One of the most common deficiencies in broadacre cropping is Nitrogen. Nitrogen deficiency is commonly characterised by leaf yellowing, leaf tip die-back and a decrease in shoot density and tillering. Nitrogen deficiencies are commonly seen in sandy soils that have been heavily leached or waterlogged.

Nitrogen is the most important nutrient in cereal production. It is a component of many structural, genetic and metabolic compounds of plant cells. Nitrogen affects both crop yield and quality. It is a major component of chlorophyll — the green pigment in plants essential for photosynthesis (the process plants use to turn sunlight into energy, as carbohydrates). Nitrogen is the primary constituent of grain protein and oil content of canola. Care should be taken with the supply of nitrogen. Increasing the yield of grain has a diluting effect on the protein. This explains why in seasons of low yield (eg: dry seasons), a larger proportion of the crop is of higher protein percentage, whereas in seasons of high yielding grain, the quality is low. Nitrogen is typically applied pre-plant, with supplementary applications made at key times throughout the season.

Nitrogen is the most important nutrient in cereal production. It is a component of many structural, genetic and metabolic compounds of plant cells.

Phosphorus deficiency is frequently characterised by older leaves developing a dark green colour that progresses to reddish-purple, wilting stand and reduced shoot and root growth during establishment.

Cereals require a readily available supply of phosphorus at all stages of growth, particularly in the early stages. Phosphorus is necessary for cell division, overall plant growth and root and shoot development. It is also involved with photosynthesis, energy transfer and movement of carbohydrates within the plant. Cereals low in phosphorus are often predisposed to damping off diseases such as Pythium. Phosphorus is generally applied at planting so it can be utilised in early growth. In some growing areas, pH or high amounts of calcium in the soil can tie up phosphorus. This means that although adequate Phosphorus soil levels may exist, it may not be plant available.

Phosphorus deficiencies are commonly seen in soils low in organic matter or high in sand content, highly weathered, iron-rich acid soils and calcareous soils.

Zinc is associated with the formation of chlorophyll. It is also involved in several enzyme systems and is essential for protein synthesis. Zinc also has a key role in the functioning and biosynthesis of several hormones including auxin, the compound that regulates plant growth rate and development. It is important that cereals receive adequate zinc from an early age which is why seed dressings are considered to be an efficient method of delivering zinc to emerging plants. Zinc also plays a regulatory role in the uptake and efficient use of water. Being an immobile element, post-emergence zinc deficiency is best corrected via foliar spray.

Manganese deficiency is not common in cereals but can occur during cool dry weather. Cereals grown in high pH calcareous soils are more prone to deficiencies. Manganese has several functions in the plant. It is closely associated with iron, copper and zinc as a catalyst in plant growth processes.

Manganese is necessary for photosynthesis and in the formation of other compounds required for plant metabolism. High manganese levels in plants may induce an iron deficiency and vice versa. Manganese also affects chlorophyll production and carbohydrate and nitrogen metabolism.

Root elongation is usually the first effect of Boron deficiency in most plant species, but it is rarely seen in wheat, However, yield responses to Boron application have been reported in many countries and some parts of Australia.

Boron is required in plants for the translocation of sugar and starch from the leaves to the grain head and fruits. It is the reproductive phase that is the most sensitive to deficiency in wheat and this result in male sterility due to disrupted pollen formation. This causes a major reduction in the numbers of grain sets and, thus a reduction in yield. This condition can only be diagnosed by either soil or plant analysis or by yield responses to Boron fertilisation.

In addition to the wheat, other crops known to be relatively sensitive to Boron deficiency, such as oilseed rape (canola) and sunflower, have been found to have a greater requirement for Boron during their reproductive phase than during their period of vegetative growth. Boron regulates flowering and fruiting, cell division, germination, carbohydrate metabolization.

The functions of calcium in the plant are associated with membrane maintenance, cell division and elongation, cell wall strength and integrity, protecting cells from toxins, cation/anion balance, and osmoregulation.

Calcium deficiency in seedlings can result in cotyledons becoming, chlorotic turning muddy yellow instead of bright yellow is seen with nitrogen and phosphorus deficiency.

Symptoms of calcium deficiency appear on new shoots and new leaves.

Calcium required boron so that calcium can perform the regular metabolic chore. It is involved in the deposition of Calcium in new cell material and in the growing tip of the pollen tube.

Magnesium is essential for the formation of chlorophyll and is the only mineral constituent of the chlorophyll molecule.

One of the symptoms of Mg deficiency is a pale green or yellow leaf. Magnesium has a key role in phosphorus transportation.

Magnesium is involved in regulating cellular pH by moderating the cation/anion balance and carbohydrate partitioning.

Boron deficiency in soils reduces plant uptake of both magnesium and calcium.