2018 ASHS Annual Conference

Georgia is one of the leading cabbage (Brassica oleracea var. capitata) producing states in the U.S. with more than 3500 ha grown annually. Currently, The University of Georgia recommends applying between 196 to 252 kg·ha^-1 of nitrogen (N) fertilizer to grow cabbage in southern Georgia. It is generally recommended to apply one-third of necessary fertilizer at planting with two additional side-dress applications during the season. Recently growers have begun banding liquid fertilizer several times during the season to reduce N leaching and enhance productivity. To determine the validity of current recommendations as well as the efficacy of applying periodic liquid fertilizer throughout the growing season cabbage, ‘Cheers’ was grown during Fall 2016 and 2017 with four levels of fertilizer applied (196, 224, 252, 280 kg·ha^-1 N) to the crop. All plots received 56 kg·ha^-1 N (5N-4.4P-12.5K) prior to planting. Plots then received a granular (27N-0P-0K, 5% calcium) or liquid calcium nitrate (9N-0P-0K, 14% calcium) applied in two or six side-dress applications during the season. Plots were arranged in a randomized complete block design with three and four replications in 2016 and 2017, respectively. There were no interactions between year, N level, or application type. Therefore main effects were analyzed. There were no treatment effects on total yield; however, N-level significantly affected early yields of cabbage. In both study years plants grown at the 196 kg·ha^-1 N level had significantly lower yields for the first two harvests compared to all other N-levels. Leaf tissue nutrient concentrations were generally not significantly affected by N fertilizer levels. However, the liquid calcium nitrate treatments did have significantly higher foliar calcium levels compared to the granular treatments. Study year significantly affected yields, average head weights, and foliar nutrient concentrations. In general plants grown in 2017 had higher foliar nutrient concentrations than those produced in 2016. Total yields were greater in 2016, but earlier harvested yields were greater in 2017. This study suggests that current recommendations are adequate for cabbage production in Georgia; however, early yields may be negatively impacted when utilizing the lowest range (196 kg·ha^-1) of recommended N fertilizer rates.