Of Calcium in the Soil – Part 4

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We’ve reached part 4 of this riveting story of how calcium and other nutrients make it into into the soil and thence into our vegetables and thence into our own bodies (and into chicken eggs). We’ve had some cliffhangers already, so be sure to check out parts one, two and three.

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4. Solubility, carbonation and chemical weathering

It is the reaction of calcium and calcium compounds with water (see last part) that makes them soluble. Solubility or dissolution is the process by which a “solute” forms a homogeneous mixture with a “solvent” (here water).

This happens as the solute molecule breaks down and its ions dissociate. The positive ions attract the partially-negative oxygen in H2O and the negative ions attract the partially-positive hydrogen in H2O. The ions thus get spread out and become surrounded by the water molecules. The dissolution is complete, or in equilibrium, once it’s all been spread around. (source)

One calcium compound is more soluble than another. Calcium carbonate (our eggshell) has a very poor solubility (47 mg/L at normal atmospheric CO2 partial pressure and 25 degrees C). As we shall see, this is important for gardeners who plan to enrich their soil with eggshell calcium, but I will come to that later.

However, if carbon dioxide is also present, that carbon dioxide will react with the water to form carbonic acid (H2CO3), which is a weak acid – it’s the bubbly in our soft drinks. This carbonic acid will in turn react with the calcium carbonate to form calcium bicarbonate (or calcium hydrogen carbonate). So

CaCO3 + CO2 + H2O → Ca(HCO3)2

Calcium bicarbonate is five times more soluble in water than calcium carbonate—in fact, it exists only in solution.

This is the main process by which carbonate rocks of the Earth’s crust are weathered. As we saw, if water is saturated with carbon dioxide, it produces a mild carbonic acid. This is what happens with (unpolluted) rainwater (water plus atmospheric CO2), which has a pH of around 5.6 (polluted, “acid” rain has a pH of as low as 3.0), and with water in aquifers underground, where it can be exposed to CO2 levels much higher than the ones in the atmosphere.

In a process called carbonation, this water’s carbonic acid reacts with the solid calcium carbonate in rocks like limestone or chalk, forming calcium bicarbonate and dissolving it. This solution of water and mineralized calcium is then borne off into the soil, where it is deposited on the colloid, and where it waits to be again dissolved in water and made available to plant roots.

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Well. That just brings us back to the beginning!

On to Part 5

Oh My.

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Amie chooses flowers

I put in my seed order. I may have gone overboard a bit, again. No, honestly now, not “again”: even more so, than last year. And these are seeds over and above what I still have left. To be honest I am ashamed to publish the list. Oh my.

But, truth be told, there will be much more space this time around. Last year we missed out on the entire Spring season in the vegetable garden. We also didn’t have those large beds up front, where I can finally put the herbs and the perennials. Planning and planting those will be a whole new ballgame for me. Oh my.

I haven’t looked at flowers yet. Or berry bushes. Or nut and fruit trees. Oh my.

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Okay. Here goes, my Fedco order:

205PO-Provider Bush Green Bean OG (A=2oz) 1 x $1.80= $1.80
249MO-Maxibel Bush Haricots Verts OG (A=1/2oz) 1 x $1.00= $1.00
299WI-Windsor Fava Bean (A=2oz) 1 x $1.40= $1.40
323JW-Jackson Wonder Bush Lima Bean (A=2oz) 1 x $1.20= $1.20-currently on backorder
332CN-Cannellini Bean (A=2oz) 1 x $1.50= $1.50
336KE-King of the Early Bean (A=2oz) 1 x $1.40= $1.40
343JC-Jacobs Cattle Bean (A=2oz) 1 x $1.90= $1.90
376RK-Red Kidney Bean (A=2oz) 1 x $1.40= $1.40
732FR-Early Frosty Shell Pea (A=2oz) 1 x $1.20= $1.20
748LM-Little Marvel Shell Pea (A=2oz) 1 x $1.20= $1.20
761GO-Green Arrow Shell Pea OG (A=2oz) 1 x $1.80= $1.80
798LG-Legume Inoculant (A=treats 8lb) 1 x $4.00= $4.00
822BO-Blizzard Snow Pea OG (A=2oz) 1 x $2.00= $2.00
893SO-Sugarsnap Snap Pea OG (A=2oz) 1 x $2.00= $2.00
1382SZ-Super Zagross Middle Eastern Slicing Cucumber (A=1/16oz) 1 x $1.30= $1.30
1688WO-Waltham Butternut Winter Squash OG (A=1/4oz) 1 x $1.20= $1.20-currently on backorder
1705JL-Jack Be Little Pumpkin (A=1/8oz) 1 x $1.30= $1.30
2018TP-Tonda di Parigi Carrot (A=1/8oz) 1 x $1.20= $1.20-currently on backorder
2300TG-Takinogawa Burdock (A=1/8oz) 1 x $1.20= $1.20
2407RO-King Richard Leek OG (A=1/16oz) 1 x $1.60= $1.60
2439EV-Evergreen Hardy White Scallion (A=1/16oz) 1 x $1.20= $1.20
2444CW-Crystal White Wax Onion (A=1/16oz) 1 x $1.20= $1.20
2474DO-Clear Dawn Onion OG (A=1/16oz) 1 x $1.40= $1.40
2510SP-Space Spinach (A=1/4oz) 1 x $1.00= $1.00
2555GW-Giant Winter Spinach (A=1/4oz) 1 x $1.10= $1.10-currently on backorder
2803TT-Tom Thumb Lettuce (A=2g) 1 x $0.70= $0.70
2865RH-Rouge dHiver Lettuce (A=2g) 1 x $0.70= $0.70
2986SM-Summer Lettuce Mix (A=1g) 1 x $1.10= $1.10
3036BL-Bright Lights Chard (A=1/16oz) 1 x $1.10= $1.10
3048PZ-Pan di Zucchero Chicory (A=0.5g) 1 x $1.20= $1.20
3058WC-Watercress (A=1/16oz) 1 x $1.30= $1.30-currently on backorder
3096KH-Good King Henry Chenopodium or Goosefoot (A=0.5g) 1 x $1.30= $1.30
3099SK-Sea Kale (A=1g) 1 x $2.00= $2.00
3122MN-Minutina (A=1/16oz) 1 x $1.30= $1.30
3168KR-Krausa Parsley (A=1/16oz) 1 x $1.00= $1.00
3192BL-Broad-Leaved Sorrel (A=1/16oz) 1 x $0.90= $0.90
3320WM-Waltham 29 Broccoli (A=2g) 1 x $0.70= $0.70
3336RN-Roodnerf Brussels Sprouts (A=2g) 1 x $1.10= $1.10
3404CS-Charming Snow Cauliflower (A=0.5g) 1 x $1.20= $1.20
3445CO-EvenStar Champion Collards OG (A=2g) 1 x $2.00= $2.00
3463WB-Winterbor Kale (A=0.5g) 1 x $1.80= $1.80
3616SF-Safir Cutting Celery (A=0.2g) 1 x $1.20= $1.20
3644DC-Diamante Celeriac (A=0.2g) 1 x $2.40= $2.40-replaced with Brilliant
3684DM-Diamond Eggplant (A=0.2g) 1 x $0.90= $0.90
3704PO-Peacework Sweet Pepper OG (A=0.2g) 1 x $1.00= $1.00
3753BO-Czech Black Hot Pepper OG (A=0.2g) 1 x $1.60= $1.60
3810AC-New Ace Sweet Pepper (A=0.2g) 1 x $1.60= $1.60
4008HC-Husk Cherry (A=0.5g) 1 x $1.00= $1.00
4059CO-Cherokee Purple Tomato OG (A=0.2g) 1 x $1.20= $1.20
4075BO-Pink Brandywine Tomato OG (A=0.2g) 1 x $1.20= $1.20
4107BB-Be My Baby Gene Pool Cherry Tomato ECO (A=0.2g) 1 x $1.20= $1.20
4125HO-Heinz 2653 Paste Tomato OG (A=0.2g) 1 x $1.20= $1.20
4282SG-Sun Gold Cherry Tomato (A=0.1g) 1 x $2.40= $2.40
4412TO-Astragalus OG (A=.5g) 1 x $1.20= $1.20
4415WO-Sweet Basil OG (A=4g) 1 x $1.50= $1.50
4481WO-Wild Bergamot OG (A=0.1g) 1 x $1.10= $1.10-currently on backorder
4511GC-German Chamomile (A=1g) 1 x $1.10= $1.10
4512CO-Chives OG (A=0.5g) 1 x $1.10= $1.10
4577GC-Garlic Chives (A=0.5g) 1 x $1.10= $1.10-currently on backorder
4582HY-Hyssop (A=0.5g) 1 x $1.00= $1.00
4698SW-Sweet Woodruff (A=0.2g) 1 x $1.20= $1.20
5280AL-Alaska Nasturtium Mix (A=2g) 1 x $1.00= $1.00
6266QO-Queen of the Meadow OG (A=0.02g) 1 x $1.20= $1.20
6333BM-Beneficials Mix (A=1.4g) 1 x $1.70= $1.70

Oh my!

Of Calcium in the Soil – Part 3

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This is the third article in a series on how calcium and other nutrients end up inside our vegetables, and on how to interpret certain soil test results. It is preceded by part 1 and part 2.

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3. Water and pH

Let’s investigate the water in the soil. For one, water brings the minerals to  the colloid, and it can take them away again (but so do the soil critters). Also, for reasons that will become clear later, calcium is available to plants only in dissolved form, that is, as part of a solution in water. Thirdly, this watery context heavily impacts the lives of soil critters. The most important factor in all these matters is the water’s pH or acidity or alkalinity.

As we saw, a molecule of water is composed of one oxygen atom and two hydrogen atoms: H2O. In a vat of pure water, most water molecules remain intact, but a very small amount of them react with each other in the following manner:

H2O + H2O ===> H3O+ + OH–

Water + Water ===> hydronium ion+ (an acidic cation) + hydroxyl ion– (a base)

The hydronium ion ( H3O+) is the chemical unit that accounts for the acidic properties of a solution, and the hydroxyl ion (OH–) is the chemical that accounts for the basic or alkaline properties of a solution. How?

Well, in pure water, the amounts of H3O+ and of OH– are equal, so the acid and the base cancel each other out, so pure water is said to be neutral, with a pH close to 7.0. Also, in pure water the concentration of H3O+ and OH– are in balance, so that an increase in the concentration of H3O+ causes a proportional decrease in the concentration of OH–.

This means that, if you add an acid like hydrochloric acid (HCl) to water, it reacts with some of the water molecules like this:

HCl + H2O ====> H3O+ + Cl–

And this increases the H3O+ or the acid concentration, throwing off the balance and lowering the solution’s pH to below 7, making it acidic. But if you add a strong base, such as calcium, to the water, it ionizes as follows:

Ca + H2O ====> Ca(OH-)2 + H2

Thus, the addition of calcium to water increases the OH- or alkali concentration of the resulting solutions, making the solution alkaline.
The cations (positively charged ions) we’re interested are either bases or acids:

  • Basic cations: calcium (Ca++), potassium (K+), magnesium (Mg ++) sodium (Na +)
    Acidic cations: aluminum (Al+++) and hydrogen (H+)

The pH of the water that saturates the soil (see 4) regulates the solubility of minerals in that soil (see 4), thus their availability to plant roots (see 5), as well as the activity of soil bacteria (see 6).

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Mm, on to Part 4: that pesky problem of solubility, which took me a while to understand. For now let me add that I forgot all the chemistry I learned in secondary school (way back), and that this excursion has proved to be a fantastic rediscovery of all that magic.


Who’s at the Feeder and Hoop House Trouble

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I enjoy nothing more, in winter, then sitting by the big window with a cup of steaming tea and a good book or chess game, and observing the birds at the well-stocked feeder. We have the usual flock of juncos, who love playing in the snow. They are having it out with a flock (the same size, 6 or 7) of passerines.  Then throw in a couple of titmice and a pair of wrens. Add to that two cardinal pairs, as well as an assortment of downy woodpeckers, among them the one Red-Bellied Woodpecker. And then there’s this fellow:

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He (she?) is new: an American goldfinch. Here’s another view. Such gorgeous coverts, and that yellow muffler!

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Yesterday I wrote about the warmish weather and watching the rain wash away the snow. Then the rain turned to ice.

It was still sleeting this morning when we woke up to a hoop house dangerously weighed down by that snow that has a bluish tint. Read: high slush content. By the time we had mobilized, the situation was dire.

The moment I touched the structure, the precarious balance gave and the whole thing started caving in. The pvc pipes creaked, something on top cracked, and clips that hold the cover to the pipes were literally flying all over the place as the plastic pulled loose. Luckily DH was there to jump inside and prop the whole thing up while I cleared away the snow. We got away with only one of the connectors on top breaking and a couple of tears in the plastic cover. What do you think: redesign?

Quick Notes on Stored Food and a Peek Inside the Hoop House

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So I did all that canning last year and ended up with a little more than what you see in the picture above. So far we’ve eaten half the tomato sauce, a lot of apple sauce and blueberry jam (but not half, not by a long shot), a quarter of the peaches, and some of the fig preserves. We liked all of those.

We did not like the green peppers (bitter, metallic taste, is that normal?) and the green beans, of which we have, sadly, a lot (good for a soup, or a casserole?). Those two veggies are going into the freezer next year!

Tomorrow I’m making split pea soup with two of the many pounds of dry split peas that I bought in bulk and store in the chest freezer. I’m also going to make an apple-peach crumble with store-bought apples and my canned peach pie filling.

My attempt, a while ago, of “root cellaring” store-bought (organic) potatoes on some stick on top of a bucket of water inside a large black plastic bin in the coldest part of our basement… resulted in all the potatoes sprouting in record time. Wha? They were in total darkness! Very strange. Could it have been the plastic? Maybe I should try a metal bin next time.

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And here is the promised peek inside the hoop house. These pictures are from when it was still freezing.

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All kinds of lettuces, mustards, and spinach, doing well

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Russian kale, Swiss chard and broccoli (in back) lying down a bit but surviving. Can’t wait to harvest those carrots (to the right)

In the third bed the parsley is also laying low but surviving. The mache and claytonia that I sowed there way too late have germinated and the seedlings are tiny but fine, waiting it out.

I haven’t been in there since the thaw started (we’re in the 40s now during the day, and at the moment it’s raining all the snow away). I’ll have a look tomorrow, when (if it stops raining) I will move the compost from the Earth Machine that’s close to the kitchen (it’s too cold for the kitchen scraps to decompose, so that bin filled up really fast) to the empty one in the hoop house.It would be great to have some finished homegrown compost by the beginning of Spring.

We readied the basement area where I will start the seedlings again. I can’t wait to turn on those lights! We decided I’d stop mucking around with  various hot germination box designs, and buy a large seedling mat (with thermostat). If you have a particular one that you’ve have tried and like, let me know…. soon.

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Don’t forget to scroll down for the second and, may I say, most riveting installment in the “Calcium in Soil and Compost” series, published a few hours ago.

Of Calcium in the Soil – Part 2

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This is the second article in a series on how calcium and other nutrients end up inside our vegetables, and on how to interpret certain soil test results. You can read the first part here.

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2. The soil’s ability to hold on to this calcium: colloids and cation exchange capacity

The soil needs to store the weathered bedrock calcium, keep it from leaching away to where the plant roots can’t reach it. Certain clays (very fine inorganic particles) and organic or humus particles form colloids: thin, flat plates with a large surface area that has a negative electrical charge.

As such they attract or adsorb large quantities of positively charged ions, or cations (pronounced cat-eye-ons), which comes to adhere to it with a weak electrochemical bond. As the cations are taken from this storehouse by plant roots (see 6), other cations in the soil water replace them on the colloid. This is called cation exchange.

For example, hydrogen (H+) is such a cation, and it’s part of H2O, so water molecules are attracted by the clay’s negative electrical charge.

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That is why clay is good to have, since it holds on to water so well. But if your soil is mainly clay, it’s not so good, because the clay will lock the water molecules into bond that is so strong that the plants’ roots will not be able to break it. So the soil may hold a large amount of water, but much of it is actually not available to plants. On the other hand, a soil that is too sandy) will not be able to hold on to anything, water or nutrients, because sand particles have no electrical charge.

Cations will compete with one another for a place on the colloid. Some are charged more than others, for instance, calcium (Ca++) is charged twice as much as hydrogen (H+), and aluminum (Al+++) is even stronger. An aluminum cation borne along by the soil water can easily knock a hydrogen cation off the colloid and take its place. If the soil water bears a high concentration of a particular cation, those cations will replace other cations on the colloid, for instance, a swarm of calcium ions against one sodium (Na++) ion.

This image (source) shows the flat, plate-like structure of the colloid and the negative charges along its edges:

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http://www.dpi.nsw.gov.au/agriculture/resources/soils/structure/cec

The stronger the colloid’s negative charge, the greater its capacity to hold the positively charged cations. The kind of clay (for more details, see here), its mixture with sand and organic matter and its crumb structure, all determine the soil’s capacity to hold cations against leaching. This capacity is termed the soil’s cation exchange capacity (CEC) – an important term on your soil test results. This CEC is expressed in milliequivalents per 100 grams (meq/100g) of soil or in centimoles of positive charge per kilogram of soil (cmol(+)/kg).

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On our soil test results the CEC is given as 15.6 meq/100g. So, in every 100 grams of our soil, 15.6 meq of soil can hold onto the goodies, calcium (Ca++), potassium (K+) and magnesium (Mg++), that come along in the soil water, as well as hydrogen (H+), and sodium (Na +) and aluminum (Al+++), which are not plant nutrients.

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That explains at least one unknown on that soil test! Next up, in Part 3, the role of water in all of this: it is, after all, the soil water that brings and that can take away these cations.


Of Eggshells and Calcium in Soil, Compost – Part 1

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It was the combination of finding an eggshell in the compost and staring at our soil test results that did it. I started researching and one thing led to another. But I figured it out, the basics of it, anyway. The result is a long text, so I’m serializing it over the next couple of days. I hope you find this sort of thing as fascinating as I do, and that it will help you with your own soil test results.

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Digging and moving my compost heaps over a month ago, it was interesting to find eggshells and bones, all over a year old and barely decomposed. I keep sifting them out and putting them back into the heap. I figured it is the high amount of calcium in them that makes them so hardy.

This made me wonder how that calcium will ever make it into my garden vegetables. In what shape or form can the calcium in the eggshell, and the calcium originating from the bedrock, be taken up by plants?

It took me a long time to find out, but I realized early on that we first need to get clear on what this “calcium” is that we’re talking about.

Calcium in its elemental state is a metal – a soft gray alkaline earth metal (Wikipedia). But it is so reactive that it is never found in its elemental state, that is, all by itself. It readily combines with whatever it comes in contact with and becomes part of a compound.

Thus in the eggshell, calcium occurs as calcium carbonate (CACO3): an eggshell consists of 94 to 97% calcium carbonate. Calcium carbonate is also the active ingredient in agricultural lime, which is mined from limestone. Calcium can also occur in the soil as part of the compound calcium bicarbonate (Ca(HCO3)2), or as part of the compound calcium nitrate (Ca(NO3)2). And so on.

The “calcium” we will be talking about here is the calcium ion in each of these compounds, because it is only this ion that can be taken up by plant roots and thus form a nutrient.

If our interest is in calcium as a nutrient for plants, we need to consider:

  1. its presence in the soil
  2. its continued present in the soil
  3. its interaction with water, and pH
  4. its solubility
  5. its relation to soil pH
  6. its uptake by the plant
  7. its availability when tied up in organic materials

1. Original presence of calcium in the soil: parent materials

First, of course, calcium needs to be present in the soil. So where would it come from in the first place? Calcium is abundant: the third most abundant metal in the earth’s crust, accounting for 3.64% of it. It is also, by the way, the fifth most abundant element by mass in the human body: what a beautiful correspondence!

Soil originates primarily from parent materials: rock. When rock is weathered or eroded, it is broken down. This can be a physical or mechanical process (abrasion by ice, for instance, or by biological agents such as lichens and mosses), or a chemical process (see 4). The left-over materials, when combined with organic materials, make soil, which is thus (almost) nothing but rock. I recommend the excellent soil page on Wikipedia.

Obviously, the more calcium (as well as N, P, S, K, Mg and all the micronutrients) is contained in the bedrock in your area (and the younger the soil), the more calcium will be present in the topsoil. So it pays to investigate what kind of rock your garden sits on: spend a day or two (or three) navigating the USGS map library, especially the surficial earth materials and bedrock lithological maps of your region.

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(http://www.mass.gov/mgis/bedlith.gif)

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Intrigued? This is only the first part of a series on calcium and other nutrients in soil and plants. Stay tuned!

Part 2 can now be read here.


One Down…

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With daytime temperatures in the single digits (F), I was motivated to cover the smallest, yet still considerably large, living room window with a thick quilt I had lying around. I just slung it over the curtain rod and then snapped on three of the handy pvc clips that hold the plastic to our hoop house. Then I tucked it in on all sides. It’s not what you could call sealed, but an improvement nevertheless. Amie likes it so much she wants to keep it on during the day, and I don’t mind because it still lets a lot of light through.

I’m hoping to find a couple of quilts that will cover the large bay window in the living room (to be removed during the day), and one small one for the bathroom window, where I will have to use a tension rod. All the little bits help.

Homestead Animals: Bees, Chickens, and Fish

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Amie welcomes the first non-human animals on the homestead

I signed up for Bee School (7 Thursdays and 1 Saturday morning) and while I was at it I also enrolled for a backyard chicken class (2 Saturday mornings, maybe Amie can come too).

It took me so long to sign up because I know that the kids living right next door to us (on the side of the property where the beehive would be located) are very allergic to many things. Though I have been told that the neighborhood kids’ chance for being stung by honey bees is minimal, I decided that if the kids are allergic to bee stings, I would can the project. But the neighbors gave us the all-okay yesterday. They’re quite albeit carefully interested in our experiments.

A visit to the wonderful Drumlin Farm chicken coop made me realize that I really have not a clue about chickens. The only chicken I have experience with is the killed, plumed and cut-up kind, raw or cooked. The one or two childhood visits to the relative who kept chickens are long forgotten, and not one of the neighborhoods I frequented in my life boasted the presence of chickens. So, there I was, staring at those beautiful, mysterious birds at Drumlin, and thinking it would be good to at least hold one, just once, before I go ahead and buy chicks. The added advantage to such a class is also that we might all pitch together for a batch from a hatchery.

Amie is very keen on the chickens, and we’ve been reading library books on the subject. Once she read that the unhatched chick finds most of the nutrition it needs in the egg yolk, she also started eating it – she now devours the whole egg. And she started this beautiful chicken drawing:

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(unfinished chicken)

The fish, lastly, were Amie’s Christmas present from several people combined. It’s a 20 gallon tank with, for the moment, 4 Zebra Danios. We had such fun at the store, ogling all the colorful variety of fishes. It was a bit of a comedown when the store assistant told us we should start with a “school” of these tiny little ones, four of them (we’ve learned, in the meantime, that six should be the minimum). Still, they’re fun to watch, and we’ve already learned a lot about fish, mainly that we don’t know anything about them. It’s Amie’s job to feed them in the morning. Just a matter of starting small…

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Also, check out this basement garden!


Honey Garlic, Finally, Almost

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Back in October I peeled about 50 garlic cloves, which I put in apple cider vinegar in a ball jar, and then plain forgot. You’re supposed to wait for only 6 weeks for the next part, but so we waited a bit longer. Tansy’s recipe is here.

I finally got around to the second part of the recipe yesterday evening: straining off half the vinegar – which I kept for a salad dressing – and replacing it with raw honey.  Oh, the aroma was to die for! When some of it overflowed, it proved to be fingerlickin’ good already!

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But okay, we’ll wait another 6 weeks. Then thanks to my forgetfulness it might be a bit late in the season for a flu remedy, but it will not be too late for a treat.

Next year I’m making more of this, with homegrown garlic and, who knows, homegrown honey.

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Tomorrow I am going to hit the neighborhood thrift stores for old quilts that I can make into heavy curtains for the two large bay windows in our living room. I’m also going swimming with Amie!