Inspired by Rob of One Straw, I went out into the cold, bright air yesterday – gloves, woolen cap – to move the compost. The idea was to transfer it from Earth Machine no.1 behind our house, which receives our daily kitchen scraps, to the Earth Machine no.2 in the hoop house.
Right before our warm spell, when it was below freezing, I measured a balmy maximum of 64F in the hoop house. So, 64F inside while outside it was 30F! The observed inside minimum, however, was 20F – the outside minimum was 7.
The low nighttime minimum is explained by the lack of a heat sink. The only mass is the beds, covered with white row covers. Earth Machine no.2 is black, but it was empty, so not much there to retain the daytime heat.
Now no.2 is full, almost to the brim, with food scraps from the past weeks, fresh straw (as insulator, aerator and carbon) and actual compost – complete with worms!
What a surprise! I had expected some of the mass in no.1 to have barely started decomposing several months ago, and most of it not to have had a chance at all. And surely it had been too cold for worms. But no, the top half was teeming with the Red Wigglers that I had observed in my compost last Fall, before the cold set in. The quarter below that was almost finished compost. The bottom quarter had decomposed somewhat, but it had ice crystals in it, so I left that in no.1.
All the rest I transferred to no.2 in the hoop house, where it will temper the indoor climate at night and where it might just get ready to go on the beds in early Spring.
These are veggies I hope to keep a little warmer:
An assortment of lettuces
Last year’s parsley, still very yummy
A whole bed full of greens and tiny broccoli, growing slowly but surely
This is the scene outside. We’re supposed to get new snow today.
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(On a side note: Firefox seems to be having problems with the Flickr badges: it keeps on loading them. If this taxes your connection, press the X – stop loading this page – button. I hope they solve it soon…)
This is part 5 of a series on how nutrients, mainly calcium, get into our soil and vegetables (click for part 1, part 2, part 3 and part 4). It is the longest and most difficult part of my expose, and the least “popular” one, judging by the fact that the issues discussed will not show up on the average soil test. Still, I include it because it gives us something to think about when we irrigate our garden and – I admit it – because it introduces that most enchanting of words in soil science. Flocculation. Come on, say it, out loud, taste it! Now you have to find out what it means.
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5. Soil structure, flocculation, salinity and sodicity
As we saw, it’s good to have some amount of clay, as clay particles are negatively charged and thus able to attract and hold on to nutrients, which are positively charged. Now clay particles can either be unattached and dispersed, or clumped together, “flocculated†into aggregates (flocs = flakes).
Flocculation happens because opposites attract and like repels like. Thus one negatively charged clay particle will repel another negatively charged clay particle. But the positively charged cations create bonds between them, shaping them into clumps or flakes.
Because of their varying charge, certain cations are good flocculants, like calcium (Ca++) and magnesium (Mg++), whereas others are poor flocculants, like sodium (Na+) and potassium (K+). Add water in the mix, and the cations’ flocculating power diminishes, because the cations will also spend some of their positive charge on attracting the hydrogen ions (H-).
Flocculation is a good thing. Unattached, dispersed single particles sit together in a dense cement that allows no air pockets, called pores. Clumpy aggregates, on the other hand, will not fit together so perfectly and create pores. It is in these pockets that the rapid exchange of air, water and colloidal cations with plant roots can take place. It is also in and through these spaces that roots grow.
But in such a lively realm as soil, flocculation is a transitory thing. It is best if the aggregates are stable, which stability depends on (1) the amount of soluble salts in the soil, and (2) the balance between calcium and magnesium (the more powerful flocculators) and sodium (the weak one).
As for (1), had I known about it, I would have shelled out the extra $5 for a soluble salt test to be done on my sample. Soluble salts are any dissolved ions, be it calcium, sodium or potassium. Ions in solution conduct electricity. The extra test would have given me the electrical conductivity (EC) of my soil, which would have given me another indicator of its nutrient richness.
As for (2), that extra test would have enlightened me about the balance between calcium and magnesium on the one hand, and sodium on the other, as it would have given me the Sodium Adsorption Radius (SAR):
[Na+]
————–
[Ca++] + [Mg++]
How do EC and SAR matter?
Well, flocculation or aggregate stability occurs (1) if the amount of soluble salts (calcium, magnesium as well as sodium) in the soil is increased: more positive ions means more electrical conductivity (EC), which means more binding of clay particles into clumps. Conversely, soil particle dispersion occurs when the amount of soluble soils and thus the EC is decreased.
Soil particles also flocculate (2) when concentrations of Ca and Mg are increased relative to the concentration of Na ions (that is, when the SAR is decreased), because Ca and Mg are much stronger flocculants. Conversely, soil particles will disperse when the SAR is increased. (I recommend this powerpoint presentation for a more visual explanation of these interactions.)
As we saw, hydrogen anions (H-) diminish the soil’s cations’ flocculating power, so irrigating with “pure†water – water that has low amounts of soluble salts and is thus a very poor conductor of electric current (EC) – can destabilize soil aggregates.
If you irrigate with so-called saline water – water with a high EC, or high amount of soluble salts – then that soil will have a good structure. However, as can be expected, if there is an excess of salts in the root zone, it will hinder plant roots from withdrawing water from the soil (this will be further explained in part 7).
Another word of caution: if you have sodic irrigation water, that is, if it contains a high amount of sodium (Na), it could damage your soil structure, making life difficult for plant roots and causing problems with irrigation.
That is because Na ions are larger than Ca and Mg ions. When too many large sodium ions (with their low flocculating values) come in between the clay particles, they act like wedges, separating the particles, breaking up their aggregation. This soil dispersion causes the clay particles to plug the soil pores and create cement.
If you soil cracks when it is dried up, you have a sodic soil. One of the solutions is to decrease the SAR by introducing calcium (mostly in the form of gypsum), which will compete with the same spaces on the colloids as the sodium, and flush them out.
Something to think about, when we water our garden!
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I really did enjoy that – no kidding. I used to study metaphysics in grad school and this reminds me of it, a bit. Let me know what it did for you!
I ordered more seeds, for those plants that were on back order in my previous order, and lots of everlasting and perennial flowers, many of them beneficials.
2068RO-Atomic Red Carrot OG (A=1g) 1 x $1.80= $1.80
2512LY-Olympia Spinach (A=1/4oz) 1 x $1.00= $1.00
3228MZ-Early Mizuna (A=1/16oz) 1 x $1.10= $1.10
3624VT-Ventura Celery ECO (A=0.1g) 1 x $2.20= $2.20
4517RO-Caribe Cilantro OG (A=1g) 1 x $1.00= $1.00
4592LV-Lovage (A=0.5g) 1 x $1.00= $1.00
4592LV-Lovage (A=0.5g) 1 x $1.00= $1.00
4644SO-Stinging Nettle OG (A=0.2g) 1 x $1.20= $1.20
4687GT-German Thyme (A=0.2g) 1 x $1.10= $1.10
4699WY-White Yarrow (A=0.1g) 1 x $1.00= $1.00
5215CP-Crystal Palace Blue Lobelia (A=0.2g) 1 x $1.20= $1.20
5234QS-Queen Sophia French Dwarf Double Marigold (A=0.7g) 1 x $2.00= $2.00
5705PL-The Pearl Achillea (A=0.05g) 1 x $1.00= $1.00
5799PE-Pearly Everlasting (A=0.1g) 1 x $1.40= $1.40
6008CQ-Cerise Queen Achillea (A=0.1g) 1 x $1.20= $1.20
6013RS-September Ruby New England Aster (A=0.03g) 1 x $1.40= $1.40
6028BC-Blue Clips Bellflower (A=0.05g) 1 x $1.40= $1.40
6068ES-Early Sunrise Coreopsis (A=0.1g) 1 x $1.40= $1.40
6204MC-Maltese Cross (A=0.4g) 1 x $1.00= $1.00
6272SD-Alaska Strain Shasta Daisy (A=0.5g) 1 x $0.90= $0.90
6333BM-Beneficials Mix (B=7g) 1 x $7.50= $7.50
I need to source more flowers and beneficials to ensure there is something in bloom from early Spring to late Fall. A beneficial that I would like to grow in my flower garden paths is either Dutch white clover or New Zealand white clover. Buying them online, in bulk, doesn’t make sense, shipping-cost-wise. I’d like to find them more locally.
I’ll order the strawberries, (lowbush) blueberries, hardy kiwi, elderberry bushes and hazelnut shrubs as soon as I’m assured that we’ll have spot ready for them when they arrive (in Early April).
I also need to investigate and source plants that will grow in very wet spots and in and around the pond. Any ideas?
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Oh, and “for a laugh,” you could read this, from The Onion. How true! A friend of mine said there must be so many Massachusetts-ers out there kicking themselves for not voting last week. I said I doubt it, for the very same reasons.
Our back garden, house and veg garden are on a little hill. The slope (in red) is quite steep, and we terraced the part where the soil had been disturbed and was eroding. We put beds on either side (only the two lowest ones shown in brown) and a path of grass in the middle. This path leads down to the “front garden,” the large stretch of land at the bottom of the hill.
This piece of land has issues.
It is home to the large septic leach field, so we shouldn’t put deep-rooted plants there, or any heavy stuff, like an asphalt parking lot for our truck (kidding).
It is the lowest part of this part of our street, so it catches all the rainwater runoff from all sides. Luckily most of it is from our own roof and hilltop, which we plan to divert (blue line) to a small pond and wetland at the lowest spot.
It was badly disturbed by the installation of the septic (by the previous owner). In direct violation of one of the first rules of permaculture (never leave disturbed soil undisturbed!), we paid no attention to it for almost 2 years now and it is overgrown with weeds and brambles. And the soil is, of course, still bed: light brown, full of rocks, waterlogged.
That soil is also very fungal, so it’s a challenge to grow and maintain grass on it. To put it simply, greens like bacterial soil, woodies like fungal soil.
It borders on the street, with in between a strip of land that belongs to the town (where a lot of snow gets dumped, so we won’t be investing in any expensive bushes over there. I don’t even know what we could do there, it not being ours.
We never go down there. In the past it was understandable: it was not inviting, and until last Fall (when we put the grass in), there wasn’t even a path that led to it. But I know that, if we don’t make it absolutely gorgeous, it will be still be a neglected area: it is so out of the way of all our traffic.
Of all these issues, no.5 seemed to me the most challenging. What good is a fancy garden down there if we would never visit it? So I kept hesitating, pushing it out of my mind. Then Amie catalyzed an insight.
She kept insisting on lots of flowers. “I want to grow lots of flowers, Mama!” Yes, why not. And we do have a beehive in mind, so we’ll need them. And flowers are beautiful, and down there they will be the first thing people will see. And if we put a bench there, visible and accessible from the street: community!
So. Strip the weeds, lay out beds in curves and organic shapes with the large stones that are native to our property. Fill those with good soil and put in perennial shade-loving flowers. Plant deep-rooted flowers and bushes (elderberry!) to the east, clear of the leach field. Make these plantings transition into the wet area. There plant reeds, put in the pond with fish, a little boardwalk. In the middle have a small patch of lawn. There put a bench. Lay a gravel path to it from the street. Sit down. Enjoy the colors and scents, the sounds of water and of the breeze in the reeds around the pond. And invite the neighbors!
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.
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
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.
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:
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?
