1:45:00 PM- 2:00:00 PM             Regenerative Potato Production: Fry in the Sky or Grounded in Reality?

Cameron Ogilvie, Soil Health Institute

               Potato production is a significant contributor to the North American food economy. At the same time, potato production is highly vulnerable to soil degradation and other negative environmental impacts that threaten industry sustainability. This has led some processing companies to adopt goals for “regenerative agriculture” in their supply chains, prompting some to question whether regenerative potato production is even possible. Through roundtable discussions with over 150 potato growers across North America, growers identified erosion, compaction, reduced water infiltration/holding capacity, nutrient leaching, and disease as common soil health challenges in their production systems. These grower-identified challenges provide a solid starting place for investigating the potential for potato production to be regenerative. This presentation explores existing research demonstrating how growers can address these challenges and enhance soil health while improving productivity and environmental outcomes in potato production. The practices explored thereby constitute a suite of practices for potato production that can be considered regenerative. As agroecosystems are complex and dynamic systems, these practices call for curiosity, adaptation, and innovation to ensure on-farm success. Many innovative growers are already doing this work, which presents promising avenues for future research and partnership to further enhance the vitality and productivity of the industry.

2:00:00 PM-2:15:00 PM              Impact of Wildfire Smoke on Potatoes

Michael Thornton, University of Idaho 

               Potato growers and processors throughout the Pacific Northwest have observed that extensive periods of smoke exposure from summer wildfires can have negative effects on potato crops. Replicated field studies were conducted during 2022 and 2023 to document the impact of smoke exposure on yield, grade and storability of three russet potato varieties (Russet Burbank, Clearwater Russet, Alturas). Potato plants were treated from July 10 to August 18 each year in clear plastic-covered hoop house enclosures between 6:00 and 9:00am MST, before rising temperatures within the enclosures would cause heat stress. The fuel used to generate smoke consisted of a mixture of the hard and soft wood tree species. Tubers were harvested in mid-September, graded, and samples placed into storage at 9oC for 6 months. Potato plants exposed to smoke did not exhibit any visual symptoms and did not senescence earlier than plants not exposed to smoke. Smoke exposure caused a decline in production of US No 1 yield and tubers greater than 170g, both of which were reduced in the range of 2-3% (p=0.09). Smoke exposure also tended to slightly increase the proportion of misshapen tubers (p=0.08).  This effect was more apparent during the 2022 trial when daytime high temperatures were often above the level considered optimum for potato growth, and less apparent in the more moderate conditions experienced during 2023.  Smoke treatments had no impact on either weight loss or decay after six months of storage. The three potato varieties tended to exhibit different responses to smoke exposure in terms of proportion of US No 1 tubers (p = 0.09). Alturas and Russet Burbank produced a lower percentage of US No 1 tubers in response to smoke exposure in both 2022 and 2023. In contrast, Clearwater Russet showed a reduction in US No 1’s after smoke exposure in 2022 but had the opposite response in 2023.  It is unclear whether or not variety selection could be used as a tool to reduce the risk of losses due to wildfire smoke exposure.

2:15:00 PM-2:30:00 PM                            Physiological and Generative Response of Potato (Solanum tuberosum L.) to Heat Stress

Olufunke Ogundiya, Washington State University, Pullman     

               "Erratic heat events, including heat domes, pose a significant threat to potato production. Potato cultivars show varying susceptibility to heat stress during critical growth stages, which impact yield and postharvest quality. While existing research explores the physiological responses of potatoes to heat stress, limited research exists on direct in-season effects and generative responses.    To clarify these gaps, cvs. Russet Burbank and Clearwater Russet were planted at three intervals (early March, late March, and late April) in 2023 at the WSU Research and Extension Center in Othello, WA. Soil and air temperatures were monitored throughout the growing season. Plant phenotypic data (emergence, stem number, % senescence) and yield (total & marketable) were collected. Post-harvest quality parameters (respiration, fry color, & dormancy) were assessed during storage.   Late April plantings showed the fastest emergence (ca. 25 days) compared to early March (ca. 66 days). Late April planting for Russet Burbank and both early March and late April planting for Clearwater Russet had the highest average number of stems (2.7, 2.3, and 2.3, respectively). The total yield for Russet Burbank was the highest in mid-April (107.7 tonnes/hectare), while late April was the highest for Clearwater Russet (139.9 tonnes/hectare). At harvest fry color was the lightest for Clearwater Russet (late April planting) with a photovolt reflectance of 47.6 indicating lower total reducing sugars for improved storage quality. The experiment is a 2-year study and will benefit regional potato growers by providing valuable insights into managing heat stress for optimized yields and postharvest quality. "

2:30:00 PM-2:45:00 PM          Practical Ways to Reduce Nitrate Leaching to Groundwater in Potato Production
Jed Colquhoun University of Wisconsin-Madison

               Deep, sandy soils are conducive to irrigated potato production and high-quality tuber development, but are also prone to leaching, particularly as the frequency of high precipitation events increases.  In Wisconsin 40% of wells sampled in 2020 in the primary potato production region exceeded the 10 ppm nitrate drinking water standard, an increase from 30% in 2015.  In response, interseeded scavenger crops and soil organic amendments were studied as ways to capture nitrogen not used by the potato crop before it reaches the shallow groundwater below the root zone.  Field studies were conducted in 2022 and 2023 to investigate the agronomic feasibility of growing winter rye (fall- or spring-seeded) or yellow mustard in strips between every third potato row.  The interseeded strip crops grew well among potato, and no differences in marketable tuber yield, size distribution or harvestability were noted in either year.  In subsequent field research, winter rye and yellow mustard were seeded in the furrow between every potato row.  Three interseeding timings (at hilling, 3 weeks after hilling, and 5 weeks after hilling) were investigated with nitrogen fertilizer either banded directly over the potato row (thus reducing nitrogen use by 66%) or broadcast applied.  No differences in tuber yield were noted among interseeding treatments or nitrogen fertilizer method.  Cover crops interseeded after hilling survived until potato desiccation, but those seeded 3 or 5 weeks after hilling were outcompeted by the potato crop and senesced by late July.  In preliminary soil column studies, biochar and lignocellulose paper mill waste were investigated as a way to temporarily immobilize nitrogen below the potato root zone, as could be accomplished when injected with commercial fumigation equipment.  Papermill waste reduced nitrate in leachate water by up to 34% and was consistent among experimental runs.

2:45:00 PM-3:00:00 PM         Evaluating Climate-Smart Practices for Pacific Northwest Potato Production Using COMET Tools

Katherine East, Soil Health Institute

               Greenhouse gas (GHG) emissions models are increasingly used for GHG estimation and reporting and are a major component of the Partnerships for Climate-Smart Commodities (CSC), including in the Potatoes from the Pacific Northwest CSC project. To gain better understanding of which Climate-Smart (CS) practices are most influential for reducing emissions in PNW potato production, a number of management scenarios were constructed and assessed using COMET-Farm and COMET-Planner, two platforms for estimating GHG emissions change. The goal was to create practice recommendations for meeting current emissions goals and understand implications of scale from selection of COMET-Farm versus COMET-Planner. Management scenarios were based on three-year rotations and input for five 120-acre pivots covering three soil groups and two growing regions, the Columbia Basin and Snake River Valley. Rotations included alfalfa, field corn, and a pea/sweet corn and carrot rotation with potato. Scenario management data from relevant enterprise budgets were used to estimate practices and timing. To some of these rotations, CS practices were added: integrating compost, adding cover crops, and reducing tillage in non-potato years of a rotation. Multiple CS practices were stacked to see if there were enhanced effects from two or more practices. Nitrogen (N) management drove the majority of GHG emissions in the scenarios. Rotations with less soil disturbance and N application, like alfalfa, had lower emissions than high-disturbance rotations like pea/sweet corn and carrot. Individual CS practices varied in their effectiveness for GHG reduction, but stacking multiple practices had the greatest reduction in GHG emissions. All CS practices increased soil carbon and available water holding capacity, though compost had the greatest effect of the practices examined. Results from COMET-Planner are not as specific as COMET-Farm and the range in GHG emission reductions from COMET-Planner often straddle 0 in PNW potato regions.

3:00:00 PM-3:15:00 PM             Implications associated with potato shipment rejections due to physical impact-related quality concerns: A case study
Rabecka Hendricks, University of Idaho

               Incorrect handling throughout post-harvest operations can lead to reduced potato tuber quality. When a potato supplier receives a rejection or downgrade notice from inspections at the shipping destination, it is important to understand what defects resulted in the notice and if changes can be made to lessen the problem in the future. The University of Idaho, in collaboration with a major retailer, compiled rejection and downgrade notices from Idaho potato shipments to the retailer’s US distribution centers during the 2018 and 2019 crop years (August to following July) to use as a case study. This unique dataset provided a comprehensive overview of the quality-related issues that caused shipment rejections. The case study dataset consisted of 706 notices over the two crop years. Approximately 72% of the rejection notices compiled were associated with shipments of russet cultivars and the other 28% was a compilation of red, yellows or specialty cultivars (15%) and organic potatoes (13%). The top rejection categories were sunken discolored (18%), shatter bruise (15%), wet rot (16%), dry rot (11%), and blackspot bruise (11%). Physical impact-related quality concerns were estimated to be 73% of all the rejections reasons. There was a 26% reduction in volume (3.1% in 2018 vs 2.3% in 2019) of rejections from 2018 to 2019, which could be partially contributed to directed bruise mitigation education and research that was initiated as part of this project. Reducing rejections by 25% per year was estimated to prevent approximately $6.2 million dollars in revenue losses to suppliers during these years. Using better bruise detection programs, investing in new handling equipment, updating handling procedures, and identifying cultivars more resistant to bruise-related defects are ways the potato industry could prevent such losses.