The term "cation exchange capacity" refers to the fact that an exchange often takes place when a cation (a positively charged ion, e.g., calcium, magnesium, potassium or sodium) is removed from the clay colloid by the hungry plant. The plant must maintain an internal electrical balance so it releases a cation whenever it takes one on board. There would be no sense in taking in one nutrient and spitting out another, so the plant releases the non-nutrient mineral, hydrogen, whenever it takes in a cation like calcium or potassium. Hydrogen is effectively exchanged on the clay colloid and this lowers soil pH, as hydrogen is the acid element.

This refers to Total Exchange Capacity. It effectively means that the percentage of the non-nutrient mineral, hydrogen, has been factored into the equation. 

Paramagnetism This is a guideline as to the productive potential of your soil. Volcanic soils serve as an antennae and receiver to attract and store an atmospheric energy called Extra Long Frequency (ELF) radio waves. This energy was originally derived from lightning bolts, where that explosive energy was converted to a more subtle and stable form in the atmosphere. Volcanic soils do more than attract and store this energy, they can convert it to tiny light particles called biophotons. The release of these measurable light particles into the soil effectively provides light for the plant roots and the army of organisms that surround them. This light energy boosts root growth and nodulation in legumes, and stimulates beneficial microbes.

Nitrogen (N) – The unstable essential

Nitrogen is the most abundant mineral found in the plant, so there will be an inevitable price to pay if this mineral is not managed effectively. Key Roles

This is the main mineral found in the green pigment, chlorophyll, so it is absolutely essential for photosynthesis, the most important of plant processes. Nitrogen is also the basis for plant amino acid production, so it has a major impact on plant growth and vitality. These nitrogen-based, protein building blocks are both structural and functional. Enzymes, for example, are proteins and therefore nitrogen dependant. They drive every biochemical reaction upon which all life is based. Nitrogen is also a major component of DNA and RNA, the genetic material that allows cells (and eventually, plants) to grow and reproduce.

There are no surprises that we have become enamoured with this particular input, because it is hugely important. The problem is that the sources of, requirements for, and application timing for nitrogen are often misunderstood. As a result of this confusion, nitrogen has become the most misused and abused of all minerals. 

Key Characteristics

Nitrogen can cycle between the soil, the plant and the atmosphere (just like carbon). The fertiliser from the bag actually accounts for much less than half of the nitrogen used to produce your crop, so it is so important to manage the nitrogen cycle efficiently. There are two forms of nitrogen in your soil – ammonium nitrogen and nitrate nitrogen. Ideally, we like to see equal amounts of each (a 1:1 ratio). The maximum soil requirement for each form of nitrogen is 20 ppm. However, plants can thrive with less than this.

The ideal ratio between these two forms of nitrogen is different in the plant, when compared to the soil. In the leaf, we are seeking three parts of ammonium nitrogen to one part nitrate nitrogen (a 3:1 ratio). This different ratio in the leaf is partially related to an inflow of ammonium nitrogen from the atmosphere, directly into the leaf, via nitrogen-fixing organisms living on the leaf surface. Nitrogen-fixing organisms in the soil also constantly boost the ammonium component within the plant. This key 3:1 ratio between ammonium and nitrate nitrogen in the plant is a really important, but often unrecognised, player in plant health and resilience. Mismanagement of this ratio is tragically common. In fact, this ratio is often inverted and, when this happens, the season is set to be dominated by stress and strife. This nitrate excess is a calling card for insects and disease and the battle begins, as every pest arrives to party.

Nitrogen is the mineral most often abused in terms of this ‘more-on' approach. Excess nitrogen can reduce resilience and lead to reduced uptake of minerals like potassium, calcium and boron.

Now, there is a hugely energy-intensive process involved to convert nitrate nitrogen in the leaf into protein. This can suck up 17% of the plants photosynthates, which could have been used much more effectively, including the boosting of your bank account via increased yield at season's end. The conversion of nitrate N to protein involves three steps – nitrates to amines, amines to amino acids, and then amino acids to protein. The energy-sucking stage of this three-step process is the conversion of nitrates into amines. The irony here is that urea is an amine. The foliar route into the plant is at least 12 times more efficient, so we can use much less urea when it is applied as a foliar. However, the key consideration here is that we are supplying an amine, which is easily converted to amino acids and then proteins. We have effectively avoided the nitrate-based energy drawdown and used much less N in the process. Urea can be very successfully foliar applied at rates of 8 – 20 kg per hectare, but it should always be combined with humic acid to buffer the N and magnify the nitrogen uptake.

Phosphorus (P) – The energiser

Key Roles

Phosphorus is essential for efficient photosynthesis. It is the "energy mineral" required throughout the process of glucose production. This begins with adenosine-tri-phosphate (ATP), often called "the battery of life". However, the critical P link continues with a suite of phosphate-based enzymes that drive the sugar factories in the leaf (chloroplasts).

Phosphorus is also essential to plant immunity, as many of the processes surrounding this natural protection system are phosphate-based.

This mineral drives all stages of the crop cycle, from early root growth to the vegetative phase, and it is in even more demand for fruit and seed filling.

Key Characteristics

Phosphorus-based fertilisers are among the most expensive and unstable of all mineral inputs. This relates to the very low solubility of phosphate complexes. 

When phosphate anions react with cations in the soil, such as calcium, iron, aluminium and manganese, an insoluble compound is formed and you have effectively lost your fertiliser investment. It is estimated that 73% of applied phosphate is destined to lock up in this manner. 

Humic acid is the best tool to stabilise your soluble phosphate inputs to prevent lockups. The humic acid and water soluble phosphate combine to create a phosphate humate that remains stable and plant available throughout the season. Magnesium can stimulate the uptake of phosphorus, while excess potassium can inhibit uptake.

Calcium (Ca) – The trucker of all minerals

Key Roles

Calcium is always the first mineral to correct in your soil, because it has so much impact upon other minerals. We often call calcium "the trucker of all minerals", because it directly stimulates the uptake of seven other minerals. It also indirectly affects all mineral uptake, as it is the doorman at the cell membrane, through which all minerals move into the cell. In the soil, calcium serves to open up the soil. This allows the easy entry of all-important oxygen and the exit of CO2 for photosynthesis (gas exchange). Calcium effectively allows your soil to breathe.

In the plant, calcium governs cell strength and associated plant resilience. It also promotes cell division, growth and crop quality. In the absence of calcium you will see an increase in problems like blossom end rot in tomatoes and capsicums. However, poor cell strength will reduce resilience and there will be multiple associated issues. The amount of calcium your soil requires is based upon the amount of clay (the medium for calcium storage) in your soil. It must always be remembered that too much calcium can sometimes be worse than too little calcium, as an excess can lock up the very same minerals that would otherwise be stimulated by this master mineral.

Calcium is the least mobile of all minerals, which means it is sluggishly delivered into the plant and poorly translocated into fruit.

Magnesium (Mg) – The chlorophyll king

Key Roles

Magnesium is the centrepiece of chlorophyll, the green pigment housed within the sugar factories (chloroplasts) that create glucose, the building block of all life. A magnesium deficiency means substandard photosynthesis, and this will always be costly. Magnesium also stimulates phosphate uptake. A deficiency of magnesium will reduce yield and will also reduce resistance to disease.

Key Characteristics

The calcium to magnesium ratio is the most important mineral relationship in the soil, because it allows the soil to breathe. This ratio also impacts optimum plant availability of both of these important minerals. An excess of either can seriously affect the uptake of the other. This is why the concept of cation balance is so critically important. These soils form clods when worked, and their poor gas exchange (oxygen in and CO2out), reduces photosynthetic potential and favours pathogens, which may not require oxygen. High magnesium soils require much more nitrogen because nitrogen fixation, recycling and availability is all compromised in high magnesium soils. You must "earn the right” to reduce nitrogen in these soils by first improving the all-important calcium to magnesium ratio. According to leaf test data, most crops do not contain the optimum levels of magnesium we are seeking, due to either a lack or an excess of this mineral in the soil (ironically, soil excesses also reduce plant uptake of magnesium). Imbalances of the other major cations, including potassium or sodium, also impact magnesium availability. As with most things in life, it is all about balance. That is the true value of a Soil Therapy™ report, because the parameters for productive balance are clearly delineated and there are suggestions for cost-effective correction of imbalances.

Potassium (K) – The spark plug

Key Roles

This super-mobile mineral does not become part of the cell structure, but rather rushes between cells, triggering multiple processes. It is essentially a spark plug that triggers many reactions.

Potassium is involved in the opening of stomata, the tiny breathing pores that suck up CO2 for photosynthesis. Stem strength is also linked to potassium, as is vegetative growth. However, the most important role of the second most abundant mineral in the plant, is the movement of sugars into fruit, seed, or tubers. This is why we call potassium "the money mineral" – because poor sugar translocation means insipid flavours and smaller seed, fruit or potatoes. You will always suffer less yield and profit if potassium is missing.

You will often experience more disease issues if you mismanage potassium. In the remarkable book (co-edited by Professor Don Huber) called "Mineral Nutrition and Plant Disease", potassium imbalance is shown to be the largest single cause of plant diseases. Most diseases have a mineral link, but potassium is the biggest player. The brown spots (Alternaria) that inevitably arrive on the lower leaves on tomatoes, eggplants, potatoes and capsicums (the Solanaceae family), are very commonly linked to a potassium deficiency in these K-hungry crops.

Potassium is the most mobile of all minerals and it will rush to where it is needed, to size fruit and push shoot growth at the top end of the plant. When it vacates the lower leaves, the sap pH drops in these regions, and this is the calling card for a variety of diseases, Measuring potassium in both upper and lower leaves with a potassium meter is a powerhouse strategy for effective management of potassium. There should never be a difference of more that 10% K, between upper and lower leaves. The moment the K in the lower leaves start falling, you need to fertilise with potassium.

Key Roles

Sodium is a key electrolyte that helps facilitate the thousands of messaging reactions that are part of the electrical life of the plant. It is not an essential mineral, but it can be used in small amounts for opening of stomata and for chlorophyll formation. The most important consideration here, however, is to ensure that sodium never exceeds potassium in terms of base saturation percentages. The ideal potassium to sodium ratio is 5 parts potassium to 1 part sodium.

However, an interesting phenomenon occurs when the percentage of sodium ions attached to the clay exceeds the percentage of potassium. In this instance, the plant becomes confused. Sodium and potassium are similar sized ions and, for millions of years in nature, there has always been a greater percentage of potassium saturating the clay colloid than sodium. However, in many areas, we have messed up that equation and the plant has not adapted to our mismanagement. When the plant requires potassium, it simply selects the most abundant of these lookalikes from the clay. If sodium is more abundant than potassium, then that is the mineral uptaken. The end result is that our crop unintentionally absorbs an unwanted, unproductive mineral, rather than potassium ("the money mineral"). Sugars are not moved, fruit and seed does not size up and there will be less yield and profit as a result. If you are deficient in sodium, it must be applied. Sea salt is the very best source. Sea salt offers more than sodium chloride. It is rich in all 74 minerals, which your soil is often lacking. We have extracted the full spectrum of minerals from our soils for many decades without giving back. Ocean-based inputs like sea salt, kelp and liquid fish can offer restitution for these withdrawals and the visual response can often be quite impressive. Humic acid and soluble silica are the most productive tools for this purpose. Humic acid changes soil structure more rapidly than any other input and this can speed the leaching of unwanted sodium.

Sulfur – The Protein Essential The single most important role of sulfur relates to protein production. The immune systems of humans, animals, plants and microbes are protein dependent. Protein is made from amino acids, and two of these essential amino acids, cysteine and methionine, are sulfur-based. If you are lacking sulfur, your crop will suffer substandard protein production and your plants, animals and customers will suffer accordingly. Sulfur availability is affected by other anions, particularly phosphorus. It can be a really productive strategy to try to maintain a ratio of 1:1 between phosphorus and sulfur in both the soil and plants (although individual ideal plant levels vary). This can help ensure optimum availability of both minerals. Both of these minerals are key players in plant immunity, so if you can balance them at 1:1 there is an associated increase in resilience. We have also found that if you maintain luxury levels of sulfur in your soils, there is much less likelihood of suffering from iron deficiency. Become sulfur aware, try to improve your phosphorus to sulfur ratio and reap the many benefits.