Managing Barley Grain Quality

Nitrogen 

A high nitrogen content in barley grain tends to arise from a large uptake or redistribution of nitrogen late in the season, or poor starch deposition. Nitrogen applications will highly influence barley grain protein concentration.

Higher rates of direct application increases barley grain nitrogen/protein. This may be desirable where the crop is being used for animal feed. Where the market is for low nitrogen malting barley however, reduced rates will be required. It is therefore important to match the nitrogen rate with the desired yield and quality targets. During the grain filling phase, nitrogen is redistributed from the stems, leaves and chaff to the developing grain. The root system will remain active during this phase which gives the potential high soil nitrogen uptake, late leading to high grain protein content.

Delaying nitrogen applications will give higher levels of grain nitrogen. If the barley is autumn sown then nitrogen applications should be made around Zadoks G.S. 25-31. In spring sown barley at least 60% of the nitrogen should be applied into the seedbed at planting, with the remaining going on at Zadoks G.S. 13. Where high nitrogen (protein) is required to improve the livestock feeding quality, nitrogen rates can be higher, and some delayed to give increased protein concentration.

Potassium 

Excess potassium can indirectly affect the grain quality. Sufficient potassium gives good stem strength, reducing the potential for ‘lodging’ and ‘brackling’, (straw stems breaking), causing ears / spikes to fall to the ground. Very often the grains in the ear begin to germinate, thereby reducing barley grain quality.

Sulphur

Sulphur is an important protein component. Sulphur deficiency leads to limited barley yield, giving a concentration effect from the nitrogen applied and leading to higher grain nitrogen levels. Where sulphur is applied, higher yields are obtained by diluting the nitrogen, which gives lower nitrogen values in barley grain. Where sulphur is deficient, it has been shown to impair the activity of the germinating enzymes. They are important during the malting process (F.J. Zhao et al, 2005).

Manganese and zinc 

Manganese and zinc play an important role in many plant processes, including the metabolism of nitrogen. Improving nitrogen metabolism increases the amount of nitrogen incorporated into developing proteins.