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  • From: "TradingPostPaul" <tradingpost@riseup.net>
  • To: livingontheland@lists.ibiblio.org
  • Subject: [Livingontheland] tomatoes in vetch mulch?
  • Date: Wed, 23 Aug 2006 17:26:59 -0600


A USDA-devised mulch system is revolutionizing tomato farming
http://www.doityourself.com/stry/tomatovetch

If you're weary of purchasing fertilizer and mulch for your tomatoes every
season, here's a way to get off that treadmill. Instead of buying, grow all
that you'll need of both, during the off-season.

The technique is very simple. In late summer or early fall, you make a bed
or beds for your tomatoes. Then sow the very hardy annual legume called
hairy vetch, Vicia villosa. In spring you kill the vetch by simply cutting
it close to the ground, and then lay it in place on the beds. Then set the
tomato transplants right through the mulch.

That's it. Nothing to buy, and no need to dig, hoe, or weed. Do your
regular staking, pruning and watering, and the tomatoes will thrive until
it's time to replant the vetch in fall, and yields will be as good as those
you get with the method you are now using, and likely even better.

High yields, much less tilling and digging, and no need for compost, manure
and other nitrogen fertilizers: If that sounds to you like a major
breakthrough, you are not alone. This system has performed so well in USDA
tests in Beltsville, Maryland, that researchers and farmers all over the
country are trying it and expanding it to other crops.

Hairy vetch is hardy enough to grow in the far north (USDA Zones 5 and
colder), the season length in those zones is too short to permit easy
exploitation of the technique. In general, the hairy vetch-tomato rotation
described here most readily adapts to gardens in zone 6 and warmer.

Beyond Plastic Mulch

This planting system evolved out of a search for an alternative to plastic
mulch, which worked like magic on tomatoes. As a matter of fact, over the
last 40 years, plastic mulch has radically altered vegetable growing, both
for farmers and many gardeners. But plastic brings problems. It is
expensive to buy and difficult to dispose of in a responsible way.
Commercial growers have begun to complain loudly, especially about the
disposal problem.

A few years ago, Dr. Aref Abdul-Baki and his colleague Dr. John Teasdale,
horticulturists with the Agricultural Research Service in Beltsville, began
thinking about the plastic-mulch-and-tomatoes problem and how to solve it.
The most obvious benefit of plastic is the soil heating that advances
harvest by one to two weeks. But plastic mulch also increases total yields,
and it does that by keeping the ground moist and blocking weeds. The
researchers realized that any organic mulch could perform these two
functions just as well as plastic does, and probably better.

Good vegetable gardeners already know that. We mulch our tomatoes with
leaves, grass clippings, hay, straw, compost or whatever, and the results
are great. But Abdul-Baki and Teasdale were thinking more about farmers,
who would want to know exactly which mulch is ideal, where to get it cheap
and how to put it on fast. If the researchers were to suggest the farmers
use shredded leaves, straw or compost, they would probably reply, Just what
we need! More work and more stuff to buy! We'll keep the plastic and its
early yields, and deal with the other problems as best we can."

So the researchers began to look for mulches that farmers could grow
themselves in the off-season, so mulch-growing wouldn't tie up valuable
ground. And they pretty quickly settled on the idea of a winter-hardy
annual, something that was easy to kill in spring and could maybe even be
grown right where the vegetables would be planted. The method worked well
from the start, and the best plant, in most regions, turned out to be hairy
vetch.

The tomato-vetch trial plots, using no nitrogen fertilizer and without any
weeding, have consistently outyielded plastic-and-fertilizer plots by about
25 percent, and fertilized bare soil by 100 percent.

Vetch Better than Plastic-plus-Fertilizer

Both systems provide plenty of nitrogen for a tomato crop, and both mulches
keep the soil moist and eliminate weeds. But the vetch mulch, combined with
less tilling, steadily improves the soil structure and the number of
microbes, worms and other soil organisms at work. The thick mulch also
keeps the soil evenly moist and cool, so roots can explore it thoroughly in
their search for nutrients. The healthier root systems are better able to
make use of available water and minerals so yields are much higher.

Vetch produce plenty of nitrogen for tomatoes, between 150 and 200 pounds
per acre. About half of that is available to the tomato crop the first
year; the other half remains bound up in organic matter and is used by the
crops that follow. The nitrogen in decaying organic matter becomes
available slowly and steadily through the season, more when it's warm and
less when it's cool, down to about 50 o F.

Adding chemical fertilizers, on the other hand, doesn't improve the soil.
Once rain or irrigation leaches them away, they're gone for good. With the
plastic-mulch test plots (and on the bare-ground plots, too), nitrogen is
applied once a week through drip lines buried two inches deep. That's a
more efficient way to apply fertilizer than spreading it before planting,
but even so, nutrients are delivered only in the zone that is wetted by the
emitters. With the vetch-mulch system, the organic matter supplying
minerals to the roots becomes part of the topsoil of the entire bed.

Start This Fall

Vetch needs to grow for about a month before the very hard frosts (about 22
o F) shut down everything in the garden, often around the same time that
most deciduous trees are losing their leaves. That means you should plant
the vetch one to three weeks before the very first fall frost. You want the
plants to get at least four inches tall before they stop growing for the
season, though in warmer regions the vetch can keep growing all winter.

Abdul-Baki and Teasdale say that the success of the system depends on using
a legume that grows well in your climate to give you the most nitrogen and
the biomass you need for weed control and soil fertility. In most places
that will mean hairy vetch, which is the most widely adapted winter-hardy
legume. It grows quickly in fall, overwinters even in the Far North, and
then starts regrowing quickly in the spring. But wherever it's quite warm
in the fall when you want to plant (as in parts of zones 9 and 10), other
legumes like crimson clover or subterranean clover may do as well or
better. Consult your extension agent to confirm which winter legumes have
proven themselves in your locale.

After you prepare a seed bed in your future tomato plot, plant the vetch,
either by broadcasting or in shallow furrows at the rate of an ounce of
seed per 10 square feet. The researchers plant in rows, seven of them
across the four-foot-wide bed, or about six inches apart.

The vetch begins to grow again in earnest early the following spring. By
the time the weather's warm enough to plant tomatoes, it will be three to
four feet tall and beginning to flower. The day before planting tomatoes,
use hedge shears or a hand scythe to cut the vetch an inch or two above the
ground and lay it in place on the bed. You should end up with a dense mulch
that is four to five inches thick. It is important to cut all the vetch and
cover the stubble. Stragglers that survive can become tangled in the tomato
plants. Plant the tomatoes down the middle of the bed by parting the mulch.
Set the plants in place and then tuck the mulch back around them.

Where weekly rainfall is not dependable, it is important to irrigate over
the vetch mulch. About 85 percent of the nitrogen in the vetch is in the
tops, with the remaining 15 percent in the roots. When cut at the prebloom
to bloom stage, vetch is very tender and decays readily, but it cannot rot
and release its nutrients without moisture. The researchers lay drip
irrigation down the center of the bed on top of the mulch to speed up its
decomposition. In gardens, wetting the mulch with a sprinkler of some kind
would be ideal. "We are developing a farming system, so we use drip tape,
which wets the mulch at individual points," says Dr. Abdul-Baki. Drip
emitters that deliver a small spray either in circles or half-circles are
available.

The researchers use the stake-and-weave method of training the tomatoes
(set a stake every two plants and weave twine back and forth around the
stakes and plants). But you can use any tomato training method you like.
Enjoy the harvest and the freedom from feeding and weeding that the
vetch-mulch method provides. By the end of the season, the mulch will have
decayed so much that only traces remain. Some late-season weeds may begin
to poke through, but they are easily pulled or cut by hand in the soft
soil. Besides, it's almost time to plant vetch again.

Before the first light frosts arrive, prepare to plant more vetch,
disturbing the soil as little as possible. Cut the tomato plants and take
them to the compost pile. Pull or lightly cultivate to destroy any small
weeds. Then plant vetch seed, either in furrows or by broadcasting.

Beyond Tomatoes

Abdul-Baki and Teasdale have some plots where they've been growing vetch
every winter and tomatoes or other vegetables every summer for four seasons
now. Any vegetable that is grown from transplants or has large seeds will
work well in this system. Cucumbers, squash, melons, peppers, eggplant,
sweet corn and even green beans are candidates. Preliminary work at
Beltsville and elsewhere hints at success that will equal the results with
tomatoes. It's a good idea to rotate tomatoes with other vegetables.

The method is not for all crops. Small-seeded, closely spaced vegetables
like beets, carrots and lettuce would have trouble growing through the
thick mulch. Where the season is very short or when you really need the
extra 10 to 14 days that only plastic mulches can provide, then the
vetch-mulch method may not apply.

But surely there is a place somewhere in your garden for this hardy and
productive legume that does so much growing while you are waiting for
things to warm up enough to plant the main-season vegetables. If we can all
start growing at least some of our own mulches, we won't have to work so
hard to find the right materials, then haul them home.

"This is the production method of the future," says Dr. Abdul-Baki. "And I
think it can work as well for gardeners as for farmers, maybe even a little
better. All I want is for gardeners to try it, on just one bed. Try it and
make the judgment for themselves."

Jack Ruttle is a former senior editor at National Gardening.
------------------

paul tradingpost@lobo.net

Beware of all enterprises that require new clothes.
--Henry David Thoreau






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