Testing Different Fertility Treatment Regimes on Ontario-Grown Hazelnuts: Results from 3 Years of On-Farm Trials

Commercial hazelnut ( Corylus avellana L.) production is relatively new to Ontario and there are no Ontario-specific fertility recommendations for this crop. With the increasing numbers of hazelnut growers entering the industry and the number of acres coming into full production capacity, this was identified as a gap. A 3-year trial was conducted to look at how four different fertility treatment regimes impact hazelnut growth and yield: (1) Ontario’s guidelines for established tree fruits, (2) Modified Oregon’s guidelines for hazelnuts, (3) Grower’s management, and (4) Control (with no external fertilizers). Four pilot demonstration sites were also established to compare fertilized plots (e.g., Ontario’s guidelines for established tree fruits) with orchard-specific grower’s management. Location-specific soil and tissue tests were conducted to determine the amount of fertilizer to apply to each orchard. Hazelnut yields and economic returns varied with location, tree age, and market price of hazelnuts; however, fertilized treatment (e.g., Ontario’s guidelines for established tree fruits) outperformed the grower’s management by up to 75 percent with net economic returns of CAD 18–44 per tree. In the orchard where all four fertility treatments were compared, yields and economic returns from modified Oregon treatment and Ontario recommendation were not statistically different. However, they outperformed grower’s management by 44 and 42 percent, respectively. Modified Oregon and Ontario treatment yielded ~7.0 pounds (lb) per tree with a net economic return of CAD 27 per tree during the 3rd year of study, while grower’s management and control treatments yielded 4.8 and 4.0 lb per tree with net economic returns of CAD 19 and 16 per tree, respectively. Also, fertilized treatments showed higher levels of residual nutrients of N, P, and K in the soil and the leaf tissues. The project results supported that Ontario’s fertility guidelines for established tree fruits can be used for commercial hazelnut production on mineral soils in Ontario. Also, testing soils every three years or plant tissues every year could help match applied nutrients more closely with plant demand, thereby enhancing economical and ecological sustainability.