing layers of coarse organic material to be buried below the influence of insects and microbes which would otherwise cause breakdown of the material. Chisel plowing, which does not have this disruptive effect, is one alternative, but it is limited to sandy or loamy soils and many farmers who work gardens do not have chisel plows.

snip

Rototilling most home gardens is sufficient, as long as plant debris accumulation is not out of hand. Rotary tilling mixes the upper layers of soil rather than completely turning the soil over, and the effect produced are generally desirable. One possible harmful effect of rototilling is the formation of a compaction layer just beyond the reach of the tinesThis also occurs when a moldboard plow is used to the same depth every year, but at a somewhat deeper level. Use of deep-rooted cover crops or double-digging can do much to prevent or alleviate this problem when it exists. Small gardens can be designed using raised beds which may be worked entirely by hand if the area is small enough.

Perhaps the best start for a fresh garden - or even a new rotation site for the garden (recommended every 3 or so years) - is to find out the composition of the soil. EarthCo from St. Louis, MO is one company that offers service for the home gardener. Various test kits run from $20-$50. They give detailed sample collection instructions, you ship the soil to them, and get the results online. Mind you, I've never used their services myself, so please don't construe this as a recommendation. However if anyone out there has tried their service, and can offer feedback, we'd all appreciate it.

FarmNetServices website offers various directories for agriculture needs. You can find a list of soil testing labs around the country on their site as well. This may be overkill for the home gardener... and we are not without our own local soil talent here in Oregon.

OSU out of Corvallis has their own "how to collect samples" brochure in a downloadable PDF for home gardeners. They also have, again in PDF form, a list of laboratories from all over the country - along with contact names, phone numbers and emails addresses. Needless to say, you can also let your fingers do the walking thru your yellow page directory as well.

OSU also offers some excellent visual tips and tricks that help you determine if your soil is short organic matter. They talk of color, drainage, and smells, along with the more obvious "can't dig a hole wet or dry" or cracked, dry summer conditions. And now is the best time to get that soil analyzed so it's properly fertilized for a spring planting. It's well worthy of a read as your first step.

Other good sites I found? 123Garden has a great article for how to plant just about anything... and plant it for life. And if you're like me, who never knows what to do each month for preparing your garden, there's the monthly "to do" lists from The Old Farmers Almanac.