Field selection is one of the most important contributors to yield and quality, and autumn is the key time to sample and test soils prior to finalising potato cropping plans.
“Potatoes are a high value crop and are grown on the best land available,” explains the Potato Council’s technical executive Chris Steele.
“That’s why many growers choose to take soil samples for nutrient, PCN and free-living nematode testing and plan drainage requirements, the autumn prior to the potato crop. The earlier this takes place, the longer there is to plan for the 2014 crop.
“As well as assessing the phosphorus, potassium and magnesium (P, K, Mg) indices to ensure that pre-planting maintenance applications meet the potential yield requirements for next year’s crop, pH also needs careful evaluation.
Soil pH and common scab
“Soil pH is fundamental to nutrient availability and optimal root growth in the potato crop. At a pH between 6.5 and 7.5 most plant nutrients are at their most available. But just prior to potatoes is not the right time to lime a soil, due to issues with common scab,” adds Mr Steele.
Common scab occurrence varies from season to season, and from field to field. Its incidence and severity is influenced by multiple factors including: the bacterial species and strain, as well as soil texture, moisture, temperature, organic matter content and pH.
Use of resistant varieties coupled with irrigation, is the reliable control method used by growers, explains Mr Steele.
“Although many new varieties display resistance to common scab, no commercially important varieties are immune to infection,” adds Mr Steele. “It’s well known that a high soil pH increases the incidence and severity.”
“At soil pH levels below 5.2, common scab is suppressed. Regulation of pH using acid-producing fertilisers such as ammonium sulphate and avoiding the use of alkaline-producing lime or manure amendments is recommended to reduce scab risk.”
Renowned soil researcher Karl Ritz is the keynote speaker at the two-day potato event and will be giving his thoughts on soil management for potato production. Visitors can also find out more about soil trials at the event taking place on 27 and 28 November in Harrogate (www.potato.org.uk/bp2013).