How well do fertilizer enhancers work?

Fertilizer enhancers can provide economic and environmental benefits but their efficacy needs to be assessed appropriately. This study analyzed available trial results of three different fertilizer enhancer products to determine if the results support product claims. All available trial results were considered for a meta-analysis of each product. Product effect was calculated for each experiment in a manner that could be compared with manufacturer claims. The distribution of trial results was examined and factors that may have influenced results assessed. Previously published assessments of the products were compared. N-Boost biostimulant sprayed with dissolved urea increased pasture nitrogen response by an equivalent of 18.0kg N/ha compared to urea alone in nitrogen-responsive and label-conditions trials. For SustaiN Green urease-inhibitor-treated urea, pasture nitrogen response was 50% higher than untreated urea if low-ammonia-volatilization-risk trials were excluded. AVAIL phosphate fertilizer enhancer increased crop yields by 4.1% over untreated fertilizer in fertilizer-responsive and non-high-soil-phosphate trials.