CORESTA Congress, Online, 2020, Agronomy/Phytopathology Groups, AP 17

Establishing nitrogen fertility recommendations for the production of organic Burley tobacco

North Carolina State University, Department of Crop & Soil Sciences, Raleigh, NC, U.S.A.

As demand increases for organic tobacco products, growers transitioning to certified organic production systems require appropriate agronomic recommendations. Two studies were conducted at the Mountain Research Station in Waynesville (W), NC and the Upper Mountain Research Station in Laurel Springs (LS), NC in 2018 and 2019. Study one investigated the effects of application methods (broadcast, split application, or side dress) of pelleted, hydrolyzed feather meal (Nature Safe® 13-0-0) and composted chicken poultry manure (Harmony 5-4-3). Study two compared application rates (168, 224, 280, and 336 kg N·ha-1) of both organic fertilizers. A conventional control (SQM 12-0-46 + 28-0-0 liquid UAN) was split applied (112 kg N·ha-1 broadcast during field prep and 112 kg N·ha-1 side-dressed at layby). Results from 2018 indicated a slight advantage when using feather meal over poultry litter as the former increased leaf alkaloid content. Furthermore, split application resulted in higher yields compared to broadcast application at W (4353.5 kg·ha-1 vs 3763.5 kg·ha-1, respectively). Fewer differences were observed from study one in 2019. Yields averaged 3747 kg·ha-1 and 2280 kg·ha-1 in LS and W, respectively, and were not affected by application method. No differences were observed in yield and leaf quality at the LS location for study two in 2019. Leaf yield from W showed a significant quadratic rate response, peaking at 2,500 kg·ha-1 with 280 kg N·ha-1. Though differences among the application methods did not exist, it is generally recommended to split apply nitrogen source material to avoid potential loss from heavy rain events. Furthermore, we found no benefit to application rates above 280 kg N·ha-1. The general lack of differences among the two organic fertilizer options and the conventional check indicate that both poultry litter and feather meal are appropriate nitrogen sources for organic Burley tobacco production.