Yara UK business manager John Keyte told Grower: "We already test all our own batches and we decided to put others' products through our own quality control."
Of the nearly 60 products sampled from the UK and overseas sources, more than 70 per cent failed to meet Yara's own quality criteria. "People say, our products are more expensive - well, here's why," said Keyte.
Yara UK also used its appearance at last month's National Fruit Show to promote three new smartphone apps for growers.
TankmixIT indicates whether a mix of chemicals in a spray tank will cause an adverse reaction, based on a database of test results.
CheckIT helps growers identify nutrient deficiencies in their crops, which can include fruit, using an extensive image library. It will then recommend a product to made good the deficiency.
ImageIT measures nitrogen uptake in a crop based on leaf cover, colour and browning, and uses the data to quantify a recommended nitrogen application.
They are available for both Apple and Android operating systems and can be downloaded from www.yara.com/media/apps.