Effect of organic nitrogen source and application rate on the yield and quality of flue-cured tobacco
Organic carbon-based sources of nitrogen, such as livestock waste or by-products, have not been recommended for the production of flue-cured tobacco. At present, there is significant demand for organically produced leaf, and in these systems the use of synthetic nitrogen is prohibited. The effect of organic nitrogen from animal by-product to the yield and quality of organically produced flue-cured tobacco are not presently known. Research was conducted in 2012 to evaluate the effect of two organic nitrogen sources: Nature Safe (13-0-0) and Nutrimax (12-1-0) applied at three different rates: 17 kg N below the recommended rate, the recommended rate, 17 kg N above the recommended rate. In 2013, 34 kg N above recommended rate was added for evaluation. A single treatment consisting of synthetic 28% Urea-Ammonium-Nitrate (UAN) applied at the recommended rate was evaluated as a control. All nitrogen was applied in one-half rate split applications 10 days after transplanting and at layby. After transplanting, tissue samples were collected at layby, at topping, and after curing to quantify nitrogen utilization. Leaf yield, quality, and chemistry were recorded as well. Due to weather variation, results were relatively inconsistent; however, the synthetic UAN treatment commonly had the highest total nitrogen content later in the season, though this factor was not always an indicator of significantly higher yield. Organic nitrogen application rate tended to have a greater impact on leaf chemistry than did organic nitrogen source, as total nitrogen content in leaf tissue was found to have increased along with applied organic nitrogen in three of the four environments. Nature Safe application did result in higher leaf yield in one environment when compared to Nutrimax. Results from this study indicate that either organic nitrogen source is likely to be acceptable for tobacco production and that application rates above recommendation are not necessary for optimum yield to be realized.