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Managing plant nutrition - macro nutrients

Date posted: 19 December 2013

While plants can make their own food (sugar and starch for energy) via photosynthesis, they need a range of other nutrients for optimal growth and development.

There are 10 macro nutrients and seven micro nutrients essential for cereal crop growth... Of these, carbon and oxygen are absorbed from the air while the others are obtained from the soil and taken up by the plant roots.

There are two main groups of nutrients; macronutrients such as nitrogen, phosphorous, potassium, calcium, sulphur, chlorine and magnesium, which are required in large amounts, and micronutrients, such as boron, cobalt, copper, iron, Manganese, Molybdenum and zinc, which are required in small (micro) amounts.

Nutrients affect all aspects of plant growth – from height, to number of stems, grains and leaves size and even the ability to respond to environmental stress. A deficiency of any nutrient may limit growth, which means there will be less grains produced.

Farmers must become skilled at assessing the plants health. A plant lacking in nutrients might have yellowing of leaves, stunted growth or a change in colour of the leaves.

There are a few different ways that farmers cure nutrient deficiencies. A common option is application of fertiliser – just like for plants at home – but also sometimes a foliar (leaf) spray is used for some micronutrients.

A nifty way to prevent nutrient deficiencies is what’s called crop rotation. Crop rotation means rotating different cereals between paddocks – for instance in one paddock you plant barley, then the next year you plant lentils. This is because while barley consumes lots of nitrogen, lentils can fix nitrogen - which means the soil will have lots of nitrogen ready for the next year’s crop!

Whoever said plants aren’t clever!


This week’s activity is a bit of fun... Check out these farmers having fun growing our food.

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