by Dan Haug | Oct 9, 2019
Nitrogen rate management (MRTN) is the low-hanging fruit of the Iowa Nutrient Reduction Strategy, a win-win for profitability and the environment. On closer inspection, that fruit is even juicier than we thought; but harder to reach.
Here’s the paradox of nutrient management that the general public fails to grasp. We don’t know with any certainty at application time how much nitrogen the corn crop will need or how much nitrogen will be left in the soil come July when the crop starts maturing. Corn stalk nitrogen tests and split applications can improve the accuracy of the guess, but farmers still have to guess. If they guess too low, they lose income. So most farmers err on the high side, which means that (all else being equal) more nitrogen will end up in our streams.
Figure by John Sawyer at ISU. The economically optimum nitrogen rate varies by year, even on the same field.
We may not know what’s the right amount of nitrogen to apply this year, but we can pinpoint a range that makes the most economic sense across sites and years. In 2005, Iowa State University researchers crunched the numbers and developed an online calculator. A farmer can enter current prices for corn and fertilizer to get the Maximum Return To Nitrogen (MRTN). Above that range, they might get a bit higher yield, but the revenue from those extra bushels doesn’t offset the cost of the extra nitrogen. Applying nitrogen at the MRTN is a rare win-win for profitability and the environment.
Along with cover crops, wetlands, and bioreactors, MRTN was one of the more promising practices for nitrogen outlined in the Iowa Nutrient Reduction Strategy. Still, the authors cautioned that it wouldn’t get us very far by itself. An average field would cut nitrate losses by 10 percent. Since some parts of the state apply less nitrogen than others, universal adoption of this practice would get us a 9 percent reduction in nitrate concentrations.
That modest reduction assumes Iowa farmers currently apply 150 lbs of N/acre on a corn-bean rotation and 190 lbs/acre on continuous corn, a figure the authors admitted were “possibly outdated.” A 2017 survey by ag retailers found that Iowa farmers apply 169 lbs/acre of nitrogen on corn after beans and apply 210 lbs N/acre on continuous corn. I updated Dr. Helmers graph with those numbers and an MRTN based on current corn and nitrogen prices to determine the potential water quality benefit. This low-hanging fruit is juicier than we thought!
And that’s just the average! Inspired by a recent essay by Chris Jones, I read a manure management plan for a field in one of our watersheds. It receives 190 lbs/acre of nitrogen and 146 lbs/acre of phosphorus in the form of liquid swine manure. If that manure could be spread over more acres at a rate of 140 lbs/acre, that could reduce nitrate losses by 31%. If it replaces rather than supplements commercial fertilizer, we could get another 4% cut in nitrate. Manure is a slow-release fertilizer and less susceptible to leaching.
Is that economical? Hard to say. Daniel Anderson reports that liquid swine manure can be moved seven miles and still be cheaper than synthetic fertilizer. In Story and Boone County that might work. Hamilton County has 218 manure management plans, so I’m not sure how far you’d need to travel to find a field not already being treated. Are there changes in processing or additional cost share that would help make it more feasible? I don’t know. No-one is talking about it. But cover crops work equally well. Winter rye grows thicker with fall-applied manure and can scavenge nitrogen that would otherwise be lost.
Unfortunately, neither of those options (MRTN or cover crops) are even suggested as part of manure management plans and the loudest voices in the room are saying livestock producers don’t need to be doing anything differently. Until that situation changes, the widespread adoption of rate management that’s assumed in statewide and watershed-based scenarios won’t happen and we will fail to meet our nutrient reduction goals.
by Dan Haug | Sep 17, 2019
GIS mapping is a big part of my job, but I’ll be the first to admit there’s a limit to what you can learn about a stream without getting your feet wet, or at least dipping a bucket into the water.
I’ve been testing West Indian Creek and Grant Creek at the lovely Jennett Heritage Area, just above their confluence. (With some help from David Stein and Rick Dietz) West Indian Creek flows through Nevada and drains 28,417 acres at this point. Grant Creek, also known as Drainage Ditch 5, drains 13,344 acres between Ames and Nevada.
Based on soils and landcover in the watershed, I’d expect Grant Creek to have comparable or slightly worse water quality than West Indian Creek. There are nutrient loading models available online and in the Story County Watershed Assessment that predict just that.
Instead, I’ve found that water quality is consistently better in Grant Creek. West Indian Creek has normal nitrate levels but very high phosphorus levels. At this point, I don’t know why.
| Orthophosphate (mg/L) | Grant Creek | W. Indian Creek |
| 5/14/2019 | 0 | 0.6 |
| 6/11/2019 | 0.1 | 1.0 |
| 7/25/2019 | 0 | 3.0 |
| 9/10/2019 (after rain) | 0.6 | 4.0 |
| Nitrate (mg/L) | Grant Creek | W. Indian Creek |
| 5/14/2019 | 2 | 5 |
| 6/11/2019 | 2 | 5 |
| 7/25/2019 | 2 | 5 |
| 9/10/2019 (after rain) | 0 | 0 |
I do know there are people in the West Indian Creek watershed working to improve water quality, both on private land and public land. If you own land or farm in the watershed and are thinking about doing more to conserve soil and water, contact our Watershed Coordinator, David Stein, to set up a free consultation.
If you live near Nevada and are want to help solve the mystery of these two creeks through water testing, contact Dan Haug. Prairie Rivers of Iowa is working with Story County Conservation and the Izaak Walton League to plan for and support volunteer stream monitoring around Story County in 2020.
A final note: Don’t judge a stream by its name, or lack of a name. The lower part of Drainage Ditch 5 is a natural creek with buffer vegetation, fish, clean water, and public access. The map below shows a pre-settlement land survey superimposed over a current topographic map. Interestingly, West Indian Creek was forested while Grant Creek was prairie. Thanks to the restoration efforts of Cindy Hildebrand and Roger Maddux, parts of Grant Creek are prairie once again.
by Dan Haug | Jul 30, 2019
“None of the lakes hereabout are very deep. They are all marsh-like, only distinguished from a thousand marshes by the courtesy of the pioneer who called them lakes to suit his fancy, recognizing their greater width and possibly, in some cases their bluffy shores.”
-Thomas H. McBride, Geology of Hamilton and Wright Counties (1910)
Two of the four lakes shown in the 1875 map (by A.T. Andreas) have been drained.
The governor has proclaimed July as Lake Appreciation Month. We’ve got a few lakes in the South Skunk River basin that we appreciate for different reasons.
- Hickory Grove Lake is a 100-acre impoundment that we appreciate for swimming and fishing. The effort involved in constructing it and now restoring it is a testament to how much Story County residents value our lakes.
- Ada Hayden Heritage Park Lake is a 137-acre former gravel pit that we appreciate for paddle sports, fishing, and admiring from the trails.
- Little Wall Lake is a 249-acre natural lake that we appreciate most for swimming and motorized sports.
- Cairo Lake is a 1300-acre former lake that we now appreciate as corn ground.
Did you know about that last one? Located between Jewell and Kamrar, it was drained starting in 1895 by a system of ditches (71 and Rahto Branch) and tiles, but you can still see the shoreline on aerial photos. “Lost Lake Farm,” a dairy on the north “shore”, is named as a nod to that history.
The scale of the work involved is impressive, especially given the technology available at the time, and was just one of many such alterations that built up Iowa’s agricultural economy. In this case it made farmable over 1000 acres of Blue Earth muck loams with a corn suitability rating of 63 to 66.
The work could not have happened without statutes adopted by the Iowa Legislature around 1890 that allowed for the formation of drainage districts, and reinforced by an amendment to the Iowa Constitution in 1908 to provide drainage districts with additional authority.
Today we have plenty of good farm ground but few clean lakes. We’ve got amazing yields but not reliable profits. We’ve got too little carbon in the soil and too much in the atmosphere. We’ve got too much nitrogen washing off our fields toward the Gulf. The environmental challenges are daunting, but when I look at old maps, it makes me wonder what today’s Iowans could accomplish, if we had the legal framework and economic incentives to make it possible.
by Dan Haug | Jul 3, 2019
This post is part of a series for 2019 Watershed Awareness Month, comparing water quality in a pair of local creeks to learn how land and people influence water.
On May 20, the Skunk River Paddlers launched their canoes and kayaks on Squaw Creek at 100th Street in Hamilton County and paddled down to 140th St in Boone County. The recent rains made it a fast ride!
However, the rain also washed a lot of sediment and quite likely some land-applied manure into the stream. I collected a water sample just before I took this photo and had a lab test it for E. coli bacteria, an indicator of fecal contamination: 2,390 CFU (Colony Forming Units)/100mL. That’s 10 times the primary contact standard for a single sample (235 CFU/100mL) and just shy of the secondary contact standard (2880 CFU/100mL).
Later that day, I collected a sample from Brookside Park in Ames with the help of my son. The lab results came back at 12,800 CFU/100mL, well above the secondary contact standard!
I don’t want to discourage people from recreating in Squaw Creek but I think a safety reminder is necessary:
Squaw Creek has consistent fecal contamination that could pose a risk of acquiring a waterborne illness. The risk is higher after heavy rains when the water is muddy—consider wearing waterproof boots when wading under these conditions. If you come into contact with the water, wash your hands or apply hand sanitizer before eating and take precautions to avoid getting river water in your mouth or on an open cut.
The numbers above are high, but not unprecedented. Over the past three years, City of Ames staff have been tracking E. coli, nitrogen, and phosphorus in Squaw Creek at Lincoln Way and we’ve been sharing the data on our website. 46 out of 48 samples exceeded the primary contact standard for E. coli!
Yes. Yes there is.
The pattern is also not unusual. In our Snapshots, we see that Squaw Creek usually exceeds the standard by the time it reaches Ames and picks up additional fecal contamination by the time it reaches Duff Ave.
The Ames City Council, Public Works Department, and Water & Pollution Control Department are concerned by the data and committed to helping find and address sources of contamination within city limits. The City of Ames spends $3.5 million a year repairing and upgrading its sanitary sewers. However, the data point to multiple sources of E. coli that will make this a difficult problem to solve. In addition to sewer leaks, we probably have some failing septic systems in the upper watershed, cattle in the stream, land-applied manure carried by runoff, pet waste, and wildlife. E. coli can also persist for a while in the sediment, and gets stirred up again after a rain.
In June, I went back to Brookside Park to demonstrate some water quality testing for kids enrolled in the Community Academy summer program. In addition to exploring nature and food systems, the kids have been hard at work improving removing invasive species, planting pollinator gardens, improving trails, and coming up with interpretive signs for Brookside Park. I’m pleased to see that one of the signs is about water quality, including a reminder to wash your hands after entering the creek, and tips on how to reduce pollution. Look for the signs to go up later this summer.
My son Leif shares a draft of a water quality sign at the Community Academy’s open house
by Dan Haug | Jun 26, 2019
This post is part of a series for 2019 Watershed Awareness Month, comparing water quality in a pair of local creeks to learn how land and people influence water.
With such a big watershed—147,000 acres—we’ll need the help of a lot of people to improve water quality in Squaw Creek. However, some of the people I talk to assume that water quality is mostly someone else’s problem—it’s the CAFOs fault, or the golf courses, or the residential lawns.
By comparing smaller streams, volunteer monitoring can help us untangle some of the influences and serve as a reality check on the finger pointing. Thanks to the Squaw Creek Watershed Coalition we have some data on a lot of Squaw Creek’s tributaries, some with urban watersheds (College Creek) and some with rural watersheds, some with hog barns (Prairie Creek) and some without (Bluestem Creek). Some streams were even sampled monthly for a few years—not always the same years, but I’ve included some monthly averages to show the seasonal pattern.
| May 2019 Snapshot | Bluestem Creek | College Creek | Prairie Creek | Squaw Creek @Duff Ave |
| Cropland in watershed | 90% | 19% | 82% | 81% |
| Nitrate | 5 mg/L | 2 mg/L | 5 mg/L | 5 mg/L |
| Phosphorus | 0.8 mg/L | 0.2 mg/L | 0.3 mg/L | 0.2 mg/L |
| E. coli | Not sampled | 1,220 CFU/100mL | 11,700 CFU/100mL | 9,600 CFU/100mL |
College Creek is almost entirely within the city of Ames. Urban streams have their own set of water quality challenges. Road salt applied in winter can lead to elevated levels of chloride. E. coli levels used to be very high due to issues with septic systems. Paved surfaces mean more runoff after heavy rains, carrying contaminants and worsening bank erosion. (A 2019 Water Quality Improvement project to install permeable pavement and tree trenches on Welch Ave will help reduce runoff to College Creek).
But despite all the athletic fields and residential lawns in the watershed, College Creek typically has lower nitrate levels than rural tributaries. If you’ve seen your neighbor over-fertilize their lawn and are wondering why that doesn’t have more of an impact, it’s worth remembering that turfgrass is a perennial and, like a good cover crop, is actively growing and taking up nutrients in April and May when most fields are bare.
Bluestem Creek is located in rural Boone County. It is usual in that it has no nearby hog barns, and presumably no hog manure applied in the watershed. It contributes plenty of nitrogen to Squaw Creek but appears to have lower phosphorus levels than Prairie Creek, another rural tributary with at least two hog confinements in its watershed. Hog manure is a good fertilizer (adding nitrogen, phosphorus, and organic matter to the fields where it is applied) but farmers don’t always account for it when applying commercial fertilizer.
Bluestem Creek does have cows, which entered the water for 5 minutes while I was doing water testing this spring. I have a soft spot for cows because their presence on the landscape can make cover crops and more diverse crop rotations financially viable. I’d rather see pasture along the creeks than have it plowed right up to the edge. But it’s true that cows can stir up sediment and poop in the water if they have access to the creek. I’ve heard feedlot owners complain that they have to fill out a lot of paperwork regarding their manure management and receive a lot of scrutiny from their neighbors, while smaller livestock producers are not held to the same standard.
Ultimately, I think stream monitoring data shows that we all have a role to play in improving water quality, whether that’s reducing runoff and erosion in urban streams through rain gardens and permeable pavement, improving soil health with cover crops and no-till, better management of manure and fertilizer, or removing nitrogen from drainage water with bioreactors and saturated buffers.
