Most growers have soils deficient in calcium – in fact, very deficient. Calcium is the camp counselor of the soil, helping to marshal other nutrients, including trace minerals, to the plant. Nutrient-dense plants have improved health, fruit flavor and disease resistance. Thus, calcium contributes mightily to fruit and crop flavor and quality.
Calcium isn’t very mobile through the phloem, although foliar applications can help. Foliar applications are like putting a little gas on the manifold – a quick rev to get the plant engine humming. Soil applications of calcium are more efficient, as with most of our nutrients that transpire through the xylem or plant roots. Calcium tends to sink out of the root zone so it’s important to be adding it regularly.
The calcium-to-magnesium ratio is one of the most important in the analysis of our soils. The ideal is 7:1. When it goes lower, the soil becomes sticky and loses more nitrogen into the atmosphere, requiring greater nitrogen inputs. In addition, crop yields are plateaued by a lack of calcium, and calcium deficiency will retard both plant cell and microbial cell development. Cell division (after pollination), for example, lasts for about 10-14 days and this is a big determinant of fruit size. The number of cells produced is this time is limited by calcium availability.
There is close to a linear relationship between available calcium and roots. When calcium is low, there are relatively few roots. As available calcium increases so does the mass of roots. When levels of calcium near those required for peak performance, the roots produce more fine root hairs that help the plant to exchange nutrients with the microbial community. Calcium responds well to microbial expansion and can actually help stimulate and maintain microbial growth.
It’s also important to know that calcium and potassium both have positive charges. Too much potassium pushes the calcium away, just as trying to put two positively charged magnets together is next to impossible. It’s clear if you have potassium-dominated soils, your calcium levels will be deficient. The tell is that calcium follows water and older plant leaves don’t require as much water, so typically calcium deficiency shows up in new leaves.
When various pathogens invade plant tissues, they release pectolytic enzymes that dissolve parts of the plant tissue and allow for further infection. The pectolytic enzymes are inhibited by the presence of calcium in plant tissues. Calcium also has a relationship with cytokinin, boosting their effectiveness on improving overall plant growth.
What are some of the better sources of calcium? Calcium carbonate, or limestone, is very good. The peak of the amount of calcium in the soil will occur about 45 days after the limestone application. And limestone not only supplies calcium, but also growth energy. In my last newsletter I wrote about the carbon atom and its influence on the magnetic properties in the soil and the ability to hold soil particles together. Limestone supplies additional carbon to the soil — about 120 lbs. of carbon per ton of limestone.
