British Potato 09: New N guidelines allow fine-tuning

New guidelines on nitrogen and other nutrients have been published in the Potato Council‘s Crop Nutrition for Potatoes guide.

For the first time, the recommendations offer guidance to growers on how to fine-tune N recommendations, the Council’s Rob Clayton told Farmers Weekly.

After calculating the soil nitrogen supply, a potential range is given for the recommended nitrogen rate for a given variety and growing season length. Previously there has been no guidance about how to fine-tune N rates in that range. Potato Council-funded research identified a number of factors that could increase or decrease N rate, Mr Clayton said.

For example, if previous crops had problems with delayed skin set, the N rate should be towards the lower end of the range recommended, while crops planted into compacted soils might benefit from a higher dose.

N rates in the guide, which has been published ahead of DEFRA’s Fertiliser Manual to help growers in their decision-making, had also been reduced in some cases, Mr Clayton pointed out. “There is nothing now over 270kgN/ha, and it also recognises where high loading of N rates of 0-40kgN/ha are appropriate.”

The grower collaboration project involving Cambridge University Farms researchers helped test some of those lower rates successfully on farm, he noted.

The guide also includes new varieties in the variety determinacy ratings and advice on how to use manures most effectively.

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