|Braun, Lois - UNIVERSITY OF MINNESOTA|
|Gillman, Jeffrey - UNIVERSITY OF MINNESOTA|
Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 20, 2009
Publication Date: October 1, 2009
Repository URL: http://hdl.handle.net/10113/37193
Citation: Braun, L.C., Gillman, J.H., Russelle, M.P. 2009. Fertilizer Nitrogen Timing and Uptake Efficiency of Hybrid Hazelnuts in the Upper Midwest, USA. HortScience. 44(6):1688-1693. Interpretive Summary: A wide variety of perennial crops are being considered for use as biomass feedstocks. Of particular interest are those that provide additional income streams for producers. Hybrid hazelnut is one such species that can be grown as hedgerows in other crops, such as alfalfa. Hybrid hazelnut is a new crop, is still in the early stages of variety development, and there are no reports about its nitrogen requirements. Nitrogen fertilizer often comprises the largest input of energy in biomass production and can be the source of significant contamination of water and the atmosphere. In research at two Minnesota sites, we found that uptake of nitrogen fertilizer was low compared to other woody crops and most herbaceous crops, regardless of the timing of fertilizer application. This may be due to inherent inefficiencies in nitrogen uptake by this crop or to the inadequacies in the method of applying fertilizer to soil. Given the high reported rates of fertilizer application by hazelnut growers, our data should result in lowering application rates, which will improve profits and reduce the risk for nitrogen loss to the environment.
Technical Abstract: Hybrids of Corylus avellana, C. americana and C. cornuta, are a potential crop for the Upper Midwest of the United States. We hypothesized that N application when the bushes were most fully leafed out would result in highest N uptake efficiency (NUE). We used 15N-labeled ammonium nitrate to measure NUE from soil applications in mid-April, late April, late May, early August, and mid-September. Nitrogen applied in either mid- or late April never comprised more than 5% of the total N in shoots or leaves, suggesting that N used for early leaf expansion came primarily from stored reserves. Applications made after April demonstrated that N was quickly translocated to rapidly growing plant parts: May applications comprised 9% of the N in leaves collected in July; August applications comprised 12% of the N in nut kernels collected in September; and September applications comprised 9% of N in catkins collected in October. Nitrogen applied in August and September appeared in new shoots the following April at higher levels than it did above ground the previous October, showing that N applied late in the season may be stored below ground over the winter. NUE was highest for August and September applications at one site and August and mid-April applications at the other, implying that summer is generally the best time to apply N for most efficient uptake. However, overall NUE was low, only 5% for August applications, suggesting a need for development of other methods of improving NUE.