by Bob Fleming
We hear a great deal these days about growing plants organically. But I wonder if this is the word we should be using. If we are going to use the word in its strictest sense then we could find ourselves looking longingly at our neighbour's garden where a more "natural" approach has been followed.
Let's face it! Many of the nutrients the plants in our garden take in through their roots have been released by the mineral portion of our soils, the sands, silt and clay that make up by far the biggest percentage of the volume of soil. Organic matter is probably somewhere between 2 and 5 percent, if we're lucky. Yes, to be sure, it is the carbonic acid from the breakdown of organic matter that assists in the release of these major - and minor - elements so essential for good plant growth. But they must be there in the mineral portion of the soil to be available to be released.
Some soils are naturally deficient in certain essential minerals like potash and phosphorus. Compost made from plants and plant wastes from soils deficient in these minerals will themselves be deficient and the resulting compost equally so. Minor elements like calcium, magnesium, copper, iron, boron, zinc, manganese and sulphur, just a few of the essential minor elements necessary for healthy plant growth, may be lacking completely or in short supply. Again, compost from such plants, deficient in these elements, will also be deficient. Organically speaking, only calcium and magnesium (as dolomitic limestone) could be considered as a soil amendment to the true organic garden.
Not only may certain vital elements be missing, or in short supply, but the nature of the soil itself may inhibit the release of those elements. Soils that are strongly alkaline may lack available phosphorus, iron and manganese soils that are moderately acid may grow good rhododendrons but lack available phosphorus. Soils that are too acid or too alkaline may release toxic amounts of certain minerals. Some areas of the continent naturally contain high amounts of toxic elements -- selenium toxicity is common in some parts of the prairie states and provinces.
However toxicity is an unusual and rare problem in home gardens but lack of nutrients may not be, whether they're macro nutrients, nitrogen, phosphorus, potash, or micro nutrients like iron, manganese, copper, sulphur , to name a few. This is why I believe "NATURAL" gardening is a better word than "organic" .
Let's talk about fertilizer. Our garden soils are made up of pulverized rock, weathered over eons of time to sands silt and clay which contain or contained some of the minerals essential for plant growth. We know that those minerals either lacking or in s short supply, will result in reduced or stunted growth, poor harvests and unattractive ornamental plants. Fortunately the extremes of deficiency are seldom seen but can occur. Naturally occurring rock formations throughout the world are rich in potassium, phosphorus, calcium, magnesium, sulphur and all the necessary minor mineral elements. Ground phosphate rock contains about 5 to 6 percent phosphorus. Basic slag, a byproduct of the steel mills, is another source of phosphorus and calcium. Phosphorus is important in root growth, flower and seed production.
Potash, or potassium is mined in Saskatchewan, the natural product being an oxide or carbonate of potash. Wood ashes, an organic source, are a good source of natural potash. Potash helps to strengthen stems and leaves and is essential for root, stem and seed production. In addition to their primary value, these mined natural minerals will provide many of the essential minor mineral elements as well.
Calcium and magnesium are readily supplied from dolomitic limestone, in southern Ontario quite visible in the Niagara escarpment.
Sulphur, a necessary component of many proteins, occurs naturally or as a component of other natural rocks like potassium sulfate (sulfate of potash). Sulphur is also a valuable tool in the defense against many fungus diseases when powdered and used as a spray or dust.
Nitrogen, the promoter of lush, deep green leaves and vigorous growth, is the most difficult nutrient to find naturally in usable form. Organically we have manures, blood meal, bone meal (also a source of phosphorus) and various seed residues from the oil extraction process (cottonseed meal, linseed meal), but usually the percentage nitrogen is quite low and much of it lost in poorly stored manure.
Sodium nitrate is naturally occurring as the crude salt and is mined in Chile. Potassium nitrate, better known as salt-petre, also occurs naturally but is rather an expensive source of nitrogen and potassium. Nitrogen fertilizers are best applied often in small amounts as it is quickly dispersed in the soil and lost through drainage, irrigation and evaporation. Growing legumes like peas and beans whose roots draw nitrogen from the air by symbiosis - a cooperative process between the plant and nitrogen fixing bacteria - is another way of maintaining nitrogen levels in the soil.
Every gardener, every home owner should be encouraged to compost and re-use all suitable organic wastes. But for the sake of the health of our plants and gardens we shouldn't ignore the natural mineral resources available to us to maintain the fertility and productivity of our soils. For the strict organic gardener these natural products are available and should be used. A soil deficient in any one or more of the essential major or minor elements will not be improved by adding compost or manures derived from plants and animals fed from that soil. Sooner or later the deficiency will appear. We have these NATURAL materials available to supplement the manures and composts to maintain the complete fertility of our garden soils. Let's use them wisely and call ourselves not organic growers but NATURAL GARDENERS.