How to put on a good bet with distilling barley
Producing distilling barley is a bit like backing a middle-of-the-road horse. It might get over the line, but there’s a fairly high probability that it will come last. In the case of producing distilling barley, it might have a high protein content.
According to a Teagasc trial, over a number of years, in which a crop was treated the same and received 150kg/ha in each year, protein content varied each year. Protein content varied between 7.7% and 13.2%. A protein content of 7.7% was recorded in 2013, a year which saw a drought towards the end of the season.
However, while the spec is difficult to be sure of, there are a few things that growers can do to get better odds.
Not as simple as lowering nitrogen rate
While many think it is as simple as lowering the nitrogen rate supplied to a crop, Teagasc’s Richie Hackett stated that reducing nitrogen rate increases the probability of achieving the protein spec, but by no means guarantees a lower protein content.
There also tends to be a yield loss at 8.8% protein, as this protein content is below the optimum for yield.
How can you achieve low-protein content?
Richie explained that the ratio of starch to protein is key. More starch and less protein is the target.
Starch is influenced by photosynthesis. Growers can aim to produce a large canopy, but have no control over the amount of solar radiation the crop will catch to increase photosynthesis. This is also true in the case of canopy longevity, which is related to the weather. In addition, drought may reduce the canopy longevity.
Farmers can control nitrogen fertiliser application to influence protein content, but have little control over fertiliser recovery or the amount of nitrogen that comes from the soil. 5kg/ha, 10kg/ha or 15kg/ha of N from the soil can have a large influence on protein content.
The dilution effect
The best way to achieve low protein is through high-yielding crops. A high-yielding, thick crop will have a low protein content.
However, a low-yielding, thick crop with poor grain fill will have a high protein content. The same can be said for a low-yielding, thin crop with poor grain numbers.
Increase yield; reduce protein
As a result of the dilution effect, it is important to consider factors that will increase yield. Sowing early and in good conditions is the first step in achieving a high yield.
Improving soil fertility can increase yield. Soils which require lime, or are low in phosphorus, potassium, sulphur or micro-nutrients may have a significantly reduced yield as a result.
Disease control is also a big factor in increasing yield, where good disease control is achieved yields will be higher and this will increase the likelihood of lower protein content.