The value of every drop of water, kilo of fertiliser and joule of energy used by potato growers has shifted dramatically in the last few months. Reassessing this is the key to increasing returns from the crop, according to experts addressing around 200 growers who attended Potato Council's West Midlands Potato Day near Newport in Shropshire on Wednesday (4 June).
"The rocketing price of fertiliser certainly does concentrate the mind, and I don't see it falling back," noted ADAS consultant Brian Chambers. The industry's fertiliser recommendations, RB209, are based on a break-even ratio of nitrogen inputs of 4:1, he explained – 4kg of ware potatoes are needed to cover the cost of 1kg of nitrogen fertiliser. Those recommendations are currently being rewritten and the break-even ratio has doubled to 8:1.
"But nitrogen is still a top-drawer input, and my assessment is that the optimum rate has dropped back by only 20kgN/ha." However, Marc Allison of Cambridge University Farm (CUF) questioned attendees on how many crops they have that are still green at desiccation – the show of hands was a good indication that nitrogen is still over used.
Potash and phosphate rises mean the value of manures and straw residues have trebled. Growers should analyse manures for nutrient value, reassess the value of straw and explore opportunities to use compost or biosolids in crop rotations, Mr Chambers advised.
Similarly, electricity prices have doubled over the past four years and the cost of tractor fuel has doubled in just 15 months, pointed out FEC Services' Andrew Kneeshaw.
"You need to get a handle on where your costs are going, which for electricity is a nightmare – there's no dripping tap telling you where the leaks are." Recent Potato Council-funded work has monitored electricity usage in eight potato stores over the winter, revealing big opportunities to save, noted Mr Kneeshaw.
According to Environment Agency's Jamie Letts, nitrate leakage is another cost farmers can ill afford. Potato crops lose about 100kgN/ha per year – the leakiest arable crop – and most of this will go into rivers and groundwater. "Water is an immensely valuable resource to farmers, to water companies, to society and to the environment."
This is the basis for Nitrate Vulnerable Zone (NVZ) Action Programme that is currently being reviewed, he explained. "The problem for farmers is that 60% of nitrate pollution comes from agricultural land, and other sources are already tightly regulated," noted Mr Letts.
Morning presentations at the Potato Day event, held in conjunction with Greenvale, McCain Foods, and the Environment Agency, were followed by afternoon field tours of Potato Council-funded related research. Experts were on hand throughout the day to discuss individual issues and bring growers up-to-date on the latest developments.
The day formed part of Potato Council's Summer of Knowledge campaign – a drive to deliver the latest technical and regulatory information direct to growers through a series of events and initiatives. Manor Farm, near Spalding in Lincolnshire plays host to East Midlands Potato Day on July 8, 2008. Potato storage will be the focus of another grower meeting at Chennels Farm, near Lincoln on July 16.
Scottish growers will benefit from the latest on water use and diffuse pollution regulation at a meeting supported by the Scottish Environment Protection Agency (SEPA) at the Swallow Hotel near Dundee on June 24. And more growers than ever are expected to attend this year's Potatoes in Practice, that takes place near Dundee on August 7. More information can be found at www.potato.org.uk/events.
