Nutrient balance in the soil - Soil Essentials: Managing Your Farm's Primary Asset - page 13

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Nutrient balance in the soil
Background
Soil studies have confirmed that for healthy soils, plants and animals, the various
plant nutrients need to be present in balanced proportions. The amount of each
nutrient can be determined by soil tests, and it is important that subsoils are tested
as well as topsoils.
Plant nutrition
Plants need to be able to access all their food nutrients from the soil in sufficient
amounts to grow to their full potential. These nutrients must also be in the correct
balance (or ratios) for healthy plant growth. Incorrect balances will cause the
plants to become prone to disease or insect attack and they will not grow to full
potential.
Soil pH
Soil pH should ideally be around pH 6.5 (water) or pH 6.0 in calcium chloride for
best biological and chemical activity. At this pH, toxicities and deficiencies are
minimised due to chemical actions. The potential for the best macro- and
microbiological growth also occurs at this pH, but this is also dependent on
temperature and moisture. The soil chemical reactions that are dependent on acidity
still continue at this pH level, helping to make the nutrients available to plants.