Raw ingredients used to make natural fertilizers are inherently rich in trace nutrients. mother nature likes diversity in the materials she creates. Humans, on the other hand, like to purify everything. Unfortunately, in doing so we tend to overlook the importance of those contaminants we exclude. Trace elements are essential for plants of any kind. However, the subtle difference between not enough and too much can easily injure or kill plant organisms. In most cases mineral soils provide ample amounts of trace elements to plants. When trace elements are deficient, it is often because of other factors, such as incorrect pH, soil atmosphere imbalances, nutrient imbalances, or inadequate weathering mechanisms in the soil. Mono-cropping can also deplete the soil of certain trace elements because of the plant variety’s constant demand for a specific nutrient.
Commercial preparations of trace elements are usually in the form of mineral salts or synthetic chelates. Because plants are very sensitive to excess trace elements, applications of these materials should be in accordance with an accurate soil test or plant tissue analysis. Natural fertilizers made from raw, unrefined, materials usually contain a variety of trace elements, which are released at a rate relative to the level of biological activity in the soil. Kelp meal or seaweed extract is also a good source of trace elements. Plants use trace elements in very small quantities for the formation of enzymes and other organic components. Once combined with organic compounds they are called chelates. The more organic matter content in a soil, the richer it will be in chelates.
Organic chelates are a major source of available micronutrients in the soil. Natural sources of trace elements are both mineral and in the form of organic chelates. Most raw minerals (such as phosphate rock, greensand, volcanic deposits and kelp) are rich in trace elements, but they are insoluble and rely on biological activity to make them available to plants. Organic sources include composts, manures, and green manures, but the trace mineral content of these sources will vary, depending on how much of these elements were in the environment where the sources were originally produced. When addressing trace element deficiencies, natural sources may not be sufficient. The diversity of elements in natural materials may be fine for maintaining a balanced level in the soil, but these materials do not have enough of any one element to address a specific deficiency. For this reason, organic certification groups allow synthetic, inorganic sources of trace elements to be used on a restricted basis. The use of concentrated commercial preparations of trace elements is not allowed without justification from a soil test or plant tissue analysis. Some manufacturers produce synthetic chelates containing specific trace elements that are in a highly available form. Others produce salts or oxides that contain trace elements, also in an available form. Great care must be taken when using these products because there is a fine line between not enough and toxic levels of trace elements.