When it comes to Soil and Plant Health – is Calcium King?

Calcium Symbol wearing Crown

Calcium – is it King of the Elements? Many people have debated what the king of elements is when it comes to soils and plants, even human health for that matter. Nitrogen by tonnes is the biggest one used in crop production closely followed by phosphorus and potassium.

Surprisingly, sulphur, is one element that in many areas has almost been forgotten. Each are critically important in crop production, as are trace elements, but do any of them quite have the effect calcium has on both soil and plants?

Here’s what the scientists say:

Calcium is a crucial regulator of growth and development in plants. The myriad processes in which this ion participates is large and growing and involves nearly all aspects of plant development. (Recent reviews in Harper et al., 2004; Hetherington and Brownlee, 2004; Hirschi, 2004; Reddy and Reddy, 2004; Bothwell and Ng, 2005).

As noted by Reddy and Reddy (2004) from their analysis of the Arabidopsis proteome, there are ∼700 known protein components that function at various stages of Ca2+ signalling. Plants thus possess myriad ways in which Ca2+ can operate as the intermediary in transducing the stimulus into the appropriate response.

When just looking at the soil, if soil cations (the positively charged ions) are not in adequate proportions, fertiliser applications can be less effective. The key cation responsible for soil flocculation, nutrient transportation and general plant health is: Calcium.

In a balanced soil, Calcium is the most dominant cation. Occupying between 65-70% of all the negatively charged sites of soil particles. It is the ratio of these cations that is often a point that is debated.

The Ca:Mg Ratio

The Ca:Mg ratio is one over time that has often divided scientists and agronomists. This ratio effectively determines if a soil can breathe or not. A soil that is open and well-structured will result in soil microbes thriving and extensive development of plant roots. This is one of Australian Agriculture’s biggest issues and can effect the different severity of different weed species.

The ideal Ca:Mg ratio varies depending on a soil’s density. In a light, sandy soil, the ratio should be closer. This is because the Mg is being used to give a little more structure to this very light medium. Ca flocculates the soil because it is a large ion with two positive charges that attach to tiny, negatively charged clay particles and pushes them apart. Mg is a small ion that does the opposite. However, Mg is necessary because it is the centrepiece of the chlorophyll molecule. Therefore, Mg is critically important in photosynthesis.

So in light, sandy soils, the Ca:Mg ratio ideally should be approx. 3:1. In a heavy, clay soil, more Ca is required to open up the soil. The ratio should be 5:1 or even some say 7:1 in favour of Ca. Now this ratio is where the ideal of science does not always meet the practical world. In many heavy clay soils the ratio can be more like 2:1 or even 1:1, and yes this causes some issues. Although many have tried to change this ratio, including us by applying tonnes of lime, but little changed. Don’t get me wrong liming in many soil types is critical for pH, but from our perspective trying to change a 1:1 or even 2:1 ratio in heavy clay soils is comparative to trying to build a Sydney harbour with just a shovel!

There are ways that you can, on a crop to crop basis, get better use or make more available the calcium in the soil. Through utilising complexed, chelated calcium product technology to achieve some very good results.

Which Element Should be Crowned King?

Subsequently, we should all understand calcium is extremely important and while it could be crowned the king there may be a worthier option.  One example is Boron, without this, calcium’s full potential benefit for plants cannot be realised. As a result, a balance of nutrients, to us takes the crown. As all nutrients play their role to assist each other do theirs.

What are your thoughts on this topic?