Hewitt Creek Performance-based Project

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The 23,005 acre Hewitt Creek watershed in Northwest Dubuque County, Iowa, has 82 farm operators that till 19,181 acres of mostly Fayette-Downs cropland classified as highly erodible. The relatively small acreage farms have abundant livestock, mostly dairy cows and cattle feeding. This intensity is historic and results in cash rent rates over $230/acre, well above farm program (CRP) rental of approximately $190/acre.


The Hickory Creek tributary is IDNR impaired for aquatic life based on macro-invertebrate and fish species. A survey conducted by ISU Extension revealed that residents consider themselves good environmental stewards, however neighbors as not so good. Neighbor-to-neighbor was identified as the most frequent source of conservation information. Residents of Hewitt Creek watershed formed a watershed council and established as their primary goal:

“To collectively join together to generate a critical mass of conservation sufficient to improve water quality resulting in the removal of the impaired waters designation.”

(Producer comments are included in quotes at the end of sections - ed.)


Iowa Farm Bureau Federation baseline funding arrived shortly before the 2005 planting season resulting in use of the traditional watershed menu of BMPs. The Iowa Watershed Improvement Fund grant planning brought the BMP menu together into the science-based and state agency adopted performance indexes, P-index, Soil Conditioning Index (SCI), and the cornstalk nitrate test. The indexes are calculated on individual fields, weighted by field acreage to attain a farm index, and the 46 cooperator farms are combined to attain a measure of watershed performance.


During the baseline period farmers were offered $400 per farm to install or improve waterways. Twenty three farmers seeded 150’ to 14,768’ per farm for a watershed total of over 17 miles. The project incentives were $9,200, approximately 10 cents per foot of waterway, saving annually an estimated 3,482 tons of soil from the highly erodible landscape. The council assumed the “low hanging fruit had been treated”, therefore set an incentive rate for 2006 of 50 cents per foot of waterway or headland, requiring a minimum width of 30’ and maximum payment length of 1,200’. This is double the NRCS Specs. of 15’ for headlands. Thirteen cooperators in 2006 seeded 260’ to 3,640’ per farm using project incentives totaling $7,330 for 27,718’, a cost of 26 cents per foot installed. Adding more than 1.2 mile of grass waterways and headlands per 1,000 crop acres should provide an immediate and long term improvement in water quality plus slow flash movement of water potentially reducing stream bank erosion.


Eight cooperators seeded cover crops using the incentive of $10 per acre up to 40 acres. Several cooperators rented a no-till drill rather than using fall tillage that would expose corn silage and soybean fields to erosion. Mostly positive experiences will result in all but one cooperator continuing the practice and three new cooperators: Coming to the meeting we discussed using oats and/or spring rye so it will die naturally rather than using chemical in the spring, and it will be easier to plant due to less fresh residue, and have less risk of spring insect infestations.


Three cooperators have received $200 incentives for installing fencing to exclude livestock from streams. Roof gutters, above lot berms to divert water from diluting and flushing manure from feedlots and/or below-lot grass filters have been installed on 6 farms using a $200 incentive.



Historical and current intense livestock production and water quality indicators prompted P-index calculations on 326 fields and 8,187 (over 41%) acres with 37 farm operators cooperating in 2006. Only 20 fields averaging 21 acres per field were in the high risk category for Phosphorus loss, primarily due to relatively close stream proximity and/or high P soil test levels. Thirty nine percent of the farms had P-indexes between 2.0 and 3.0 earning a $400 performance reward, and 1/3 scored below 2.0 P-index earning an additional $200 bonus. Twenty-seven percent of the cooperators received no P-index payment due to scores over 3.0 on a medium (2.0 to 5.0) P-index scale. A technician outlined in writing to each cooperator, remedial opportunities targeting the highest indexing fields. Frequently suggested were extending rotations, conversion to grazing, no-till, more waterways, in-field and edge of field buffers, contour planting and rigorous manure and commercial P fertilizer management. The field-size-weighted baseline P-index average for the watershed was 2.48 with 36 mostly no-till and grazing fields scoring 0 to 1. “I decided to hire a neighbor to no-till three fields to corn and it looks great." If these 3 fields, 58 of 163 farm acres remain in no-till the farm P-index will decline from 2.28 to 1.81 earning a $200 performance improvement reward in 2007. The SCI on this farm will also improve from 0.22 to 0.44 earning an additional $440 performance improvement reward. “I assumed my P-index would be a problem with the amount of livestock and manure I have. It was not and now I know on what fields I can most safely use the manure."


This computer model predicts the effect of cropping systems and tillage on soil quality and change in soil Organic Matter (OM). The baseline SCI values were calculated for 326 fields and 8,187 acres resulting in a field-size-weighted watershed index of 0.54. A loss of OM was predicted for 6 fields due to aggressive row crop rotation and tillage practices and ranged up to 1.10 for one field on a rotational grazing farm. “This performance program recognizes the environmental value of forages protecting water quality by rewarding grazing and alfalfa in rotation unlike the current farm program that mostly rewards corn and soybean production."


This test is a direct performance evaluation of commercial nitrogen and/or manure N management by quantifying the end-of-season nitrate-N concentration in the lower cornstalk. To measure annual project progress in N management, baseline sampling was conducted in 73 fields on 28 farms in 2006. Analyses in 2006 ranged from 37ppm to 11,600ppm on a scale of optimum concentrations, 700ppm to 2,000ppm. The average analyses, 3,512ppm was 26 percent lower than 2005. Cooperators compare at least two N management alternatives. One cooperator at 429ppm qualified for the performance reward and bonus totaling $600. The results did prompt, with some new confidence, nearly all cooperators to refine manure and commercial nitrogen use in 2006 with plans for additional refinement in 2007. “Corn yields and stalk nitrate analyses on 12 side-by-side tillage, manure and N-rate comparisons proved to me that 3,500 gallons of hog manure can produce 200 bushel corn using no-till.” “One guy does it and sees it works, others will do it too."


The requirement of a recent P soil test for the P-index exposed a deficiency also found in other watersheds. About 1/3 of farmers have not tested for P, about 1/3 of those who have tested – the results are retained by the fertilizer dealer and less than 1/3 are actively managing their farm phosphorus needs. Sixteen cooperators have used the $300 incentive to grid sample 40 or more acres.

“The higher concentration of phosphorus in distillers grains, a great by-product of ethanol production, will need to be offset by using less traditional phosphorus in cattle rations.”


Seventeen cooperators contracted for the $200 manure management incentive with 14 completing the activity under project technical assistance. Solid manure annual application rates ranged from 11 to over 40 tons per acre and most analyses showing normal nutrient concentrations. Most cooperators will increase speed of travel to apply less manure, thus nutrients per acre and cover more acres.

“When farmers know their manure rate and analysis – it makes a big difference how much commercial fertilizer they need and use."
“Some have recommended that after manure 115 N, 35 P, and 45 K is needed due to nutrient tie-up and prior crop removal - just keep pouring it on – you get that stuck in some guys’ minds."


Monthly and multiple high flow event monitoring and two annual macro-invertebrate evaluations were conducted by UIU staff at three stream locations. The year-to-year and neighboring watershed comparison N, P, turbidity and fecal coliform data are very encouraging.

“I farm several fields along the creek, therefore I see it frequently – even with more rainfall than usual in 2006 after being dry in 2005, I have never seen the stream so clear, and with more fish than ever.”
“The number of blue heron was up considerably this year – you know they are filling themselves with fish – and the number of swallows feeding on water-surface insects in the evenings was up significantly.”


Thirteen farmstead assessments have been completed, 11 with the technical assistance of a Farm Bureau Federation contracted technician.

“The assessment took nearly two hours, I picked up some good ideas – it was well worth the time.”


  • Watershed cooperators,
  • Iowa Farm Bureau Federation,
  • USDA CSREES Water Program,
  • Iowa State University Extension,
  • Iowa Watershed Improvement Fund,
  • Iowa Department of Agriculture and Land Stewardship IFLMDP
  • Upper Iowa University