“Poo cakes” made out of human waste intended to be used as fertiliser have been poo-pooed by farmers who say it may see crops rejected by the whisky industry. The idea was put forward as a cost-effective alternative to artificial fertilisers which can cost up to £250 per tonne. Despite the human waste cakes costing only £2.45 per tonne, NFU Scotland (NFUS) has warned its members against using the product as it believes that crops using the hermal hydrolysis (TH) could be rejected by the whisky industry. Organic matter is removed from 165 tonnes of sludge processed at Scottish Water’s Seafield treatment site daily. John Davidson, farm manager at Penicuik Estate in Midlothian, believes the TH cakes are better for the environment and reduce financial pressure on farmers. He said: “I’ve managed to cut my usage of artificial fertiliser by around 30%. It’s a very slow-release fertiliser whereas the artificial kind is an instant hit and doesn’t last as long and can also leech into water courses. Another factor is that potash, used in artificial fertilisers, is not an endless resource, it has to be mined and won’t be there forever.” But NFUS combinable crops chairman Ian Sands, who farms in Perthshire, has advised caution. He said: “NFUS would advise any of our members who are thinking of using thermal hydrolysis cakes as fertiliser for crops of any type, to be cautious and consider whether its use is acceptable for current or future buyers of crops grown on their land. “For going on 20 years, the Scotch whisky industry has not accepted malting barley which has been grown on land which has ever had this kind of fertiliser used on it.” A spokesman for Veolia, which runs Seafield for Scottish Water, said the cakes are suitable for a wide range of agricultural uses and meet the “highest safety and quality standards.”
Scotland's Scottish Water's has issued a warning to farmers discouraging use of human waste cakes for fertiliser. The union argues the Scottish whisky industry will not accept crop grown on land that uses this type of fertiliser. Some farmers have started using the thermal hydrolysis cakes because of its substantially lower price of £2.45 ($3.43) per metric tonne in comparison to artificial fertilisers which can cost up to £250 per mt, while others appreciate the environmentally sustainable quality of it. The organic matter is a by-product of sludge processed at National Farmers Union Seafield treatment site.