Sunday, December 11, 2016

Daikon as Clay Soil Amendment (and Tasty Vegetable)!

Daikon foliage, pre-deer (the stems coming out of the daikon at the bottom of the photo are actually from another annual - redwhisker clammyweed - that was growing in the same area where I scattered the daikon seeds)

In the U.S., when we think of radishes, many of us think of the cute little red skinned radishes.

I like those little reds as much as the next guy, but let me tell you something - they do not thrive on heavy clay. And by 'do not thrive', I mean that when I tried growing them, most of them failed to develop anything resembling the round, bulbous shape that the word 'radish' conjures. It was an abject disappointment.

But daikon radishes - sometimes known as tillage radish - is in a different category altogether. In fact, daikon radishes are so renowned for their ability to penetrate compacted clay soils that some people use them as a winter cover crop to aerate the soil (example Delta Farm Press). Note that if you're growing it to amend the soil, the idea is not to harvest the radish, but to allow it to winter kill and then decay in the soil.

Daikon foliage, post-deer (or possibly post-rabbit)

Having just removed some shrubs from a garden bed, I had some bare soil in September and no firm idea what I wanted to plant there yet. I thought I'd do a trial planting of daikon to see (a) if it could make a good cover crop and (b) if I could get any sizeable radishes from the bed for eating.

I happen to enjoy eating daikon radish, for instance sliced and added on top of a salad.

I sowed the seeds (from Sow True Seeds) in September, gave them a couple drinks of water to get started and then basically left them alone to fend for themselves during two months of severe drought that followed.

How did they fare?

Color me impressed. As a cover crop, daikon produced a nice head of leaves that sheltered the soil and blocked weeds. (The leaves are also edible, fyi.)

And the roots actually did manage to penetrate the hard-as-concrete parched clay soil. In fact, the soil was so tight that I had to water the plants just to pull some of the radishes without having them break in the middle.

A couple of daikon radishes pulled from the concrete, er... clay, soil

Now, it's true that my radishes did not reach the mammoth portions of ones grown in sandy-loamy soils. In Japan, where daikon radishes are quite popular, the roots can easily be 12 inches long with the diameter of a baseball bat. My daikons were only about one-third that size, but consider their growing environment and the lack of rain (which would probably have softened the soil and allowed the daikon root to expand deeper and wider), I was quite impressed and pleased with their performance.

How was the taste? I was expecting that the lack of rain would have made the radishes hot and spicy, and indeed the first daikon I ate was almost too hot to handle, but the subsequent ones I consumed generally had just enough bite.

Sliced daikon makes a lovely salad topping

I did run into two problems - deer and rabbits.

The daikon leaves seemed mainly untouched in late October, but throughout November, I saw more and more herbivore damage (and telltale deer droppings scattered around the backyard pointed to the culprits). I figured the deer shouldered all the blame, but late in November, I spotted a well-fed bunny scampering from the radish patch, so I'm dividing the blame among both types of critters.

Still, I can't blame them too much. A nearby wood has been mostly clear-cut this summer, and the drought meant that much surviving wild vegetation was parched, dead or dormant. Finding this green salad bar in my backyard probably seemed like quite a treat - maybe even a life-saving one - for the critters.

I saved some seed and hope to try again in the spring. If we have normal rainfall this winter (the last week has been promising), hopefully there will be plenty of other wild greens for the local herbivores to eat and I'll get a chance to see how the daikon fare without being denuded of their foliage. (Neither the rabbits nor the deer touched the radish root, so technically I could still dig up and eat some of the daikons, but I think I'll let them decompose over the winter to help the soil.)

Overall, I'd say this experiment was quite fun, tasty and successful. So much so, that I plan to grow a lot more daikon in the future. And for any other gardeners out there stuck with heavy compacted clay - consider giving daikon radishes a try!


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