Fertilizers, herbicides, and insecticides have various ecological effects, toxicity, and chemical fate and transport based on the product’s chemical components. Depending on the chemicals’ characteristics, they can have unintended harmful effects on terrestrial and aquatic plants and animals, and can end up in our soil, water, and air. Nitrates from fertilizers can migrate through the soil profile and contaminate ground water supplies beyond safe drinking water levels.
Phosphorus from fertilizers contributes to eutrophication of surface water bodies that depletes oxygen levels and can lead to fish kills. This fact sheet provides guidance on program development for minimizing fertilizer and pesticide application.
Practicing proper fertilizer, herbicide, and pesticide application reduces the risk of these materials being transported by stormwater to downstream water bodies. Minimizing chemical use by employing best management practices (BMPs) for both application and material handling helps to eliminate a significant cause of stormwater pollution. Some BMPs have the potential to reduce costs associated with grounds keeping and maintenance, while improving the aesthetics and vegetative health of grounds where they’re implemented.
Programs designed to manage and minimize chemical application typically include a combination of the elements identified below. The BMPs and chemical alternatives discussed can provide the content for training programs and public education materials.
Integrated pest management (IPM) is a pest control system that employs mechanical, biological, cultural, and/or chemical mechanisms as determined by a thorough evaluation of the conditions rather than addressing every condition with chemicals.
The following are IPM strategies:
I PM strategies are employed only when pest populations reach an unacceptable economic or aesthetic threshold.
The following guidelines should be followed when preparing and handling chemicals:
The following guidelines should be followed when preparing and handling chemicals:
Organic fertilizer Most organic fertilizers release nutrients more slowly and contain lower concentrations of nutrients. The slow-release function provides the lower concentration of nutrients over a longer period of time which is good for sandy soils where fast-release fertilizers can leach nutrients into the ground water. Fast-release fertilizers are more effective for heavy clay or compacted soils. Organic fertilizers have the additional benefit of recycling waste that would otherwise contribute to landfills and/or pollution.
Grass clippings Mulching mowers create fine grass clippings that will break down and add nitrogen and organic matter to the soil. Leave grass clippings on the lawn over the season to provide the equivalent of one regular fertilizer application that will not cause thatch.
Aerate Aerating a compacted lawn punches holes in the soil to allow air, water, and nutrients to reach the roots. Leave the small plugs of thatch and soil on your lawn and they will quickly decompose. The best time to aerate is in the early fall.
Compost Apply a thin layer of compost (1/4” or less) to provide nutrients and additional water retention properties to combat dry periods. High-quality compost is available in nurseries by the bag or in bulk, or you can make your own. The best time to apply compost to lawn is in the spring using a wheelbarrow, shovel and lawn rake. A 1/4” layer requires about one cubic yard of compost per 1,500 to 2,000 square feet of lawn area.
Soybean fertilizer Michigan State University began using soybeans as turf fertilizer in 2000. Their studies suggest that soybeans perform equal to or better than chemical fertilizers. Ground soybeans provide a slow-release of nutrients to the lawn and are harmless to people, pets, and other plant material. In addition, soybeans are phosphorus-free. Because they are organic, each application improves the growing media, and they will not burn the grass.
Develop public education brochures to encourage residents to limit chemical use by educating them about the human health risks and natural resource impacts associated with improper application. Typically tri-folded, double-sided informational sheets can be mass-mailed to educate residents. If ordinances or fines are associated with improper chemical application, these would also be included in this education piece.
Introduce a law enforced by the MS4 whereby individuals or entities responsible for chemical application receive a fine for chemical application that varies from product labeling. Other city-developed regulations might include required soil testing before fertilizer application.
The Minnesota Department of Agriculture (MDA) requires all persons who apply fertilizer or pesticide for hire (regardless of whether the product is custom blended, bagged, bulk, etc.) to obtain a fertilizer or pesticide applicator license, respectively from the MDA. A license is required for any application, including applications to lawns, plants (including trees and shrubs), and interior landscapes. Annual attendance at applicator recertification workshops is required.