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Learning from a Soil Test

28 February, 2021 by amygwh Leave a Comment

front of a soil sample box for Mississippi State Extension soil testing lab, showing mailing instructions

I finally sent off a couple of soil samples to the state testing lab. The soil here is new to me (sand, not north Georgia’s red clay), and last summer’s garden was less productive than I had hoped. Getting a baseline set of measurements will boost my understanding of what the soil needs to produce more good food.

logo for Mississippi State Extension

The routine test for home gardens provides quite a bit of useful information, but I also paid for a couple of extra bits, the organic matter content and percent nitrogen. One sample that I sent in (labeled Veg) was a composite of two scoops each from seven garden beds. The other (labeled Fruit) was a composite of several scoops taken down the length of a newly-dug 6×30 foot bed that will be home to some berries and other small fruiting plants.

The results came back, and they contained some surprises. Here is the information in table form:

 ComponentVeg — 7 garden bedsFruit — one garden bed
pH6.4 5.4
Phosphorus (P)353 lbs/acre (very high)104 lbs/acre (high)
Potassium (K)171 lbs/acre (low)39 lbs/acre (very low)
Magnesium334 lbs/acre (very high)79 lbs/acre (high)
Zinc28.6 lbs/acre (very high)22 lbs/acre (very high)
Calcium2331 lbs/acre496 lbs/acre
Soluble Salts0.1 (low)0.1 (low)
% Organic Matter4.23.6
% Nitrogen0.160.11

What this all means

Seeing the numbers for the two areas side-by-side makes the differences stand out, but I will go over the components measured, one by one, to explain how I am using the information.

pH

For both samples, pH was on the acid end of the spectrum. The pH of 6.4 for the Veg sample is excellent for most vegetables, and no additions of limestone were recommended for that set of garden beds. However, the pH for the Fruit sample, at 5.4, was too low, too acidic, for many fruits. Blueberries will be happy at 5.4, but not much else. The Fruit test results came with a recommendation to add limestone: 75 pounds per 1000 square feet, to bring that pH up a bit.

The surprise here is that I had used a simple, home pH test kit last spring on part of the vegetable garden area. The pH as measured with the kit was at least 7 (neutral) or possibly higher. The pH kit relies on color-matching, and it seemed to me that my sample could have been between the colors for seven and eight.

We did find, though, when digging the beds, a couple of the plastic tags that come with tomato plants, that tell which variety they are. This suggests that a previous owner also had a veggie garden in this area, and they probably added lime to bring up the pH. Last spring, the soil sample for measuring the pH was from just a couple of beds, because it took awhile to get them all dug. It is possible that the new sample, a composite from seven beds, includes a mix of high and low pH areas.

I will need to check the pH of each of the seven planting beds to figure out which have a higher pH and which have a lower pH. Some may need a little limestone to improve the pH.

Phosphorus

Just wow. Neither of my planting areas needs any more phosphorus, possibly for years. These came back High (Fruit) and Very High (Veg). It may seem as though having high nutrient levels would be a good thing, but high levels of phosphorus can interfere with a plant’s ability to take up micronutrients, like zinc, that it may also need for good growth and productivity. The Texas A&M article Phosphorus — Too much and plants may suffer indicates that phosphorus levels above 150 ppm may harm plant growth, and levels above 350 ppm can kill some plants. It may be a miracle that my garden has been able to support any crops at all!

The high phosphorus levels mean that I should avoid composts that include manures, especially chicken manure, since those can add extra phosphorus to the soil.

My fertilizers also need to be low on phosphorus. Most fertilizers are labeled with the percentages of nitrogen, phosphorus, and potassium they contain. These are listed in that order, as N-P-K (nitrogen-phosphorus-potassium). That middle number, for my garden, needs to be as low as possible. The good news here is that one fertilizer that I keep on hand is a fish fertilizer labeled 5-1-1. This product offers plenty of nitrogen with a low amount of phosphorus.

Potassium

Measurements for potassium (K) came back low for both areas.

My 2018 article about potassium sources for organic gardens describes pros and cons of several potassium sources. In addition, my Garden Planner and Notebook contains, on page 12, a list of some commonly available organic fertilizer ingredients and what nutrients each one provides. Looking down the list, I can see that greensand is the one I will want to use.

Wood ashes add potassium but also can raise the soil pH. Since the “soil” here generally seems to have a low pH, that is not a drawback. The issue is more one of finding the wood ashes. Kelp meal would be a possible source to try, except that it can also add phosphorus, which I need to avoid. And, sul-po-mag brings magnesium with it, which the garden also seems to have in abundance.

Magnesium

Measurements for magnesium content for both planting areas came back as high (Fruit) and very high (Veg). No magnesium is needed, apparently, even though epsom salts (a magnesium source) did seem to help last year. I wonder whether the super-high levels of phosphorus made it harder for plants to use the magnesium that was already in the soil

Alternatively, it is possible that the magnesium in the soil was tied up somehow, bonded in a way that made it less available to the plants. Also, if the soil pH is very low, plants are less able to take in nutrients they need, like magnesium, phosphorus, and potassium. So, low pH could have been a factor in some of the Veg beds. (Another reason to check soil pH in each of the seven beds…)

The limestone recommended to bring up the pH in the Fruit area also will add more magnesium to that space, since limestone contains both calcium and magnesium in abundance.

Zinc

Zinc measurements came back high in both planting areas. If all the yards around here are high in zinc, that might explain the success of pecan trees locally. Pecans are big users of zinc. Many yards here have at least one pecan tree, and we saw lots of pecans in the fall. In north Georgia, pecan trees often need supplementation with zinc in order to make good crops, since zinc is less abundant in the soil up there.

Calcium

Calcium level in the Veg sample was a lot higher than the level in the Fruit soil sample, but a value-judgement of whether the levels were low-medium-high-or-very high was not given. A Mississippi State University Extension article includes this bit of information about calcium availability in soils that have low pH, such as in the Fruit sample:

Soils with favorable pH levels are normally not deficient in calcium. Acid soils with calcium contents of 500 pounds per acre or less are deficient for legumes, especially peanuts, alfalfa, clovers, and soybeans. At this level, limited root system crops such as tomatoes, peppers, and cucurbite would also need additional calcium. Soluble calcium is available as the Ca2+ ion and is needed for peanuts at pegging time and for peppers and tomatoes to prevent blossom end rot.

Secondary Plant Nutrients: Calcium, Magnesium and Sulfur ; publication number IS1039, by Larry Oldham, phd, 2019

For my garden areas, this means, again, that checking soil pH for each of the seven beds in the Veg area will be a good thing to do, in case any of these show a super-low pH. Maybe low calcium explains the wimpiness of last year’s green bean plants!

It also provides more support to add the recommended limestone to the Fruit area to improve plant health.

Soluble salts

The low measurements for soluble salts were another big surprise. Here we are, just five blocks from the beach, and the soluble salts are low! I will count this as a blessing. Many garden crops are less productive when soluble salts are high.

Organic matter and percent nitrogen

These measurements are just to provide a little more information about this new (to me) soil. The percentages of organic matter are better than I had expected. At 4.2 and 3.6, I may have to stop calling my yard a sand dune and refer to it instead as a sandy loam.

When working in the garden, it just seems like a lot of sand, but my past 30 years of working in north Georgia’s red clay may be coloring my judgement here. However, in that clay soil, I would want a higher percentage of organic matter, to help break up the clay and improve how it both holds and drains water.

To work on these numbers, to boost them slightly higher, I will need to rely more on cover crops than on composts and manures (because of that phosphorus problem…).

Fertilizers for the year, based on the soil test results

The soil test reports recommended additions of 34-0-0 fertilizer, for the nitrogen, and muriate of potash (0-0-60) for the potassium. These are both conventional fertilizers that are in the form of soluble salts. Muriate of potash is, essentially, potassium chloride. (You may recall from a long-ago science class that table salt is sodium chloride.) These salts dissolve readily in water and are instantly available to plants as soon as they are watered in to the garden.

However, I am an organic gardener. Soluble salts are not part of my game plan. Hence, the decision to use greensand as a potassium source. In addition, I will be adding some Azomite (not listed in the Garden Planner and Notebook), another kind of pulverized rocks, as a source of additional micronutrients and a tiny bit more potassium.

My nitrogen source, selected by looking at page 12 of my Garden Planner and Notebook, could be either feather meal or alfalfa meal. Feather meal smells a lot like dead things, but the odor only lingers for a few days. No local stores carry feather meal, though, which leaves me (thankfully) with the better-smelling alfalfa meal.

I plan to follow Kevin Meehan’s instructions for DIY alfalfa fertilizer, posted on Rodale Institute’s website, which uses alfalfa pellets that can be found at any local feed store. This should be — yet another — interesting adventure, along with the other “special projects” I have listed in my Garden Planner for the year. Wish me luck?

Filed Under: Organics, Soil fertility Tagged With: garden pH, organic amendments, soil preparation, soil test

GGIA Trade Show Notes for Organic Gardeners

29 January, 2019 by amygwh

Leaf over drawing of the state of Georgia, image from GGIA logo

The trade show at this year’s WinterGreen conference of the Georgia Green Industry Association (GGIA) provided a look at some new (and not so new) products and plants for organic gardeners. The event was held last week, in Duluth, GA.

Most vendors at the trade show specialized in ornamental (non-edible) plants, machinery for large operations, products for commercial nurseries, and chemical-companies, but I located some local/sustainable/organic-related vendors, to share with you.

Recycled plastic nursery pots

East Jordan Plastics, in Michigan, displayed planting trays, growing pots, and some larger containers made from recycled plastics. Many gardeners are concerned about the excessive use of plastics in gardening. It is good to know of a plant-product company that is working to cut back on plastic waste, by re-using containers and recycling other plastics to create new containers.

RootMaker pots

Image from the RootMaker catalog showing difference in root growth between sprout in regular pot versus sprout in RootMaker pot.
Image from RootMaker catalog.

RootMaker trays and pots for growing plants are the result of research in container design, with the goal of more robust root systems. The trays and containers that I examined seemed very sturdy — like they would last for years — and the informational literature was very compelling. The pots and trays have an unusual pattern of protrusions and holes inside, and those, according to the information, guide root growth into more-branched root systems.

I will be trying a RootMaker tray this year. The representative at the Trade Show did give me a couple of fabric liners, for use when growing plants in cinderblocks, so I cannot say that I am 100% unbiased. I will have to buy the tray, though.

Rice hulls for mulch

Until this trade show, I had not heard of using rice hulls as mulch in containers or as a substitute for perlite in planting mixes.

PBH brought samples of parboiled rice hulls, so people could see the actual product and understand how it can be used. The rice hulls are approved for use in organic systems. I did not bring home a little baggie of rice hulls, but I could have. There were plenty on the table. I did bring home the informational literature, to learn more.

Rice hulls pictured on the cover of an article titled "Rice Hulls 101".

PBH Nature’s Media Amendment is from Riceland Foods. This shouldn’t have been a surprise, but it was. It makes sense that the rice industry would want to find a good use for this bi-product of rice production. Looks like they were successful.

Pope’s CBD oil

This isn’t organic and it isn’t about growing, but I did learn that Tennessee grows industrial hemp. The CBD oil was displayed in what was otherwise an all-succulent-plants booth, for Pope’s Plant Farm. CBD oil seems to be a popular product these days. If anyone was looking for a local (-ish) source of CBD oil, Pope’s Plant Farm is one place to try.

Display for Pope's Plant Farm at the 2019 GGIA Wintergreen Conference.

The little succulent plants in the Pope’s booth were very cute. If I were more of an indoor gardener, I would probably grow some. My oldest son in Colorado does grow little succulent plants, so I pay more attention to them than I used to.

Bottom’s Nursery for fruit trees and other plants

Its plants are not organically grown, but after they are planted, most of the varieties at Bottoms Nursery will not need intensive programs of chemical sprays. All the varieties I saw in the catalog are relatively easy-care fruits that would do well when switched to organic management after planting, even in the South. Some are varieties that would do well in small space gardens.

Front cover of the 2019 catalog for Bottoms Nursery, which is in Concord, GA.

The fruit trees at the back of the booth are what attracted my attention. The first tagged tree I noticed was a Kieffer pear, which I know to be both hardy and a producer of good-tasting fruit.

I wasn’t the only person drawn to the booth of Bottoms Nursery. Another vendor was there, discussing trees and other plants to order, to sell in his General Supply store.

General Supply, Inc, in Blairseville, GA

General Supply is the kind of “everything” store that makes some gardeners go into raptures. This is the store mentioned above that will be selling plants from Bottoms Nursery, but it is also a source of tools, pet supplies, small farm supplies, and a million more interesting things.

Hand tools display in General Supply booth at GGIA 2019 Wintergreen Conference.

Of course, hand-tools are pretty appealing for gardeners working in small space gardens. We don’t need a large assortment of full-sized equipment for our little plots, but good tools make the work easier.

I was especially interested in the Truper brand tools (long-reach 15″ length, ash wood handles, sturdy forged “business ends”), but a full line of Corona tools — which are long-lasting and easy to use — was also on display.

The guy at the booth (so sorry that I did not record his name!) and I discussed the ergonomic benefit of tools that have the “business end” at a right-angle to the handle, when he showed me another tool designed for easier use.

Two Corona brand pruners, showing a difference in angle of the cutting edges.

The pruner on the right, in the nearby image of two Corona-brand pruners, has a different angle for the cutting edges. Do you see the difference? According to the guy in the booth, the angled pruner on the right would be easier to use on some branches, because it allows your arm and wrist to stay aligned, rather than to bend.

I haven’t tried it, so I don’t whether that really works, but I would be interested to try. When late-winter pruning time comes around (soon!), it would be good to avoid aggravating old injuries.

Gardeners heading toward the Blairesville area might want to put this store on their list of places-to-visit.

What else happens at the GGIA WinterGreen conference?

In addition to the trade show, the event provides continuing education opportunities for commercial lawn and garden folks. I did attend a workshop about Beneficial Insects, but that story is for another post.

Filed Under: News, Organics, Ramblings Tagged With: fruit for Southern yards, fruit trees, hand tools, organic amendments, seed starting

Coffee Grounds for Gardens

9 September, 2018 by amygwh

Coffee grounds (used) in and out of the free bags picked up at an independent coffee shop.

The season of falling leaves is nearly upon us, which means it might also be the season for collecting used coffee grounds from nearby coffee shops. The grounds combine well with raked-up leaves in a compost pile to create compost for your next-year garden.

Used coffee grounds can also be mixed directly into the garden soil, as a soil amendment, but then the soil-microbes need a few weeks to start breaking those grounds down before anything is planted in the area.

An explanation is in the video below (video – for a change of pace!). If you can’t see the video on this webpage, you can find it here on YouTube.

 

The information from Oregon State University is linked here.

Hoping that all your gardens are growing well!

Filed Under: Fall Vegetable Garden Tagged With: compost, organic amendments, vegetable garden

Planting Begins for My Fall Garden

23 August, 2018 by amygwh

First seeds planted for my fall garden, plus one last summer herb.

The first seeds in the ground for my fall garden are two kinds of carrots and a winter radish. I also planted one last round of basil, so there will be more pesto in my freezer to use in wintertime meals.

First seeds planted for my fall garden, plus one last summer herb.
First seeds planted for my fall garden, plus one last summer herb. PHOTO/Amygwh

This year’s carrots: ‘Bolero’ and ‘Short Stuff’

The two varieties, ‘Bolero’ and ‘Short Stuff’, are shorter carrots that will do well in the clay soil of my in-ground garden.

‘Short stuff’ is also recommended as a good choice for container plantings. The fully-mature carrots will be only about 4-inches long, but wide at the top.

‘Bolero’ will be longer, closer to 6-inches at harvest, but slender all the way down.

I amended the soil by adding a nearly-full bucket (5-gallon size) of yard compost to the garden bed before planting. This addition will loosen the soil and improve the odds that the carrots will grow as they should.

The seedlings have not yet come up, but when they do, they will get a dose of the kind of fish emulsion fertilizer that promotes root growth (higher phosphorus than nitrogen).

You may be wondering why I already planted seeds for carrots, in mid-August. The reason is that crops mature more slowly in fall than in spring. If I want to harvest carrots before mid-December, they need to be in the ground, in my garden, now. (For more details, read my book.)

The first winter radishes

‘Watermelon’ winter radish seeds also are in the garden. The current packet says they take 60 days to reach maturity, but older packets from other seed companies have claimed 70-days, which is closer to the speed they grew in my garden. I decided to use 70-days as my working number to determine the planting date, as a result.

Most of the winter radishes will only make good bulbs in fall, in the time of shortening day length. I don’t know why. Some plants are just like that.

That means, though, that this is a crop that can ONLY be had from a fall garden. If anyone in your family loves radishes (a rare thing, I know), plant these soon!

Heat sink surprise

Raised bed planted with beet seedlings and young onions, in mid-August, in Chicago.
Raised bed with beet seedlings and young onions, in mid-August, in Chicago. PHOTO/Amygwh

When I was in Chicago last week, I noticed that many vegetable gardens already contained plenty of cool-season seedlings. Considering how much further north Chicago is from here, it made sense that fall gardening would already be well-underway.

However, when I looked up its hardiness zone, I was surprised. Chicago is in plant hardiness zone 6a, according to the newer USDA Plant Hardiness Zone Map. The plant hardiness zone where I live, north of Atlanta, is 7b. That difference in hardiness zones, between Chicago and north-metro-Atlanta, is less than I expected.

Most of area around Chicago (all the northern half of Illinois) is in plant hardiness zone 5, according to the USDA map. That seems more reasonable than 6a. Chicago, which is a large city containing a lot of concrete, must be the same kind of heat-sink that Atlanta is (most of Atlanta is in zone 8a). That could account for part of the difference. Lake Michigan could account for the rest, since enormous bodies of water also help keep nearby air temperatures more moderate.

Update on the ‘Astia’ zucchini

Flower buds forming on young 'Astia' zucchini plant.
Flower bud on young ‘Astia’ zucchini plant, in the “v” between two stems (main stem and leaf petiole). 

The ‘Astia’ zucchini that is growing in my half-barrel planter is still alive. There are no signs yet of leaf-mildew-diseases, which is good news. The other good news is that, even though the seedlings have only been up for a couple of weeks, I can see the buds of flowers forming on the plants.

These flower buds will keep growing, until the flower buds open. Some flowers will be “girls”, which are the ones that make the zucchini that we eat. Some flowers will be ‘boys’. After the boys have done their job of pollinating the girls, I plan to harvest those boy flowers to use in cooking.

While in Italy over the summer, Joe and I enjoyed fried squash blossoms at the Sax Wine Bar in Montepulciano. We are going to make those ourselves, since the good ladies at Sax Wine Bar are in Italy and we are not.

 

Filed Under: Fall Vegetable Garden, Herbs, Vegetables Tagged With: cool-season vegetables, fall garden, herbs, organic amendments, organic fertilizer, varieties for small gardens

Potassium Sources for an Organic Garden

9 February, 2018 by amygwh

Greensand is a good sources of potassium for organic gardens.

Potassium is one of the Big Three nutrients that plants need in large amounts (the other two are nitrogen and phosphorous). These are the essential nutrients that are represented by three numbers, such as 5-10-15, on bags of chemical fertilizers.

If you’ve had the soil of your organic garden tested and learned that it is very low in potassium, you may be looking for ways to boost the amount of this essential plant nutrient in your organic garden.

The good news? There are several good sources for potassium available for organic gardens.

Greensand – This is a mined product, made from natural deposits of a marine sediment called glauconite. It is smashed into very small bits (making it into “sand”) for you to mix into your soil. The potassium content can vary between brands. You will need to read the label of your bag to know how much potassium (the percentage) is in there.

Greensand is a potassium source for organic gardens.
Greensand is a potassium source for organic gardens.

Greensand does not contain any nitrogen; some brands may contain a tiny bit of phosphorus, but not enough to really count if your garden needs phosphorus, too. The potassium is released SLOWLY, so if your garden’s need is dire, you might want to use a faster-release potassium source along with the greensand.

When I make my own organic potting mix, I add a little greensand (about a half cup for a 6-gallon batch of potting mix). McGee and Stuckey, in their book The Bountiful Container, also recommend adding a bit of greensand to organic potting mixes.

Wood Ashes – This is a fast-release and FREE source of potassium for home gardens. Wood ashes may be as much as 3-7% potassium! This is similar to the percentage in many bags of greensand (my current bag has less), making wood ashes an option to consider for gardens that need a lot of potassium Right Now. The potential drawback to this organic potassium source is that it will raise the pH of your garden’s soil.

Did you have the soil from your organic garden tested this year? If you did, you will have a record of the soil pH, which is how acidic or basic it is. A pH number below 7 is acidic. A pH number higher than 7 is basic. Most garden vegetable plants will be more productive when grown in soil that is in the 6-7 pH range (slightly acidic). If your soil pH is already in that desired range — or higher — then wood ashes are not a good potassium choice for your garden.

Sul-Po-Mag – This is another mined source of potassium, available to gardeners as bags of pulverized rock. The name Sul-Po-Mag is shorthand for the longer name of Sulfate of Potash Magnesia. This has a very high percentage of potassium, as much as 22%. Even though it is from rocks, it is considered a fast-release source. If your organic garden needs a lot of potassium right away, and the pH is high enough that wood ashes are not a good choice, then this may be what you want. Sul-Po-Mag also provides sulfur, magnesium, and some micronutrients. This product is generally pH-neutral, meaning that it will not swing your soil’s pH in either direction.

Locally, we have used Sul-Po-Mag when mixing up batches of organic fertilizer for community gardens that have a soil-pH higher than 7.

Kelp Meal – This is a slower-release source of potassium. It is not a concentrated source (about 1% potassium), but it also provides nitrogen, phosphorus, and a host of essential micronutrients that can improve the nutrient state of poor soils. If you are working with native soil, in an in-ground garden in the Southern US, and your organic garden is fairly new, you may want to choose kelp meal as your potassium source. In my area, the clay soils are all worn-out (decades of cotton fields) or washed-out (erosion from high rainfall), and benefit greatly from a dose of kelp meal.

How much of any of these should you use? If you have a report from a soil lab, the recommendation it offers for a chemical fertilizer can be converted to organic amendments, if you are reasonably good at math. The linked UGA publication includes the equations to use. I have done these conversions for our local community gardens.

An alternative is that you mix up a batch of organic “10-10-10” (or another listed formula), following the recipe in the above-linked UGA publication about converting to organic amendments. The recipes on the last page of the document list options for the nitrogen source (pick one from the list), options for the phosphorus source (pick one), and options for the potassium source (pick one).

Filed Under: Organics Tagged With: organic amendments, organic fertilizer, organic garden

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