Category Archives: Soil Amendments

Round Robin Discussion on Green Manures and Cover Crops

We were very sorry that Dot Perkins could not join us to lead our workshop about cover crops for our August. Unfortunately, she had severely injured her knee and could not manage to make it to the meeting. We hope she recovers quickly and is “good as new” very soon!

Buckwheat is a green manure/cover crop that can be planted in bare spots after harvest.

We soldiered on with a lively round robin discussion sharing our collective experiences and knowledge about cover cropping. Here is what we learned…

• A cover crop is essentially a green manure that you grow to till back into the soil. Cover crops enrich the soil, preserve nutrients and prevent soil erosion that comes from leaving the soil bare.

• Not all cover crops are good for home gardeners! Many cover crops require heavy farm equipment to till the crop back into the soil. Home gardeners require cover crops that are easy to cut down and dig back into the soil by hand. Here are a few suggestions…

Spring: The perfect cover crop for the early spring is Peas! Plant ordinary garden peas all over your entire garden in the early spring. Harvest your peas and dig in the plants. They create a really beautiful soil for your summer crops. If the peas aren’t ready to harvest and you are ready to plant other crops, simply dig in the plants. The plant material is a wonderful nutrient for your soil.

Summer: Buckwheat was highly recommended as an excellent summer cover crop. It does not require much water and it tolerates poor soil fertility. The stalks are tender and brittle and can be easily cut down with a scissors or yanked out by hand. Buckwheat is inexpensive (you can find it at Agway or Blue Seal) and it germinates very quickly. It is a good weed suppressant. Cut down the buckwheat before it starts flowering and  setting seed. Once cut down or pulled up, dig into the soil. It decomposes within a week so that the home gardener can plant quickly and creates a fine textured soil that is perfect for new seed beds.  Click here for more information about Buckwheat.

Spring and Summer: Mustard has also been recommended as a good cover crop to nourish the soil and suppress weeds. Plant around all of your plants and harvest as needed or simply cut and lay on top of the soil as a mulch. Replant as needed.

•Late Summer/Fall: Winter Rye or Rye mixed with Vetch are good cover crops for overwintering. Plant in the fall after you harvest the last of your crops. In the very early spring, you will see a hint of green as the rye begins to sprout. DIG IN RIGHT AWAY! It grows quickly and will become more difficult to dig in as it gets larger.

Cover Crops for Weed Suppression…

Rye or Rye plus Clover: Gardeners have had good success with growing rye or rye combined with clover to smother out weeds and nourish the soil in problem areas. In the spring, dig or rototill the weedy areas and then broadcast the  seed like grass seed. Keep the area mowed over the summer so the plants don’t set seed. The following spring, dig in as soon as you see the rye beginning to green and wait a couple of weeks to plant. Your new bed will be nourished with the green manures and mostly weed-free.

Comfrey’s many uses in the garden…

Comfrey is a plant that is extremely useful in your garden. You can use it as a mulch, compost activator, liquid fertilizer and soil amendment. HOWEVER…be careful when planting because comfrey can take over your garden! Ask around and  you will most likely have a friend who has some comfrey running rampant in their garden and is more than willing to have you harvest it.

Here is a link for more information about Comfrey

Final note…

I was so pleased with how much knowledge the gardeners had to share at the meeting. We all learn so much from each other and really benefit by sharing our experiences!  I also want to mention that the children had a wonderful time creating beautiful terrariums with the Lisa Aquizap and her Green Team.  The kids have been having a blast!


May Meeting Summary: Soil and Soil Amendments

Soil Amendments

Get ready to dig in some amendments to your soil!

by Eleanor Baron

Gardeners in attendance at the Capital City Organic Gardeners May 19 meeting enjoyed an overview of soil structure and biology, and received basic recommendations for creating healthier soil through use of soil amendments. Extension Educator Amy Ouellette tailored her presentation to organic soil-building techniques and provided valuable insight into understanding soil test results.

A basic overview of soil demonstrated that soil’s main purposes are to anchor plants, provide a reservoir or 16-18 nutrients and allow for water and air exchange. The ideal soil will be comprised of 25 percent water, 25 percent air space, 2 to 5 percent organic matter and 44 to 48 percent minerals (weathered bedrock). Soils in New Hampshire are very variable in composition because of the random nature of glacial deposits throughout the state.

Soil separates into clay, silt and sand particles. Because sand particles are many, many times larger than clay, the resulting surface area is many times greater. Therefore, sandy soil requires smaller quantities of soil amendments than clay soil to achieve a desired change. For this reason, Amy advised against gardeners limiting their soil testing to use of a pH test from the garden center. Without knowing the exact soil composition, it’s impossible to know the right quantities of amendments to use; a full soil test will recommend specific amounts.

Soil pH, a measure of hydrogen ions, is an important indicator of the soil’s ability to absorb and pass along nutrients to plants. If pH is either too high or too low, nutrients will simply leach away, unused by the plants that need them to thrive. Most of the elements that are needed for plants to grow are chemically most available between a soil pH of 6.25 and 6.75. New Hampshire soils tend to be acidic (low pH), because of granite content, and should be treated with dolomitic limestone (which contains calcium carbonate and magnesium carbonate) or wood ash to raise the pH. To lower the pH (for example, for blueberries), add elemental sulfur.

Soil organic matter is a critical component of overall soil health. Microorganisms, dying plant roots and small animals living in the soil all contribute to nutrient cycling, create air spaces and add materials that hold soil together. Leaving roots when harvesting plants contributes to building organic matter. Adding compost and composted manure is an excellent way to build up soil organic matter. Amy advised caution when using horse manure, due to the high carbon content of the wood chips or straw that are usually in the mixture. The high carbon to nitrogen ratio leaves the nitrogen unavailable to the plants. It’s best to compost horse manure separately and add it when fully composted.

Use composted animal manure carefully to avoid increasing the soil’s phosphorus levels too much. Amy pointed out that many organic gardens have soil with too much phosphorus, because of over-reliance on animal manures. (Compost made from all vegetable matter is not high in phosphorus.)

In summary, organic matter adds nutrients, allows the soil to hold water and contributes to the nutrient cycle. Maintaining good organic matter content in soil helps to prevent erosion, as does practicing gardening methods that leave soil undisturbed.

Although testing soil in the spring (or at any time) is a good idea, Amy advised adding soil amendments to correct pH in the fall When ideal soil pH has been achieved, legume cover crops should be used to help to maintain soil health.

New Hampshire soil is generally not ideal for growing vegetables and requires use of soil amendments to make it ideal. Achieving optimum pH will allow soil to hold and transfer nutrients to plants. Building up the soil’s organic matter will create a living, breathing soil structure with a life-giving nutrient cycle that’s sure to grow beautiful and nutritious garden vegetables.

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