36th International Carrot Conference Abstract

IMPACT OF N FERTILIZER TIMING AND PLACEMENT ON CARROTS AND WEEDS IN MICHIGAN

C. Noyes, D.C. Brainard and Kurt Steinke

Most processing carrot growers on sandy soils in west Michigan currently broadcast urea 3 or 4 times during the season. Such broadcast applications represent an important cost of production, and likely result in losses of N through leaching, volatilization and uptake by weeds. Slow release nitrogen (SRN) products including polymer coated urea (e.g. ESN) may replace some or all of these top-dress applications and improve the overall efficiency of N use in carrot production. Field and greenhouse experiments were conducted to evaluate the impact of ESN on carrot quality, yield and weed competition. In field trials conducted in 2012, ESN applied at three different timings (deep-banded with strip tillage; early July or late July) was compared to standard grower top-dress applications. The same total N rate was examined in all treatments, with one less application timing occurring in ESN treatments. In a complementary greenhouse study, the effects of ESN placement (surface, 3” or 6”) on the growth of both carrots and the problematic weed Powell amaranth were evaluated. We hypothesized that deep placement of ESN would shift weed-carrot competition in favor of the carrot crop. Results from field trials in 2012 failed to demonstrate significant benefits of ESN in terms of crop yield or quality. However, one fewer tractor pass was required in ESN treatments. Unusually hot and dry conditions during the 2012 growing-season may have influenced these results. Contrary to expectations, carrot growth was reduced and Powell amaranth growth increased with deep placement of ESN in our greenhouse study. Further studies aimed at understanding the impact of N form and placement on carrot quality, yield, and carrot-weed competition are needed to help growers optimize their N management programs.

Last updated Thursday, 25-Jul-2013 11:54:25 CDT