Woody Agriculture Weblog
The Future of The World Is Nuts!(TM)

We knew hazels had big root systems (we've dug some up before)- but this time we're using a backhoe and water, to wash soil away- and the root systems are FAR bigger than we thought- and NOT shaped the way ANYONE would expect. It's GOOD news- but definitely should affect the way we care for the plants, and how we weed them.

This excavation project came about because of Lois Braun's need to really know what the structure is supposed to be- Lois is the PhD student working on the nutritional requirements of Badgersett hybrid hazels for her thesis, funded by the University of Minnesota's Experiment in Rural Cooperation. She got the hole going; and as long as it's open; we're going further every day (in our spare time...)

We have dug up several hazels to examine root structure before; but the only tools we had were shovels- and necessarily, we had to give up before getting too far. That, combined with digging and transplanting several hundred 2 year old field grown hazel seedlings (which we vowed never to do again, since the root systems at 2 years are TOO BIG to go through a tree transplanting machine, and so big that hand digging is killing work) gave us THIS idea of what most hazel root systems were going to look like. Obviously, this is a very simplified schematic drawing- real root systems don't grow in consistent curves; and they have side roots; but this was the general idea.

Once we opened a 6 foot deep trench with the backhoe, and started washing soil away from the roots, we quickly discovered that we had BADLY UNDERESTIMATED the size of the root systems. And didn't understand their structure really, either.

The big surprises:

A) With the hazel at the age of 10 years, Mitch and Lois followed one root down as far as they could reach- which was 9.5 feet below the surface; and it was still going down at that point.

B) We discovered the plants also put out EXTENSIVE roots JUST BELOW THE SURFACE - right in the grass sod- and these roots extend 12-15 feet from the crown of the plant- that's a diameter of 24-30 feet. The top of the bush was only 5 feet in diameter. AND- the reason we missed this before; this kind of surface root doesn't taper much, and is fairly slender to start with- we thought they were not going far when we dug them before. But they do; AND they drop MAJOR deep roots off the surface feeder trunks- all the way out to the tips.

C) Some roots near the crown are very thick- looking like they are designed for storage of something; nutrients and/or water-

My hand in the above photo is pointing to the cut-off hazel top; you can see this was NOT a really big bush; just a modest one. Virtually ALL the roots in the photo are from this hazel.

D) The ground near the hazel crown is so dense with roots it is VERY difficult to wash the soil out- even with a 90 PSI water jet. AND - MOST of the fine roots in this dense sod- are from the hazel. We thought at first it was mostly grass sod- but after careful dissection- nope- there is some grass; but most of it is hazel roots.

Main thing to realize is that ALL the roots in the picture are hazel roots- and most of the very fine roots get washed away in the process of clearing the soil...

WHAT THIS MEANS -

Apparently grass and weeds don't scare hazels- they grow roots right in the surface, and SUCCESSFULLY just fight the weeds for the water.

UNLESS YOU CUT THEIR ROOTS OFF; or otherwise damage them.

We've had several instances where folks have reported mortality in their hazels; and couldn't understand it, because "we hoed them clean, and watered-"

In fact, the hazels are trying to grow roots BOTH deep AND shallow- and hoeing close is very likely to cut all the shallow roots off.

Mature hazels clearly tap very deep soil moisture- but the young ones, specifically, may need the surface roots most during drought. IT'S VERY POSSIBLE THAT THE SHALLOW ROOTS MAY BE THE MOST IMPORTANT to surviving drought in the early years of the plant's life -

Huh? What?-

Because- near the surface, there is SOME water, from heavy dew- and the tiny rains that happen, wetting only the surface. It looks like the hazels, which are from North America, remember, may be able to catch and use these meager water resources- BETTER than the weeds, better than other woody plants.

But not if we cut off their developing roots; or drastically damage them by pulling up big weeds nearby that have their roots intertwined with the hazels.

Does this mean the best thing to do is NOT weed? No- just use a weeding method that does NOT disturb the hazel roots- Roundup, or mowing, or a weed-whacker of some kind. CUT the weeds off, don't pull, close to the hazels. Leaving some weeds in place is very unlikely to harm the hazels; in fact the shade and wind protection may do more to prevent drying of the soil than they cost. Some weeds will also help distract rabbits- and deer, giving them something else to focus on.

And remember- that dinky little hazel seedling probably has roots out MUCH further than you think.

I've been growing these guys for 25 years; digging and moving them; have planted about 70 acres of them myself- in a zillion ways-

And these new root excavations ASTOUNDED me.

We're going to keep working on the excavations all Fall, most likely- the dry soil is much harder to wash away than we expected- but the trench will be open, and the roots visible, through October.

Come and see. No photo or diagram can really convey the extent of these amazing root systems.