From food labels to cotton sheets, the concept of going “organic” is alluring. The idea is open to much discussion and debate, but it’s a fact that many municipalities are imposing bans or restrictions on the use of pesticides, especially around schools, sports fields and public grounds.
Now, the magazine you are reading is focused on golf courses, and the article I’m discussing is about sports fields, but I’m writing about it because it’s a novel paper that examines the effects of organic management programs for turfgrass that include things such as compost teas and manures. Although there’s a ton of interest in organic programs for turfgrass, there’s actually not a lot of published work in this area, and this paper is a detailed look at organic programs.
As of 2010, the state of Connecticut has prohibited the use of many turfgrass pesticides on public and private school grounds (through eighth grade). To help develop management programs, researchers at the University of Connecticut examined the quality of trafficked Kentucky bluegrass athletic fields as affected by conventional and organic management regimes.
For two years, research plots received one of the following six programs: (1) conventional (fertilizers were urea, triple superphosphate and potassium chloride); (2) organic manure (dehydrated poultry litter); (3) organic protein (soy + alfalfa + molasses); (4) manure + compost tea (vermicompost-based); (5) organic protein + compost tea; and (6) nothing (control).
In all, 4 pounds nitrogen/1,000 square feet (195 kilograms/hectare), 1 pound phosphorus/1,000 square feet (49 kilograms/hectare) and 4 pounds potassium/1,000 square feet were applied in each year to the conventional plots. In the organic protein treatments, the yearly totals were 4 pounds nitrogen/1,000 square feet, 2.8 pounds phosphorus/1,000 square feet (122 kilograms/hectare) and 1 pound potassium/1,000 square feet. In the manure treatments, it was 4 pounds nitrogen/1,000 square feet, 3 pounds phosphorus/1,000 square feet (147 kilograms/hectare) and 1 pound potassium/1,000 square feet.
Weed control in the conventional plots was done via applications of dithiopyr and quinclorac, and in the organic plots, corn gluten meal was applied (this also supplies nitrogen, and nitrogen was applied to the conventional plots at the same time to get a uniform nitrogen rate). On conventional plots, the fungicides azoxystrobin and propiconazole were applied, while organic plots were treated with the biofungicide Bacillus licheniformis SB 3086. For white grub control, conventional plots were treated with the insecticide imidacloprid, and organic plots received a treatment of parasitic nematodes (Heterorhabditis bacteriophora). And last, all of this was studied with and without a fall overseeding of perennial ryegrass, which was seeded at 260 pounds/acre/week (292 kilograms/hectare/week) for 10 weeks, starting in August.
Collected data included turfgrass color, turfgrass quality, percent cover (artificial traffic was applied) and weed populations. The conventional management regime outperformed the organic regimes for overall quality, reduced weed populations, and better color in mid- to late fall. By the second year, there was no difference in percent turfgrass cover, and plots under organic regimes were equal to those under conventional management. Application of compost tea never enhanced turfgrass color, quality or cover during the duration of the study. Application of corn gluten meal was largely ineffective as well.
The best management strategy in the organic systems? Overseeding.
Overseeding with perennial ryegrass in every management system decreased broadleaf weeds (and crabgrass), increased cover and improved turfgrass quality. The authors concluded that the greatest limitation to their organic turfgrass management was weed control, and much more work is needed in this area.
Source: Miller, N.A., and J.J. Henderson. 2012. Organic management practices on athletic fields: Part 1. The effects on color, quality, cover and weed populations. Crop Science 52: 890-903.
Beth Guertal, Ph.D., is a professor in the Department of Crop, Soil and Environmental Sciences at Auburn University in Auburn, Ala., and the 2019 president of the Crop Science Society of America. She is a 20-year member of GCSAA.