Most growers underestimate the importance of calcium. I call this mineral King Calcium, for good reason. Calcium is the first mineral to address in any nutrition program, as it is the most important mineral in the production of abundant, healthy, resilient crops. Here are some of the reasons why this mineral is so pivotal:
1) Calcium governs the cellular delivery of all minerals, because it is involved in the uptake of minerals across the cell membrane. Hence, if your crop is lacking calcium, it is often lacking other minerals. A good example of this phenomenon can be seen when using a refractometer. This invaluable tool measures dissolved solids in your crop, and is effectively a measure of your growing skills. However, a refractometer can also be used to monitor the calcium status of your crop. A blurry line indicates good calcium levels, but it also indicates good overall mineralisation because calcium is, in effect, the trucker of all minerals.
2) Management of gas exchange is of primary concern when producing a healthy, problem-free crop. Oxygen is the most important element in the growing equation. It is constantly required by plant roots and the beneficial organisms that surround them. You are striving to create a soil that can breathe, and the ease of that breath is critical. Oxygen must be able to freely diffuse from the atmosphere into your soil and then, when it has been utilised by roots and soil life, there is an out-breath. Now, as CO2 diffuses from the soil, the leaves perform their magic. The tiny breathing pores on the underside of every leaf, called stomata, suck up this CO2 and combine it with water and sunlight to produce glucose, the building block of all life. The better your gas exchange, the more productive your crop and the fewer problems your soils will suffer. Gas exchange is determined by calcium. This mineral holds clay colloids together as stable soil aggregates with air-spaces (pores) in between. This process is called “flocculation”, which opens up the soil and facilitates ease of breath.
3) Calcium governs cell strength. When chasing a problem-free crop, the cell wall should be seen as the physical barrier that resists the insistent hyphae of pathogens or the mandibles of pest insects. If you can strengthen the cell wall with calcium (and silica), you have strengthened the plant fortress and seriously reduced the likelihood of pest pressure.
4) Finally, calcium governs crop quality. When we pump a crop with N and K, we must keep up the calcium to ensure the extra cell division to sponsor a healthy growth increase. When we are sizing fruit or grain there is a requirement for extra calcium – this can be a problem, because calcium is the least mobile of all minerals.
Seven Calcium Secrets
Calcium is one of four minerals we like to see at luxury levels on a leaf test, but it is rarely found in this zone. Here are seven solutions to this problem:
1) The full potential of calcium can not be realised in the absence of boron. Boron is deficient in the vast majority of soil and leaf tests we examine. For some reason, most growers downplay, or fail to recognise, the prime importance of this trace mineral. Boron does not just drive calcium – it increases reproductive performance in all crops. Boron also opens the trapdoor that allows the translocation of sugars from the chloroplast, throughout the plant. This is hugely important, because a serious boron deficiency can mean we are starving the microbial workforce that crowds around every root awaiting their daily feed.
Boron is only able to be stored on the humus colloid, so, as we have lost 2/3 of our humus due to extractive agriculture, we have also lost our associated capacity to retain boron. An absolute minimum of 1 ppm of boron is required (according to a soil test), but this essential level is rarely achieved in most soils. Boron deficiency can predispose the plant to fungal pressure, particularly from destructive mildews.
2) Calcium storage and delivery is not just a physical process, involving the attachment of this positively charged mineral to the negatively charged clay colloids in the soil. It is, equally, a biological phenomenon, largely linked to beneficial fungi. This is the main reason why humic acid is such a perfect partner to limestone. Humic acid is the most powerful known fungal stimulant, so it helps to proliferate the fungi that store and deliver calcium. Fungal-based composts, combined with lime, can really kick some calcium goals (as NZ farmers adding composted woodchip to their limestone have discovered).
Mycorrhizal fungi are particularly adept at calcium delivery. This living, microscopic root extension increases root surface area tenfold and that entire biomass is constantly releasing acids to break the bond between locked-up calcium and phosphorus, delivering both minerals to the plant. The popular NTS inoculum, Nutri-Life Platform®, delivers four different species of mycorrhizal fungi and five Trichoderma strains to the root zone. Trichoderma also solubilise calcium and phosphate, whilst improving plant resilience, building humus and promoting root growth.
3) Silica helps with calcium uptake and this mineral partners with calcium as the second cell-strengthening component of cell walls. However, that protective barrier is compromised in most soils through want of plant-available silicic acid. Silica is the building block of phloem and zylem, the nutrient pathways into and around the plant. Calcium is the least mobile of all minerals, but this slug-like mobility can be countered if we can optimise these nutrient pathways with the help of silica. We have found that liquid micronised diatomaceous earth (Dia-Life Organic™) is a versatile and user-friendly silica source. Potassium Silicate is another productive option, but is less versatile due to incompatibilities with most other fertilisers and farm inputs.
4) Foliar sprayed calcium is hugely beneficial in fruit crops, to counter the poor mobility of calcium. Calcium is required for the cell division that drives fruit size and quality, but there is often poor translocation into the fruit. A foliar spray of chelated calcium can be a remarkably productive helping hand. This can be achieved with proven products like Cal-Tech™ (which also features boron), but you can also do it yourself. This is as simple as adding a little NTS Fulvic Acid Powder™ to some calcium nitrate to create a calcium fulvate. Typically, this involves just 3 – 5 kg/ha of calcium nitrate per hectare with around 200 grams of NTS Fulvic Acid Powder™. We have found that this simple combination is amongst the best techniques to deliver calcium, and it is cheap enough for broadacre farmers to benefit.
5) Burnt lime is a great, fast-food calcium source to kickstart a calcium-deficient soil. George Washington was named "the father of American agriculture", because he recognised the potential of burnt lime to activate calcium-starved soils. Ancient lime kilns pepper the U.S. countryside as testimony to this recognition. Calcium carbonate (limestone) only contains 5 kg of soluble calcium from a total of 400 kg of Ca per tonne. Gypsum features 15 kg from a total calcium component of 200 kg per tonne. Burnt lime (calcium oxide or calcium hydroxide) contains a whopping 150 kg of soluble calcium per tonne. Sometimes you can source ash byproducts from industry that contain calcium oxide and silica, and they can be genuine bargains. You can even apply builders’ lime (calcium hydroxide) with water and achieve a great response. However, this material is extremely "hot" (alkaline) and should always be buffered with humic acid to avoid crop damage.
6) Calcium is at its most powerful when applied with phosphorus, because these two minerals deliver a real kick when combined. Unfortunately, this combination is not easily achieved because soluble calcium and phosphorus are not compatible. In fact, they rapidly form insoluble calcium phosphate when mixed together. There is no surprise that there is a great response when you reduce the natural incompatibility of these two minerals, which are crucial players in the most important plant process, photosynthesis.
We have discovered two ways to achieve this big bang. The first involves our foliar fertiliser, Phos-Force™, where we have mastered a fusion technology that allows the two minerals in one formula. The other involves our most popular Micronised Mineral Suspension (MMS) product, Phos-Life Organic™. Here, calcium and phosphorus are small enough (5 microns) to be absorbed and utilised together, but they are not in ionic form, so they can’t lock up. This is a great way to deliver calcium with a phosphorus sidekick, to achieve the big bang without the lock-up. The resulting photosynthetic boost has made Phos-Life Organic™ hugely popular around the globe.
7) Liquid, micronised lime is a great tool to deliver calcium without the unwanted tag-ons. Calcium is rarely found at the luxury levels we like to see in a leaf test, but your options are limited when you choose to address this issue. The main readily available form of this mineral is calcium nitrate, but many leaf tests reveal that you already have more than enough nitrate-nitrogen in your crop. In the search for another option, we discovered that we could create a liquid mineral suspension involving more than 1.6 kg of micronised lime (5 microns) jam-packed into 1 L of water. This MMS option, called Lime-Life Organic™, involves a formula with an amazing 39% plant-available calcium. This calcium-dense product can be fertigated or foliar applied to deliver this crucial mineral without the unwanted nitrogen.
Calcium is the key to healthy, productive, resilient crops and yet it is deficient in most leaf tests we analyse. When you address this master mineral using some of the strategies I have shared, you will become a calcium convert! I would love to hear details of the differences you observe when the base is in place.
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