Calcium (Ca), Potassium (K), Magnesium (Mg) balancing is crucial for the health of your plants and soil

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Understanding how nutrients cycle through the soil and become availability to the plant is critical to achieving physical harmony and nutritional balance in your farming system. 

Today, many growers face the challenges of balancing metal ions due to the accumulation of salts, including sodium, which can be a hidden ingredient lurking in a farm’s water sources. When found in the correct ratios or in manageable levels, salts can be low impact or beneficial. When building a soil balancing approach, it is also important to consider soil physical properties and how nutrient balance, such as calcium, potassium, and magnesium, affects overall crop yield.

Most crop plants grow in environments that are suboptimal, which prevents the plants from attaining their full genetic potential for growth and reproduction (bray et al, 2000)

Testing of soils at periodic intervals is necessary due to soil-level fluctuations throughout the growing cycle. When it comes to assessing and managing the levels and ratios of Ca:Mg and K in soil, soil tests are crucial. Whenever soil reports are run, all micronutrients should be analyzed.

Managing the Ca:Mg Ratio

In the absence of a calcium supply outside the root system, root extension ceases within a few hours. (Marschner, 1986) 

Calcium is a powerful ally in the fight against salinity and is thought by many to be a macronutrient. Plants require generous levels of calcium to manage many other ions in the colloid. In the rooting zone, calcium will moderate the harmful effects of sodium, chlorides, and other salts. There are well more than 1,000 genes that are activated and deactivated in response to salinity. Under conditions of extreme salinity, proteins are precipitated. Together with magnesium and potassium, calcium helps neutralize organic acids formed during plant metabolism.


In plant tissue, magnesium and potassium are responsible for regulating chlorophyll production. Thus, if Mg or K is deficient, the shortage of chlorophyll can’t capture sunlight needed for photosynthesis. Magnesium also helps to activate specific enzyme systems.

To keep ratios intact, knowing the nutritional influences is paramount to keeping them available. Calcium is directly affected by phosphorus, zinc, magnesium, and manganese and has an effect of its own on magnesium. Low calcium and magnesium levels are generally defined as less than 300 parts per million (ppm) and 35 parts per million (ppm). Each crop has its own tolerances and references should be made on a case-by-case basis with up-to-date and historical soil reports.

Increasing the Ca:Mg ratio will require more time and additional amendments on soils with a higher cation exchange capacity (CEC). The cost of soil balancing may be prohibitive depending on how much change is needed and the value of the crop.

Consider calcium sources when looking for a calcium product to moderate salts and improve the uptake of plant nutrients. It is possible that calcium nitrates and other sources of calcium could contain limiting factors, along with a higher salt index component or associated chemistries that may decrease their effectiveness. A concentrate of highly processed calcium will allow you to increase surface area without overloading the soil with large amounts of fertilizer.  

Calcium also helps the plant adapt to stress by influencing the signal-chain reaction when stress occurs. It has a key role in regulating the active transport of K for stomatal opening and is particularly effective at helping reduce summer heat stress, minimizing wilting and leaf damage. (Harris, 1992)

Potassium (K) Availability Concerns

As the pH of soils drop below 6, potassium availability becomes a concern and potassium absorption can be seriously affected. If the CEC is below 10 meq/100 g, a K deficiency may develop. It is possible to develop deficiencies of potassium and magnesium quickly if cations have a low holding capacity.

For balancing acidic soils around or below 6, always monitor with regular soil tests. Choosing a plant-derived potassium at this stage, with an easier uptake, can be a go-to source for low pH soils. In vines, by keeping Brix levels monitored, we can add either soil calcium or foliar calcium if they’re not around the 18 to 20 numbers. By adding a calcium shot to your late-season applications, will help with both overall vine health and plant tissue rigidity.

Sodium can inhibit the assimilation of several nutrients, including potassium. Plant cells will begin “leaking” potassium as they assimilate sodium. Metals like manganese, iron, and aluminum all influence potassium. A plant’s signaling, osmoregulation, and balance of cations and anions are dependent on K. The availability and mobility of K are important for starch synthesis, enzyme activation, and cytoplasmic pH regulation.


Nutrient and ion availability and how they work with each other determines not just soil health, but can hurt yields in certain calculations. By developing a program and monitoring system to periodically monitor all metal and nutrient levels in both soil and tissue throughout the season, nutrient use efficiency can be expanded through a balanced, healthy soil profile.

Sponsored Message

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