Final report for FNC24-1436
Project Information
Jim Stute operates Stute Farms in Walworth County, located on the edge of the Kettle Moraine in Southeast Wisconsin. The farm is roughly 160 acres and the operation consists of owned and leased land, all treated identically. Soils are primarily Fox silt loams, common to the region, which are lighter textured, rolling, have limited moisture holding capacity and are erosion prone. The farm is in the Mukwonago River Watershed, classified as an exceptional water resource by the Wisconsin Department of Natural Resources. The farm is in an area of high ground water recharge-defined and delineated by WDNR and included in the 2010 Walworth County Land and Water Resource Management Plan (Walworth County LURM, 2010). This area is critical for prevention of soluble nutrient leaching (including nitrate and sulfate) to protect baseflow of the Mukwonago River.
Current crop production includes corn, soybean and occasionally wheat, all no-till. Additional conservation practices include cover crops, use of certified nutrient management planning, in-season diagnostic tests, integrated pest management and subsurface application of nutrients. The farm has been in continuous no-till since 2003 and cover cropped since 1998. Crops have been “planted green” into cereal rye for the past 5 years.
Stute holds graduate degrees in agronomy from the University of Wisconsin-Madison and is a Certified Crop Advisor/ Professional Agronomist. Professionally, he has 15-years’ experience as an Extension Educator and his research results, including those from this farm have informed University of Wisconsin-Extension soil fertility recommendations and numerous publications. He is an active member and official of the Watershed Protection Committee of Racine County, a producer-led watershed protection group. He has successfully completed four previous SARE Farmer/Rancher projects (please see the Exhibit).
Planting green into cereal rye enhances sustainability gains of no-tilling and using a cover crop but presents technical challenges which may prevent adoption. In my case, I was initially concerned with three issues which may reduce crop yield: interception of residual herbicide spray by the green canopy reducing its efficacy; uptake and immobilization of nutrients applied as starter fertilizer; and creation or maintenance of a favorable environment for slugs, leading to more crop damage and/or stand thinning.
My initial approach to planting green was aggressive use of row-cleaners in both corn and soybean to both clear crop residue and partially dislodge rye plants. The rationale is to create a row clear of plant residues to improve spray coverage, limit rye nutrient uptake and create an unfavorable environment for slugs while also increasing soil warming. The problem with this approach is that dislodged plants can build up the spike wheels requiring frequent cleaning and partially dislocated plants can make planting slot closure more difficult. These problems are compounded by the wetter soil conditions of no-till. Based on observation, I am also of the opinion that disturbed plants are slower to die after application of termination herbicide, creating more competition with the crop. Aggressive row cleaning also accelerates wear on soil engaging tools, increasing maintenance costs.
Is row cleaning really necessary in a plant-green system on my soil types?
We conducted replicated trials in corn and soybean over the 2024 and 2025 growing seasons, evaluating three levels of row cleaning: none; intermediate (enough to remove crop residue but not dislodge rye); and full, removing crop residue, disturbing soil, and dislodging in-row rye plants. We measured crop emergence dynamics, plant populations (stands), slug damage, tissue nutrient concentration at flowering and grain yield at maturity and used common statistical methods to determine if differences we observed between treatments were real. Project results and lessons learned were shared at a field day and at other outreach events.
Results were inconsistent in corn. Averaged over years, there was no apparent yield difference caused by row cleaning but inconsistent performance by the intermediate level of clearing clouds the results and introduced some uncertainty in the analysis. Comparing just the full-up and full down treatments, it was obvious that the need for row cleaning was dictated by conditions at planting: row clearing was unnecessary under warm conditions when rapid crop emergence can be expected while there was a clear advantage under cooler conditions. In soybean, we found a clear disadvantage under warm conditions, similar to corn. We were unable to test the response under cooler conditions, warranting further investigation.
We will continue this work to gain more years of insight. Meanwhile, in our routine crop production we will make the adjustment based on soil temperatures and conditions at planting: no clearing if rapid emergence can be expected and full clearing if not.
Objectives
- Determine if row cleaning impacts crop production and yield in green planted corn and soybean comparing no cleaning to two levels of residue removal: light and heavy (near complete removal as practiced currently.
- Communicate results and experiences with the no-till community and their advisors.
Cooperators
- (Educator)
Research
We examined the use of row cleaners and their impacts on both corn (2024 and 2025) and soybean (2024) production in field trials near East Troy, Wisconsin. The soil type is a Fox silt loam (common in the region) and has a 20-year continuous no-till history; in corn-soybean rotation for the past 10 years. Crops have been planted green into cereal rye for the past 4 years. Rye is typically 6-8” in height at planting.
We evaluated three levels of row cleaning: none, intermediate and full, described in the introduction. The trial used Yetter model 2967 ridged (fixed position) row cleaners, mounted on Kinze/ John Deere Max Emerge style planter row units. Row cleaner adjustments were made in non-plot areas to ensure final functionality matched the treatment descriptions under current soil conditions before plot planting.
The independent (not connected statistically) corn and soybean trials used the other routine cultural practices of the farm including use of starter fertilizer to meet crop P and K maintenance requirements in addition to S, as well as the crop specific residual herbicide, applied preemergence along with glyphosate for rye termination. In corn, this co-application typically occurs 5-7 days after planting (DAP) but in soybean applications can be split, depending on soil moisture conditions. Residual herbicide is typically applied within 3 DAP and rye terminated at that time if conditions are dry or it can be delayed and made in a separate application up to 2 weeks later if moisture is favorable to increase biomass production and weed suppression. Wet conditions in 2024 forced a change from routine practice by delaying planting and preventing the PRE application of residual herbicide. Trial conditions are reported in Table 1.
To assess the impact of row cleaning on the production issues discussed above we measured:
Emergence dates (first emergence, 50%, final)
Stand (population) 30 days after emergence (30 DAE):
Final stand with concurrent estimates of:
- % slug feeding damage (plants)
- % peepers (plants of reduced size indicating delayed emergence)
- Visual weed control rating (in-row plant density will be measured if differences occur)
Tissue nutrient concentration at flowering (R1)
Grain yield at maturity (harvest stand, yield, grain moisture, and test weight)
Stand measurements were made to assess the level of rye residue interference with the planting process. Tissue nutrient concentration was measured to assess whether rye disturbance by row cleaning reduced its propensity for uptake of nutrients applied as starter fertilizer.
The experimental design is a randomized complete block with four replicates. Plots were 100’ in length and the center two rows (both crops planted in 30” rows) were harvested for yield determination. We established two (2) 20’ sections within each set of harvest rows to measure emergence dynamics and take the 30 DAE measurements, ensuring we are measuring the same spots to eliminate planter row unit and other spatial variability. Normal data was subject to analysis of variance; count and proportion data was analyzed with a general linear model using the appropriate error family (R Studio 2023.09.1). Means are separated with the least significant difference (LSD) at the 5% level of probability where appropriate.
Contrasts (with vs. without row cleaning, labeled “Up vs. Down”) were used to examine the overall effect on variables of interest to answer the “Up or Down” question. From there, the degree of row cleaning was examined if warranted.
A word about statistical analysis and p values:
We use statistical analysis to judge whether the differences between two values, treatment means for example, are real or if they are caused by random variation (the term mean is the same as average). We replicate (repeat) the treatments to estimate the amount of variation within an individual treatment measurement (yield for example) as well as that between the treatments. The analysis of the variability results in an estimate of probability, P, which indicates whether the difference between two means is real or is due to random variation. P values are reported as a decimal on a scale of 0 to 1, the lower the value, the greater the probability that the difference is real and not caused by the random variation. As reported, p values can be confusing but become more apparent when converted to a % probability, simply calculated by subtracting the p value from 1. For example, p= 0.15 is an 85% probability that differences are real (1- 0.15 = 0.85, 85% probability). For ease of interpretation, we report p values both ways. In general, we approach probability interpretation from a managerial standpoint and consider values over 80% as worthy of consideration.
Contrasts group treatments into categories to determine if there is an aggregate difference, in this case “row cleaning”: none vs. cleaning which is the combination of “intermediate” and “full” cleaning. In the analysis, we considered the row cleaning contrast first, proceeding to the next level when needed.
The coefficient of variation, CV, reported as a percentage (%) is an indicator of overall variability in a measurement, the greater the percentage, the greater the variability in the individual measurements which are included in the calculation the treatment means. An increase in overall variability can make the detection of real differences between two treatments more difficult: p values for measurements with high CVS’s should be considered carefully.
Growing season conditions
The 2024 growing season offered several challenges which impacted trial results. Southeast Wisconsin experienced an unusually warm, open winter resulting in greater rye growth and biomass production than we routinely expect. Above normal precipitation and frequent precipitation events Table 2 delayed planting and other field operations and prompted the change of weed control strategies from preemergence residual to post emergence. The combination of greater rye growth and delayed planting meant our trial examined row cleaning on the upper end of rye biomass production and plant maturity. Figure 1, Figure 2 depict both the level of rye biomass and the degree of row cleaning of each treatment.
Precipitation patterns changed abruptly in mid-summer, switching from excessive moisture to drought conditions. While we ended the growing season (April-Sept.) 5 inches above normal, the later season deficit limited the yield of both corn and soybean and reduced test weights. Growing degree day (Base 50oF) accumulation was 105% of normal.
The 2025 growing season was exceptional in SE Wisconsin. Ample precipitation and normal GDD accumulation resulted in record corn and near record soybean yields (Wisconsin Agricultural Statistics Service, 2026), further aided by drier spring conditions which permitted timely planting. As with 2024, total growing season precipitation was greater than 5.0 inches above normal and the season ended with a pronounced dry period, but ample August rainfall carried the crop to maturity. Trial corn yields were 14% greater in 2025 than 2024.
A comparison of growing season precipitation patterns is shown in Figure 3.
Results
Row cleaning had minimal impact on corn (Table 3) but affected soybean, reducing yield as well as tissue N and S concentrations (Table 4). Corn results are reported as the 2-year trial average. Except for tissue N and yield, the indicator variables responded similarly to treatments despite differing growing seasons, so the combined presentation simplifies discussion. Insights into differential tissue N and yield performance will be provided in their respective sections. The 2025 soybean trial was abandoned during planting so only one year of data is available for reporting. Trial planting was abandoned because corn stalks from the 2024 harvest were inadvertently chopped (chopping head not turned off), resulting in a residue mat on the soil surface which required row-cleaning for planting, eliminating the possibility for a non-cleaned control.
Neither emergence dynamics nor stands were affected by row clearing in either corn or soybean (emergence data not shown). This is an unexpected result because the intent of row cleaning is to produce more uniform conditions for seed placement as well as to speed soil warming. We attribute the lack of difference in 2024 to later planting under warmer than normal conditions (Table 2), ample soil moisture for germination at planting followed by numerous rains which kept soil moist, aiding rapid germination and emergence. Rye was also taller than usual at planting which partially shaded cleared rows, minimizing the soil warming effect of row clearing. Rye was eleven inches shorter in 2025, but still taller than the typical 6-8” due to favorable overwinter conditions, resulting in row shading and likely similar soil temperatures. Frequent precipitation events kept soil moist to aid emergence and, combined with cooler than normal temperatures, likely contributed to uniform soil temperatures between treatments. In corn, it took 11 days from planting to reach full emergence in 2024 with a 3-day interval from first emergence to full stand. In 2025, final emergence was extended to 16 days, with a 6-day interval from the first emergence to full stand.
Tissue nutrient concentration at flowering assesses plant nutritional status at a critical point in plant development which can affect grain yield. One of the goals of row clearing is the disruption of rye growth, slowing or preventing its removal (by uptake) of starter fertilizer nutrients from the fertilizer band which in turn makes them unavailable to the crop. If effective, this effect would be important in both years because favorable overwinter conditions and delayed planting produced more rye biomass than usual, which included its associated nutrient removal.
In corn, we found a tendency of row cleaning to increase tissue N and P concentration while leaving K and S unaffected. We speculate that row clearing did disrupt the short-term (from planting to rye termination) nutrient uptake by rye from the starter fertilizer band, especially P where its “fixed” by soil and therefore unable to move outward into soil solution after planting. It should be noted that all tissue levels were sufficient under University of Wisconsin-Extension recommendations (please see the footnote on Table 3 for sufficiency range values) except for N in the non-row cleaned, “Up” treatment. We speculate that rye nutrient uptake before crop planting in 2024 was greater than we typically experience and limited early season availability to the crop, resulting in borderline deficiency conditions even though nutrients were applied at recommended rates. In general, tissue N was lower in 2024 than 2025, 2.16 vs. 3.06%, and levels were lower without cleaning (2.09%) compared to cleaning (2.19%) in the 2024 Up vs. Down comparison (p=0.393, data not shown). This validates our hypothesis that preplant rye nutrient removal was greater in 2024 and row cleaning was partially effective in reducing further uptake. In soybean, we saw the opposite behavior, a tendency of clearing to reduce tissue N and S concentrations (p= 0.051, 0.184 respectively) defying explanation. In this case, S concentration was deficient which may partially explain row cleaning yield impacts. Nitrogen, P, and K were in the sufficiency range and should not have impacted yield.
Overall corn yield was as expected in 2024 with later planting and the drought conditions during the grain-fill period. The same also applies to the overall trial yield for soybean, but: weed escapes in two of the four replicates also played a role in yield reduction. Close examination of the data indicates treatments performed similarly between the replicates (in other words there was no apparent interaction (changes in ranking) between the treatments and the replicates, an effect we couldn’t test statistically due to the experimental design), so the net effect of weed escapes was to lower the overall trial yield by lowering yield in these replicates, but not changing conclusions about row cleaning. The weed escapes were due to a mid-application rain shower which reduced efficacy of the post emergence herbicide being applied to affected replicates. Herbicide could not be reapplied due to label restrictions. 2025 corn yields were as expected, given the growing season conditions and more timely planting
On average, row cleaning had no apparent impact on corn yield (p=0.871, 12.9% probability), but reduced soybean yield 7.7% (p=0.047, 95.3% probability). Our corn yield analysis requires further examination because of the important interplay between treatments and growing seasons discussed above.
In corn, row cleaning (“Up vs. Down”) resulted in differential responses based on the growing season, reducing yield 3.8% on average in 2024 while increasing it 2.0% in 2025. This relationship is evident in Figure 4 which separates the “Down” treatments into intermediate and full cleaning. More important than the annual upward or downward trends, there is an interaction between the intermediate row clearing treatment and the two seasons, indicated by the inflection in the mean trendline. On average, there was no difference between the two extreme treatments, none and full, but the intermediate treatment performed differentially, reducing yield to a greater extent than full cleaning in 2024 (-4.8 vs. -2.9%), a year when row cleaning clearly tended to reduce yield. Conversely, in 2025 when row cleaning increased yield, the gain from intermediate row cleaning relative to full was marginal, 0.4 vs. 4.8%. We suspect that this differential performance stems from the inherent and subjective difficulty in making the row cleaner adjustments to just “tickle’ residue from the row without disturbing soil. This difficulty is compounded by the variability of the soil surface: variable terrain results in intermittent row cleaning and inconsistent levels of in-row residue across the field. We suggest that this variability created enough “noise” in the data (c.v.= 11.4%) that the statistical analysis indicated no difference. From a practical standpoint, this variability suggests a risk in the form of inconsistent results: if the decision is made to clean rows, row cleaning must be uniformly effective. Row units should be adjusted to remove residue more completely, dislodge some plants, and possibly moving some soil to get consistent results.
In soybean, the opposite effect was observed. In evaluating the level of row cleaning (none, intermediate, full), it is evident that the soybean yield reduction is solely due to the change from intermediate to full cleaning, a reduction 17.7% (p <0.001, 99.9% probability). More years of data will be necessary to draw firm conclusions which could lead to changes in farm management.
Up or Down?
In corn, the results suggest the decision should be based on the nature of the growing season at planting time. Under warmer than normal conditions (as in 2024) when more rapid emergence is expected, row cleaning is probably not necessary, and this decision will prolong the life of row cleaners by reducing wear. In cooler conditions (as in 2025), the results suggest that rows should be cleaned and units should be adjusted for uniform engagement, possibly moving some soil and dislodging rye plants but completely removing crop residue. In soybean, results are less clear, based on only one year data.
We will continue this work on a reduced scale, measuring yield impacts. This is important because more data is clearly needed for firm guidance and although the yield impacts are relatively small, they matter in the current farm economy.
Educational & Outreach Activities
Participation summary:
We held a spring cover crop management field day, June 5, 2025. Project results were shared and discussed with participants as part of a broader discussion of cereal rye cover management including termination timing, nitrogen management in corn and weed suppression in the context of herbicide resistance management. Participants (45 total: 41 farmers, 4 Agricultural Support Professionals) learned of 2024 results and of the opportunity to learn full results in the project final report.
Project results were discussed at the 2026 National No-Till Conference, January 8, 2026, St. Louis. The presentation, entitled “Do cover crops pay? Here’s what the numbers say…,” based on SARE project LNC21-456, resulted in a broader discussion of cereal rye cover management including row cleaning. Participants (120 in total: 108 farmers, 12 Agricultural Support Professionals) were directed to the SARE website to find project results as well as the other useful information related to sustainable agriculture available there.
Project results will continue to be disseminated in my routine outreach programming related to cereal rye best practices. This underscores the need to continue the project, even on a reduced scale.
Learning Outcomes
Results were variable, discussed earlier, and require further study. In my farming operation, I will continue to use row cleaning in both corn and soybean, striving for an adjustment somewhere between the two row-cleaning treatments examined in the study.
For others, I would suggest continuing with their current practice if they feel it works for them until more conclusive data is available.