Potato Review

36 POTATO REVIEW MAY/JUNE 2021 NUTRITION E AST Yorkshire independent agronomist, Richard Johnson, has shared with Potato Review readers his advice on potato crops grown on challenging soils in the Wolds and his strategy of routine tissue testing and timely application of balanced nutrition is key to healthy, high yielding crops. Achieving the right balance Routine testing and a balanced nutrition programme are key to high-yielding potato crops in drought-prone areas, says agronomist. “Many of the potato crops I look after aren’t irrigated which has its challenges, but when this is combined with a stony soil profile that has high levels of calcium, and a high pH, then nutrition is really important,” said Richard. “Alkaline soils tend to lock-up magnesium, making it unavailable to the plant and in mid- summer when the crops have drought pressure, they can come under immense stress.” As well as magnesium deficiency, Richard also measures low levels of phosphorus when carrying out routine tissue testing. “We can pre-empt the results of our tissue tests which generally show low magnesium and phosphorus levels. “If the plant is low in magnesium, the lower leaves will go black and if low in phosphorus there is generally stunting in growth, which limits the plant’s ability to photosynthesise and can inhibit tuber yield and quality,” he said. To combat this, Richard recommends applying a foliar fertiliser that contains magnesium, potassium and phosphorous. “We find a foliar magnesium and phosphorous application is crucial and we “Alkaline soils tend to lock-up magnesium, making it unavailable to the plant and in mid- summer when the crops have drought pressure, they can come under immense stress.” Alkaline soils tend to lock- up magnesium, making it unavailable to the plant.