Calcium spray for tomatoes

CALCIUM IN PLANTS AND SOIL

MOBILITY AND UPTAKE OF CALCIUM BY PLANTS

Calcium uptake by the plant is passive and does not require energy input. Calcium mobility in the plant takes places mainly in the xylem, together with water. Therefore calcium uptake is directly related to the plant transpiration rate.

Conditions of high humidity, cold and a low transpiration rates may result in calcium deficiency. Salinity buildup might also cause calcium deficiency because it decreases the water uptake by the plant.

Since calcium mobility in plants is limited, calcium deficiency will appear in younger leaves (die back or burns) and in fruits (blossom end rot, bitter pit), because they have a very low transpiration rate. Therefore, it is necessary to have a constant supply of calcium for continued growth.

ROLES OF CALCIUM IN PLANTS

Calcium is an essential plant nutrient. It has many roles:

  • Participates in metabolic processes of other nutrients uptake.
  • Promotes proper plant cell elongation.
  • Strengthen cell wall structure – calcium is an essential part of plant cell wall. It forms calcium pectate compounds which give stability to cell walls and bind cells together.
  • Participates in enzymatic and hormonal processes.
  • Helps in protecting the plant against heat stress – calcium improves stomata function and participates in induction of heat shock proteins.
  • Helps in protecting the plant against diseases – numerous fungi and bacteria secret enzymes which impair plant cell wall. Stronger Cell walls, induced by calcium, can avoid the invasion.
  • Affects fruit quality.
  • Has a role in the regulation of the stomata.

FACTORS AFFECTING THE AVAILABILITY OF CALCIUM TO PLANTS

Calcium forms insoluble compounds with other elements in soil, such as phosphorous. Calcium that is in the form of an insoluble compound is not available to plants.

Since calcium is a positively charged ion, it is adsorbed in the soil to the surface of clay and organic particles which are negatively charged.
Positively charged ions adsorbed to soil particles are termed “exchangeable ions” because they can be exchanged by other ions present in the soil solution. Soil analysis determines the level of exchangeable calcium ions, and not the total calcium in soil, because the exchangeable calcium is the form which is available to the plant.

Several factors in the soil analysis can help in assessing the availability of calcium to plants:

  • Soil pH – usually soils with a higher pH level contain more available calcium.
  • CEC – this is a soil characteristic that describes the total amount of positively charged exchangeable ions that the soil can hold. A higher CEC indicates a higher capacity of the soil to adsorb and hold calcium, and therefore higher calcium availability.
  • Presence of competing ions – calcium competes with other positively charged ions, such as sodium (Na+), potassium (K+), and magnesium (Mg+2). Applying too much of these positively charged ions might decrease calcium uptake by plants. Sodium ions can replace the adsorbed calcium, damage soil structure and decreases calcium availability.

OTHER REACTIONS OF CALCIUM IN SOIL

Calcium-phosphorous precipitation – when free calcium accumulates in the soil solution (e.g. when soil pH is high), calcium tend to form insoluble compounds with phosphorous. Consequently, phosphorous availability is also significantly decreased.

Calcium stabilizes soil structure – the calcium that is adsorbed to soil particles helps in stabilizing the soil structure. Adsorbed sodium might cause the soil to crack when dry and swell up when wet. Calcium replaces the adsorbed sodium and prevents damages to soil structure.

CALCIUM DEFICIENCY

Calcium deficiency is usually caused due to low calcium availability or due to water stress which results in low transpiration rates. The symptoms of calcium deficiency include curling of young leaves or shoots scorching or spotting on young leaves, poor growth, leaf tip burns, stunted roots, and damage to fruit.

SOURCES OF CALCIUM FOR PLANTS

The most common calcium sources are calcium nitrate, calcium chloride, lime, gypsum, calcium chelates and some organic sources.

Author: Guy Sela, international expert in plant nutrition and irrigation.

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While blossom end rot is caused by a lack of calcium to the developing fruits, it doesn’t mean there isn’t enough calcium in the soil. It is most often related to an inconsistent amount of water in the soil or being taken up by the plant. Calcium is brought to the fruit in the water the plant takes up from the soil so allowing the soil to dry out too much between waterings can cause blossom end rot. Pot-grown tomatoes are especially susceptible.
Once fruits begin to form, water to supply 1-2″ per week from rain and irrigation combined. Water deeply 1-2 times per week rather than frequent shallow waterings to promote good root growth. Water is drawn into the plant partly in relation to the amount of water lost from the leaves via transpiration. Transpiration slows down when there is high humidity, resulting in less water being needed from the soil. Less water from the soil = less calcium coming into the plant so extended periods of high humidity can also result in blossom end rot.
The best way to see if there is a pH problem or calcium deficiency in the soil is to get a soil test done. The best pH for tomato is 6.0-7.0 and if it’s already there, you don’t want to add lime which will raise the pH. A mulch can help the soil retain moisture. Other tips include not planting the tomatoes when the soil is too cool (affects early fruits), don’t overfertilize with nitrogen, and be careful not to injure the roots if cultivation is needed near the plants. Some sources recommend calcium chloride sprays on the foliage but use caution with these. They can cause plant injury and some reliable sources say they don’t really help.

Organic Calcium Sources for Gardens

Organic calcium sources like dolomite lime and ground oyster shell are relatively cheap and readily available, but your kitchen generates free organic calcium you probably didn’t know about—eggshells.

Dried, Ground Eggshells are a Great Source
of Free Organic Calcium © Steve Masley
Click IMAGE to Enlarge

Dried, ground eggshells are a great source of calcium for vegetable container gardens and salad tables.

Calcium is a component of plant cell walls, and it’s needed for enzyme formation and nitrate uptake. Organic calcium can also be used to help neutralize excessively acidic soils, which is especially important when you’re growing green, leafy vegetables like lettuce and spinach, or cruciferous vegetables like cabbage, broccoli, cauliflower, and kale.

Organic calcium sources include dolomite lime, calcite, ground oyster shell (oyster shell flour), and crushed eggshells.

Organic Calcium Sources–Links with the Linkout symbol ( )
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Soil Amendment N-P-K Description Lasts Application Rate
Dolomite Lime Cheap and readily available source of Ca and Magnesium (Mg) in acidic soils. Do not use if soil Mg levels are adequate or excessive, or plant toxicity may result. If in doubt, use Calcite or Oyster Shell Flour for supplemental Ca. 3-12 Months In clay soil, 8.75lbs/100 sq ft raises pH 1 point
In sandy soil, 2.5lbs/100 sq ft raises pH 1 point
Ground Oyster Shell 0.25-0.15-0.25 Finely ground oyster shells. A long-term, slow-release organic Ca source. Fuels microbial growth in soil. Excellent for balancing out acidic conditions in worm bins. 1-2 Years 4-6lbs/100 sq ft
Dried, Crushed Eggshells The trick is to dry them first in a can on top of the refrigerator. Mash down as needed, then grind to a coarse powder in a food processor. Great for seed starting mixes & cruciferous vegetables. 3-12 Months Up to 2lbs/100 sq ft
3Tbs/10” pot
Calcite (Hi-Calcium Lime) Good alternative when dolomite lime is inappropriate. 3-12 Months 1-2lbs/100 sq ft

Top of Organic Calcium Sources Page

Dried, Ground Eggshells

Organic gardeners know that if you just toss eggshells into the compost, they’ll disappear quickly in a hot compost pile, but they’re surprisingly resilient in cool composting systems like static compost piles or a worm composting system.

Eggshell in a Cool Compost Pile 4 Months,
Membrane Still Intact
© Steve Masley…Click IMAGE to Enlarge

The reason for this lies in the membrane between the embryo and the shell, which has evolved to be highly resistant to microbial attack, even when the shell is cracked. As long as the membrane is moist, the embryo remains protected.

Long after the egg sizzled in the pan, the membrane under the shell continues this protective function in your compost pile or worm bin.

Eggshells eventually do break down even in cool composting systems, but you’ll have big chunks of shell left in your compost or worm castings. It will be many months before the calcium in these chunks becomes available to your vegetables.

The trick with using eggshells in the garden is to dry them out first. Once the protective membrane has dried out, the shells can soak up moisture—and microbes—from the soil, and begin to break down.

Making and Using Dried, Ground Eggshells in the Garden

Dried, ground eggshells have an NPK value around 1.2-0.4-0.1. The nitrogen content varies with the amount of egg protein left in the shells. Eggshells also contain significant amounts of calcium, as well as trace minerals.

This free organic calcium source is great in potting mixes for container vegetable gardens, for transplanting mixes to pot up seedlings, and as a way to neutralize excess acidity and provide grit in worm composting systems.

Use 1-2 Tbs per gallon of potting soil, or up to ½ cup in a 5-gallon pot.

Cruciferous vegetables, lettuce, and spinach all thrive with finely ground eggshells mixed into their soil. Tomato, pepper, and squash seedlings grown with a small amount added to their potting mix are particularly robust.

Dried, Crushed Eggshells are a Great Free Organic Calcium Source
(Click IMAGE to Enlarge)
Dry egg shells in a coffee can.

After cracking the eggs into the pan, toss the shells into a coffee can and place it on top of the fridge.

It’s okay if a little egg white is left in the shells—it increases the nitrogen content of the eggshells—just don’t put yolks or large amounts of egg whites into the shell can. As long as it’s mostly eggshells, you won’t have any problems with odors or insects.

When the can is almost full , crush the shells down with the bottom of a glass or jar. Do this when the last eggshells you added have dried for 2-3 days, then continue to add eggshells as you use eggs in the kitchen, and crush them down a couple days after they dry out.
In 2-3 months, the can will be almost full. There will be a pound or two of coarsely crushed eggshells. It’s surprising how much accumulates just scrambling eggs 2-3 times a week. More, if you do any baking.
Place the dried, crushed eggshells from the can into the bowl of a food processor. Process the dried, crushed eggshells in a food processor for 1-2 minutes, grinding them into a coarse powder.
This is a noisy and dusty process, so it’s best to open the windows, turn on the kitchen fan, and walk out of the room for a minute or two.
The finer the grind, the more quickly the calcium becomes available to your vegetables. A mixture of fine and coarse particles is best. The fine particles supply calcium early in the season, and the coarser particles break down throughout the growing season.
Store in a jar with a tight-fitting lid. Use in seed starting mixes and container gardening potting soil, or as an organic calcium source for your vegetable garden.

In large amounts, dried, ground eggshells can be used for raising soil pH, but it’s better to spread this valuable organic calcium source around, and use it in small amounts with many plants. Especially when organic calcium sources like oyster shell flour are available.

Organic NPK Fertilizer
(N)itrogen | (P)hosphorus | (K) Potassium | (Ca)

by Rick Pickett, Eco-Ola

Building soil fertility in the humid tropics is a difficult project. Not only because the soil itself is thin, but due to the fact that below the fertile surface of leaf litter, rotting trees and decaying organic matter is a mineral and nutrient deficient zone of usually acidic clays called oxisols or, less commonly, utisols. With up to 90% of tropical forest biomass living within the plants and organic matter and only a paltry 10% occurring in the actual soil, protection and cultivation of soil is extremely important in sustaining fertility.

For many of our farm partners, like Federico, we’re rehabilitating slashed-and-burned lands that have been heavily leached of nutrients or are lacking the balance of minerals needed to allow plants access to important nutrients like phosphorous. One technique used extensively in tropical climates to take advantage of oxisols is the heavy application of lime or calcium carbonate to raise the soil pH and begin improving the soil structure and mineral availability for plants.

We would love to pump multiple metric tons of lime or calcium into the soil, but our distant location from traditional sources and concerns about mineral extraction practices makes large-scale delivery undesirable. But, our plants need their calcium. What to do?

… Enter the mighty eggshell.

Composed of 98% calcium carbonate, eggshells are an untapped source of calcium, but in their solid form they are very slow to decompose into a form ready for plant uptake. To change the eggshell into a soluble form, we need to use vinegar (acetic acid) to breakdown the calcium carbonate and transform it to water-soluble calcium acetate. From there we can use the diluted solution as a foliar spray on the plants for fast absorption, usually in 24-56 hours.

Calcium is an essential nutrient for cell wall reinforcement as well as protein synthesis, water transfer and carbohydrate translocation. The challenge is that calcium is mostly immobile in plants and won’t be sent to areas in need. By applying a bi-weekly treatment of calcium acetate mixed with other nutrients, we’re able to counteract the calcium-deficient soils and provide needed nourishment for the plants.

The Solution

Two-months ago we started collecting eggshells from various restaurants in Iquitos, especially Dawn of the Amazon Cafe, and food vendors in the Eco Ola Permaculture Capital of the Amazon, Mazán. Instead of letting more organic waste be trashed in the local dumps, we’re able to recycle these essential minerals for improving plant health and robustness.

The process goes like this:

  1. Eggshells are picked up daily in Mazán or delivered weekly to the farm from Iquitos
  2. The shells are sun-dried to evaporate any moisture, limit pests and reduce toasting time
  3. Shells are then crushed to increase surface area to further reduce toasting time
  4. We toast the shells over a wood fire until the majority have a nice black char to them (we’ve noticed over multiple solutions that the shells seem to dissolve faster with longer toastings
  5. A volume mix of 1:1 of table vinegar and toasted eggshells is prepped and shaken in a bottle
  6. Every day we shake the bottle and add more vinegar as space is created in the production of carbon dioxide gas
  7. In roughly four-weeks the eggshells have mostly dissolved and we use a 15-21 tablespoon dilution in 15-liters of water for foliar spraying

Toasting the eggshells is a bit unpleasant, especially at first when we were toasting them wet and filled with maggots. At least the maggots added some additional nutrients, but introducing the sun-drying before toasting has made the process much more pleasant. But, do be warned, as you will reek of toasted eggshells, especially if doing multiple batches.

We look forward to documenting the process and sharing photos of our test plots of the solution with you all!

How to Make Water Soluble Calcium at Home

Believe it or not, calcium is as essential for plants as it is for humans. It is commonly found in nature and is second to being as common as oxygen. In the form of calcium carbonate, calcium can be extracted from something as common as eggshells when paired with vinegar. Natural and organic farmers, even gardeners, tend to create their own water soluble calcium at home. This is because all of the ingredients required are those you can find in most households, especially if you love eggs. So, how do you make water soluble calcium?

What’s the best recipe?

Not all water soluble calcium techniques are the same, but they all have a universal idea with similar ingredients. Our recipe generally includes eggshells (as many as you can find) and vinegar. Eggshells carry lots of calcium carbonate, but it is trapped within the eggshell and needs to be extracted. Vinegar is useful for this since it separates the calcium from the eggshell while producing carbon dioxide.

As for the best recipe, that’s up to you! We like to keep it pretty simple when making the solution, as we explain below. Of course, there are other options out there, so feel free to test away or even make your own recipe!

But, why even make water soluble calcium?

Water soluble calcium is ideal for farmers and gardeners who wish to give their plants and crops a quick calcium boost. It prevents crops and certain plants from overgrowing, increases the longevity and hardness of fruits, provides plants and crops with proper nutrition and encourages plant-life to absorb nutrients much easier.

Ingredients Needed:

  • Eggshells
  • Vinegar (ideally Brown Rice Vinegar)
  • Mason Jar or Polyethylene Container
  • Paper Towel
  • Rubber Band
  • Crushing Tool (optional)

How do you make water soluble calcium?

  1. Gather your eggshells and clean them out. Be sure to remove any sticky layer within the underside of the eggshells. This will ensure the eggshells solely contain the calcium we wish to extract and nothing else.
  2. Using your crushing tool, or your palm, carefully crush the eggshells into small pieces. Avoid crushing the eggshells into a powder form. Crushed eggshells will allow the process to be quicker and much more effective.
  3. *Optional: Roast the shells over a fire to remove any substances that could possible rot during the process of making water soluble calcium. Be sure to avoid browning or burning the eggshells. (We usually roast ours)
  4. Fill your mason jar or polyethylene container with your vinegar and add in the eggshells. The eggshells will move within the jar or container and will produce bubbles while they melt into a liquid.
  5. Your solution is done when there is no longer any movement or bubbles being produced.

Tips:

  • Once you rinse or clean out your eggshells, allow them to dry.
  • Slowly place your eggshells into the vinegar solution, little by little.
  • The lack of bubbles means the eggshells and spaces in between them are saturated with vinegar.
  • For any eggshells that sink to the bottom, remove the water soluble calcium solution and add in more vinegar to make more solution out of the leftover eggshells. This happens when there are too many eggshells in the vinegar, making it hard to melt.
  • Know that your home/kitchen will smell of vinegar and eggs, so open some windows and turn on a fan or two because it’s about to get stinky!
  • Store your solution in a cool, shady area at room temperate. Be sure there is no contact with sunlight in your storage area. We generally put it in a kitchen cupboard that is rarely opened and all the way in the back.

How do you use water soluble calcium?

Water soluble calcium can be used widely across your garden and farm. You can use your solution for a variety of things, including when:

  • plants or crops overgrow
  • plants or crops aren’t growing correctly
  • leaves are discolored
  • flower buds are discolored
  • fruits are too soft
  • plant nutrition is low
  • flower blossoms begin to fall
  • you want to increase the flavor of vegetables and/or fruit

Your water soluble calcium solution should be diluted prior to applying to your plant’s or crop’s soil. The dilution ratio is typically 1 part calcium solution to a 1000 parts non-chlorinated water. However, depending on the strength of your batch, you may find you need more or less than that by a little. To figure this out, you can do one spray and wait a few days to see where the health of your plants are at. If there isn’t much change, you may decide to lean more towards a 1:500 ratio instead.

It’s all a balancing act and once you get your recipe down, you’ll know the exact amount needed in no time. After just two or three batches, we figured out the ratio we needed to keep when feeding this to our plants. Generally, the only time we use it is if the plants are showing a calcium deficiency, but it can be used at any time if you wish.

SFF may receive commissions from purchases made through links in this article. As an Amazon Associate I earn from qualifying purchases.

Your tomato plants are tall and green; you’ve taken the time to carefully stake or cage them to support their growth. Right now they are loaded with tons of green tomatoes, and some of them are just starting to blush red. And then three days later, it all goes horribly wrong.

There is nothing more disheartening than to see that all of your ripening tomato beauties (or peppers or squash) are now rotting from the bottom—right on the vine!

What is Blossom-End Rot?

Blossom-end rot looks like a discolored, watery, sunken spot at the blossom end of the fruit, most commonly tomatoes. The spot will start out small, and grow larger and darker as the fruit continues to grow.

Blossom-end rot can quickly cover half the fruit, making it totally inedible. Secondary diseases or mold can also form on the affected areas, overtaking the entire fruit.

Blossom-end rot is more common if you planted in cold soil or when your garden experiences extremes in soil moisture levels—either too dry or too wet.

How to Stop Blossom End Rot

Blossom-end rot is a disorder caused by calcium deficiency in the plant.

While this may be a result of low calcium levels in the soil, more often than not, it is the result of erratic watering.

When the plant is allowed to get too dry, or is given too much water over a period of time, its ability to absorb calcium from the soil is greatly diminished. In other words, your soil might have plenty of calcium, but it just isn’t bioavailable and being taken up and utilized by the plant.

If your soil is indeed low in calcium (determined by a soil test) the easiest solution is to add garden lime several times per year, according to the directions on your soil test results. (Don’t just add lime without testing your soil first, as you might disrupt the optimal pH for growing your crops.)

Over fertilization, especially with high nitrogen fertilizer, can also cause blossom-end rot. Over fertilization can cause such rapid growth that nutrients such as calcium won’t be able to keep up with the growth. Always soil test before fertilization and fertilize according to the results.

You can also choose varieties of tomato that are resistant to blossom-end rot. Varieties of tomatoes that produce large fruit tend to be more susceptible to blossom-end rot, while varieties with smaller fruit are less likely to suffer it.

Blossom-end rot is much easier to prevent than it is to cure. Once it has set in, it can be really hard to reverse, but there are a few things you can do that have a good chance of turning things around.

Ensure Consistent Water Supply

If the issue is erratic moisture, here are some tips:

1. Make sure your soil isn’t allowed to dry out. The best defense against blossom end rot is a nice, consistent soil moisture level.

2. As the summer rolls on, it is easy to forget to water the garden regularly. If it is hard for you to be consistent, or if you plan to take a vacation, consider installing a drip irrigation system and a timer. Drip irrigation is a major time-saver, affordable, water-wise and an outstanding disease prevention method because it both keeps soil moisture regular and keeps water (and therefore fungus spores) from getting onto the leaves of your crops. (This is the system I use)

3. Mulch. By adding a three-inch layer of organic mulch, you can help maintain adequate soil moisture levels, even during dry spells. It is best to add the mulch after your soil has warmed in the spring.

4. Plant susceptible crops (such as tomatoes, melons, squash, peppers, and eggplants) in well-drained soil that has been amended with compost or well-rotted manure. Soil amended with plenty of organic matter will retain moisture better and supply plenty of nutrition (including calcium) to your plants.

Fortify Your Crops at Planting

In addition to making sure you have consistent moisture levels in your soil, you can fortify your plants when you put them in the ground to make sure they get plenty of calcium throughout the season.

Many people use garden lime to adjust their garden pH and add calcium at the time of planting. This will treat the entire garden soil. (If your soil pH doesn’t need adjusting, use gypsum instead of lime.) You can also add 2-3 Tums tablets or other calcium carbonate antacid to each planting hole to add extra calcium.

I personally like to use a teaspoon or two of eggshell calcium to each hole as I plant my tomatoes, peppers, squash, etc. This is a great way to use up a common food waste product. Here’s how to make it.

If you already have signs of blossom-end rot, you can make a solution from 2-3 calcium carbonate antacid tablets, 8 ounces of milk and a quart of pure water, and irrigate your plants with it daily to help keep blossom-end rot from destroying more of your crops than it has to. This might help turn things around, but isn’t foolproof.

Don’t bother with the calcium sprays at the garden store that promise to stop blossom end rot. While they can help with other issues related to nutrient deficiency, to stop blossom end rot, the calcium has to come up from the soil through the roots, not through the leaves.

Prevention is really the cure here.

Preventing Blossom End Rot is the Best Cure

Good, fertile soil and consistent watering can make all the difference in stopping this heartbreaking problem before it starts and ruins your crops. Get your soil tested each spring, and amend it accordingly.

Understanding Calcium and pH

Gardeners tend to worry first about the NPK levels of their soil, neglecting the soil’s calcium. Without adequate calcium, all the fertilizer in the world will do you little good. Calcium benefits soil and plants by improving the soil’s physical structure, raising the pH of the soil and directly contributing to the plants’ nutritional needs.

Soil Structure: Free calcium ions have a double-positive charge, so they help to stick negatively charged clay soil particles together. This is called flocculation. Clumped particles—instead of dispersed particles—increase soil porosity, which means more oxygen in the root zone and better water penetration (think about the relative air space available in a bucket of tennis balls vs. a bucket of marbles).

Effects on pH: When lime is applied to acidic soil, the hydrogen ions react with the calcium carbonate to produce water and carbon dioxide. This reduces the level of free hydrogen ions in the soil and raises the pH. pH levels that are significantly below neutral will limit the availability of many important plant nutrients and inhibit plant growth.

Plant Nutrition: Calcium helps plants build strong cell walls, which means bigger healthier plants and better resistance to disease. It is important to the metabolism of nitrate and other plant nutrients. Also, it helps to regulate leaf stomata, so plants need adequate calcium to cope well with heat stress. Fruiting plants deficient in calcium may suffer blossom end rot or other quality problems.

How much lime should you apply? Don’t even try to answer this question without a professional soil test! The quantity will depend not only on the current pH and calcium levels of your soil, but also on your soil’s cation exchange capacity (CEC) and perhaps on what crops you plan to grow (most garden vegetables are pretty happy with a pH around 6.5, but if you’re growing larger quantities of one thing then it’s important to know that potatoes like a much lower pH than asparagus). Even on very acidic soils, most experts recommend that applications not exceed 3 tons per acre per year (about 140#/1000 sq ft). Lime recommendations on soil-test reports typically assume you are applying straight calcium carbonate. The effect on pH of other liming agents is reported as a “calcium carbonate equivalent,” and quantities should be adjusted accordingly.

When and how should you apply lime? Calcium moves very slowly in the soil: if applied to the surface, it will move downward a rate of just 1″ per year. The liming materials permitted for use in organic production may take 6 months to a year to react fully, longer if the soil is dry. For best results, liming should coincide with a tillage event to incorporate it as deeply into the root zone as is practicable. Applying in the fall gives the lime more time to react before plant growth, and probably moister soil conditions. The good news is a lime application is for the long haul: you typically need to apply lime only once every 5–10 years.

A soil test will help identify an appropriate calcium source for your location:

  • Aragonite Calcium carbonate equivalent 94%.
  • Gypsum 23% calcium, 17% sulfur. Granulated. The sulfur buffers against any change in pH. Provides calcium when pH is already at desired level.
  • Calcitic Limestone Granulated calcium carbonate. Calcium carbonate equivalent 95.8%.
  • Dolomitic Lime Calcium carbonate with 42% magnesium carbonate. Powdered. For use on soils with a magnesium deficiency. Calcium carbonate equivalent 102.9%.
  • Wollastonite Calcium oxide with silicon dioxide. Calcium carbonate equivalent 76%.

Adding Calcium

Tino Carnevale

TINO CARNEVALE: Lime is always recommended to people who are looking to raise their soil pH, or what is referred to as ‘sweetening’ your soil. Now there are a few forms of lime and they all work slightly differently.

Good old garden lime here, or calcium carbonate is a great way of adding a good dose of calcium to your ground. It should be applied at about a handful every square metre or so and it’s essential for plants like apples, pears and these brassicas here. Actually a handful of lime will prevent problems like club root.

Dolomite is a coarser form of lime so it’s slower acting. It’s like garden lime, but it’s got a good amount of magnesium in it, meaning it’s good for preventing or correcting magnesium deficiencies which present themselves on the plant as a yellowing off the leaf and a greening off of the venation and it only affects older leaves because magnesium flows through the plant very freely. Now this Pepino here is an acid-loving plant and a lot of people think you can’t put lime down on acid-lovers. You can – you just need to apply it a little bit more lightly.

Gypsum is sold as a clay breaker, but unlike the limes, it doesn’t affect the soil pH, but it does add a good amount of calcium. Now it only works on some clays – sodic clays. The way to test this is get a clod of your clay and put it in a jar of water. If the water goes cloudy, then the gypsum will work. If it’s clear, then I’m sorry to say, the only answer is organic matter. Now apply it 2 to 3 handfuls per square metre and water it in.

COSTA GEORGIADIS: Some time ago, I visited the Hawkesbury Flood Plain, which is also referred to as Sydney’s food bowl. Now since the First Fleet arrived, the fertile soil has enable Sydney’s market gardens to thrive, but urbanisation is changing the region.

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