A recent ADAS open day provided an opportunity for growers and scientists to share news and views on the latest crop research. Abby Kellett reports.
Herbicide resistance, nitrogen recommendations and pathways to optimum wheat yields were among the topics discussed at the event at ADAS Boxworth, Cambridge.
In response to the increasing yield potential of winter barley since RB209 guidelines were published, an ADAS project has revealed higher yielding crops require more nitrogen to optimise yield.
The project, funded by AHDB, found where barley crops exceed eight tonnes per hectare (3.2t/acre), there was extra demand for nitrogen, above the rate suggested by RB209.
Sarah Kendall, crop physiology consultant at ADAS said: “We have found that for a crop which yields more than eight tonnes per hectare, for each additional tonne of yield, farmers should be applying 27kg more nitrogen.
Studies also confirmed that modern barley varieties responded positively to higher rates of nitrogen.
While the yield of older varieties such as Maris Otter and Venture tended to plateau or even drop when rates exceeded around 150kg/ha of N, some of the newer varieties such as Meridian were still responding to nitrogen at 300kg/ha.
Dr Kendall said: “Our studies have shown that newer varieties generally have a much greater response to N, and hence a greater yield potential.
“However clearly there are managements issues associated with applying more nitrogen such as increased disease and lodging risk”
Further research suggests including more N in the first split, between the end of February and tillering, is beneficial in terms of maximising the crops yield potential. This is consistent across a range of varieties.
“We have found that were 50 per cent of nitrogen was applied before stem extension, there was a 0.6 t/ha yield increase, in comparison so only applying 30 per cent of N prior to stem extension,” said Dr Kendall.
Results of an ADAS project aimed at developing practical solutions to prevent resistance to ALS herbicides have confirmed the importance of non-ALS chemistry.
ADAS embarked on the project in response to dwindling chemical options and increasing broad-leaved weed resistance. In the UK, resistance to the common poppy is the most immediate danger.
Lynn Tatnell, ADAS researcher said: “We have been focusing on poppy which we believe will develop resistance the quickest, it produces a vast about of seed which is viable for a very long time in the seed bank.
“Within the project we have looked at whether we can minimise broad-leaved resistance, change it or push resistance in populations that didn’t have resistance already to find out the key factors that trigger it.”
As expected, the research has found that using ALS chemistry alone is not an option.
“You always need a range of different chemistry. It is a very simple message, as soon as you put a modifier in the mix, you can manage resistance.
“We have concluded that at the moment, there is no rapid increase in broad-leaved weed resistance and you can control it if you use the right chemistry,” Mrs Tatnell said.