Final report for FNE18-894
This project sought to test the efficacy of a variety of mulch treatments, and a native, edible mushroom (Stropharia rugoso-annulata), to help to alleviate soil compaction on an urban farm. Two novel crops were also tested for growing compatibility and consumer preference, as well as impacts to cabbage and beet roots.
The research utilized a split-plot design across eight blocks. The mulch treatments included a control, 2-year decomposed hardwood chips, fresh wood chips mixed with grass clippings, ramial willow chips inoculated with Stropharia rugoso-annulata spawn, and mixed hardwood chips inoculated with Stropharia rugoso-annulata spawn. In year one, cabbage and lemon cucumbers were grown in each block. In year two, beet root and cabbage were grown. The number of individual plants or fruits and pounds harvested were compared across the treatments and years.
The research revealed challenges in getting the Stropharia to fruit. The mycellium successfully inoculated wood chips, but resulted in virtually no fruit and was unable to be tested as an edible crop. Across the treatments in year one, crop productivity was very low for both species. Lemon cucumbers were highly regarded by customers, and led to requests for more in the following year, though the cost of production and challenges with pests and disease outweighed the potential market revenue.
Year two of the program resulted in a significantly greater average weight per plant of cabbage in ramial plots (1.3 lbs) versus all other treatments except hardwood inoculated with Stropharia (1.1 lbs), with grass in wood chips weighing 0.5 lbs, control averaging 0.7 lbs, and decomposed wood chips averaging 0.8 lbs.
Stropharia grown as a sole crop results in a profit loss, but grown in conjunction with cabbage results in a potential profit of $179 per field. Beets hold the best profit potential at $117 per field, and cabbage grown by itself and lemon cucumbers could generate $32 per field, though other considerations such as source of chips, and the presence of pathogens and pests should be considered in making an assessment.
Customers at market stands and CSA were surveyed as to their preference for the lemon cucumbers. Outreach was offered during on-farm visits and workshops with community and school gardeners, other small farmers, and beginning refugee farmers.
This project will provide a feasibility study for improving soil health and crop productivity in poorly-performing urban soils using Stropharia mushrooms. Farmers will gain information about the possible benefits and economic feasibility of using woodchips with and without Stropharia mushrooms to improve soils and crop yields. Farmers will also learn about the commercial viability of two crops that can be readily grown but are rarely sold in Central New York. The market viability study will reduce risk to farmers interested in diversifying their operations with these new crops, either preventing loss from a poor crop choice or increasing income by adding a niche product with demonstrated demand. Because woodchips are an affordable and readily available Organic soil amendment, farmers will learn how to utilize a low-cost soil amendment.
Objective 1. Test efficacy of various woodchip substrates and Stropharia to improve marginal agricultural soils.
Objective 2. Test impacts of Stropharia-inoculated and composted woodchips on yields of lemon cucumbers, cabbage and carrots.
Objective 3. Test marketability of two novel crops: lemon cucumbers and Stropharia mushrooms.
Objective 4. Measure economic viability of various soil amendments used to improve productivity of poorly performing soils.
Agricultural soils everywhere face performance decline from erosion, poor drainage, compaction, and loss of organic matter. Poor soils can take many years to rehabilitate. Compaction is a significant problem, especially for urban farmers attempting to reclaim previously developed land. Remediating compaction and affording soil improvement techniques are critical for all farms seeking to be economically sustainable, and is the emphasis of this project. The goals are threefold: assess the effectiveness of wood chips as soil amendments; measure the benefits of Stropharia rugoso-annulata (wine cap) mushrooms to mitigate soil compaction; and assess marketability of two novel products. The first two goals are accomplished by comparing the effectiveness of five different soil amendments to improve soil microbial activity, available nitrogen, soil nutrition, compaction, and crop yield. Treatments include ramial and mixed hardwood chips inoculated with Stropharia; naturally decomposed ramial and mixed hardwood chips; and an untreated control. Eight repetitions of the treatments are each planted in lemon cucumber and cabbage, then beets. The second goal is accomplished by surveying customers who purchased lemon cucumbers and wine cap mushrooms from the farm. Outreach occurs by three methods: offering factsheets and experimental tours through a county-wide Farm Day, submitting results to local agency newsletters, and hosting workshop and tours for farmers, gardeners and students interesting in improving soils or growing Stropharia mushrooms and/or lemon cucumbers. The desired impact of this work is to bolster regional knowledge of soil amendment techniques using easily attained biomass and market viability of new agricultural products for growers in the Northeast.
Wood chips are a readily available organic matter in urban and rural settings. They are rarely used as a soil amendment due to losses of bioavailable nitrogen when the wood decomposes, and wood chips also are difficult to cultivate with equipment. Ramial mulch describes mulch that is sourced from woody material that is originally no larger than 3” in diameter. The extra nitrogen available through a higher cambium to wood ratio, helps to prevent nitrogen depletion and speed nutrient release of the chips. Brian Caldwell wrote a paper for the University of Vermont summarizing a 15-yr study on the usefulness of woodchips as a soil amendment in Marcellus, NY. The study ended in the 1970’s. Mr. Caldwell compared this research to studies conducted in Quebec, Canada analyzing the use of ramial mulch as a soil amendment. Both studies showed the promise of wood chips as a soil amendment, and he highlights the need to ensure adequate nitrogen to prevent reductions in crop yield. Shrub willow in Canada is made into ramial mulch and sold as a high end landscaping product, but it has not a common material used in the United States.
Stropharia rugoso-annulata is in the white rot family, which is known to break down cellulose and lignin. When the cellulose and lignin in wood chips are first broken down by Stropharia, nitrogen and other nutrients from those woodchips become bioavailable sooner. This could also allow wood chips to be integrated as soil amendments, and not limited to a top-dress application. The combination of Stropharia cultivation in a wood chip amendment may expedite soil building, nutrient availability, and increase crop yields.
In 2014, Eric Fabio of Dr. Smart’s Willow Lab at Cornell University, and Jessi Lyons at Cornell Cooperative Extension of Onondaga County tested the potential of woodchips and Stropharia rugoso-annulata to reduce soil compaction in urban gardens. This pilot study revealed almost 40% increase in soil penetrability due to woodchips grown with Stropharia mushrooms. The study set out to compare ramial mulch sourced from shrub willow wood chips versus readily-available mixed hardwood wood chips, as a growing medium. The study revealed that higher nitrogen substrates supported more flushes of mushrooms, though there was not a significant difference between the willow and the mixed hardwood due to an excessive amount of green leaf litter combined with the hardwood chips. This left a question about the role of nitrogen in supporting the Stropharia growth, and the long-term use of wood chips as a fertilizer. The study did not measure the viability of growing crops in these substrates, or the potential impact of undecomposed wood chips and nitrogen mineralization on future crops.
Stropharia rugoso-annulata has been actively researched at Cornell University in recent years as a viable agro-forestry product. The research has not directly extended into agricultural field production. The benefits of Stropharia mushrooms have been touted for soil moisture retention and increasing symbiotic relationships with plant roots, increasing plant nutrient uptake. Stropharia is an uncommon market crop due to its fragility post-harvest, the inability to predict and control fruiting, and because wildlife and slugs favor the fruit. While Stropharia in itself may not be worth growing as a source of revenue, it can be seen as a “bonus” crop that can provide supplemental income to existing crops.
This is a not-for-profit urban farm with 5.8 acres of land in central New York, with 4 acres actively used for production. At the beginning of this project, the farm had been actively growing for two seasons. The site had been vacant for 12 years, and previously had a few iterations of apartments. Contaminated soil was removed when the apartments were razed, though concrete foundation and remnants of sidewalks are still present. Amending and rehabilitating soil is a large portion of the work conducted at the Farm.
We use organic practices to grow mixed vegetables for a CSA and market stands. We also grow in two high tunnels.
No special tools or equipment were used in this project. Wood chips and compost were manually spread using wheel barrows. Due to our urban location, we are able to receive free deliveries of wood chips from local arborists. Ramial willow mulch was donated by SUNY College of Environmental Science and Forestry. Compost was purchased through the Onondaga County Resource Recovery Agency, which allows for yards of compost to be purchased and consumers must transport it themselves. We used a standard pick-up truck to haul both the compost and ramial mulch used in this experiment. Larger applications may require larger trucks to transport the material.
- - Technical Advisor (Researcher)
Eight blocks containing 70' rows were established to test multiple mulch applications, viability of Stropharia rugoso-annulata on the plots, and impacts to cabbage, lemon cucumbers, and beets.
Mulch treatments were randomized within each block, separately for each crop. Due to a loss of cabbage seedlings in year one, lemon cucumber and cabbage were planted in separate trials. In year two, the beets and cabbage were planted on the same date. Each plot of cabbage consisted of one plant. Lemon cucumber plots consisted of three total plants, and beet plots consisted of four groupings of 3-5 beets per plot. The crops, however, occupied space adjacent to one another in the same rows, so that soil conditions should be similar. In year one, lemon cucumbers and cabbage were tested, and beets and cabbage were tested in year two. Five mulch applications were tested: control; ramial wood chips sourced from shrub willow and inoculated with Stropharia; 2-year old decomposed mixed wood chips; fresh mixed hardwood chips inoculated with Stropharia annuala-rugosa; and fresh wood chips mixed with fresh grass clippings.
Each treatment received one inch of compost application to bare soil prior to mulch treatment and planting. Stropharia rugoso-annulata spawn was applied between the compost and ramial mulch and hardwood mulch applications, respectively and watered in. In year one, lemon cucumber was planted in June and harvested between July 26 and August 24. Cabbage was planted in August, and harvested on December 3. In year two, beets and cabbage were planted in May. Beets were harvested August 3, 2019 and cabbage was harvested August 11, 2019.
Fresh weight and fruit number were recorded for each plot on each harvest date of lemon cucumber. Fresh weight yield and fruit number were summed across all dates within plots in order to analyze total yield and fruit number separately as response variables. For cabbage, only one harvest occurred at the end of the season with one sampling unit (cabbage head) per plant harvested, so only total yield was considered for a response variable. For beets, all plants were harvested on the same day and the total mass of each plot was measured.
For statistical analysis PROC MIXED in SAS was used to perform a one-way analysis of variance (ANOVA) with random blocks. We used this approach because some plants died during the experiment, but we did not attribute this to the mulch treatments. Therefore, we had missing data for some plots and PROC MIXED is the best fit for experiments with missing data. The probably of significance was tested at P = 0.05 and at 0.10 levels. When the ANOVA showed significant main effects of mulch treatment, an all-pairwise comparisons means separation test was used to find significant differences between mulch treatments
Soil samples were taken prior to the treatment, and following the final cabbage harvest in year one.
Plants were maintained with regular watering (at least 1" of water per week when rainfall wasn't adequate) and organic pest prevention as necessary. Pest prevention consisted of manual removal of striped cucumber beetles, row covers over cabbage to protect from Swede midge and application of diatomaceous earth around cabbage for slug control. No additional fertilizer was applied beyond the original compost and mulch treatment applications. Lemon cucumber fruits were weighed upon harvest, based on a standard harvest size. Plants were monitored daily for ripeness.
Stropharia mycellium was monitored throughout the growing season, and fruits were weighed when harvested.
The costs of production were measured based on: labor spent spreading amendments at $17/hr, amendments, potential wood chipper rental, and delivery of materials. The costs and benefits were extrapolated to reflect 4 - 100' x 36" beds planted at standard rates used by Johnny's Seed Company. Income from each crop was estimated based on average farmer's market prices in the peak season in central New York: beets $2.50/pound, lemon cucumbers $2/pound and cabbage $1/pound. Yield estimates were based on the treatment that generated the highest yield for a respective crop. The yields were all nearly 50% of what is estimated by Johnny's Seeds as average yields, and so a 50% yield value was used. Stopharia yield was estimated at 2 pounds per square yard, at a sales rate of $10 per pound. While this trial didn't result in fruiting mushrooms, previous research supports that yield as a plausible volume.
1. The first objective was to test efficacy of various wood chip substrates and Stropharia to improve marginal agricultural soils. We tested this by analyzing soil nutrition (pH, Al, Ca, Fe, K, Mg, and Mn, and organic matter) and microbial activity of the soil (NO3, CO2 and SLAN) after the year one growing season. We analyzed effects by treatment, crop and treatment with crop. There was no difference in pH, aluminum, calcium, magnesium or manganese by treatment. We found that iron was significantly less in the control than ramial and mixed hardwood, whereas potassium was significantly less in the control than in the mixed hardwood and hardwood with grass. Organic matter was significantly greater in the ramial treatment than control, and nitrate was higher in the control than in ramial, mixed hardwood and mixed hardwood with grass. There was no significant difference in SLAN or CO2 by treatment.
We also found that pH, calcium, iron, potassium, magnesium and manganese were all significantly lower in the cabbage plots compared to lemon cucumber plots. SLAN and organic matter were also significantly higher in lemon cucumber than cabbage plots.
2. The second objective was to test impacts of Stropharia-inoculated and composted wood chips on yields of lemon cucumbers and cabbage. First, we tested for the effects from different mulch applications on plant productivity, as measured by mass and also number of fruits of the lemon cucumbers.
Year One. For total fruit number produced by lemon cucumber, the ANOVA test did not find significant differences in mulch treatments at the P = 0.05 level, but there was a significant effect at the P = 0.10 level (Table 2). Using the P = 0.10 significance level, the means separate test showed that for total fruit number per plot, decomposed wood chips had the greatest mean total number of fruits. They were not statistically greater than ramial mulch, but they were significantly greater than the mixed hardwood and grass treatment.
The cabbage trial did produce a crop, though none of the plants had fully made a head before they were harvested in December. The cabbage was planted in late August due to a loss of seedlings earlier in the season. The plants were then covered with row cover due to a significant presence of Swede midge on other cruciferous crops. The combination of late planting and continual presence of the row cover late in the season likely inhibited growth. The row cover also made it difficult to see damage from slugs. When the row cover was removed in late October, significant slug damage was noted and the plants were treated with diatomaceous earth. Slugs were documented primarily in the hardwood, ramial, and wood chip/grass treatments, likely due to the large air spaces in these mulches providing ideal habitat whereas the decomposed wood chips and control treatments have smaller pore space. We did find a significant effect from mulch treatments, where the control had significantly higher biomass than all other treatments, and hardwood mixed with grass was higher than the ramial.
We again analyzed the second year yield data separately by crop. There were no statistically significant differences among mulch treatments for total yield of beets. For cabbage, there was no significant difference among treatments for harvest number or total yield. There was however a significant difference for individual cabbage weight at the alpha = 0.10 level, with the ramial mulch having significantly greater weight than all but the hardwood chip mulch treatment.
3.The third objective was to test marketability of two novel crops: lemon cucumbers and Stropharia mushrooms. The Stropharia mushrooms successfully colonized the test plots, and mycellia were observed throughout the growing season. The mycellia were not as abundant and deep as we expected, and only two of the 80 test plots had fruit production. The mushrooms that did fruit came over a weekend when they were not observed, and were too mature to properly measure or consume when they were discovered. These mushrooms were discovered in the cabbage plots where row cover was protecting them. The presence of the row cover partially concealed their presence, but also may have created conditions to encourage the very late emergence (early November). Not enough of Stropharia produced fruit to provide any further analysis or results. The Stropharia mycellia did not recolonize the plots in 2019.
Lemon cucumbers were sold at the CNY Regional Market and added to the customer CSA boxes. Customers sought out the cucumbers at the market stand and they sold out within a couple hours of being offered. Market customers who tried this crop would regularly seek them out. Lemon cucumbers were not grown in year two, though customers expressed regret that we did not grow them a second year. Five customers who either visited the farm directly, or the market stand specifically requested that we grow them again. Two community gardens who grew the cucumbers also requested that we grow seedlings for them in future. The demand for these cucumbers far exceeded what we grew. The negative responses from customers related to the "seediness" of the cucumbers, while some customers preferred the more mellow taste and crispy texture.
4.The fourth objective was to measure economic viability of various soil amendments used to improve productivity of poorly performing soils. We assessed this by doing a cost benefit analysis considering the cost of the material, cost of labor spent spreading the material, the potential improvement in sales over time. We extrapolated our costs out to cover a field with 4 - 100' x 36" beds. We found that the greatest costs come from the cost of the Stropharia spawn ($900). If wood chips are not able to be sourced and delivered for free, the cost of renting a chipper is the next greatest expense ($405/day for large wood materials, $140/day for ramial size materials). And compost is the next greatest expense at roughly $219 to cover all four beds. Cabbage was the only crop shown to positively change due to soil amendment, with the greatest improvement in the ramial mulch and hardwood beds inoculated with Stropharia. Thus cabbage grown with Stropharia could lead to a profit of $172 for the four beds. If the hardwood chips are not able to be acquired for free, the cost of chipping them outweighs the benefits (-$265). Other treatments did not show a significant difference by crop. Thus renting a chipper to apply ramial mulch, or simply applying compost lead to the greatest profit margin: beets at $117-$106, respectively; lemon cucumbers and cabbage at $32-$20, respectively.
We found that the application of ramial willow wood chips inoculated with Stropharia can improve crop yields over time, compared to other mulch treatments and a compost-only control. While there was an immediate negative effect on crops in year one, the second year showed a significant increase in crop yields compared to other treatments.
The combination of Stropharia helping to hasten the decomposition of lignin, and the higher nutrient content of ramial mulch compared to other forms of wood chips, helped to increase yields relative to other applications after two years. Whereas the mixed hardwoods were also inoculated with Stropharia, they take longer to decompose and release nitrogen due to the chip size and nitrogen content relative to a ramial mulch. The decomposed wood chips in year one performed better than ramial, but not the control, but the effect did not last into year two. This could be explained by the more available nutrients being depleted in year one, similar to the compost-only treatment. Wood chips mixed with grass were significantly better than ramial in year one, but were significantly worse than all other treatments in year two. This could be explained by the nitrogen in the grass adding a nitrogen boost to crops in year one, but the lack of a decomposer like Stropharia to further decompose the remaining wood chips meant that nutrients were unable to be released from the chips in year two. And control had the highest amount of nitrogen in year one, compared to all other treatments, indicating that all mulch applications are less useful as a nitrogen supplement in the first year of an application. Not surprisingly, the control also had significantly less OM compared to ramial, again indicating a higher C:N and less initially available nitrogen in ramial mulch.
In consideration of use of wood chips for future land use applications, the presence of Stropharia as a primary decomposer is important. And a ramial mulch that naturally has higher nitrogen content than standard wood chips in combination with Stropharia, will have greater yields than other Stropharia-inoculated wood chips.
It was valuable to note that cabbage seems to be a heavier feeder than lemon cucumbers and the production of cabbage itself may have impacted soil characteristics. Cabbage yields increased in the second year in the ramial plots, which may be attributed to the delayed release of nitrates in those treatments due to the initial high lignin content. The higher organic matter present in the lemon cucumber plots also indicates that cabbage was depleting these nutrients more than lemon cucumber. Calcium in the soil was less in the cabbage plots, which may also explain the decrease in pH in those plots. This was an unexpected result worth considering for future soil amendments where pH is very high. For future uses of mulch as a soil amendment where vegetable production will be concurrent, it will be important to consider the specific nutrient requirements of the various vegetables and how they will respond to nutrient availability based on the timing of the mulch application.
Using Stropharia does come at a potential risk. In the case of this study, growing conditions and potentially poor quality of spawn impacted the production of Stropharia fruit, resulting in an net profit loss. While the benefit of selling those mushrooms was lost, the overall positive affect on soil health in year two is worth considering. Customers and visitors were eager to try the mushrooms, and demand was created simply through outreach conducted in this project. Customers were disappointed that the crop didn't turn out, and that demand resulted in support of indoor winter production of oyster mushrooms for the CSA.
As a result of this project we are continuing to use wood chips as a long-term soil amendment. Wood chips are now being used in-between rows to allow them to decompose for 2 years, then they will be adding as a topdressing to beds. Because the demand for mushrooms is increasing, we have increased our cultivation of shiitake and oyster mushrooms, and will be adding Stropharia to specific areas with high compaction.
Since the study concluded, we have conducted extensive soil nutrient tests and will strategically plant cabbage in areas know for high calcium. Ramial mulch is a product we'd like to continue to use, when we can find it cheaply or for free.
Education & Outreach Activities and Participation Summary
We hosted two on-farm field days that were open to the general public. Each of these field days highlighted our research project to visitors going on the tours. In 2018 we had four farmers attend the field day and specifically stopped to learn about the project. We also had 180 visitors from the general public attend the tour and learn about the project. In 2019 we had just one farmer attend the tour, in addition to over 200 members of the public, and six agriculture educators. In 2019 we hosted two educational workshops for refugee farmers. With help from interpreters we were able to highlight the project to 18 new farmers. We also hosted twelve Master Gardener volunteers for a tour to explain the project, and two other community garden groups totalling 22 gardeners. Additionally, five farmers from the Brady Farm were intimately involved in the research implementation, data gathering and discussion of results. A local farmer and a local urban gardener have requested information about the results of our project and feasibility of implementing wood chips and Stropharia to build organic matter on their site. Eight students from SUNY-ESF, and 12 youth from Huntington Middle School Garden Club assisted with plot establishment.
For the farmers immediately working on the project, we significantly increased our awareness of on-site soil conditions and dynamics, the utility and limitations of wood chips as a soil amendment and Stropharia as a catalyst to decomposition.
For visiting farmers, they reported an increased awareness of alternate soil management practices; new knowledge about two novel crops (Stropharia and lemon cucumbers); and new knowledge about the difference between ramial mulch and standard wood chips.
Our farm will be utilizing wood chips further, though more judiciously. The free source of organic matter is crucial to our farm's long-term sustainability, both economically and productively. We will be applying the wood chips as a mulch to prevent weeds in paths for two years, before adding them as a top-dressing to beds.
Customer demand for these two novel crops - lemon cucumbers and wine cap mushrooms - was enlightening. There is potentially a high cost to investing the energy into growing both of these, with potentially negative returns. While the demand for the mushrooms spilled into other mushroom crops that are more reliable to grow, there is not a similar novel substitute for lemon cucumbers. We've encouraged customers to grow their own in lieu of giving up precious growing space at the farm. Stropharia will be used in limited applications if our next grant application is awarded.
A thorough assessment of the costs required to improve these severely compacted fields helped us to come to terms with the fact that not all our fields are worth amending, and alternative practices or uses should be considered.
This project gave us an important opportunity to talk with customers, community gardeners, and the general public about the challenges of urban farming, as well as new approaches that can work at a smaller scale. The story of soil is critical to farmers, but is usually unknown to the general public. This gave us a platform to explain basic science and research methods to school age kids and adults.
There were a few challenges to the research methodology. We did not test non-inoculated ramial mulch against the other treatments. This would have helped us to pull out the effects of the Stropharia more strongly.
An additional application of the Stropharia in year two could have also helped us to better understand the role of Stropharia in this system. The mycellium was clearly doing work to breakdown the wood chips, even though fruiting didn't happen. The source of the Stropharia may have been poor quality. Previous experience with the spawn had bags densely filled with spawn. The spawn was not densely inoculated, possibly from the haste of the seller to produce the quantity we required. Purchasing large volumes of Stropharia is prohibitive due to production practices, and this could be possible for multiple sellers.
While we ultimately answered the questions around soil health and mulch, a third year of research could have been very eye-opening. Because wood chips take years to breakdown, we expect that the change to soil nutrients and impacts on various crops would have continued after another year. We're left to wonder if the positive effect from the Stropharia on cabbage would have disappeared in year three as those nutrients were used up and as more nutrients were released in the other treatments.
We did not successfully answer questions around customer demand for the mushrooms and cucumbers due to poor productivity. We chose to test beets in year two because we already knew they didn't perform well in those fields. A third year of data would have told us more about crops like beets that need the greater rooting depth. Lemon cucumbers should have been tested in year two as well, though we opted to omit them because they proved to be a vector for cucumber beetles and pathogens, and we didn't want to increase the pressure on other high value cucumbers.
We will continue to test Stropharia on a smaller scale, with hopes of establishing enough natural spawn to use it to spread in specific areas. We will not likely grow more lemon cucumbers due to the pest and pathogen issues, and relatively short fruiting season (3-4 weeks). Wood chips will continue to be used as they are a free source of soil amendment. An unexpected result was the interaction between cabbage and calcium. We plan to test out if we can strategically plant cabbage in fields as a means of calcium mining to help lower the soil pH.
These results are particularly useful for urban farmers, and growers working with marginal lands, or adding novel crops in the Northeast US.