Progress 09/01/20 to 08/31/24
Outputs
Target Audience:The target audience for this project included organic farmers, researchers, educators, and students. Organic farmers and vegetable growers were engaged through: 1 poster presentation at the Great Plains Grower's Conference in Missouri (200 participants) 1 translated webinar for refugee farmers at Community Crops in Nebraska (8 participants) 2 workshop presentations at the Nebraska Local Food and Healthy Farms Conference (60 participants) 1 field day tour at the University of Nebraska Research Farm (65 participants) Organic researchers, educators, and students were engaged through: 2 invited research seminars - one at Purdue University in Indiana (30 participants) and one at Korea University in South Korea (20 participants) 3 oral presentations and 1 poster presentation at the American Society for Horticultural Sciences annual conferences (85 participants) 1 webinar for Nebraska Natural Resources Conservation Service educators (100 participants) 1 interview with Mulch Matters podcast 1 newsletter article for sustainable mulch educators and researchers 2 peer-reviewed research publications Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?One Ph.D. graduate student (Caleb Wehrbein) continued training and objectives 1-4 will form the basis of his dissertation. A total of 8undergraduate students have been trained in field research methods because of this project and were mentored by the Ph.D. student. How have the results been disseminated to communities of interest?Initial research results were shared with Yazidi refugee farmers from Northern Iraq in beginning farmer programs at the local non-profit organization Community Crops. We developed a 90-minute recorded presentation about organic weed management options in small-scale vegetable production, which was translated into Arabic for the farmers. We workedwith these farmers to test different mulch options on their farms in their pepper and eggplant crops, including biobased organic mulches compared to landscape fabrics and hand weeding. Results were also shared in July 2023 with gardeners at Frogtown Farm in Minneapolis, MN and farmers in the Kilimo Minnesota Organic Incubator Farm. Eight individual gardeners and farmers learned about the biobased fabric mulch production system and tested acommercially available biobased mulch product in organic arugula, carrots, jute, radish, turnip, sweet corn, and cantaloupe. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Objective 1. Year 1 carrots and spinach. Carrot was direct seeded onto PLA mulches and top-dressed with a layer of compost to facilitate carrot germination and rooting through the semi-permeable mulch surface. PLA mulch reduced total weed emergence by 90% relative to bare soil. Yields were not significantly different among mulch types and bare soil controls, in part because weeds were removed weekly after counting. PLA mulch reduced plant available soil nitrate (NO3) by 47% relative to bare soil controls. After a failed spinach crop in year 1, we replaced spinach in our trials with spring mix lettuce. Years 2 and 3 carrots. Six mulch variants with different levels of thickness and fertilizer weight/types were tested in combination with mixed or yard waste compost in addition to three no mulch treatments. Carrot was seeded on top of PLA mulches without planting holes and top-dressed with 0.5-in of compost to aid germination and establishment through the mulch. All PLA mulches reduced broadleaf and grass weed emergence by >89% compared to bare ground, and fertilizer-enriched PLA mulches were not different from PLA-only mulches. There was no difference in plant available soil N among mulch types and no mulch controls, which suggests PLA did not immobilize N but also that the fertilizer-enriched mulch did not increase plant available N. PLA-only mulches reduced carrot yield by 26% compared to no mulch compost groups in 2022. Although PLA-only had improved carrot yield by 30% relative to no mulch compost groups and fertilizer-enriched PLA mulches in 2023, yield reductions in fertilizer enriched-PLA was more related to ammonium phytotoxicity in the mixed compost reducing carrot germination. Years 2 and 3 lettuce. Six PLA mulch composites composed of different organic fertilizer types and densities and two compost sources were evaluated against three no mulch treatments. Baby leaf lettuce was planted onto PLA mulch surfaces (or planted into no mulch treatments using seed furrows) in late summer of 2022 and 2023. Compost top-dressings were applied to a 0.5-in thickness in 2022 and to a 0.25-in thickness in 2023. Broadleaf and grass weed emergence was 97% and 89% respectively in PLA mulches relative to no mulch no compost. Soil nitrate was reduced in all treatments at 14-28 days after planting (DAP) compared to 0-14 DAP without differences among fertilizer-enriched PLA mulches, non-enriched PLA mulches, and no mulch groups. Lettuce stand densities were highly variable across treatments in both years as a consequence of supra optimal temperatures for lettuce germination as well as elevated soluble salt concentrations in compost substrates. Positive correlation between stand densities and yields in 2022 indicate that higher yields are achieved with higher establishment. Our data support that lettuce can root through and establish in a PLA mulch when planted in a compost substrate, and the yield of lettuce established in PLA mulch is similar to no mulch control groups given that germination is not inhibited. Objective 2. Microbial quality was assessed before planting and at harvest, with a focus on food safety indicators. All samples (mulch, compost, soil pre-plant and at harvest, vegetables at harvest) were tested for Shiga toxigenic Escherichia coli O157:H7 (STEC O157) and Salmonella. In 2021 STEC was enumerated, and enrichments were performed for detection of targets present at low numbers. In 2022 and 2023, only the enrichment cultures were run. Similarly, there was a methods modification for Salmonella. In 2021 culture-based methods were used to detect and isolate Salmonella, while in 2022 and 2023 a hybrid culture + gene-based PCR method was used. Three fecal indicators were enumerated for all samples. Generic E. coli and Total Coliforms were assayed for all three years, and Enterococcus was assayed for 2021 and 2022. In 2023, the Enterococcus assay was dropped to allow deeper sampling of other parameters. A suite of antibiotic resistance genes was assayed for all samples using PCR and quantitative PCR, and in 2021 selected samples were examined for the presence of nine genes associated with nitrogen cycling. Results included: All samples in all years were negative for STEC O157. Salmonella was only detected in two samples across the three years of the study. Both occurred in 2022, one in a soil before planting, and one on a carrot at harvest. Generic E. coli was occasionally detected, most often in soils and compost, particularly in the compost feedstock that included animal manures. Total coliforms and enterococcus were common in most, sometimes all, soils and compost, and some vegetables. Low numbers were detected on the mulch in 2021, but not in 2022 or 2023. Possibly due to external contamination during initial handling. The occurrence of antibiotic resistance genes was higher in the compost compared to the soil, and absent completely from the mulch samples. There was a slight trend for ARGs to be more frequently detected in samples associated with the manure-based compost. Objective 3. Time spent hand weeding was recorded in each plot, and combined with yield data, was used to determine the hand-weeding-replacement cost for a biobased weed barrier for high density, narrowly spaced crops. Hand weeding plots in this study required an average of 4 minutes/linear bed ft (1/15 hr) A $15/hr wage x 1/15 hr = $1/linear bed ft Total cost to implement biobased mulch system = $0.42/linear bed tt Based on material costs of the most cost-efficient biobased mulches used in this study, the approximate wholesale cost for the mulch = $0.35/linear bed ft Compost topdressing used = $0.06/linear bed ft Custom application of compost and mulch = $0.01/linear bed ft In this study, the biobased mulch system was 42% of the total cost of hand weeding and mulch will remain more cost effective than hand weeding if growers are paying for hand weeding for more than 1.7 minutes per linear bed ft. Objective 4. We developed and delivered a 1-credit independent study titled "Organic Weed Management for Small Farms and Gardens" to 7 graduate students at the University of Nebraska - Lincoln in spring semesters of 2023 and 2024. Students in the course explore and synthesize current scientific literature on ecological weed management, organic weed management philosophies, stale seed bedding, tarping, biobased herbicides, mulches, cover crops, tillage, flaming, and robotics, and then create an organic weed management plan for a farm. Objective 5. Disseminate project results to current and future organic farmers and researchers. Project results were disseminated to current and future organic farmers, researchers and educators through a variety of methods most appropriate for each group. Organic farmers and vegetable growers were engaged through: 1 poster presentation at the Great Plains Grower's Conference in Missouri (200 participants) 1 translated webinar for refugee farmers at Community Crops in Nebraska (8 participants) 2 workshop presentations at the Nebraska Local Food and Healthy Farms Conference (60 participants) 1 field day tour at the University of Nebraska Research Farm (65 participants) Organic researchers, educators, and students were engaged through: 2 invited research seminars - one at Purdue University in Indiana (30 participants) and one at Korea University in South Korea (20 participants) 3 oral presentations and 1 poster presentation at the American Society for Horticultural Sciences annual conferences (85 participants) 1 webinar for Nebraska Natural Resources Conservation Service educators (100 participants) 1 interview with Mulch Matters podcast 1 newsletter article for sustainable mulch educators and researchers 2 peer-reviewed research publications
Publications
- Type:
Peer Reviewed Journal Articles
Status:
Published
Year Published:
2024
Citation:
Wehrbein, C., I. Kadoma, and S.E. Wortman. 2024. First field evaluation of a polylactic acid-based weed barrier with compost for carrot production. HortTechnology 34(2):204-210. https://doi.org/10.21273/HORTTECH05370-23
- Type:
Peer Reviewed Journal Articles
Status:
Published
Year Published:
2024
Citation:
Shcherbatyuk, N., S.E. Wortman, D. McFadden, S. Weyers, W. Ahmad, D. Bajwa, S.P. Galinato, A. Formiga, G. Gramig, and L.W. DeVetter. 2024. Alternative and emerging mulch technologies for organic and sustainable agriculture in the United States: A review. HortScience 59(10):1524-1533.
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Progress 09/01/22 to 08/31/23
Outputs
Target Audience:Project results from 2021 and 2022 were shared with organic farmers, researchers, and educators through a presentation at the Local Food and Healthy Farms Conference in Aurora, NE (40 growers and 4 educators), a poster at the American Society for Horticultural Science annual conference (20 participants and archived online), and an invited seminar at Purdue University Department of Horticulture and Landscape Architecture (30 researchers and educators). Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?One Ph.D. graduate student (Caleb Wehrbein) continued training and objectives 1-4 will form the basis of his dissertation. A total of 6 undergraduate students have been trained in field research methods because of this project and were mentored by the Ph.D. student. How have the results been disseminated to communities of interest?Results were shared in July 2023 with gardeners at Frogtown Farm in Minneapolis, MN and farmers in the Kilimo Minnesota Organic Incubator Farm. Eight individual gardeners and farmers learned about the biobased fabric mulch production system and tested the first commercial product in organic arugula, carrots, jute, radish, turnip, sweet corn, and cantaloupe. What do you plan to do during the next reporting period to accomplish the goals?Objective 1. We will analyze data from the 2023 field trials and begin preparation of publications in peer-reviewed journals. Objective 2. We will finalize lab work to detect and quantify potential foodborne pathogens from 2023 soil, compost, and biomulch samples. Objective 3. We will complete analysis of partial budgets using empirical data from field trials along with cost estimates from biomulch manufacturers. Objective 4. The new course, "Organic Weed Management for Small Farms and Gardens" will be offered for the second time and we will finish development of the course for non-academic credit to stakeholders at Community Crops and beyond. Objective 5. Project results from 2023 will be presented to organic farmers at the Local Food Healthy Farms Conference in Columbus, NE and to organic researchers and educators at the American Society for Horticultural Science annual conference in Hawaii. We will prepare publication of project results in peer-reviewed journals.
Impacts
What was accomplished under these goals?
This project is framed by three research objectives, one education objective, and one extension objective: Objective 1.Quantify the effects of biomulch properties and compost top-dressings on agronomic performance in organic spinach and carrot production systems, including weed suppression, nitrogen dynamics, soil temperature and moisture, disease incidence, and crop yield. Objective 2.Determine the effect of biomulch and compost top-dressings on foodborne pathogens and fecal indicators in organic spinach and carrots. Objective 3.Perform a partial budget analysis to identify potential labor and cost savings of the proposed biomulch system for organic spinach and carrots. Objective 4.Develop curriculum and teach a new online course for academic and professional audiences titled, "Organic Weed Management Innovations for Specialty Crops." Objective 5.Disseminate project results to current and future organic farmers and researchers. Objective 1. Field experiments were conducted in summer 2023 in Lincoln, NE in organic carrot and lettuce crops. Treatments included six different biobased mulch fabrics varying in thickness and nutrient composition [polylactic acid (PLA) @ 120 g/m2, PLA @ 180 g/m2, PLA @ 120 g/m2 + 30 g/m2 turkey litter fertilizer, PLA @ 120 g/m2 + 90 g/m2 turkey litter fertilizer, PLA @ 120 g/m2 + 30 g/m2 soybean meal fertilizer, PLA @ 120 g/m2 + 90 g/m2 soybean meal fertilizer] and a no mulch control, and two different compost media for seedling establishment (yard waste feedstock and animal manure feedstock). Data was collected for weed density, soil nitrogen availability, soil and surface temperature, soil moisture, and crop establishment and yield. Results for 2023 are being analyzed but results for carrot and lettuce in 2022 have been analyzed and are summarized below. In 2022, PLA mulch treatments (regardless of weight basis or fertilizer treatment) reduced emerging grass/broadleaf weeds by 86% and 92%, respectively, compared to no mulch controls in both crops. Reductions in time spent hand weeding were proportional to weed density. In addition to the weed suppressive benefits of the biofabric mulch, it appears compost alone has some weed suppressive potential. Compost presence reduced density of grass/broadleaf weeds by 66% and 51%, respectively, compared to no mulch, no compost control in lettuce. In contrast to our expectations, fertilizer-enriched biofabric mulch had no effect on soil nitrate availability relative to controls or PLA-only mulch. Carrot yield was not affected by mulch treatments, whereas lettuce yield was reduced 23 to 56% in PLA-120 and PLA-180 treatments compared to controls and fertilizer-enriched mulch. Yield reduction in PLA-only mulch, but not PLA mulches enriched with fertilizer, suggests the fertilizers may have helped counteract potential N immobilization from the carbon-rich mulch (despite a lack of measured differences in potential N update via PRS probes). The lack of yield differences between hand-weeded controls and mulch treatments in carrots and most lettuce treatments suggest the mulches were effective in eliminating weed-induced yield loss. Objective 2. We collected soil, compost, and biofabric samples at planting, and plant samples at harvest in all carrot and lettuce plots. These samples were frozen for PCR analysis of potential foodborne pathogens this winter. Analysis of 2022 results suggest that none of the biofabric mulches or compost are a source of foodborne pathogens nor are they contributing to enrichment of foodborne pathogens in the soil or on the harvested plant material. Objective 3. Data was collected for time spent hand-weeding each plot throughout the growing season along with time spent applying mulch and compost treatments relative to planting operations in the control plots. Manufacturing and retail costs of a commercial biofabric mulch have been collected. Along with crop yields, these labor and supply costs will serve as the major variables in the partial budget analysis. Objective 4. Developed and delivered a 1-credit independent study titled "Organic Weed Management for Small Farms and Gardens" to 5 graduate students at the University of Nebraska - Lincoln in spring semester 2023. Objective 5. Project results from 2021 and 2022 were shared with organic farmers, researchers, and educators through a presentation at the Local Food and Healthy Farms Conference in Aurora, NE (40 growers and 4 educators), a poster at the American Society for Horticultural Science annual conference (20 participants and archived online), and an invited seminar at Purdue University Department of Horticulture and Landscape Architecture (30 researchers and educators).
Publications
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Progress 09/01/21 to 08/31/22
Outputs
Target Audience:We presented results from project year one in a poster at the Great Plains Growers Conference in St. Joseph, MO, titled, "RootThru Biofabric: Integrated nutrient and weed management for leafy greens, carrots, and strawberries." There were over 200 specialty crop growers, researchers, and educators in attendance at the two-day conference, many of whom are certified organic. Results were also shared with 25 specialty crop researchers and educators through an oral presentation at the American Society for Horticultural Science annual conference in Chicago, IL, titled, "Developing a biobased mulch system for carrot production: Effects on weed suppression, soil fertility, and yield." We also collaborated with Community Crops, a non-profit organization in Lincoln, NE, to provide organic weed management education to eight Yazidi farmers (an ethnic minority group from Northern Iraq). Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?One Ph.D. graduate student (Caleb Wehrbein) continued training and objectives 1-4 will form the basis of his dissertation. Three undergraduate students were trained in field research methods as a result of this project, and were mentored by the Ph.D. student. How have the results been disseminated to communities of interest?Initial research results were shared with Yazidi refugee farmers from Northern Iraq in beginning farmer programs at the local non-profit organization Community Crops. We developed a 90-minute recorded presentation about organic weed managment options in small-scale vegetable production, which was translated into Arabic for the farmers. We are also working with these farmers to test different mulch options on their farms in their pepper and eggplant crops, including biobased organic mulches compared to landscape fabrics and hand weeding. What do you plan to do during the next reporting period to accomplish the goals?Objective 1. We will conduct a third year of field trials in organic carrot and lettuce identical to the treatment structure in year two. Objective 2. We will continue lab work to detect and quantify potential foodborne pathogens in this production system. Objective 3. We will begin analysis of partial budgets using empirical data from field trials along with cost estimates from manufacturers. Objective 4. The course will be offered for the first time as an experimental independent study, and development will continue to offer the class for non-academic credit to stakeholders at Community Crops and beyond. Objective 5. Project results from years one and two will be presented to organic farmers at the Nebraska Specialty Growers Conference in 2023.
Impacts
What was accomplished under these goals?
This project is framed by three research objectives, one education objective, and one extension objective: Objective 1.Quantify the effects of biomulch properties and compost top-dressings on agronomic performance in organic spinach and carrot production systems, including weed suppression, nitrogen dynamics, soil temperature and moisture, disease incidence, and crop yield. Objective 2.Determine the effect of biomulch and compost top-dressings on foodborne pathogens and fecal indicators in organic spinach and carrots. Objective 3.Perform a partial budget analysis to identify potential labor and cost savings of the proposed biomulch system for organic spinach and carrots. Objective 4.Develop curriculum and teach a new online course for academic and professional audiences titled, "Organic Weed Management Innovations for Specialty Crops." Objective 5.Disseminate project results to current and future organic farmers and researchers. Objective 1. Field experiments were conducted in summer 2022 in Lincoln, NE in organic carrot and lettuce crops. Treatments included six different biobased mulch fabrics varying in thickness and nutrient composition [polylactic acid (PLA) @ 120 g/m2, PLA @ 180g/m2, PLA @ 120g/m2+ 30g/m2turkey litter fertilizer, PLA @ 120g/m2+ 90g/m2turkey litter fertilizer,PLA @ 120g/m2+ 30g/m2soybean meal fertilizer, PLA @ 120g/m2+ 90g/m2soybean meal fertilizer] and a no mulch control, and two different compost media for seedling establishment (yard waste feedstock and animal manure feedstock).Data was collected for weed density, soil nitrogen availability, soil and surface temperature, soil moisture, and crop establishment and yield.In contrast to year one results, carrot establishment was limited by water erosion of compost media off of the bed tops in mulched plots, and the effect worsened with increasing thickness of the PLA. Established carrot populations were reduced by 45% in PLA-120 mulch and 58% in PLA-180 mulch compared to the bare soil + compost controls. The PLA-120 mulch was used in year one, and no reductions in stand establishment were measured, but we experienced more intense rainfall events during crop establishment in year two. A new planting method is being developed to remediate this issue in project year threewhere small furrows will be created lengthwise on bed tops to prevent erosion off the sides of beds and also create a deeper media profile for establishment of roots.Plots with biofabric, regardless of type, increased volumetric surface moisture in the top 15 cm of soil by 48% compared to the bare soil control. Biofabric reduced total weed emergence one month after planting by 86% to 98% depending on mulch type. PLA-120 and PLA-180 were most effective against weeds, and the presence of fertilizers in the fabric seemed to reduce weed suppression slightly. Similarly, biofabrics reduced hand weeding labor requirements and cost by 92% to 98%. Lettuce were planted in July of year two using the same experimental design as for carrot, and harvested two times in August and September. Data will be analyzed and reported during the next reporting period. Objective 2. We collected soil, compost, and biofabric samples at planting, and plant samples at harvest in allcarrot and lettuce plots. These samples were frozen for PCR analysis of potential foodborne pathogens this winter. Analysis of year one results suggest that none of the biofabric mulches or compost are a source of foodborne pathogens nor are theycontributing to enrichment of foodborne pathogens in the soil or on the harvested plant material. Objective3. Data was collected for time spent hand-weeding each plot throughout the growing season, and manufacturers were contacted to determine a range of possible biofabric production, wholesale, and retail costs. Along with crop yields, theselabor and supply costs will serve as the major variables in the partial budget analysis Objective 4. Developed 1-credit independent study titled "Weed Management in Organic Specialty Crops" that will be offered in January 2023. Course structure, activities, and bibliography of course readings were developed. Objective 5. Project results from year onewere shared to organic famers, researchers, and educators through a poster at the Great Plains Growers Conference (200 attendees) and an oral presentation at the American Society for Horticultural Science annual conference (25 attendees).
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2022
Citation:
Wehrbein, C., and S.E. Wortman. 2022. Developing a biobased mulch system for carrot production: Effects on weed suppression, soil fertility, and yield. American Society for Horticultural Science (ASHS) Annual Conference. Chicago, IL.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2022
Citation:
Wortman, S.E., C. Wehrbein, and I. Kadoma. 2022. RootThru Biofabric: Integrated nutrient and weed management for leafy greens, carrots, and strawberries. Great Plains Growers Conference, St. Joseph, MO.
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Progress 09/01/20 to 08/31/21
Outputs
Target Audience:
Nothing Reported
Changes/Problems:We have replaced spinach in our trials with spring mix lettuce. Spinach is a difficult crop to grow in Nebraska due to the potential for extreme heat during seedling emergence. The organic market demand for spring mix lettuce and the weed management challenges are similar; thus, we believe this is a suitable alternative with comparable potential for impact in the organic farming community. What opportunities for training and professional development has the project provided?One Ph.D. graduate student (Caleb Wehrbein) began training and objectives 1-4 will form the basis of his dissertation. Three undergraduate students were trained in field research methods as a result of this project, and were mentored by the Ph.D. student. How have the results been disseminated to communities of interest?Initial research results were shared with Yazidi refugee farmers in beginning farmer programs at the local non-profit organization Community Crops. We developed a 1.5 hour recorded presentation about organic weed managment options in small-scale vegetable production, which was translated into Arabic for the farmers. We then participated in a field day to answer farmer questions about organic weed management and helped them design and manage on-farm trials to test new methods. What do you plan to do during the next reporting period to accomplish the goals?Objective 1. We will conduct a second year of field trials, which will include four new biofabric treatments: 1) 180 g/m2 PLA + Sustane organic fertilizer, 2) 240 g/m2 PLA + Sustane organic fertilizer, 3) 180 g/m2 PLA + soybean meal organic fertilizer, and 4) 240 g/m2 PLA + soybean meal organic fertilizer. We will grow carrots and spring mix lettuce in these biofabric by compost top dressing treatments and collect the same agronomic data as in year one. Objective 2. We will begin lab work to detect and quantify potential foodborne pathogens in this production system, and use this information to inform sampling efforts and experimental design in year two. Objective 3. The partial budget analysis will be conducted in year three using empirical data from the field trials. Objective 4. Course development will begin in year two. Objective 5. Project results from year one will be presented to organic farmers at the inaugural Nebraska Specialty Crop Growers Conference in 2022.
Impacts
What was accomplished under these goals?
This project is framed by three research objectives, one education objective, and one extension objective: Objective 1.Quantify the effects of biomulch properties and compost top-dressings on agronomic performance in organic spinach and carrot production systems, including weed suppression, nitrogen dynamics, soil temperature and moisture, disease incidence, and crop yield. Objective 2.Determine the effect of biomulch and compost top-dressings on foodborne pathogens and fecal indicators in organic spinach and carrots. Objective 3.Perform a partial budget analysis to identify potential labor and cost savings of the proposed biomulch system for organic spinach and carrots. Objective 4.Develop curriculum and teach a new online course for academic and professional audiences titled, "Organic Weed Management Innovations for Specialty Crops." Objective 5.Disseminate project results to current and future organic farmers and researchers. Objective 1. Field experiments were conducted in summer 2021 in Lincoln, NEin organic spinach, carrot, and leafy greens. Treatments included two polylactic acid (PLA)biofabric mulch thicknesses (80 and 120 g/m2), two compost sources, and bare soil controls with and without compost. Data was collected for weed density, soil nitrogen availability, soil and surface temperature, soil moisture, and crop yield. Surface temperatures of compost topdressings on biofabrics were up to 1°C warmer than bare soil, but below-surface (2.5 cm) temperatures were similar across treatments.Compared to the bare soil controls (with and without compost),season-long weed emergence was reduced by 93% in the thicker biofabric(120g/m2) and 88% in the thinner biofabric (80 g/m2). Given the reduced weed suppression in the thinner biofabric, it will be omitted from year two field trials. Despite the presence of a compost topdressing, the PLA mulch and its high C:N did reduce soil mineral nitrogen availability by 33-59%for the first 6 weeks of the growing season. To address this issue, we will include four newbiofabric treatments in 2022 trials that include organic fertilizers embedded in the matrix of PLA fibers (these treatments were excluded in 2021 trials due to supply chain issues at 3M, the manufacturer of these prototype biofabrics). Compared to the no biofabric and no compost control, carrot yield was increased by an average of 23% across all compost and biofabric treatments. Because weeds were removed shortly after emergence, the weed suppressive value of the biofabrics is not reflected in this yield estimate; however, it is noteworthy that yield in biofabric treatments was not reduced compared to compost treatments given the observed differences in available soil N. Spinach yield data was not collected due to poor establishment across all treatments. A preliminary trial was conducted in these plots to determine a replacement crop for 2022; spring mix lettuce grew well in all compost by biofabric treatmentsand will replace spinach in 2022. Objective 2. We collected soil, compost, and biofabric samples at planting, and plant samples at harvest in select spinach and carrot plots. These samples were frozen for analysis of potential foodborne pathogens this winter. Objectives 3-5. No upates to report.
Publications
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