SPRING barley yield potential has increased significantly in the last 10 years, with breeders pushing for higher yields – but it’s important to get the crop right from the start to ensure crop potential is met.

That's the view of Ron Granger, the arable technical manager for breeder, Limagrain, who said that new malting varieties now have equal or better yield potential than standard feed varieties. That's thanks to breeders' influence on germplasm: “In fact over the last 10 years we have been seeing an increase on yield of 1% per year, which is substantial.”

However, recognising how we grow spring barley to achieve both high yields, and meet contractual specifications of the chosen end market is crucial to success. Evaluating the agronomic requirements of a spring barley crop and the subtle differences between varieties, ensuring both high yield and end use specifications are met, is crucial, he added, offering some timely advice to The Scottish Farmer for those soon to be sowing spring barley:

Seed rate

"Limagrain does not advise definitive seed rates for spring barley and can only suggest suitable seeding rates, based on the breeder’s knowledge of the variety gained through both plot and field trials," he said.

“We have carried out trials for three consecutive years looking at both drilling date and sowing rates across Scotland and the rest of the UK to determine optimum seed rate figures.

“This work has found that a starting point of 350 seeds/m2 appears to be the optimum for most varieties in ideal growing conditions. This figure can then be either decreased or increased depending on the situation as outlined previously and this would concur with standard seed rates of around 325-375 being used by growers on farm today.

“Drilling date would certainly appear to have an influence on final potential yield, but it’s important to stress that very early drilling should only be pursued if weather and soil conditions, including temperature, allow for good germination and plant establishment are ideal.

“Patience is a virtue, especially regarding the sowing of any spring crop – waiting until conditions are favourable is essential.”

Tiller counts

The target final tiller number in the AHDB Barley Growth Guide is 775/m2 (three shoots per plant), looking at both trials and farm plant populations this appears to be underachieved in many situations, suggesting that full yield potential is not being reached,” added Mr Granger.

Establishing and more importantly securing a final tiller count of around 775/m2 will ensure full yield potential, is his advice. “We have been recording tiller counts for several years in Scotland. The data strongly indicates that newer varieties such as Octavia, Sienna and Ovation are producing higher tiller counts, with the benefit of increased yield.”

He said varieties with high tiller counts were better able to cope with stresses, like drought, showing that they can compensate when plant numbers are low. Whereas low tillering varieties are limited in their capacity to compensate.

“Our trials have shown that final tiller counts can be pushed over 1000/m2 in fertile soil conditions, but results would suggest no additional yield performance over the 750/m2 final tiller target. Additionally, it can lead to negative agronomic traits being induced, such as lower specific weights, higher screenings, additional lodging pressure and increased disease pressure.”

Nitrogen interaction

"We have a theory that if spring barley yields have increased by more than 10%, perhaps the conventional approach to the fertiliser regime should be investigated, to see if additional yield performance can be obtained with higher rates of nitrogen," said Mr Granger.

“This is not straight forward as the final grain nitrogen percentage cannot be compromised, especially if growing for the malt distilling market which requires a low grain nitrogen content.

"Higher grain nitrogen levels required by the brewing and grain distilling contracts should offer opportunities for driving for additional yield potential with higher rates of nitrogen, while still achieving the specific grain nitrogen percentage."

Limagrain has been conducting trials work looking at variety interaction with differing nitrogen rates in some detail over the last couple of seasons and data has been gleaned from a trial done in conjunction with Scottish Agronomy looking at two nitrogen inputs over a range of Limagrain varieties.

“Two nitrogen inputs were tested, 120 kg/ha in total applied in the seed bed, supported by an additional 30 kg applied at tillering, making a total input of 150 kg/ha. The result was an additional 0.4-0.5 t/ha yield across the varieties. This is significant certainly in a commercial situation, but this has to be compared with the actual grain nitrogen percentage figures. [See Table 1]

“Interestingly, the grain nitrogen percentage did not increase significantly, remaining well within the contract specification of below 1.65% grain nitrogen for malt distilling contracts. One could argue that the additional yield had a dilution effect on the final grain nitrogen percentage as anticipated. [See Table 2]

“We should also take into account that grain data from both internal and external trials during 2016 confirm that it was a season of lower grain nitrogen accumulation levels, highlighting the importance of continuing trials over several seasons.”