Barley grain yield is made up of three components, the most consistent of which is average grain weight. Most yield variation between sites and seasons is due to differences in grain number rather than grain size with a strong relationship between grain number per sq m and yield, but only a weak relationship between average grain weight and yield.
Nitrogen and potassium are the nutrients required in the highest quantity for maintaining high barley yields.
The phosphate requirement, on the other hand, is similar to sulphur. It is during rapid spring growth that the demand for all macronutrients occurs.
A balanced crop nutrition strategy is important and should also include secondary and micronutrients which are essential elements in achieving high yields. As with macronutrients, peak demand will occur during peak growth periods.
Transient deficiencies can occur when soil conditions are unfavourable towards nutrient availability (e.g. cold, wet ,dry). Knowing the nutrient content per tonne of production is useful and can be used together with yield levels as the basis for a full Nutrient Management Plan.
Spring barley yields about 20% less than winter barley. In spring barley, 30-35% of grain carbohydrate comes from the flag leaf and peduncle (stem), 25-45% from the ear and 20-45% from the rest of the plant.