Soil Nutrients and Nutrient Cycles

The Circle of Life from a Soil Nutrient Perspective

Most soil nutrients used by plants are circulated over and over again through a complex process referred to as the nutrient cycle. Most inorganic nutrients released into the soil are made available for uptake by plants by the work of soil microbes. Some plants are then consumed by animals where the nutrients are once again returned to the soil in manure. Other plants that either die back naturally or those killed by injury or disease return nutrients to the soil as they are broken down by soil microorganisms. Even animal bodies themselves, upon death, return nutrients as they decay. Most all this happens through the tireless work of soil microorganisms.

A couple exceptions to the nutrient cycle are the nutrients that have leached below the root zone or those released back into the atmosphere. Another possible exception is when the plant materials, and the nutrients they contain, are carried away by flowing water or by people, birds, or animals.

In this manner, forests, prairies, marshes, and other natural landscapes have thrived since the beginning of creation.

The 16 Essential Soil Nutrients

Plants need 16 inorganic nutrients for normal growth. These 16 nutrients are categorized under Macronutrients and Micronutrients. Which category a particular nutrient falls under is determined by the amount required plants.

Macronutrients represent those nutrients that are required in the greater amounts. They are:

  • Carbon, Oxygen, Hydrogen, Nitrogen, Potassium, Calcium, Phosphorus, Magnesium, and Sulfur.

Micronutrients represent those nutrients that are required in the least amounts. They are:

  • Iron, Chlorine, Copper, Manganese, Zinc, Molybdenum, and Boron.

Of the nutrients listed above, only carbon, hydrogen, and oxygen are derived from air and water. The rest are derived from the soil.

Soil Nutrients, Nutrients Cycles, and Home Lawns

Very often the cycling of nutrients are cut short on home lawns. This is partially due to necessary maintenance practices needed to produce quality turf. To complicate things further, some turf species and certain turf situations, such as sports turf, require intense maintenance and added nutrients to meet the high level of expectation. This requires the removal of fallen leaves, twigs and branches, and even grass clippings, that would otherwise have returned nutrients back to the soil. Those lost nutrients must be replaced.

Fertilizers are the most often used method of replacing lost nutrients. Modern fertilizers have improved tremendously in recent years with more attention to environmental concerns. Fertilizers offer many combinations of nutrient types, nutrient amounts, and release times. Organic fertilizers can be very low in macronutrients, but often contain a wider range of micronutrients than synthetic fertilizers.

Top dressing lawns with organic compost is another method of completing the nutrient cycle. This environmentally friendly approach of adding nutrients by feeding soil microorganisms has increased in popularity in recent years. The nutrients are released slowly as the organic matter is broken down in a manner similar to natural settings. Compost spread thinly over the lawn adds essential organic matter to the soil and alters soil structure, while delivering an excellent source of slow released nutrients.

Top dressing with commercial organic fertilizer is another excellent method of replacing soil nutrients. Depending on the product, each bag provides essential organic matter that help keep microbes healthy. While it is extremely helpful in many ways, the amount of organic matter in a bag of fertilizer is usually not sufficient enough to help build better soil structure. Compost is better for that particular job. However, many professional organic fertilizers now include synthetic organic nitrogen to provide an immediate source on nitrogen while waiting on the microbes to slowly release the other nutrients.

To learn more about organic and synthetic fertilizers click on the fertilization section of this site.

The Steps and Biology of Grass Seed Germination

Discovering the steps grass seed must go through to complete a successful germination is extremely helpful. It is the very basis of these steps that determines the proper procedures for overseeding and watering a new lawn. It helps answer the question "Why is planting a lawn done this way?"

Plant Transpiration Explained

Plant transpiration is an essential process in plants and is closely tied to photosynthesis. This page explains the basics of transpiration and its effect on plants.

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