What is turning our farmers’ straw pink?

PUBLISHED: 12:06 21 September 2018 | UPDATED: 12:06 21 September 2018

Samples of this year's pink-tinged straw (right) compared with a sample from 2017 (left). Picture: Stuart Alexander / Agrii.

Samples of this year's pink-tinged straw (right) compared with a sample from 2017 (left). Picture: Stuart Alexander / Agrii.

Stuart Alexander / Agrii

Farmers across East Anglia have noticed a pink tinge in their straw this year – caused by a surplus of potash in cereal stalks after the dry summer.

Stuart Alexander, a precision agronomy manager for Agrii, sent some samples from his home farm at Pulham Market to a laboratory to find out what was causing the unusual colouring.

Compared to last year’s sample, the results showed the straw contained three times as much potash – a fertiliser which supplies the soil with potassium, a key nutrient for plant growth.

“Everyone was asking me what this pink straw was,” he said. “I had seen this pinky/peachy colour in the stubble so I thought: Let’s bag some up and send it off to the lab, with some from last year as a comparison.

“Some cleverer people than me said it might be potash, because it’s red in colour. When we got the results back we found that had near enough trebled this year.”

Mr Alexander said this could have been caused by the speed at which crops matured before harvest, and the lack of rainfall.

“When the plant senesces [dries out and dies before harvest] the stalk naturally cracks and then when it rains it helps wash some of these nutrients out of the straw,” he said. “This year it dried out so quickly it did not have the chance to crack so much and we obviously didn’t have the rain to wash it out, so that potassium was held in the straw itself.”

The agronomist said the amount of potash in the straw was measured at 2.4kg per tonne compared to 0.8kg last year.

“It is taking nutrients out of the soil, but on a per-hectare basis it is a drop in the ocean,” he said. “So it is not really a problem, just a question of where that potash is going if you are baling straw, as quite a lot of us are this year.

“If it comes back onto the farm as muck, then it will go back into the soil, but otherwise you may need to replace it.”

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