2019 ASHS Annual Conference

Florida and Georgia are major cabbage production states in the United States. In both states, cabbage growers have challenges with soil nitrogen (N) leaching caused by coarse textured soils and heavy rainfall events. Consequently, N-fertilizer is applied in high rates to ensure yield. The objective of the study was to identify the N-fertilizer management that mitigate N-fertilizer rates without impact cabbage yield. Field experiments were conducted in Hastings, FL, during 2016 and 2017 cabbage seasons, and in Tifton, GA, during the 2018 cabbage season. Cabbage plants were grown at 8-in and 12-in in-row spacing in Florida and Georgia, respectively. In both locations, treatments were a two factorial of N-fertilizer rate (175, 225, and 280 lbs./ac) and cabbage variety (Bravo, Cheers, Capture, Bronco, Ramada, and Bruno) randomized in a complete block design (r = 4). At harvest, cabbage total and marketable yield was measured. Regardless of variety, the application of 170 lbs./ac of N had no significant difference in total yield compared to 225 and 280 lbs./ac in Florida for 2016, when rainfall accumulation was 10.5 in. Average total yield among N-fertilizer treatments in 2016 was 45,391 lbs./ac, while the variety Cheers had the highest total yield (48,410 lbs./ac) and Capture the lowest total yield (43,660 lbs./ac). In 2017, there was an interaction between N-fertilizer rates and varieties in Florida. The application of 175 lbs./ac sustained yield for Capture and Ramada which averaged 50,715 and 50,217 lbs./ac, respectively. The varieties Cheers, Bronco and Bruno required a minimum of 225 lbs./ac to increase total yield, and averaged 59,730, 43,062, and 54,801 lbs./ac, respectively. While, Bravo required 280 lbs./ac to achieve the highest yield (54,751 lbs./ac). Rainfall accumulation in Florida cabbage season of 2017 was 2.1 in. In Georgia, there was no significant difference among N-fertilizer rates, regardless of variety. The N-fertilizer rate of 175 lbs./ac was sufficient to sustain total yield (38,206 lbs./ac) when rainfall accumulation was 22.3 in. Regarding variety, total yield was the highest for Bronco (45,299 lbs./ac) and lowest for Capture (30,880 lbs./ac) in Georgia. Overall, marketable yield represented 27% and 8% of total yield in Florida and Georgia, respectively. The effect of N-fertilizer rates on marketable yield was similar to those measured in total yield. Thus, the N-fertilizer rate of 175 lbs./ac sustained cabbage yield but still a proper N-fertilizer management should consider rainfall distribution to ensure soil N leaching is not reducing cabbage yield.