Barley protein: Nitrogen timing more important than rate

There is still a lot of spring barley to be sown across the country. However, some crops are up and out of the ground and others – which are being grown for malting and distilling barley – will need to get nitrogen early in order to try and meet protein specifications.

There has been conflicting nitrogen advice in the past number of years. Where growers were once told to split applications, they are now being advised that timing isn’t all that important before GS32.

Many growers now apply the nitrogen balance to their crop when the tramlines appear and leave the fertiliser spreader out of the field for the remainder of the season.

Late sowing

The nature of this late-sowing season could also mean that there will be a fast spurt of growth. If there is, early nitrogen application may help to keep protein contents down; nitrogen taken up by the crop after flag leaf will – almost always – increase grain protein percentage.

Following the extremely wet and long winter we have just had, it could be expected that there is very little soil nitrogen available to plants – but no certainty can be given on this.

Protein specifications remain a gamble and the weather that comes after sowing and fertiliser application has a part to play in this.

Nitrogen rate

In an article earlier this year, AgriLand reported how Teagasc’s Richie Hackett stated that reducing nitrogen rate increases the probability of achieving the protein specifications, but by no means guarantees a lower protein content.

The researcher went on to explain that growers who apply 90-120kg/ha of nitrogen have a 50% chance of making the 8.8% protein content. This figure increased when the protein specification was brought up to 9.3%.

Starch content up

More starch and less protein is the key. Starch content will increase with increasing photosynthesis. The more green leaf area a plant has, the more photosynthesis that will occur and the more starch that will be produced.

Early disease control or prevention, as well as the application of trace elements to prevent deficiencies, will prevent the loss of green area and, therefore, increase photosynthesis.