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How can I make best soil mix for new raised beds?

Posted by jimigunne 9A (My Page) on
Sun, Dec 25, 11 at 7:33

I am putting in 5 4x8 ft x 8 in. raised beds for all types of vegetables. The soil on the property I would say is a loam...not much clay or sand.Its very dark, close to black. Haven't had it analyzed. I plan to dig up some of that soil where I am going to put a pond in, and then amend it for optimum vegetable garden use. Any recommendations on what to mix in with it? I guess some sphagnum peat moss would help, but how much and what else? Its going to be 100% organic. I will also be brewing compost tea for application in the beds. Thanks all!

Follow-Up Postings:

RE: How can I make best soil mix for new raised beds?

It's best to get a soil test through your county extension. If you want to get pH of your soil quickly, boil 50 cents of red cabbage for 10 minutes in DISTILLED WATER. Strain off the purple juice, and disolve 1 tablespoon of your soil while the juice is warm. Compare the change in color with vinegar (pH 3), MiracleGro potting soil (pH 6.5), and baking soda (pH 9). If the cabbage juice changes to bluish purple in your soil, then it's alkaline. If the cabbage juice is pinkish, the same color as MiracleGro potting soil, then your soil is acidic.

If your soil is acidic - do not add peat moss (pH of 4). If your soil is alkaline, peat moss is great. A big bag of alfalfa meal from the feed store costs around $10 to $15, with pH around 5, and would add NPK of 2-1-2 to your bed. It has the root-stimulating growth hormone, and would help in rooting.

A good place for a quick soil report is EarthCo.($30 for all tests, inclusing magnesium, calcium, and micronutrients), or your local extension, or a nearby university. Loam soil is usually neutral in pH, but it's best to get tested for micronutrients as well.

RE: How can I make best soil mix for new raised beds?

Contact your counties office of your state Agricultural Universities Cooperative Extension Service about having a good soil test done (usually in the $6.00 to $15.00 range). These simple soil tests,
1) Structure. From that soil sample put enough of the rest to make a 4 inch level in a clear 1 quart jar, with a tight fitting lid. Fill that jar with water and replace the lid, tightly. Shake the jar vigorously and then let it stand for 24 hours. Your soil will settle out according to soil particle size and weight. A good loam will have about 1-3/4 inch (about 45%) of sand on the bottom. about 1 inch (about 25%) of silt next, about 1 inch (25%) of clay above that, and about 1/4 inch (about 5%) of organic matter on the top.

2) Drainage. Dig a hole 1 foot square and 1 foot deep and fill that with water. After that water drains away refill the hole with more water and time how long it takes that to drain away. Anything less than 2 hours and your soil drains� too quickly and needs more organic matter to slow that drainage down. Anything over 6 hours and the soil drains too slowly and needs lots of organic matter to speed it up.

3) Tilth. Take a handful of your slightly damp soil and squeeze it tightly. When the pressure is released the soil should hold together in that clump, but when poked with a finger that clump should fall apart.

4) Smell. What does your soil smell like? A pleasant, rich earthy odor? Putrid, offensive, repugnant odor? The more organic matter in your soil the more active the soil bacteria will be and the nicer your soil will smell.

5) Life. How many earthworms per shovel full were there? 5 or more indicates a pretty healthy soil. Fewer than 5, according to the Natural Resources Conservation Service, indicates a soil that is not healthy.
may be of some help in determining what you have.

A good soil for plant growth will have between 5 and 8 percent organic matter.

RE: How can I make best soil mix for new raised beds?

Some good helpful info there! I did obtain a digital PH meter, and the soil tested 6.5....pretty much neutral. So does this indicate I shouldn't add spagnum peat moss, as (I think) it's best to maintain the PH where it is for growing a variety of veggies? I will definitely get a soil test done, in my case it would be through the Texas A&M extension service in College Station....that is unless the Earthco price beats theirs.

RE: How can I make best soil mix for new raised beds?

Thank you, Kimmsr, for great info. - I appreciate your helping garderners for the past several years. I agree with Kimmsr that earthworms indicate good organic matter. There were tons of earthworms where I dumped grass clippings. My soil tested high in organic matter by EarthCo.

It's important to get calcium and magnesium tested, before dumping epsom salt (magnesium sulfate) as recommended for veges. My alkaline clay soil tested exceedingly high in magnesium, and barely adequate in calcium.

Peat moss has zero nutrients, but is useful in breaking up heavy alkaline clay soil like mine. Peat moss put on top of soil blocks out water, but when mixed well with soil helps to retain water. It's not recommended for soil pH lower than 7, since most veges grow best at pH of 6 to 7, except for tomato that grows well at pH of 5.5 to 7.5.

RE: How can I make best soil mix for new raised beds?

Most all plants will grow best in soils with a pH of 6.2 to 6.8 because that is where most all nutrients are most readily available.
Texas A & M charges $10.00 for a basic soil test, more for more things, so be sure you compare apples to apples when looking at the prices for soil tests.
If you live where there are a lot of tree leaves to use there is no good reason to spend money on peat moss.

Here is a link that might be useful: Chart of nutrient availability

RE: How can I make best soil mix for new raised beds?

Kimmsr, thanks for that chart. That made me more conscious of the need for nitrogen in alkaline soil. The biggest annoyance of alkaline soil is the nitrogen-fixation weeds: those stringy weeds around my evergreens. They went away when I dumped blood meal.

The chart shows high phosphorus in alkaline soil, that's correct - but only for plants' roots that can secret enough acid to extract phosphorus at the high pH range. Despite the info. on the chart, my alkaline clay soil is exceedingly high in magnesium. The chart is right about my soil tested barely adequate in calcium (I think it's tied up with phosphorus).

Blood meal is excellent in nitrogen NPK of 12-0-0, and it has iron as well. It's lower in salt than chemical fertilizers. There's the risk of mad cow disease from using blood meal, and the rosarian Karl Bapst suggested using pigs' blood from slaughterhouse, which is an excellent source of nitrogen and iron, without the risk of mad cow.

RE: How can I make best soil mix for new raised beds?

Bone meal was once suspected as a vector for Mad Cow Disease too. Several rose gardeners in England had seemingly no other route of exposure. I wonder if that was eventually discounted.

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