Plant Nutrition

Plant nutrition concerns the supply, uptake and utilisation of mostly mineral elements by plants.

There are 16 generally recognised plant nutrients – carbon, hydrogen and oxygen (that come from the air and water), nitrogen, phosphorus, potassium, calcium, magnesium, sulphur, iron, copper, manganese, molybdenum, zinc, chlorine and boron (which come from the soil, though some nitrogen is fixed from the atmosphere by bacteria – Rhizobium –- in association with legumes and some free living bacteria in soil). Plant nutrients are required for the plant to complete its life cycle, and to contribute to the nutritive value and shelf life of crops. Inadequate supply (i.e. deficiency) of one or more nutrients will reduce plant growth and ultimately yield, and if severe may lead to plant death or failure to set seed.

The supply of plant nutrients is influenced by many factors – including chemical and physical properties of soils, type of clay in the soil, nutrient reserves in soils, temperature, water supply, instances of leaching and waterlogging, amount of organic matter in soil, effectiveness of fixation of nitrogen by Rhizobium, and soil management practices such as cultivation, irrigation and residue retention, crop rotation practices and of course fertiliser input. Fertilisers are usually supplied by application to soil, but some nutrients may be applied as foliar sprays – for example, nitrogen, copper, zinc and calcium.

Plant nutrition is very important to both yield and quality of crops, and increasingly to environmental outcomes, as loss of nutrients from farms can adversely affect the environment. Efficiency of use of nutrients is becoming increasingly important as sources of raw materials for fertilisers become more scarce and expensive, farmers seek cost reductions and environmental regulations become more stringent.

So plant nutrition is important and will become more so – from production, economic, consumer and environmental points of view.