Progress report for GW20-217
To improve farming sustainability and resiliency, growers in the Inland Pacific Northwest (IPNW) are transitioning from traditional cereal production systems by diversifying crops and rotations. Diversification with cover crops benefits soil health and increases agroecosystem resiliency. However, adoption of this alternative strategy is novel in the IPNW and it is unknown how aspirational crops and cropping systems impact belowground soil arthropod communities. Conserving soil arthropod biodiversity and function is critical to soil health, decomposition, nutrient cycling, and pest control and promotes plant productivity. This project will compare belowground arthropod community composition and functionality in soils under cover crops with soils from less intensive and less diverse “business-as-usual” practices on three, representative working farms over two-years. To complement the on-farm surveys, a replicated small-plot study will examine how cover crop taxonomic and functional diversity drives soil arthropod community dynamics. Finally, to tie soil arthropod community composition to function, manipulative field experiments will examine associations between arthropod biodiversity and residue decomposition. This study will be the first in the region to examine rigorously how cover crop diversity impacts the biodiversity of belowground arthropod communities and their contributions to soil processes. Results will be disseminated to regional farmers through outreach at cereal schools, field days, and extension literature, and to the scientific community via peer-reviewed publications and presentations at professional meetings. Outcomes will be more informed adoption and improved management of cover crops as a component of sustainable farming practices and improved understanding of arthropods in agricultural soils.
1. Determine how cover crops currently used by some producers in the IPNW affect soil faunal diversity. Working on three cooperating producers’ farms we will assess the effect of cover crops vs. BAU farming without cover crops on belowground arthropod biodiversity over two years. We will test the hypothesis that soil arthropod biodiversity is greater under cover crops than in the absence of cover crops.
2. Determine whether cover crops with greater plant species diversity have greater belowground arthropod biodiversity. In small-plot studies with collaborators at an NRCS site, we will assess the effects of experimentally manipulated cover crop diversity on the abundance and diversity of belowground arthropods. We will test the hypothesis that soil arthropod diversity increases in response to increased cover crop diversity.
3. Measure the association between soil arthropod diversity and a key soil ecosystem function, crop residue decomposition. On soils with differing belowground arthropod diversity as assessed in Objective 2 we will measure decomposition rates of a standardized cover crop residue. We will test the hypothesis that rates of residue decomposition increase with soil arthropod community diversity.
4. Assess IPNW soil health using arthropods as bioindicators. The QBS-ar index will be used evaluate soils in cover crops and BAU farming and among treatments in the small plot study to demonstrate the applicability of this novel tool for assessing soil health in the IPNW.
- - Producer
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Growers in our study region are increasingly interested in rotational diversification with alternative crops and intensification strategies such as cover cropping. This project addresses how cover crop use and cover crop diversity affect soil arthropod biodiversity and functioning relative to the “business-as-usual” (BAU) rotations that reflect past and current conventional management strategies. The typical BAU rotation for farms in our study region consists of a spring legume-winter wheat-spring grain rotation. Growers in the region are shifting away from BAU rotations by diversifying their rotations with cover crops (e.g., spring legume-winter wheat-cover crop). By focusing on soil arthropods, which are typically understudied in the context of cover crops and agricultural diversification, this project is making unique contributions to research on cover crops and how they affect soil health and soil biodiversity in Inland Pacific Northwest (IPNW) agroecosystems.
This research is being conducted on small-scale replicated cover crop plots (1.6×2.4 m2) that were established in Pullman, WA in 2019 to initiate a multiyear study. The cover crops we are investigating include flax, sunflower, spring pea, and sweet clover. Cover crop treatments include each species planted individually, a mixture of all species, and a fallow control. Treatments (n=6) are replicated 3 times for a total of 18 plots. Soil arthropod communities are collected using soil cores (2L) at a depth of 0-10 cm. At sampling, soil temperature and volumetric water content from each sample are measured and a soil sample from each core is taken to measure soil pH. Soil arthropods are extracted from soil cores using a Berlese funnel system, collected in a preservative, and are characterized and counted under a stereomicroscope. The effects of cover crop treatment on community metrics, including taxon richness, abundance, Shannon's Diversity and functional group diversity, are being compared. Information on how monoculture cover crops affect soil arthropod biodiversity and function relative to polyculture cover crops will enable producers to select cover crops that augment desired arthropod-mediated ecosystem services.
Throughout 2019-2020, we have investigated how the taxonomic and functional diversity of cover crop mixes affects soil arthropod communities (Obj. 2 of our proposal). Support from WSARE enabled us to continue this evaluation for a third year (2021). The historic drought conditions of 2021 resulted in weak cover crop establishment, but we proceeded with sampling these plots for soil arthropods. Information from the small plot research will be provided to producers to help them understand the effects of different cover crop composition on soil biota and soil health and will help inform cover crop mix selection.
We are currently in the process of evaluating the legacy effects (i.e., arthropod biodiversity) of each cover crop treatment on winter wheat, a primary cash crop in the IPNW. Winter wheat was planted in the small plots on October 12th, 2021, with a drill at a seeding rate of 120lb/acre. Evaluating cover crop legacy effects on soils planted to winter wheat is relevant to farmers who will be using cover crops in rotation with cereals. This change in our original design will improve the applicability of our results. By the conclusion of the project, we will have 3 years of data on soil arthropod communities from 6 cover crop treatments and 1 year of data assessing the legacy effects of each cover crop treatment on soil arthropod communities in the following winter wheat crop. Sampling in winter wheat to evaluate cover crop legacy effects is occurring throughout July 2022.
Cover crop termination leaves crop residue on fields, and soil arthropods play a substantive role in decomposition, but their overall contribution to organic matter breakdown has not been studied in the context of cover crops and crop rotations in the IPNW (Obj. 3 of our proposal). To link changes in arthropod biodiversity to function, a litterbag decomposition experiment is underway. To measure the contribution of soil arthropods to litter decomposition in winter wheat following cover crops, two litterbag mesh sizes were used: mesh size 4.0 mm allows both microbes and soil arthropods to access the litter, and mesh size 0.4 mm excludes soil arthropods. Litterbags (10×10 cm) of each mesh size were filled with 3.0 g of standardized crop residue cut to 6-10 cm length. Litterbags were placed at the soil-litter interface in each of the small-plots on November 24, 2021. Litterbags were collected at 3 different time points across the growing season, and each litterbag set for each collection time point had 3 litterbag subsamples for a total of 324 litterbags used in the study (3 replicates X 6 cover crop legacy treatments X 3 collection points X 2 mesh sizes X 3 subsamples/collection time point). Six litterbags (3 subsamples of each mesh size) were collected from each plot on March 8 and May 24, 2022. The final collection will occur after the winter wheat has been harvested (approx. the last week in July 2022). After collection, the litterbags were placed in a Berlese funnel under a 60W bulb for 72 hrs to extract soil arthropods. Soil arthropod communities collected from litterbags were characterized and analyzed as described for communities collected from bulk soil. Litter was further dried at 50°C in a drying oven until changes in mass due to water loss were no longer evident. Litter was removed from the mesh bags and weighed to determine litter mass loss for each mesh size and cover crop legacy treatment. Results from the litterbag experiment will be summarized in the final report.
To complement the small-plot research, WSARE support is enabling us to conduct research on producer-cooperator farms that are experimenting with cover crops in 2021 and 2022 (Obj. 1 of our proposal). Our goal is to determine how cover crops already used by progressive farmers in the region affect belowground arthropod biodiversity relative to traditional BAU rotational crops on working farms. Two of three cooperator farms are large-scale commercial operations, and one is a smaller-scale organic for-profit farm.
Due to the historic drought conditions that affected the region in 2021, one large-scale commercial farmer (Thorn Creek Ranch) did not plant cover crops, so their fields were not able to be sampled. Working on Wolf farms and the soil stewards farm in 2021, we sampled soils in cover crop fields and BAU fields (Table 1) at 3 time points during the growing season: at the onset of planting, during the growing-period, and post-termination. Samples of the soil arthropod community were collected using soil cores obtained at two randomly selected sites along each of three randomly oriented 50m transects in each field (25m transects at the organic farm). Arthropod communities were collected, extracted, characterized, and analyzed as previously described. At sampling, soil temperature and volumetric water content from each sample are measured in the field and a soil sample from each core is taken to measure soil pH.
2022 on-farm sampling work is underway. We are sampling a new cover crop-BAU field pair at Wolf farms (Table 1). We will have a total of four cover crop-BAU field pairs from Wolf farms for analysis at the conclusion of this study. To complement the small-plot legacy effect work, we are sampling BAU chickpeas that were planted into the fields in 2021-field pair 1 at Wolf farms to evaluate the legacy effects of cover crops on subsequent cash-crops planted on large-scale commercial farms. At Thorn Creek Ranch, we are sampling two cover crop-BAU field pairs (Table 1). By the conclusion of this project, we will have sampled a total of six different cover crop-BAU field pairs on large-scale commercial farms. The Soil Stewards Farm planted a green manure summer cover crop on 5 July 2022.
Finally, we utilized the Soil Biological Quality index (QBS-ar) to characterize the effects of different rotational crops (i.e., BAU crops or cover crops) in our small-plots and on-farm locations on soil health using soil arthropods as bioindicators (Obj. 4 of our proposal). The QBS-ar is an index that weights soil arthropod taxa based on their adaptation to the soil habitat, assuming that the number of arthropod groups morphologically adapted to the soil is higher in healthier soils. The index is sensitive to land use change and short-term variations in management practices, making it ideal for our producer-cooperators to assess how their management decisions influence soil health. We are seeking feedback from our producer-cooperators to understand the utility of the QBS-ar index as a tool for producers to measure soil health in IPNW agroecosystems.
Table 1. Producer-cooperator farms sampled in 2021 and 2022.
|Lester Wolf Farms (Wolf)||2021||2022|
|BAU||Cover Crop||BAU||Cover Crop|
Field Pair 1
|Spring wheat||Spring pea, spring wheat, mustard, turnip, clover||Spring chickpea (spring wheat in 2021, legacy effects)||Spring chickpea (cover crop mix in 2021, legacy effects)|
|Field Pair 2||Spring chickpea||Flax, turnip, chickpea||Spring chickpea||Crimson clover, sweet clover, forage pea, soybeans, berseem clover, sorghum, turnip, radish, white mustard, brown mustard, pumpkin, sunflower|
|Field Pair 3||Spring chickpea||Spring pea, spring oat, turnip, radish, triticale|
|Thorn Creek Ranch (Jensen)|
|Field Pair 1||Farmer chose to not plant cover crops due to drought conditions||Spring lentils||Buckwheat, sorghum sudangrass, balansa clover, chickling vetch, sunn hemp, flax|
|Field Pair 2||Spring barley||Chickling vetch, german millet, sorghum sudangrass, balansa clover, common vetch, sunflower, canola|
|Soil Steward Organic Farm (Detjens)|
|Field Pair 1||Potatoes||Spring pea, oats||Potatoes or Squash||Green Manure Mix (Spring pea, oats, vetch)|
Field sampling and data analysis for 2022 are underway. Results presented here include data from 2019-2021 in the small-plots and 2021 data from on-farm research.
Small Plots (Obj. 2)
A total of 20,518 individuals from 51 different taxa were collected and identified from cover crop plots during 2019-2021. The most abundant groups collected were Acari and Collembola, with 12,657 individuals and 4,563 individuals, respectively. Psocodea, Thysanoptera, Hemiptera, and Coleoptera were the most abundant insect orders, with 1,286 individuals, 782 individuals, 463 individuals, and 198 individuals, respectively.
Preliminary results from the small-plot cover crop studies (2019-2021) indicate that cover crop species and diversity influence soil arthropod biodiversity. Arthropod abundance was highest in pea and polyculture treatments compared to fallow (Table 2). We observed that Shannon's diversity was higher in pea, clover, and polyculture treatments compared to fallow (Table 2). Taxa richness was greatest in polyculture cover crops compared to all other treatments (Table 2). We observed that QBS-ar was highest in the polyculture treatment compared to fallow or flax (Table 2). There were no differences in soil abiotic variables across treatments (Table 2).
Table 2. Mean soil abiotic variables and soil arthropod abundance, Shannon's diversity index, taxa richness, and QBS-ar for cover crop treatments. Mean ± s.e.m. Means with rows assigned different letters are significantly different at P < 0.05. Polyculture treatment is a mix of all species.
|Abundance||94.92 ± 28.20ab||54.52 ± 8.46a||115.63 ± 14.02ab||163.70 ± 29.83b||90.70 ± 16.48ab||162.41 ± 29.89b|
|Shannon's Diversity||0.80 ± 0.10a||1.13 ± 0.11ab||1.19 ± 0.13ab||1.25 ± 0.12b||1.29 ± 0.11b||1.52 ± 0.12b|
|Taxa Richness||4.54 ± 0.46a||5.67 ± 0.62ab||7.56 ± 0.72bc||7.89 ± 0.76bc||8.11 ± 0.77c||11.37 ± 1.03d|
|QBS-ar||32.69 ± 2.77ab||27.70 ± 2.11a||46.74 ± 4.17bc||45.44 ± 4.26bc||43.33 ± 3.95abc||56.26 ± 4.59c|
|Soil pH||5.22 ± 0.08||5.29 ± 0.06||5.28 ± 0.05||5.35 ± 0.04||5.36 ± 0.04||7.23 ± 1.86|
|Soil VWC (%)||5.42 ± 0.56||4.54 ± 0.45||5.24 ± 0.65||4.63 ± 0.56||4.35 ± 0.51||5.42 ± 0.65|
|Soil Temp. (°F)||76.91 ± 0.87||76.69 ± 0.91||77.14 ± 0.98||76.93 ± 0.86||76.65 ± 0.85||76.43 ± 0.89|
Contrasts between monoculture cover crops and fallow and polyculture cover crops and fallow comparing QBS-ar revealed that polyculture crops significantly increased the soil's QBS-ar score compared to fallow, whereas we observed no significant difference in QBS-ar between monoculture cover crops and fallow (Figure 1).
On-Farm (Obj. 1)
A total of 15,402 individuals from 55 different taxa were collected and identified from producer-collaborator fields sampled in 2021. 5,488 individuals were collected from Wolf farms and 9,914 individuals were collected from the Soil Stewards organic farm. Acari and Collembola were the dominant taxa collected. At Wolf farms, 3,140 Acari and 805 Collembola were collected. At the Soil Stewards farm, 4,460 Acari and 4,412 Collembola were collected. A more detailed breakdown of arthropod community composition for each producer-cooperator farm can be found in the 2021 Soil Arthropod Biology reports for each farm (see Education and Outreach section). Impacts of cover crops on functional groups of soil arthropods (predators, detritivores, herbivores) relative to BAU crops are reported below. Additionally, we summarize the effects of crop type on QBS-ar for each producer-collaborator farm.
Soil Stewards Organic Farm
Cover crops influenced the diversity, but not the abundance, of predators and herbivores (Table 3). The abundance and diversity of detritivores did not differ between cover crops and potatoes (Table 3).
Table 3. Mean soil arthropod abundance and Shannon's diversity for predators, detritivores, and herbivores by crop type. Mean ± s.e.m. Means with rows assigned different letters are significantly different at P < 0.05.
|Potatoes (BAU)||Cover Crop|
|Abundance||54.67 ± 18.12||69.42 ± 15.44|
|Shannon Diversity||0.33 ± 0.07a||0.88 ± 0.10b|
|Abundance||310.50 ± 117.44||348.75 ± 57.92|
|Shannon Diversity||1.27 ± 0.08||1.45 ± 0.07|
|Abundance||9.50 ± 3.92||20.17 ± 4.18|
|Shannon Diversity||0.34 ± 0.11a||0.86 ± 0.13b|
QBS-ar was greater in soils under cover crops compared to potatoes (F1,22 =9.28, P=0.005) (Figure 2).
Three field-pairs were sampled at Wolf farms in 2021. For the purpose of this progress report, data shown here are averaged across all the field-pairs sampled at Wolf farms. Detailed data for each field-pair can be found in the 2021 Soil Arthropod Biology reports for Wolf farms (see Education and Outreach section).
Cover crops influenced the diversity of predators, detritivores, and herbivores (Table 4). The abundance of predators and herbivores, but not detritivores, increased in cover crop fields (Table 4).
Table 4. Mean soil arthropod abundance and Shannon's diversity for predators, detritivores, and herbivores by crop type. Mean ± s.e.m. Means with rows assigned different letters are significantly different at P < 0.05.
|Spring Crops (BAU)||Cover Crop|
|Abundance||17.68 ± 3.09a||30.22 ± 4.70b|
|Shannon Diversity||0.48 ± 0.06a||0.80 ± 0.07b|
|Abundance||41.76 ± 6.22||91.52 ± 20.35|
|Shannon Diversity||0.80 ± 0.08a||1.03 ± 0.08b|
|Abundance||4.48 ± 1.45a||13.37 ± 7.58b|
|Shannon Diversity||0.28 ± 0.07a||0.55 ± 0.10b|
Reflecting our results for the Soil Stewards farm, QBS-ar was greater in soils under cover crops compared to BAU spring crops (F1,50 =23.5, P< 0.001) (Figure 3).
We took a multivariate analytical approach to compare the effects of cover crops and BAU crops on soil arthropod community composition. We applied non-metric multidimensional scaling to the combined community dataset from both producer farms sampled in 2021 (n=76 communities). We visualized the composition of soil arthropod communities by crop type (BAU vs cover crop) (Figure 4). The extent of the overlapping ellipses in the ordination plot indicates community similarity. The lack of ellipse overlap between BAU crops and cover crops indicates that soil arthropod communities differ between crop types.
The responses of soil arthropod communities to cover cropping have never been documented in the IPNW prior to this project. Preliminary results from this project indicate that cover crop type and diversity influence soil arthropod communities. Planting cover crops promotes the abundance and biodiversity of functional groups that benefit sustainable agriculture goals.
"Is there potential for producers to manage their soil biology with cover crops?" is one overarching question guiding our project. Initial results from our research indicate "yes". For example, compared to a monoculture of flax, there were more soil arthropods and greater taxonomic richness in polyculture cover crops. This observation supports our hypothesis that soil arthropod biodiversity increases in response to increased cover crop diversity (Obj. 2). However, not all monoculture cover crops are created equal. Clover, for example, supported greater soil arthropod taxa richness compared to flax. Overall, flax failed to promote soil arthropod abundance and biodiversity relative to other cover crop treatments and was even outperformed by fallow in terms of benefit to soil arthropods (e.g., soil arthropod abundance). Producers seeking to promote their soil arthropod biology should avoid the use of flax monocultures as a cover crop.
In contrast to soil arthropod responses, we observed no changes in soil abiotic variables between cover crop treatments during our small-plot study. Notably, there were no detectable changes in soil water content relative to fallow. This effect can depend upon when cover crops are terminated. Cover crop treatments in our small-plot experiment were terminated by mowing in the last week of July (2019-2020) and the third week of August (2021). Concerns over soil moisture retention have been a major limitation to cover crop adoption in dryland farming regions. Results from our small-plot study suggest that fallow provides no water retention benefits compared to the cover crop treatments used in our study. No detectable changes to soil water content relative to fallow, along with augmented soil arthropod biodiversity and abundance, have the potential to make polyculture cover crop mixes, especially the mix tested here, a great tool to improve soil health and sustainability in IPNW agroecosystems.
The positive effects of cover crops on soil arthropod communities observed in our small-plot studies were consistent in our on-farm studies. Cover crops changed the composition of soil arthropod communities relative to conventional "business-as-usual" crops planted in 2021 on producer-collaborator farms. When producers choose which crops to plant, they are also determining the biodiversity and composition of soil arthropod communities that regulate soil processes crucial for agroecosystem productivity. This suggests there is potential for producers to manage and promote these belowground communities through cover cropping.
The biodiversity of predators, detritivores, and herbivores was greatest in cover crop fields compared to conventionally managed non-cover crop fields at Wolf farms. The cover crop field at the Soil Stewards Farm increased soil arthropod diversity relative to the BAU potato field, but in contrast to the results at Wolf farms we observed no differences in abundance between any functional groups. These results support our hypothesis that soil arthropod biodiversity is greater in cover crop fields than non-cover crop fields (Obj. 1). Notably, cover cropping did not affect the abundance of detritivores, which include Acari and Collembola taxa, at either farm. Conventional farming practices are known to reduce the abundance and biodiversity of soil arthropods within the functional groups that underpin naturally regulated soil processes like nutrient cycling and pest control. Cover cropping practices, such as those used by the producer-cooperators in our study, that increase the biodiversity of beneficial functional groups, like predators and detritivores, could lead to increased ability of soil biological communities to regulate soil processes. Improving soil arthropod biodiversity can contribute to making soil productivity less reliant on off-farm inputs and can provide resiliency to the soil ecosystem so disturbances related to agricultural management or climate change do not result in a loss of naturally regulate soil processes.
The Soil Biological Quality index (QBS-ar) is an index that was developed to assess soil quality by using arthropods as biological indicators. The QBS-ar weights soil arthropod taxa based on their adaptation to the soil habitat, assuming that the number of arthropod groups morphologically adapted to the soil is higher in healthier soils. This index combines soil arthropod community biodiversity and the arthropod's level of adaptation to the soil environment. Results from our small-plot studies suggest monoculture cover crops do not improve soil quality compared to fallow, as measured using QBS-ar. In contrast, the polyculture cover crop improves soil quality relative to fallow and monocultures. Growing a polyculture cover crop seems to maximally promote soil arthropod biodiversity and soil quality relative to the monoculture crops we evaluated.
Results from the on-farm studies were consistent with our small-plot experimental work. Cover crops grown by our producer collaborators affected the composition of the soil arthropod communities and the QBS-ar values of their soils. Soil quality, as measured by QBS-ar, was greater in cover crop fields compared to BAU non-cover crop fields. This increase in soil quality, measured using arthropods as bioindicators, suggests that cover crops are improving soil health in our producer-cooperator fields. The creators of the QBS-ar index report that a mean QBS-ar of 93.7 "can be considered a tentative threshold that separates high quality soils and values which are typical for poor soils". Soils sampled from the cover crop field at the Soil Stewards farm surpassed this threshold, but soils sampled from cover crop fields at Wolf farms remained below this threshold value. Whether this difference in cover crop effect on QBS-ar between organic and conventional farms is a consistent pattern deserves further attention. The rapid and measurable change in QBS-ar suggests this index may be a useful tool for monitoring soil quality after changes in managements practices. In the past, evaluating soil health in response to management practices has focused on chemical (e.g., pH) and physical (e.g., volumetric water content) parameters. But by solely measuring these physiochemical parameters, which may not always respond quickly to management changes, we may be overlooking biological indicators that can provide important clues as to how management practices influence soil health.
Compared to conventional dryland farming practices, like fallow or planting spring crops, cover crops increase soil arthropod biodiversity, potentially improving the delivery of ecosystem services in agroecosystems. Cover crops that augment desirable functional groups, like predators and detritivores, can potentially be used to ecologically engineer agroecosystems to benefit producers. Results from our on-farm and small-plot studies so far indicate that cover crops, in addition to agronomic benefits they may provide, can simultaneously promote diversity in beneficial soil arthropod communities, enhancing ecosystem services and agroecosystem sustainability.
Educational & Outreach Activities
We have participated in several outreach activities centered around agricultural diversification in 2021 and 2022. Information on cover crops, soil arthropods, and preliminary project results were shared with producers and professionals at the Genesee Area Crop Tour in Latah Co., ID (2021 (26 participants) & 2022 (12 participants)) the Bonners Ferry Field Day in Boundary Co., ID (2021 (23 participants)), the Northern Idaho Collaborative Field Day in Nez Pearce Co., ID (2022 (approx.40-50 participants)), the Prairie Area Crop and Conservation Tour, Lewis Co., ID (2022 (approx. 25-30 participants)), the Farmington Field Day in Whitman Co., WA (2022 (10 participants)), and the Soil Stewards Farm Day in Latah Co., ID (2022 (5 participants)). Factsheets that included project results and take-home messages complemented the field day presentations and were distributed to all attendees. (Field Day Handouts 2022, Field Day Handout 2021)
Additionally, preliminary results were reported in the 2022 Dryland Field Day Abstract book (pg. 57) that is published jointly by Washington State University, Oregon State University, and the University of Idaho. Field day abstracts are available for free download from extension sites across these three universities enhancing our outreach capabilities across the Inland Pacific Northwest.
Producer-collaborators Frank Wolf and Alison Detjens (Soil Stewards Farm) were provided with reports (hard copies and electronic) that summarized the 2021 preliminary results from on-farm sampling. Additionally, attendees of the Soil Stewards Farm Day all received the 2021 Soil Stewards Soil Arthropod Biology report. Producer-collaborator Jensen was also provided with these reports from his colleague's farms. Jensen will receive a similar report summarizing 2022 sampling efforts. These reports also include information on abiotic soil factors that were collected at the time of arthropod sampling, like pH, soil temperature, and soil volumetric water content.
Project objectives and preliminary results were presented and discussed during the 2021 University of Idaho Entomology, Plant Pathology and Nematology departmental seminar series in a talk titled, “The ecology of soil arthropods in agroecosystems: Effects of agricultural diversification on community structure, function, and interactions”. Additionally, Elmquist delivered an oral presentation reporting and discussing project results titled, "Effects of cover crops on the structure and function of soil arthropod communities" at the 2021 Entomological Society of America national meeting (Oct 31-Nov 4 Denver, CO). Project results were also presented in a poster at the 2022 Institute for Health in the Human Ecosystem Annual Research Symposium on April 7, 2022 at the University of Idaho in Moscow, ID. Elmquist won an award for best PhD poster. Data from this project will be included in an invited oral presentation at the 2022 Entomological Society of America meeting (Oct 13-16 Vancouver, B.C., Canada) titled "Designing agroecosystems to promote soil arthropods" delivered by Elmquist.
Elmquist was recently a guest on the Wheat Beat Podcast with Dr. Drew Lyon where they discussed the effects of agricultural diversification practices on soil arthropod communities. The podcast will be released on the Washington State University Wheat and Small grains website. While cover crops and the Western SARE work were not the main subject of discussion, a link to this project on the SARE website was provided for listeners to access more information about cover crops and soil arthropods. The podcast will be available on iTunes, Stitcher, SoundCloud, ApplePodcasts, and Spotify some time in August 2022.
Due to COVID-19, the 2021 Washington State University Wheat Academy was canceled, so results from this project were not presented at this venue during 2021. However, results and take-aways from this project will be presented to producers and professionals in a workshop session at the 2022 Washington State University Wheat Academy (Dec. 13-14) in a session titled, “Macrofauna & Soil Health: Getting to know our below-ground partners in PNW wheat systems”. The workshop will include a breakout period where attendees will observe live soil arthropods. A similar workshop session that focused on soil arthropods and soil health in 2019 sparked the interest of several producers who wanted to know how these organisms impact soil health. We will be prepared this year to answer such questions more substantively based on the results of this WSARE funded project and will be able to provide recommendations about cover crops based on their impacts on soil biology.
In our initial proposal we planned to produce a guide booklet that outlined the QBS-ar index protocol, accompanied by pictures of soil arthropods commonly encountered in the IPNW. We planned to test the utility of this index with producers at various outreach events, like the Washington State University wheat academy, that ended up being canceled due to COVID-19 in 2021. We saw this as an opportunity to re-think our strategy on publishing educational materials and opted to create a University of Idaho Extension Bulletin titled "An introduction to soil arthropods of Palouse agroecosystems". The publication proposal form sent to UI extension publishing services was peer-reviewed and accepted in June 2022 (pre-proposal form can be provided upon request). Bulletin creation is underway. To our knowledge there are no similar sources of information about soil arthropods in the Pacific Northwest. The USDA-NRCS has a general information page on soil arthropods, but our bulletin would be regionally based and include research-based management recommendations that can be used to promote soil arthropod abundance and biodiversity. Research-based management recommendations involving cover crops would come from data generated by this project and would include results from small-plot and on-farm studies. The bulletin will be posted online at the University of Idaho extension website where it is free to access and download. Additionally, we will print high-quality hard-copy bulletins to send to extension centers in Northern Idaho to include in their educational material offerings. Furthermore, the bulletin would be shared with Western SARE and would ideally be available for download on the Western SARE project website and could perhaps be included on the SARE factsheet website as a SARE product. Posting the bulletin on the SARE website as a product would enhance its reach. The bulletin will be completed by 10/1/2022. In contrast to the QBS-ar guidebook previously proposed, we anticipate this bulletin will be more accessible to a wider audience and will enable better dissemination of project results. The bulletin is in preparation and will be included in the Information Products section of the final report.
Finally, results from this project will be reported to the Landscapes in Transition (USDA-NIFA award #2017-68002-26819) project leadership and the stakeholder advisory committee, as well as presented at the Landscapes in Transition annual meeting in October or December 2022 and included on the Landscapes in Transition website (https://www.pnwlit.org/home).
Achieving long-term agricultural sustainability goals will require preserving agroecosystem biodiversity and the ecosystem services that it provides. Although this principle is generally understood, the contributions of soil arthropods are underappreciated, and management of these taxa is not currently a part of stewardship. We are developing a robust understanding of how cover crops affect the biodiversity of belowground arthropods. Our study is evaluating how cover crops can influence soil arthropod biodiversity and the ecosystem services they provide, like decomposition. Initial results suggest that cover cropping promotes soil arthropod biodiversity and improves soil quality (measured using the QBS-ar). We are conveying this information to IPNW producers to inform their decisions about cover crop mix selection and management. We are incorporating our findings into outreach presentations and, eventually, extension materials aimed at producers and other stakeholders. This research is contributing to a regional cover crop knowledge base to promote the adoption of cover crops and improve agroecosystem resiliency, thus benefiting the overall sustainability and well-being of rural communities in the region. Information from this research will not only inform soil management practices but will also fill knowledge gaps about the complex interactions between plants, soil arthropods, and their associated ecosystem services. These results are also applicable to other regions looking to utilize cover crops.
Producers in the IPNW are adopting new practices to improve agricultural sustainability. Nonetheless, cover crop adoption has been slow in the region. Through our interactions with producers as part of this project, we have become more knowledgeable about the constraints faced by farmers and what is motivating them to understand and implement cover cropping on their farms, even by conducting their own on-farm trials. This interest and enthusiasm for alternative agricultural practices, including cover crops, is growing with potential to guide impactful ongoing research partnerships between producers and scientists like those affiliated with land grant universities including the University of Idaho.
We have also learned that growers in our region, as across the USA, are interested in how farming practices impact the biological parameters of their soil, specifically microbes and arthropods. This understanding can help us refine our research and outreach approaches by focusing specifically on how farming practices affect the abundance and function of soil organisms. A clear need is improved delineation of the functions of certain soil organisms and their contributions to desirable agricultural outcomes (e.g., pest control or litter decomposition). In addition, improving how we communicate with producers and stakeholders about soil biology may increase producer awareness of the system-wide benefits of sustainable agriculture that go beyond economics. The proposed extension bulletin will serve as an optimal introduction to the belowground world of soil arthropods in agroecosystems and should stimulate producer interest and knowledge about this important, but overlooked, group of soil organisms.