Carrot Seed Yield as Affected by Nitrogen Rates at Side-dress

Central Oregon produces 85% of the carrot seed grown in the United States. Very little research is available regarding the nitrogen (N) response of carrots and carrot seed production in this region.

This field project is underway at two farmer fields in Central Oregon to refine fertilizer recommendations for carrot and carrot seed production. A second objective is to measure nutrient uptake and partitioning in both the aboveground (including seeds) and below ground carrot biomass during the growing season that extends over two years. This work will provide new information on the "Right Time" aspect of 4R Nutrient Stewardship for carrot fertilization to more appropriately meet peak nutrient uptake demand periods.

Hybrid carrot seed was planted in 2017 at two low-N sites and irrigated through furrows (Colman site) or drip (Weigand site). Nitrogen fertilizer was basally applied, and additional N was applied at three rates (0, 75, or 110 lb N/A) at bolting. Carrot roots and tops from both female and male plants are harvested twice a month, then weighed, cleaned, dried at 60 degrees C, and then weighed again to determine plant dry matter. Ground plant tissue samples are now being analyzed to evaluate nutrient accumulation patterns during the growing season.

Additional sampling of soil and plant tissue will continue in 2018 during the seed-production phase of carrot cultivation. Plant tissue and soil samples will be used to monitor N movement and accumulation. The quantity and quality of the carrot seeds will also be evaluated to measure the influence of nutrient management practices.