When fertilizer chemicals (phosphorus and nitrogen) escape farm boundaries and enter waterways, they can end up in protected biodiversity hotspots such as wetlands and estuarine environments, where they cause problems by disrupting natural nutrient cycles. The end result can be catastrophic toxic algal blooms (due to nutrient enrichment) which may affect the functioning of the whole ecosystem.
The annual costs associated with nutrient pollutants are estimated to be from $100 million in the UK and Wales and $240 million in Australia, to a staggering $2.2 billion in the U.S. These figures include not only spending on recovery of threatened species and drinking water, but also components such as the value losses in recreation, real estate and tourism. However, worldwide total spending on responding to the problem is minute in comparison to these annual costs. If simple changes can offer an economic benefit to the landholder and avoid these significant downstream costs then everyone wins.