Weed Supression with Winter Annual Cover Crops in Potato

Final Report for GNC10-123

Project Type: Graduate Student
Funds awarded in 2010: $9,950.00
Projected End Date: 12/31/2012
Region: North Central
State: North Dakota
Graduate Student:
Expand All

Project Information

Summary:

A research experiment was conducted near Oakes, North Dakota in 2009 and 2010, and repeated at Carrington, North Dakota, in 2010 and 2011 to evaluate the potential for weed control and potato yields using cover crops in irrigated potato production. Cover crop treatments included no cover crop, triticale, rye, hairy vetch, and rye/hairy vetch. The hairy vetch winter killed at Oakes and was replaced with turnip/radish and rye/canola cover crop treatments. Cover crop termination methods for both locations were disk-till, roto-till, and herbicide. The results were analyzed as a RCBD with a factorial arrangement and as a RCBD with a check. Locations were not combined due to winter-kill of hairy vetch in 2009-2010 and replacement with turnip/radish and canola. At Oakes compared to the no cover crop treatment cover crops treatments had 5% greater weed control 14 DAP, 14% greater 29 DAP, and 2% greater 51 DAP. At Carrington compared to the no cover crop treatment cover crops had 1% greater weed control 13 DAP, 1% greater 26 DAP, and 1% lower 42 DAP. Cover crops did not affect potato yield at Oakes, though negatively impacted yields at Carrington with 18% greater marketable yield without a cover crop. The results of this experiment support the consideration of cover crops in an irrigated potato system as a means of additional weed control. Longer maturing potato cultivars present a problem as they require resources during the same part of the season that is critical for cover crop biomass accumulation.

A field experiment was conducted at Fargo, North Dakota, from 2009-2010 and repeated near Carrington from 2010-2011 to evaluate the potential for weed control and potato yields using cover crops in non-irrigated potato production. Cover crop treatments included no cover crop, triticale, rye, hairy vetch and rye/hairy vetch. The hairy vetch winter killed at Fargo and was replaced with turnip/radish and canola cover crop treatments. Cover crop termination treatments for both locations were disk-till, roller-crimp, and herbicide. The results were analyzed as a RCBD with a factorial arrangement and as a RCBD with a check. Locations were not combined due to winter-kill of hairy vetch in 2009-2010 and replacement with turnip/radish and canola. At Fargo compared to the no cover crop treatment, plots with a cover crop had 17% greater weed control 17 DAP, 15% greater at 34 DAP, and 5% greater 49 DAP. At Carrington, plots with a cover crop had equal weed control to plots without a cover crop planted at 12 and 28 DAP, though plots with a cover crop had 5% greater weed control at 47 DAP than those without a cover crop. Yield in Fargo was low on average due to cover crop treatment and soil conditions. In Carrington, average marketable yield from the no cover crop plots was 35% greater than cover crop treatments. The results of this experiment support the consideration of cover crops in a non-irrigated potato system as a means of additional weed control.

Introduction:

Cover crops are any plant grown for a set purpose in between times of cash crop growth (Brady and Weil, 2008). Cover crop integration into conventional agriculture rarely occurs today due to growers’ ability to easily overcome production problems with pesticides, fertilizer, and crop rotation. However, more growers are beginning to consider the use of cover crops to enhance soil retention, soil and environment quality, as well as to provide alternate methods for fertility management and pest control (Blevins et al, 1990).

Furthermore, cover crops are often relied upon in organic and sustainable agriculture systems and continue to increase in acreage each year with North Dakota ranking second in the U.S. for organic crop production (Knopf, 2011). Over the last three growing seasons, from 2008-2010, potato production in North Dakota ranked fifth in the U.S. for potato acreage, with an average of 34,000 hectares devoted to this crop. Weed control in organic potato production relies on the effectiveness of cultivation, harrowing, and weed suppressing cultivars (Beveridge and Naylor, 1999). Unfortunately, regular precipitation and slow soil drying due to the clay soil texture in the Red River Valley, make timely cultivation difficult and often impossible. Growing winter annual cover crop species provides a potential alternative early season weed suppression method. The growing season found in the Upper Midwest, specifically North Dakota, will limit many aspects of cover crops due to shorter growing seasons than other locations in the United States (Snapp et al, 2005; Teasdale, 1998).

This research evaluated the effects of cover crop, termination method, and potato cultivar on weed control in potato. The first objective was to determine if cover crops improved weed control in potato production where chemical control was not desired. The second objective was to determine how cover crops influenced potato yields. Results of this research will be relevant to potato producers who are considering adding cover crops to their potato production systems.

Project Objectives:

This research evaluated the effect of cover crop, termination method, and potato cultivar on weed control in potato. The first objective was to determine if cover crops improved weed control in potato production where chemical control was not desired. The second objective was to determine if cover crops added or detracted from potato yields. Through this research it is anticipated that potato producers could add cover crops to their potato production in a way that would benefit their unique cropping system.

Cooperators

Click linked name(s) to expand
  • Grant Mehring

Research

Materials and methods:

Field experiments were conducted from 2009-2011 to evaluate weed control with cover crops in irrigated potato. Field experiments were conducted at the Oakes Research Extension Center (OREC), near Oakes, North Dakota (46.07N, -98.09W; elevation 392 m) in 2010 and repeated in 2011 at the Carrington Research Extension Center (CREC), near Carrington, North Dakota (47.51N, -99.13W; elevation 475 m). The experimental design was a randomized complete block with a two factor arrangement and four replicates. Cover crop termination treatments were herbicide, disk-till, and roto-till. Cover crop treatments were triticale, rye, hairy vetch, rye/hairy vetch, and no cover crop. Hairy vetch winter-kill during 2009-2010 resulted in the spring planting of turnip/radish and canola. To include a check treatment, no factorial combination of no cover crop with roto-till was included, with roto-till being substituted for no termination treatment. Certified seed potatoes were cut into 57 g ± 14 g seed pieces that were stored at 16 C with approximately 90% relative humidity for 2-7 days to allow for suberization before planting. Potatoes were grown using standard recommended grower practices for soil fertility, irrigation, and insect and disease management practices unless specifically described in the following Oakes or Carrington sections. Individual cover crop treatment plots were 3.66 m wide by 7.62 m long while individual treatment plots were 1.83 m wide by 7.62 m long and contained two potato rows.

Early-season weed control was estimated by weed species counts, weed above–ground fresh weights, and visual evaluations. Weed evaluations (weed counts, weights, and visual control ratings) were taken three times, approximately 14, 28, and 42 days after planting (DAP). Cultivation was conducted with a two-row disk cultivator (Harriston Industries; Minto, ND, USA) immediately after the first two weed evaluations. Weed counts were taken within a 0.09 m2 quadrat placed on top of a potato row. Visual weed control evaluations were taken using a rating scale of 0 to 100%, where 0=no control and 100=complete weed control, referenced to the alleyways of the research where no weed control existed.

Harvested tubers were graded in Fargo with a single six station slide ejection photo sizer (Hagen Electronics; Reno, NV, USA). Tubers were separated into non-marketable (<113 g) and marketable (>113 g) yields, the table stock standard for potato. Ten tubers from each plot were randomly selected for hollow heart and sun scald evaluation. Hollow heart was detected by slicing each potato in half and identifying the presence of a hollow center, while sun scald was measured by analyzing the halved potatoes for greening between the skin and inner flesh. Data from each location (Oakes and Carrington) were analyzed individually using PC SAS 9.2 (SAS Institute Inc.; Cary, NC, USA). Proc ANOVA and Proc GLM procedures were used with an alpha value of 0.05 for all agronomic data. Means were separated, where appropriate, using Fisher’s Protected least significant differences (LSD) test at P?0.05.

Oakes, 2010. The experiment was conducted on an Embden loam (coarse-loamy, mixed, superactive, frigid Pachic Hapludolls) and Gardena loam (coarse-silty, mixed, superactive, frigid Pachic Hapludolls). The previous crop in 2009 for half of the trial was spring wheat and the other half dry edible bean. The plots received overhead irrigation using a linear system. Winter annual cover crops (triticale, rye, and hairy vetch) were planted on 28 Sept. 2009 with a grain drill (Case International Harvester; Racine, WI, USA). Triticale, rye, and hairy vetch were planted at 151.3 kg/ha, 132.4 kg/ha, and 33.6 kg/ha, respectively. In the combined planting, rye was planted at 65.4 kg/ha and hairy vetch was planted at 33.6 kg/ha. A spring granular fertilizer of 31.1 kg N/ha, 20.9 kg P/ha, and 47.4 kg K/ha was applied 6 Apr. 2010 to replications 1 and 2 where the spring wheat was grown the previous year to compensate for soil testing differences in replications 3 and 4. Due to the hairy vetch winter-kill a turnip/radish combination and canola were planted on 16 Apr. 2010. Turnip/radish took the place of the hairy vetch treatment and were planted by manual spreading and subsequent raking seed at 5.6 kg/ha turnip and 5.6 kg/ha radish into the soil. Canola was manually over seeded at 12.4 kg/ha into the rye/hairy vetch treatment to become the rye/canola cover crop treatment. A burn-down herbicide application of glyphosate at 861.8 g ae/ha was applied 24 May 2010. Cover crop biomass was harvested on 1 June 2010 inside a 0.09 m2 quadrat and dried at 105 C for a dry weight measurement. Each whole plot was mowed with a 1.5 m rotary mower (John Deere; Moline, IL, USA) prior to either tillage treatment on 1 June. The roto-till treatment was performed with a 1.8 m roto-tiller (Woods; Oregon, IL, USA) while the disk-till treatment was performed with a 2.13 m disk (John Deere; Moline, IL, USA). Potato seed pieces were planted on 2 June with a two-row potato planter (Iron Age Co. (out of business); Glenoch, NJ, USA). A granular fertilizer, 32-10-10 (N, P, K) was banded in-furrow during potato planting at 160 kg N/ha, 50 kg P/ha, and 50 kg K/ha. Six soil samples (0-15 cm) were taken within each plot and composited into one, before planting on 12 May and 14 DAP on 16 June, and analyzed for NO3-N content at the North Dakota State University Soil Testing Laboratory. Weed evaluations were taken on 16 June, 1 July, and 23 July. Potato stand counts were taken on 3 Aug., to evaluate if cover crop influenced seed piece survival. Potato tubers were harvested on 13 Oct. with a single-row potato digger (US Small Farms; Torrington, WY, USA).

Carrington, 2011. The experiment was carried out on a Heimdal loam soil (coarse-loamy, mixed, superactive, frigid Calcic Hapludolls), and the previous crop was barley. The plots received overhead irrigation using a center pivot system. Winter annual cover crops (triticale, rye, and hairy vetch) were planted on 26 Aug. 2010 with a grain drill (Case International Harvester; Racine, WI, USA). Triticale, rye, and hairy vetch were planted at 151.3 kg/ha, 132.4 kg/ha, and 33.6 kg/ha, respectively. In the combined planting, rye was planted at 65.4 kg/ha and hairy vetch was planted at 33.6 kg/ha. A burn-down herbicide application of glyphosate at 861.8 g ae/ha was applied 3 June 2011. Cover crop biomass was harvested on 15 June inside a 0.09 m2 quadrat and dried at 105 C for dry weight measurements. Each whole plot was mowed with a rotary mower (John Deere; Moline, IL, USA) prior to either tillage treatment on 16 June. The roto-till treatment was performed with a 1.8 m roto-tiller (Woods; Oregon, IL, USA) while the disk-till treatment was performed with a 3.05 m disk (John Deere; Moline, IL, USA). Potato pieces were planted on 16 June with a two-row potato planter (Iron Age Co. (out of business); Glenoch, NJ, USA). A granular fertilizer, 32-10-10 (N, P, K) was banded in-furrow during potato planting at 160 kg N/ha, 50 kg P/, and 50 kg K/ha. Six soil samples (0-15 cm) were taken within each plot and composited into one before planting on 2 June and 13 DAP on 29 June, and analyzed for NO3-N content at the North Dakota State University Soil Testing Laboratory. Weed evaluations were taken on 29 June, 12 July, and 28 July. Potato stand counts were taken on 28 July, to evaluate if cover crop influenced seed piece survival. Potato tubers were harvested on 13 Oct. with a single-row potato digger (US Small Farms; Torrington, WY, USA).

Fargo, 2010. The experiment was conducted on Fargo silty clay (fine, montmorillonitic, frigid Vertic Haplaquolls). The field was left fallow during 2009. Winter annual cover crops (triticale, rye, and hairy vetch) were planted on 24 Sept. 2009 with a grain drill (Case International Harvester; Racine, WI, USA). Triticale, rye, and hairy vetch were planted at 151.3 kg/ha, 132.4 kg/ha, and 33.6 kg/ha, respectively. In the combined planting, rye was planted at 65.4 kg/ha and hairy vetch was planted at 33.6 kg/ha. Due to the hairy vetch winter-kill a turnip/radish combination and canola were planted on 20 Apr. 2010. Turnip/radish took the place of the hairy vetch treatment and was planted by manual spreading and subsequent raking seed at 5.6 kg/ha turnip and 5.6 kg/ha radish into the soil. Canola was manually over seeded at 12.4 kg/ha into the rye/hairy vetch treatment to become the rye/canola cover crop treatment. A burn-down herbicide application of glyphosate at 861.8 g ae/ha was applied 14 June. Cover crop biomass was harvested on 23 June 2010 inside a 0.09 m2 quadrat and dried at 105 C for dry weight measurements. All plots, except the roller-crimp treatment plots, were mowed with a 1.5 m rotary mower (John Deere; Moline, IL, USA) prior to the tillage treatment on 24 June. The roller-crimp treatment was performed with a 3.1 m roller-crimper (I & J Manufacturing; Gap, PA, USA) while the disk-till treatment was performed with a 2.1 m disk (John Deere; Moline, IL, USA) on 25 June. Potato seed pieces were planted on 25 June with a two-row potato planter (Iron Age Co. (out of business); Glenoch, NJ, USA). A granular fertilizer, 32-10-10 (N, P, K) was banded in-furrow during potato planting at 160 kg N/ha, 50 kg P/ha, and 50 kg K/ha. Six soil samples (0-15 cm) were taken within each plot and composited into one, before planting on 3 June and 16 DAP on 9 July, and analyzed for NO3-N content at the North Dakota State University Soil Testing Laboratory. Weed evaluations were taken on 12 July, 29 July, and 13 Aug. Potato stand counts were taken on 29 July to evaluate if cover crop influenced seed piece survival. Potato tubers were harvested on 22 Oct. with a single-row potato digger (US Small Farms; Torrington, WY, USA).

Carrington, 2011. The experiment was carried out on a Heimdal loam soil (coarse-loamy, mixed, superactive, frigid Calcic Hapludolls). Previous crop was barley in 2010. Winter annual cover crops (triticale, rye, and hairy vetch) were planted on 27 Aug. 2010, with a grain drill (International Harvester; Racine, WI, USA). Triticale, rye, and hairy vetch were planted at 151.3 kg/ha, 132.4 kg/ha, and 33.6 kg/ha, respectively. In the combined planting, rye was planted at 65.4 kg/ha and hairy vetch was planted at 33.6 kg/ha. A burn-down herbicide application of glyphosate at 861.8 g ae/ha was applied 6 June. Cover crop biomass was harvested on 29 June inside a 0.09 m2 quadrat and dried at 105 C for dry weight measurements. All plots, except the roller-crimp treatment plots, were mowed with a 1.5 m rotary mower (John Deere; Moline, IL, USA) prior to the tillage treatment on 29 June. The roller-crimp treatment was performed with a 3.1 m roller-crimper (I & J Manufacturing; Gap, PA, USA) while the disk-till treatment was performed with a 2.1 m disk (John Deere; Moline, IL, USA). Potato seed pieces were planted on 30 June with a two-row potato planter (Iron Age Co. (out of business); Glenoch, NJ, USA). A granular fertilizer, 32-10-10 (N, P, K) was banded in-furrow during potato planting at 160 kg N/ha, 50 kg P/ha, and 50 kg K/ha. Six soil samples (0-15 cm) were taken within each plot and composited into one, before planting on 2 June and 14 DAP on 12 July, and analyzed for NO3-N content at the North Dakota State University Soil Testing Laboratory. Weed evaluations were taken on 12 July, 28 July, and 16 Aug. Plots were hilled using a two-row cultivator (Harriston Industries; Minto, ND, USA) immediately after the first weed evaluation, but the intended second hilling could not be performed due to wet field conditions and potato row closure. Potato stand counts were taken on 28 July to evaluate if cover crop influenced seed piece survival. Potato tubers were harvested on 18 Oct. and 20 Oct., with a single-row potato digger (US Small Farms; Torrington, WY, USA).

Research results and discussion:

Irrigated Locations
Cover crop biomass. Cover crop treatment had a significant effect on total dry weight biomass accumulation of the cover crop at Oakes in 2010. Cover crop biomass accumulation was greater for rye/canola and triticale compared to no cover crop or the turnip/radish cover crop (Table 1). Biomass for the no cover crop treatment was from a combination of weed species. The rye and triticale treatments accumulated far less than reported in the Eastern U.S., but above the level reported to suppress weeds in greenhouse studies (Mohler and Teasdale, 1993). Cover crops were terminated prior to anthesis of the cereal crops due to foreseen irrigation needs by other crops under the linear system (earliest termination date out of all four locations within both experiments of this research). De Bruin et al. (2005) found significant rye regrowth when mowed at growth stages before anthesis. Rye and triticale terminated 1 June did not exhibit regrowth in treatments where mowing was followed by a termination treatment of roto-till or disk-till.

Cover crop and termination method affected average weed control 14 and 29 DAP. At 14 DAP, roto-till and herbicide termination methods had greater weed control than disk-till across all cover crop treatments besides rye/canola (Table 2). Herbicide termination when no cover crop was planted had 10% greater weed control than disk-till termination. Similarly, roto-till and herbicide termination treatments had 10% greater weed control in turnip/radish cover crop than disk-till termination. Cover crop treatments of rye and rye/canola had greater than or equal to 93% weed control across all termination methods. At 29 DAP, no termination method had greatest weed control across all cover crop treatments. Both disk-till and roto-till termination treatments had greater weed control than herbicide termination on a rye cover crop. Herbicide termination when no cover crop was present had 13% greater weed control than disk-tilling no cover crop. The importance of weed control early in the season has been demonstrated previously, with only 16% potato yield loss when weeds were controlled up until three weeks after potato emergence compared to 45-65% yield loss when weeds were not controlled (Nelson and Thoreson, 1981). At both 14 and 29 DAP the cover crops of triticale, rye, and rye/canola across all termination methods demonstrated early season weed control with 85% or greater weed control, compared to slightly lower weed control in turnip/radish and no cover crop plots with certain termination treatments. Moore et al. (1994) reported significantly lower redroot pigweed control when glyphosate terminated a triticale cover crop in no-till soybean compared to a glyphosate terminated rye cover crop. The authors did not mention an explanation for this particular finding, though rye allelopathic effects on redroot pigweed were discussed throughout the article. Moore et al. (1994) results were somewhat contrary to those at Oakes as herbicide terminated rye and triticale cover crops had similar weed control at 14 DAP. The reverse effect was seen at 29 DAP with triticale terminated by an herbicide having 4% greater weed control than herbicide terminated rye. However, average weed control with no cover crop at Oakes was relatively high at 86% 14 DAP, and the additional cultivation further improved the weed control.

Cover crop and termination method had a significant effect on average weed control 13, 26, and 42 DAP. At 13 DAP all treatment combinations had 95% or greater average weed control (Table 3). At 26 DAP all treatment combinations had 94% or greater average weed control. No termination method had consistently high weed control across all cover crop treatments. At 42 DAP no treatment combination was lower than 90% weed control. The presence of a cover crop did not affect weed control above no cover crop. Weed control decreased slightly at 42 DAP, but potato row closure occurs shortly after this evaluation and provides weed control for the remainder of the growing season.

Total tuber yield paralleled marketable yield, thus discussion will focus on marketable yield. There were no significant interactions or main effects for marketable yield. Yields exceeded 21 Mg/ha for all cover crop and termination method combinations except when a rye cover crop was killed with the glyphosate application (Table 4).

Total tuber yield paralleled marketable yield, thus discussion will focus on marketable yield. There were no significant interactions between cover crop and termination method on potato marketable yield. Cover crop had no effect on marketable potato yield. Yields were greater than 19 Mg/ha for all cover crop treatments (Table 5).

Non-Irrigated Locations
Cover crop treatment had a significant effect on total dry weight biomass accumulation at Carrington in 2011. Cover crop biomass accumulation was greater for triticale, rye, and rye/hairy vetch than no cover crop (Table 6). Biomass for the no cover crop treatment was a combination of weed species. Rye/hairy vetch averaged 7,603 kg/ha dry weight while hairy vetch alone averaged 4,539 kg/ha, exemplifying the standards for these two cover crops alone and in combination. Cover crop accumulation was high in part due to a key factor recognized by Teasdale (1998); that winter annual cover crops take advantage of the cold winter and long wet spring. Cover crops in this study were allowed to grow until 29 June (latest termination date out of all four locations in both experiments). Cover crops terminated 29 June did not exhibit regrowth in treatments when mowing was followed by a termination treatment of disk-till.

Cover crop and termination method were considered treatments and compared to the check, which consisted of no cover crop, and no termination method, and thus was considered a no-till conventional treatment at Fargo, ND. Treatment had a significant effect on weed control averaged over all three weed evaluations. The check treatment had the lowest average weed control with 24% (Table 7). Roller-crimp terminated turnip/radish had the next lowest weed control with 35%. Roller-crimping a turnip/radish cover crop was problematic due to the inability to terminate turnip plants effectively, as well as limited biomass production to create a mat of residue to shade the soil. The check treatment had 22% lower average weed control than the herbicide terminated no cover crop treatment, which presented nearly identical no-till conditions, except that glyphosate was applied 12 days before planting. Weed control was greater than 60% in all triticale and rye cover crop plots under all treatment combinations, but never reached the industry standard of 85% weed control.

Cover crop and termination method had a significant effect on average weed control 12, 28, and 47 DAP. All combinations of cover crop and termination method had 91% or greater weed control 12 DAP (Table 8). Herbicide termination consistently had average weed control above 98% across all cover crop treatments. Roller-crimped hairy vetch cover crop had lower weed control than disk-till and herbicide termination methods for hairy vetch. When no cover crop was planted, weed control was identical to most treatment combinations with a cover crop, evidence that cover crop residue did not improve weed control over the no cover crop treatment at 12 DAP. Herbicide termination consistently had average weed control at or above 94% across all cover crop treatments 28 DAP. Roller-crimped hairy vetch and rye/hairy vetch cover crops had significantly lower weed control than disk-till or herbicide termination treatments for the cover crops. Similar weed control was found when no cover crop was planted to all cover crop treatments with disk-till and herbicide termination methods. At 47 DAP roller-crimp termination had the lowest weed control among the three termination methods across all cover crops at around 80%. Results suggest that roller-crimping is not a viable cover crop termination method for weed control in non-irrigated potato production.

Cover crop treatment significantly affected marketable yields at Fargo, ND. Triticale plots had greater marketable yields than plots with rye, rye/canola, or no cover crop (Table 9). When rye was included in the cover crop treatment, marketable yields were lower than any cover crop treatment. This negative potato response to a rye cover crop may have resulted from the allelochemical properties of rye and does not appear to be a response to cover crop biomass as triticale, rye, and rye/canola had similarly high biomass exceeding 10,000 kg/ha. Rye and triticale had greater weed control at 17 and 34 DAP, which Nelson and Thoreson (1981) reported would lead to higher yields. The marketable yield for triticale reinforced conclusions from Nelson and Thoreson (1981), as it had significantly higher average yields than any other cover crop treatment with 6.7 Mg/ha. In contrast, rye cover crop plots had the lowest marketable yields despite high weed control at the first two evaluation timings.

Cover crop had a significant effect on marketable yield at Carrington, ND. The no cover crop treatment had greater marketable yield than any other cover crop treatment (Table 10). Results suggest there is a negative yield response from cover crops due to the difficulty in forming adequate hills with high biomass accumulating cover crops terminated by roller-crimping, herbicide, or disk-tilling.

Participation Summary

Project Outcomes

Project outcomes:

The comprehensive results from two years and four sites worth of investigation into potato production in cover crops have provided results that could make a difference for a specific type of potato producer, specifically those that farm small acreage or niche potato markets. Overall, cover crops did not have a negative effect on potato yield besides one location. Knowing that yield is likely unaffected by the presence of a cover crop, producers are free to find a cover crop that fits the other needs of their operation such as water use efficiency, erosion control, nutrient retention, and other specific abilities of certain cover crops. Weed control was often improved with the presence of a cover crop, though this would be highly variable for a small producer who may cultivate more than twice a season, as was the case in this research.

Recommendations:

Areas needing additional study

The effect of cover crops on potato yield warrants further investigation. We found varying results, which could be clarified with further statistical power through additional site-years. Cover crops did not detract from potato yields in all but one of the site-years. Additionally, research into the machinery aspect of cover crops and potatoes would pay dividends for farmers looking at the system. Specialized machinery which currently exists but was not used in this research could improve the results and overall success of the system.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.