Micronutrients are mineral elements that are needed in small amounts to maintain good health in people. They are also known as trace minerals or trace elements. They include iron, copper, zinc, cobalt, chromium, iodine, manganese, selenium and molybdenum. They are a normal part of the life of healthy soil. Organic gardeners and farmers who practice sustainable agriculture often test soil for its micronutrient content.
Standard soil testing analyzes the mineral content of soil to assess synthetic fertilizer needs. Tests determine if soil needs nitrogen, phosphorus and potassium, which are the main components of traditional fertilizer products. Tests also provide a few soil chemical characteristics, such as the pH levels. Organic gardeners have difficulty translating these soil tests into information about the micronutrient content of their soil.
Organic soil fertilizers and amendments contain a wide range of micronutrients that do not fall into the traditional testing parameters. The National Sustainable Agricultural Information Service describes biological assessment tests as focusing on “soil organic matter and microbial activity.” Organic matter and microbe content are indicators of soil fertility and productivity.
Soil is a foodweb community of mutually dependent microorganisms that create the nutrients in food. “There are billions of organisms that make up the soil foodweb,” according to the Michigan State Department of Agriculture, and “these include bacteria, fungi, protozoa, nematodes, arthropods and earthworms. Each type of organism plays an important role in keeping the soil healthy for all living things.”
Trace minerals are essential for good health and are related to organ and blood function. Health problems associated with lack of micronutrients include anemia, high blood pressure, heart attack and stroke. Soil devoid of biological activity does not create the micronutrients that plants need to meet mineral nutritional requirements. Soil tests can help home gardeners determine the biological activity in their soil.
Adding compost to garden soil is the easiest way to increase its biological activity and micronutrient content. Backyard composting also reduces pressure on city waste management systems. Vegetable and fruit remains, grass clippings and dry leaves are food for earthworms, bacteria and fungi in the compost bin. Nutrient recycling is created when these materials are digested by microorganisms, are returned to the soil, and become a part of vegetables and fruit.