This article doesn't mention it, but I've heard the suggestion that far more of the runoff is from over-fertilized suburban lawns than from agriculture.
At least commercial agriculture tends to be a bit more concerned about wasteful inputs, etc. (At least where subsidies haven't distorted it too much.)
But I see some incredibly excessively perfectly green lawns which are such a waste of resources unless you're playing golf or lawn bowling.
Glad to know I'm not alone. I live in a "wimbledon lawn" neighborhood in the NE US. Along with that comes vast caravans of clanking landscaping vehicles, a near constant drone of lawnmowers, leaf blowers, weed whackers, etc., and tiny yellow flags stuck into lawns with X marks covering pictograms of children and dogs.
The kicker: it's a lake community, where you're supposed to be able to swim and fish, and for the past two years the lake has been declared a biohazard* by late summer. Every month or so they treat the lake with some chemical cocktail that renders it "dangerous for swimming" for a week in an effort to fight the algae blooms.
Truly insane...I have to get out of here. And of course I'm an outcast for keeping my lawn all-natural. I do succumb to keeping it mowed so I'm not driven out of the neighborhood.
You might double check your source. Lawn fertilizer is a $5B industry, but it is usually priced at a dollar a pound, and a 50 lb bag might have 5-10 lb of N and 5-10 lb of P. USDA numbers for fertilizer use by crop are available, and based on those it looks to me like lawns account for less than 10% of the national fertilizer consumption. Corn uses 50%.
Lawns in general are goddamn stupid idea. The most common irrigated crop in the United States? Turf grass. They're a huge waste of water and a huge waste of fertilizer and both of those have very negative impacts on our immediate environment.
By definition, a well manicured lawn is wasteful. Lawns began as a way for nobility to signal that they could afford to take care of land, but not have it _produce_ anything.
I mow my lawn and I seed in the fall to keep erosion problems at bay, but that's about it. One of my neighbors has a putting-green like lawn with an in ground sprinkler system. It's amazing. It's the envy of the neighborhood, and it just makes me shake my head when I actually take the time to think about it.
Excuse me, but a huge portion of the US population lives in places that do not have water scarcity problems. I live in Iowa, we have more water than we know what to do with. Irrigating my lawn doesn't hurt the environment or any of my neighbors. Not everyone in the US lives in the southwest.
I bet you irrigate your lawn with potable water which takes energy to purify. So you're wasting clean water to maintain a furry green carpet (try some FieldTurf or native plants) that serves no purpose since it doesn't feed you (grow some vegetables) or act as that good of a carbon sink.
Some quick googling shows 45 million acres of turf of which 25 million are tended[1]. Compared to 408 million acres for crops[2]. Not definitive but it seems like agriculture is the bigger culprit. Though lawns are definitively stupid.
But an acre of farmland and an acre of suburban front-lawns are wildly different.
Agricultural chemicals are tightly regulated, various environmental groups watch them like a hawk and are quick to push for legislation against new chemicals. The EPA has strict rules on chemical run-off, retention in soil or ability to impact drinking water. On top of this, most farming is relatively low margin and farmers don't want to spray any more than they have to because of cost.
Meanwhile, the average suburban American will gladly dump 10x the appropriate amount of chemicals on their lawn in an attempt to keep up with the Jones' next door. Or think nothing of their fertilizer-infused irrigation spraying half onto the driveway or sidewalk, flowing directly into the storm sewer rather than being absorbed by the soil.
I'd be interested in solid numbers, but my own guess is that they will differ in the opposite direction, with the average farmer dumping many more chemicals per acre than the average lawn owner does. Crop-dusting in some areas happens daily, and when not daily, 1-3x per week. By contrast, very few lawn owners will apply pesticide to their lawn every day. Few will do it even once a week. The norm where I've lived seems to be 1-2x per year, which is hilariously infrequent to a farmer. Even if they over-apply in their very occasional pesticide treatment, they're starting from a baseline of much less frequent application.
At least commercial agriculture tends to be a bit more concerned about wasteful inputs, etc. (At least where subsidies haven't distorted it too much.)
But I see some incredibly excessively perfectly green lawns which are such a waste of resources unless you're playing golf or lawn bowling.