Organic Gardening Info from Peaceful Valley

by Amber TIppett, PV Store Manager & Willow Hein, FreshmanFarmer & PV employee

“Cover Crop” is a general term referring to a crop grown to cover and protect the soil. The term “Green Manure” would more specifically apply to a Cover Crop grown with the intent to till back into the soil. Below we’ve outlined a few Cover Crop Solutions for clay or compacted soils, vegetable bed rotations & erosion control. Looking for more solutions? Check out our Cover Crop Solution Finder.

Cover Crops (or, “Green Manure” crops) for Clay or Compacted Soil

Planting cover crops is an excellent way to help break up compacted and clay soils. Plant something with a large taproot, or deep reaching root system that can penetrate the hard soil or compacted soil pan. Examples of these include Bell Beans (SCL700), Winter Rye (SCN395), Rape (SCN900), Daikon (SCN112) and Mustard (SCN755 or SCN750). You’ll want to plant these cool weather crops in the fall after the first rains when the soil is softer and can be tilled and prepared for planting. The cover crops will grow all winter, and then can be turned in during the spring to add organic matter to the soil. The cover cropped area can then be planted with vegetable or ornamental crops, or planted with a summer cover crop to continue breaking up the soil if it is still too compacted. Examples of good summer cover crops for this purpose are Crotolaria Juncea (SCL815) and Sesbania (SCL855). You will need to irrigate these crops through the summer if you live in an area where it doesn’t rain.

Cover Crops (or, “Green Manure” crops) to plant in a Vegetable Rotation

Planting a winter cover crop is a great way to replenish your soil after a season of vegetable or production cropping. You want something that will fix nitrogen back into the soil, hold the soil in place during winter storms, and grow vigorously for maximum organic matter and weed suppression. Peaceful Valley carries a great cool weather cover crop mix (Soil Builder SCM120, SCM121) which contains bell beans, winter peas, purple vetch, common vetch, and cayuse oats, a blend that addresses all the above-mentioned needs. The bell beans, peas, and vetches are legumes that fix nitrogen from the air through a symbiotic relationship with a group of naturally occurring soil bacteria known as rhizobacteria. The bacteria form nodules on the roots of the plants and convert gaseous nitrogen into plant-usable nitrogen. Be sure to inoculate (ISE350, ISE505, ISE500) your seed with the rhizobacteria before you plant it to make sure this process happens in your cover crop. The oats provide scaffolding for the vetch to climb up and have fibrous root systems that suppress weeds and help with erosion control. Other great cover crops for the winter include clovers and alfalfa.

Cover Crops for Erosion Control

Erosion of hillsides can be a major problem in some areas, and should be a concern to anyone who wishes to protect valuable topsoil. Erosion control mixes typically consist of annual grasses and clovers that have extensive root systems and strong reseeding abilities. The Premium Erosion Mix (SEC300) has wildflowers in the mix to enhance the beauty of the area. Individual varieties of seed for erosion control include Crimson Clover (SCL310), Ryegrass (SCG560), BlandoBbrome (SCG150), and Zorro Fescue (SCG299). Timing is an important issue in establishing an erosion crop. It should be planted in the Fall while the soil is still warm, and be given supplemental irrigation until the natural rains can take over. If supplemental irrigation cannot be provided, the area should be covered with Jute Netting (EC400) after it is seeded. If irrigation will be provided year round, then perennial grasses or clovers can be planted instead of annuals.

A PVFS Customer question – Staff answered:

Question:

I just received your email newsletter which talked about cover crops.   I’m very interested, and I have some questions.

There is a section that talks about hillside erosion control.   Our ‘back yard’ is a hillside, and I would love to plant something on it that would control erosion, but that wouldn’t turn into a weed-eating nightmare in the summer.   We are required to have 100′ in all directions either be green, or no taller than 4″.    It appears that all of these erosion control plants that you mention are around 2′ tall.   Do they turn brown in the summer (which would then require weed-eating)??

Also, I have about 1/2 acre of my ‘garden’ that is not fenced.   I would like to plant a cover crop that will help break up the clay soil, and that will also fix some nitrogen.    I have 2 concerns/questions:    1)  Since that area is not fenced, the deer have discovered the area….   would they simply eat all of the sprouting cover crop down to the nubs??   2)  We cleared and tilled the area last spring, but did not spray it at all, so I’m assuming that the native grasses will start sprouting up again.   Would it make more sense to wait until we get those under control before we try to grow a cover crop??   Otherwise, I’m afraid it will just be overcome by the native grasses.   What are your thoughts?

Answer:

The erosion control mixes we carry are annuals, so they would grow up and green in spring, form flowers, drop seeds, then die and turn brown, requiring weed-eating.  We do carry lower growing plants that can be used for erosion.  If you plan on watering during dry times, you can go with a perennial that will stay green year round.  If you don’t water during dry times, then you can choose a low growing annual (however, unfortunately, even the low growing annuals we carry can grow up to 12″ so sounds like they won’t work for your regulations).  Good low growing perennial choices are creeping red fescue, perennial clover, mini perennial clover-grass mix. To sum up, if you irrigate, you can choose any perennial grass or clover you want since it will stay green year round.  If you do not irrigate, you’ll have to weed-whack (but only once) after the plants have dropped their seeds and dried.  Another option is to go with native grasses.  If you live in a dry area of CA, they generally go dormant in the summer.  I suggest you contact your local Natural Resource Conservation Service (NRCS) for options.

As far as your garden area, 1) deer will graze the green manure crops you grow.  Whether or not they eat it down to the nub is uncertain.  I’d say that if you are planning on fencing the area anyway, you should do it before growing a green manure crop.   2) If the grasses are grown up in that area, ie, the ground is not clear, then yes, you should re-till before planting your cover crop seed.  One consideration is that if the grasses are annuals and they’ve dropped seed, then you have seeds in the soil that will grow up whenever water is provided.  One solution is to clear the area and irrigate while the soil is still warm to let those unwanted seeds sprout, then till the seedlings down.  this can be repeated several times to exhaust some of the “seed bank”.  If you don’t want to do that, then grow the cover crop anyway, it is a good competitor against native grasses that might grow once you start irrigating.

Hope that helps and thank you for growing organically!