Increasing N rates in oat crops will drive yields up to when the optimum levels are exceeded. Rates above this levels will have no positive yield impact.

The results from the nitrogen response trial carried out on Husky oats on Index 1 soils were presented by John Finnan at the Teagasc National Tillage Conference last Thursday.

John’s research showed that the beneficial yield impact from increased N rates on winter oats was capped at between 120-150 kg/ha. Rates of N above these levels had virtually no positive yield impact.

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A key message from John’s presentation however was the effect nitrogen rates had on hectolitre weights which is an important quality parameter in oats.

When nitrogen rates were increased, hectolitre weights were found to decrease. The research found that for every 30kg N/ha of additional N applied to the crop, there was a corresponding 3.3% decrease in hectolitre weight.

This indicates that excessive rates of N will not only not increase oat yields but they will also decrease hectolitre weight.

When it came to N timings and varying rates between two main applications, John found that a 50:50 split of N at GS30 and GS32 was most beneficial to maintaining a high hectolitre weight while not impacting yield potential.