The chemical fertility of soils

Plant growth, vigour and yield are dependent upon the availability of a number of essential element nutrients. Detailed lists of these elements vary slightly but most sources identify three essential, non-mineral elements: carbon, oxygen and hydrogen; six major or macronutrients: nitrogen, phosphorous, potassium, sulphur, calcium and magnesium; and a range of micronutrients which include, molybdenum, copper, boron, manganese, iron, nickel, chlorine and zinc. In addition to these elements there are also nutrients that are either essential to some but not all plants or beneficial but not essential. Plant uptake of all nutrients is limited by the single, scarcest element and not by the availability of an individual element. Many of the soil types found in Australia are deficient in some of the essential nutrients and the solution is not as simple as just adding fertiliser. A plant’s ability to take up nutrients, even when they are abundantly available, is strongly influenced by the availability of water, the presence of soil organic matter, soil structure and microbiology