Crop Rotation, Cover Crops and More

Packet of Sunn Hemp (Croteleria junicea) seed from my friend Susan Metz. Generally speaking, the best seed of any kind you’ll ever acquire are those from a friend who lives nearby.

Replenish Your Soil with Crop Rotation, Cover Crops and Green Manure

Crop rotation is the practice of growing different types of crops in the same beds from season to season. Different plants use different amounts of nutrients from the soil. For example, corn is a high nitrogen user while legumes such as beans make their own nitrogen. Tomatoes are heavy users of magnesium and nitrogen. In the off-season most organic gardeners either plant cover crops or put compost, molasses and manure on their beds. If you have enough space it is best to do both: grow different crops in the same space from season to season and replenish the soil with organic nutrients before planting a new crop.

The healthier the soil, the better the harvest. Conversely, the poorer the soil, the poorer the harvest. Most of the area of North Texas is part of the eco-region known as the Blackland Prairie. Our soil, while rich in organic matter, is a heavy clay. In order to successfully grow edibles in our area, gardeners must amend to the soil to make it more “fluffy” and not so dense.

Our dense clay soil makes it difficult for roots to pull nutrients and water up to the plant. Thus it can starve a plant to death—regardless how much the plant is watered. To remedy this condition gardeners add substances such as expanded shale and perlite to the soil. These amendments create air spaces in the soil and make it fluffy and easier for the roots to breathe and pull nutrients from the soil to the plant.

Farmers have practiced Crop Rotation for thousands of years.

Farmers have long understood the important relationship between the soil and the quality of the edibles at harvest. For thousands of years in Europe and the Middle East farmers followed a two-field crop rotation. Under this system of crop rotation, half the land was planted in a year, while the other half lay fallow. Then, in the next year, the planting in the two fields was reversed.

Then, around 814, farmers in Europe transitioned from a two-field crop rotation to a three-field crop rotation. Under the three- field crop rotation, farmers divided available lands into three parts. One section was planted in the autumn with rye or winter wheat, followed by spring oats or barley; the second section grew crops such as peas, lentils, or beans; and the third field was left fallow. The three fields were rotated in this manner so that every three years, a field would rest and be fallow.

Under the two-field system, if one has a total of 600 acres of fertile land, one would only plant 300 acres. Under the new three-field rotation system, one could plant 400 acres. But the additional crops had a more significant effect than mere quantitative productivity. Since the spring crops were mostly legumes, they increased the overall nutrition of the people of Northern Europe. [Source Wikipedia]

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My Sunn Hemp seeds on a damp paper towel. Inoculant I ordered from MBS in Denton should be here in a couple of days.

Sunn Hemp—A Cover Crop Is Coming to the Garland Community Garden

This week I am planting the sunn hemp Seed that Susan Metz, a local farmer and A&M educated agricultural researcher, gave to me. [Note: Sunn Hemp is a member of the Crotalaria genus and is legal to grow; therefore there are no concerns about the appropriateness of its use as an agricultural crop. The Crotalaria genus has 600 known species all with varying characteristics. Please see this USDA article for more information. http://www.seedland.com/seedland/info-PDF/sunn-hemp.pdf ]

In late August we will pull up the sunn hemp, chop it up into small bits and then spread it on top of the bed like topsoil. After preparing the bed in this manner we will plant a winter crop of turnips, beets, cabbage, broccoli and kale. The soil will not require fertilizer and there should be no weeds.

Sunn Hemp has many advantages.

Sunn hemp originated in India where it has been grown since the dawn of agriculture. It has been used as a green manure, livestock feed, and as a non-wood fiber crop. It has also been grown in Brazil and Bangladesh as a soil-improving crop. It matures 60 to 90 days from planting at around 6 ft tall -- this may increase under proper conditions, to a height of 10 -12 ft. This means around the first of September we can cut it down and use it as green manure for our winter garden.

Sunn hemp (Crotalaria juncea L.) is a legume that when grown as a summer annual can produce over 5,000 pounds of biomass and over 100 pounds of nitrogen per acre.
Moves a minimum of 10 lbs of residual phosphorous from the subsoil to the topsoil -- this can be as high as 20 lbs
Moves around 80 lbs of residual potash from the subsoil to the topsoil -- under favorable conditions this may increase to 160 lbs
Suppresses rootknot and nematodes as well as weeds!
A great soil builder, increases drought tolerance and yield and cash value of the next crop
The leaves of Sunn Hemp contain 30% protein
Food plots -- Deer love the leaves; turkey and quail love the cover provided; Livestock will eat the dried leaves or 'hay'.
When properly planted Sunn Hemp will eliminate weeds -- an advantage for food plots and farmers alikeInoculate the Seeds

Inoculate Seeds

Raw Sunn Hemp seed will thrive with cowpea-type rhizobia bacteria.

The inoculant can be purchased at a quality garden store. You can spread inoculant on an old dinner plate and, after soaking the seeds, roll them in the inoculant. But you can also sprinkle the inoculate right from the can after laying the seed in its furrow and before covering with soil.

There are several types of Rhizobium bacteria and most are plant specific when setting up symbiosis. The bacterium that works together with beans and peas is Rhizobium leguminosera. I have never inoculated my bean seeds. I might try next year and see what happens. However, a friend of mine mentioned that she inoculated her bean seeds last year and could not tell any improvement in the production or general health of the plants.

I’ve read that inoculation is recommended when the field has no past history of growth of your particular legume, or when you have a high value crop for which you want to ensure successful growth. Often, inoculant rhizobia can remain viable in the soil without the presence of a legume for a few years, and then be ready to form nodules when its host plant is sown.

Specifically, inoculation is recommended if the field has been out of host plant production for 3–5 years, or never planted to the host. Further, inoculation can help increase rhizobia populations in fields with unfavorable environmental conditions for the bacteria's long-term survival.

Take care of your inoculants. They are Alive*

Inoculants come in many forms, but the most common is as a bacteria-infused peat that has a black, dust-like appearance. The bacteria on the peat particles may not look like much, but they are indeed alive, and should be treated with care. Although peat has been shown to mediate unfavorable conditions such as high temperatures and long storage times, certain precautions are necessary in order to increase inoculant effectiveness.

Inoculant packages come with an expiration date that should be heeded—use of an inoculant past its expiration date could mean that you are adding bacteria to your seed that are not alive or healthy. Treat the inoculant as you might treat a living organism—don’t leave it in the sun for extended periods of time, and store it in a cool dry place when not in use, such as a refrigerator. Many manufacturer recommendations offer a suggested temperature of 40°F.

Inoculants can be added to the soil or directly to your seed prior to planting.

*Source:

http://articles.extension.org/pages/64401/legume-inoculation-for-organic-farming-systems - accessed May 17, 2017