Fewer herbicides and pesticides in agriculture or in home and city lawns and gardens can help reduce pollutants in the environment. Chemicals don't always break down very quickly and they can build up in the soil and harm earthworms, beneficial soil microbes, and the growing tips of plant roots. Excess chemicals also wash off the surface of soil or lawns and can enter ponds, lakes, rivers, and the ground water or ocean water. The toxins or excess fertilizer nutrients can cause an imbalance in algae growth. Fertilizers can cause overgrowth which can contaminant drinking water with toxins or harm marine life. The overgrowth eventually runs out of the extra fertilizer nutrients or available oxygen and then a mass die-off and leave an oxygen free area in which the marine life may not be able to survive.
Phosphorus or nitrogen based fertilizers may cause overgrowth. Switching to more traditional methods of fertilizing with composted/partially digested animal or human waste water (sewage) is better for people, the planet, and water supplies. Our planet has limited amounts of bio-active phosphorus available for mining and current methods of agriculture don't recycle it in the way the traditional compost fertilizer returns it to the soil for the next year's crops. For more about increasing use of treated wastewater for fertilizer see: "Sewage Industry Fights Phosphorus Pollution," Scientific American. The bonus could be better health for bees and pollinators and possibly for humans and agricultural workers too. Pesticides and herbicides have been associated with the loss of bumblebees and other butterfly pollinators and also with some types of human health problems.
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