A three-year on-farm trial in Cambridgeshire has shown that biostimulants can replace conventional phosphate fertiliser without compromising crop performance, offering growers a sustainable and cost-effective alternative.

Arable farmer Russell McKenzie, based near Cambridge, faced a common challenge three years ago when the price of Diammonium Phosphate (DAP) soared. Rather than absorbing the rising cost, he decided to test whether biological alternatives could maintain yields while reducing input costs.

"This led to a three-year project comparing our standard 200kg/ha DAP programme with 1 litre/ha of Luxor in the first year," says Russell. "In years two and three, we adjusted the approach to 0.5 litres/ha of Luxor combined with 0.5 litres/ha of Calfite Extra to improve nutrient use efficiency in second and third wheats."

The results were clear: across all three years, the biostimulant treatments performed as well as – and often better than – conventional DAP. In the first year, Luxor alone outperformed DAP, delivering an additional 0.9–1.3t/ha yield on first and second wheats. In years two and three, the combination with Calfite Extra continued to deliver, increasing yields by 0.65–1t/ha in the second year and 0.65–0.7t/ha in the more challenging third year.

The trials, conducted as tramline strip tests across five fields covering 70 hectares, demonstrated that biological products can replace fertiliser inputs without compromising output.

"We started this work to reduce reliance on expensive fertiliser," Russell says. "Three years on, I can say with confidence that Luxor and Calfite Extra perform as well as – and often better than – standard DAP, at a fraction of the cost."

The success is underpinned by the biostimulants' mode of action. Luxor supplies key nutrients in a highly available form, while Calfite Extra releases phosphate bound in the soil and supports root growth. Tissue analysis showed treated plants had nutrient levels consistently 20% higher from the T0 stage through to flag leaf.

"Early application is key," explains Andrew Cromie, Unium Bioscience. "Applied in winter and followed in spring, the products stimulate rooting, boost photosynthesis, and improve the plant's ability to capture and use nutrients. Stronger roots drive photosynthesis, pumping carbon back into the soil and unlocking yet more nutrition."

The approach creates a synergistic cycle of healthier roots, more tillers, and greater biomass – all contributing to higher yields. Russell now uses the combined product Luxical, which integrates both Luxor and Calfite Extra, alongside a straight 30kg/ha A/N application.

Agrovista agronomist Phil Warham notes the wider adoption of these products: "Luxor and Calfite Extra complement conventional nutrition programmes by improving nutrient use efficiency and crop resilience. They help the plant make better use of what's already in the soil, support rooting and photosynthesis, and fit seamlessly into existing programmes."

For Russell, the economic case is just as important as the agronomy. At £14/ha for Luxor compared with £130/ha for DAP, the savings are clear. With carbon benchmarking now a feature of his business, reducing fertiliser applications also helps cut emissions.

"Luxor and Calfite Extra have proven their value. We now use Luxor plus Calfite Extra to supply phosphorus and strengthen rooting in the autumn, alongside a straight 30 kg/ha A/N application. The cost works out at around £47/ha for the three products, compared with £118/ha for DAP.

"After three years of consistent on-farm results, it's clear this is about more than just cost savings – it's about growing more resilient, efficient crops," adds Russell.

The trial confirms that biostimulants have a vital role to play in future farming systems, providing both agronomic and economic advantages while supporting sustainable crop production.