Search

Hybrids between Corylus avellana and Corylusamericana are one of several new perennial and winter annual crops being developed as part of the Forever Green Initiative at the University of Minnesota. As a woody perennial shrub, hazelnuts in agroforestry systems can provide a new revenue source for rural landowners; continuous living cover to prevent soil erosion, sequester soil carbon, protect water quality, and provide wildlife habitat; and a delicious and healthful new local food. If hazelnuts are to fulfill their potential, better germplasm and better nitrogen fertilization recommendations are both needed. We modeled these trials after trials by R.E. Worley, who showed that yields of pecan trees fertilized only when leaf nitrogen (N) fell below critical thresholds were maintained with lower levels of applied N, benefitting both the environment and growers' profits. Results of trials at three Minnesota sites, comparing N applied only when leaf N fell below 1.8%, 2.0%, or 2.2% with annual N applications and no N over 4 years, support using 2.2% leaf N as the critical threshold for N fertilization. Our results showed that whereas only 8% of N applied annually ended up in the harvested nuts and husks, N that was applied to plants that demonstrated hunger for it was more efficiently taken up. Our results suggest a need for more productive germplasm and further research to develop best management practices for N fertilization. [ABSTRACT FROM AUTHOR]

The article focuses on a study which assessed nitrogen (N) responses to variable rates of N applications to young established hybrid hazelnuts in the Upper Midwest of the U.S. trials were done in seed-propagated hybrid hazelnut plantings in Minnesota from 2003 through 2005. Results indicate variations in management system and soil conditions among the four field sites considered for the study. It was revealed that nitrate and ammonium were correlated with N application rates.

The article discusses a research on the responses of newly transplanted hybrid hazelnut seedlings to variable rates of nitrogen (N) in the field and the leaf and soil analysis as diagnostic tools in order to develop N fertilization rate recommendations for growers. N rate trials were done from 2003 through 2005 in three new hybrid hazelnut plantings in Minnesota. The plant mortality data supports the recommendations from Oregon to delay N fertilization until the second or third year after transplanting.