Soft Rock Phosphate Fertilizer

NEW on the Pantry shelf!

Unlike my other fertilizers which mostly contain a broad spectrum of nutrients in small amounts, micronized soft rock phosphate is very nutrient specific, delivering 25% phosphate and 23% calcium, plus small amounts of other elements. Micronization means the material has been ground down to a very fine powder. The tiny particles go into suspension when mixed with water and are readily available for plant uptake through roots and foliage.

I chose this particular fertilizer because it addresses two common plant nutritional needs at once.

Phosphorus (P) plays important roles in plant growth from roots to flowers, fruit, and seeds, in energy conversion, and in DNA formation. Like calcium, it supports nitrogen fixing bacteria in the soil. As a negatively charged ion, it does not attach to the soil's fine clay particles, and is not easily stored in soils low in organic matter. It is prone to be washed out of the root zone. Pollution from conventional P over-fertilization is a big problem "downstream"! However, micronized soft rock phosphate is used in very small amounts unlikely to cause harm.

In the long run, it pays off to increase soil organic matter content with compost and mulch. Remember, mycorrhizal fungi also facilitate phosphorus transport to plant roots. In the short run, if you notice acute P deficiency, it makes sense to supply some phosphorus until your organic matter and fungi are in place.

Calcium (Ca) is a hugely important yet often under-appreciated nutrient. Its benefits to plants include strong cell walls and membranes, information transfer between cells, and activation of enzymes. It also supports nitrogen fixing bacteria in the soil. Calcium ions have a positive charge and can be held on clay particles, which is good, but some soils are low in clay. Again, organic matter is our friend, as it improves the soil's ability to hold on to all nutrients, the positively and the negatively charged ones.

There is another aspect of soft rock phosphate that has me excited. The combination of P and Ca supports soil and plant health.

According to organic agriculture pioneer, William Albrecht, calcium in crop producing soils should account for as much as 60% to 68% of soil base saturation for optimum plant health. This is rarely the case outside of limestone based soils. Jay McCaman ("Weeds and Why They Grow"/"When Weeds Talk") and Arden Andersen ("The Anatomy of Life and Energy in Agriculture") took this a step further and showed that occurrence of plant diseases and insect damage, as well as weed presence, are high in soils whose levels of P and Ca are low.

Andersen's work lists common fungal and bacterial problems such as blight, rot (including blossom end rot), leaf spot, wilts and cankers, rust, mold, and mildew; common plant feeding insects like aphids, cutworms, weevils, mites, thrips, flea beetles, fruit worms and borers; and even weeds such as bindweed, dandelion, knotweed or broom; all thriving where there are deficiencies of P and Ca.

It is important to understand that phosphorus and calcium will not act in any way that is toxic to these disease organisms, insects, or unwanted plants. Rather, adequate and balanced levels of key nutrients will empower plants to mobilize their own defenses against their predators. Together with good amounts of soil organic matter and a rich and diverse soil microbiology, soft rock phosphate is one more tool in our organic toolbox.

Made by Reindeer Natural Plant Foods, Lake Cowichan, BC.