Turning over cover crop
 

How long does it take winter rye and hairy vetch to decompose for transplants to benefit?

Here's an interesting article on organic nitrogen sources and their availability: [url]http://horttech.ashspublications.org/content/17/4/431.full.pdf[/url]

About four pages in there's a graph that illustrates the nitrogen availability from a turned-in cover crop. Availability follows a bell curve and looks like it peaks at about 3 weeks. Most sources advise planting tomatoes 2-3 weeks after you've turned-under the crop. By doing this, the N needs of the tomato and the N availability of the CC will be asynchronous. In other words, you'll be missing most of the nutritional benefit of the cover crop.

Great article! Already answered some questions I had and I'm only half way through it. Thanks so much for posting it.

ginny

Winter rye decomposes at about the same rate as straw (in fact one can
buy rye straw some places that sell wheat straw, oat straw, etc). Hairy
vetch decomposes more quickly (a lot less cellulose, more nitrogen
in the top growth). Winter rye does a better job of filling the soil with
roots and preventing erosion, and it recycles nitrogen that may have
been left over from the previous crop, releasing it more slowly as it
decays than vetches.

When growing winter rye alone, I usually mow it and use it for mulch
rather then turning it into the soil. It is tall, stiff, and awkward to turn
in with a shovel. It also has allelopathic effects on small-seeded weeds
that may interfere with direct seeding of some vegetable crops if it
is incorporated into the soil before seeding. (No big deal if you have
a plow, where you can just cover it with a layer of dirt and seed in that.)

Thanks for the article. It was very helpful. I'll be delaying the turning schedule now.

I have a question about this.
In the heat of summer, I might have some unused garden space. I was thinking about trying something heat tolerant and fast growing as a cover crop. Maybe southern peas. First of all, can I harvest the peas before tilling in the green stuff and still get the nitrogen?
Also, how much time should I plan, say for an early southern pea like pinkeyes? Before planting the next crop?
Should I mix them with something else like buckwheat or sorghum for maximum results?

Yes, you can harvest peas before incorporating the top growth into
the soil. A lot of the nitrogen contribution is fixed on their roots by
bacteria if they have been inoculant-coated before planting or if
the same bed has grown those or other legumes that the same
bacteria fix nitrogen on the roots of (if there is holdover nitrogen-fixing
bacteria in the soil compatible with pea-vetch-fava-bell_bean roots).
I expect that any fruit on the plants are only a small part of nitrogen
contribution from turning in the crop.

What the article above was saying was that maximum nitrogen release
from the incorporated cover crop was 2-3 weeks after turning it into
the soil. If you are planting seeds into it, you probably want to plant them
asap, so that they at least sprout before you reach that point. If planting
transplants, you probably want to wait no more than 2 weeks. (That
2-3 weeks probably varies with the cover crop.)

Buckwheat does not fix nitrogen on its roots, but it does exude enzymes
that make phosphorus in the soil more available to subsequent crops.
Mostly it contributes lots of organic matter. (There is some nitrogen
contributed by the leaves as they break down, but it may not be more
than what soil bacteria digesting the rest of the plant require.)

I do not know anything about the crop timing of southern peas in hot
climates. Winter peas (a kind of field pea I guess) are a fairly useful
winter cover crop in warm climates, but summer peas in such areas
probably have different planting and harvest timing.

Thanks, Dice! Southern Peas are incredibly heat tolerant. I'll probably plant them in one of my gardens when one of the spring crops ( like tomatoes) dies due to heat. Pink eyes are a pretty fast crop. I could also do long beans, they are very similar and we enjoy them as a green bean alternative since its too hot in the summer time to grow green beans. Hate to keep a garden empty and summer is our most difficult growing season, much like winter in the north.
I could also grow okra and shred the stalks but we simply don't need that much okra. A few plants is more than enough. Plus, the extra nitrogen will be nice before planting brassicas and lettuce in the fall.

Planting cowpeas in the unbearable part of the summer is exactly what I did this year, and it worked out so much better than I could have imagined. Like most legumes, cowpeas start off slow, so I was a little dissapointed at first. After about a month though, they really took off. No real disease or pest problems, laughs at the heat, and lots of fresh "green beans". I used mung beans as well which also did fantastically (just used grocery store seed for both). Cut them down by hand with trimmers. The only problem I saw was that the stalks take a while to decompose. I covered them with mulch before I planted my fall tomatoes, but that was mostly for aesthetics.

One of the most over looked cover crops is the radish which is completely grown in 30 days. If planted close in the spring or fall it can be turned under quick or if left in the ground till spring the radish itself under the ground turns under nicely! I grew a 10 by 50 area of sunflowers this year that are huge and will make agreat amount of compost material! The leaves alone are great for compost but you also have for the bottom 3 inch in diameter stems. The seed flowers after the seeds are gone can be ground or just thrown into the compost!
+++
Lots of birds add much nitrogen with their droppings! I mean hundreds of birds come to eat the seeds. The seed hulls are all over the ground spread by the birdsamke good mulch for the ground! I over did it this year but next year I will make a less wide row of abut2 feet by a 100!. The flowers are also nice to look at with over a 1000 flowers of all sizes and colors! I will also put a row of clmbing beans and peas along the 100 foot row to climb up the sun flowers!

Careful with sunflower residue, as it's allelopathic. The seed husks in particular are very strong - you can make a tea from them to use as an herbicide.

I'm going to try daikon radish this year as a "tillage radish".

Thanks I will keep a eye out for that!

[QUOTE=bobberman;302327]One of the most over looked cover crops is the radish which is completely grown in 30 days. If planted close in the spring or fall it can be turned under quick or if left in the ground till spring the radish itself under the ground turns under nicely! I grew a 10 by 50 area of sunflowers this year that are huge and will make agreat amount of compost material! The leaves alone are great for compost but you also have for the bottom 3 inch in diameter stems. The seed flowers after the seeds are gone can be ground or just thrown into the compost!
+++
Lots of birds add much nitrogen with their droppings! I mean hundreds of birds come to eat the seeds. The seed hulls are all over the ground spread by the birdsamke good mulch for the ground! I over did it this year but next year I will make a less wide row of abut2 feet by a 100!. The flowers are also nice to look at with over a 1000 flowers of all sizes and colors! I will also put a row of clmbing beans and peas along the 100 foot row to climb up the sun flowers![/QUOTE]

Is this the regular, small radish, like Cherry Belle, or some other kind?

Ya the regular radish. you can buy them cheap by the pound fron shrumway! you can save the seeds also!

I like the radish idea. Also, chard or spinach. Since we can always eat more greens. Mustard also has a long season here.
I have a lasagna garden still being built in a bad spot with too much shade and I can't seem to get it filled enough for anything. Maybe I'll throw some chard, spinach, favas, etc for the winter. This will give it something that may do okay in the lower light, then I can finish filling it this spring and use it for things that require shade next spring.
Last fall, I planted a bunch of mustard seed from a spice store in an area I was starting to plant for flowers. It gave me greens for the chickens and really opened up the rock hard soil. The mustard did amazingly well with no tilling or water.