Tag Archive for: soil health

African Company Provides Agrisolar Refrigeration 

“A company called AkoFresh is providing solar-powered refrigerated storage that it says extends the shelf life of perishable crops from about 5 days to 21 days. This will boost seasonal income for farmers by more than $10 million, as well as reduce greenhouse gas emissions by 15%. Farmers can rent a space in the cold store for a daily fee of $0.30 per 20-kilogram crate of produce or take up a weekly subscription. They can also pay for the cold storage with crops instead of cash.” – World Economic Forum 

Research Being Conducted at Pennsylvania Agrisolar Site 

“In recent years, the environmental management of solar farms has become an exciting area of academic research, to assess how different practices affect the productivity of solar and agricultural enterprises and the land on which they operate. Two studies seeking to answer research questions around these topics are currently underway at Lightsource bp’s Nittany 1, 2 and 3 solar projects in Pennsylvania.   

All three sites were designed and are being actively managed to boost biodiversity and support pollinator populations, in addition to generating clean energy for Penn State and their students. Lightsource bp seeded the sites with a mix specifically formulated by the American Solar Grazing Association (ASGA), in partnership with Ernst Conservation Seeds and Pollinator Service. The seed mix, aptly named ‘Fuzz and Buzz,’ was designed to support pollinator species at solar sites, in addition to flocks of sheep. At Nittany 1, more than 700 sheep are managing vegetation through rotational grazing, an example of agrivoltaics, or co-located solar and agriculture.” – Lightsourcebp 

 New Zealand Solar Farm Will Host Sheep 

“Harmony Energy New Zealand has been granted approval to develop a solar farm in the Waikato which will generate electricity to power 30,000 homes as sheep graze underneath. The Environmental Protection Authority (EPA) has approved Harmony’s proposal for approximately 330,000 solar panels to be installed on 182 hectares of a 260-hectare site at Te Aroha West. The land will remain in the ownership of Tauhei Farms Limited, with livestock grazing continuing with sheep, rather than the current dairy herd.” –https://www.stuff.co.nz/business/300693453/hauraki-solar-farm-that-could-power-30000-homes-gets-green-light Power Technology 

What are asset managers looking for when they evaluate proposals from solar graziers? What kinds of concerns do asset managers have about grazing that need to be resolved to get to the contract stage?

Keanen Ryan and Lexie Hain from Lightsource bp joined us for a wonderful conversation that answered these questions from the solar operations perspective. Keanen and Lexie also discussed what they’re looking for from graziers in terms of services and experience in order to meet the economic and sustainability standards of Lightsource bp.

NCAT’s Energy Program Director Stacie Peterson takes us on the Follow the Sun Tour to their Minnesota stop at Connexus Energy Headquarters. The tour included a solar Farm to Table Sampler featuring solar grown food next to Connexus’ AgriSolar project.

The AgriSolar Clearinghouse is an NCAT project that is funded by the Department of Energy to form a community gathering , networking, and information hub regarding the colocation of solar energy production and agriculture.  The project will lead tours around the country to offer the public an opportunity to visit AgriSolar sites, talk with farmers, ranchers, landowners, and researchers about the projects, and network with the AgriSolar community. These tours showcase what is possible and help build the resources, network, and enthusiasm needed to create successful AgriSolar projects around the country.

Check out this awesome story from a recent AgriSolar event!

ASGA Board President Jonathan Barter and “The Grass Whisperer” Troy Bishopp joined us to talk with ASGA members about the principles of planned grazing and the specific issues one needs to know to do solar grazing. We had a lively discussion, with ASGA folks bringing up a number of practical questions about how to plan your grazing management (fencing, having retreat sites, rotations, and more) and the importance of having a grazing plan to fulfill contracts and keep operations profitable. The conversation also touched on grazing large-scale solar sites with larger herds, as well as regional variations.

We ended up running out of time, but Jonathan and Troy have promised to hold a round 2 of this Teatime soon. Keep a lookout for that one.

Carolina Solar Services has an impressive solar grazing operation based in North Carolina with high performance standards for the industry.

For our July Teatime, Brock Phillips from Carolina Solar Services talked with us about how they run their solar grazing operations and handle sustainable vegetation management at solar arrays. Brock touched on how they manage livestock, optimizing sites for sheep, seed mixes, the ecological benefits of their grazing, and more.

About the Speaker:

Brock Phillips is the Director of Livestock Services for Carolina Solar Services (CSS), a utility-scale solar O&M company based in Durham, NC. He manages a portfolio of solar sites across the Piedmont region of North Carolina through the integration of rotational livestock grazing and conventional vegetation maintenance. He began solar grazing in 2014 and since 2018 has worked with CSS to develop livestock grazing as a low-impact, ecological solution to solar farm maintenance.

Land use change is a major driver of soils’ properties variation and potential degradation. Solar photovoltaic plants installed on the ground represent a key to mitigating global climate change and greenhouse gas emissions. However, it could represent an emerging source of land consumption, although reversible, which prevents the use of soils for agricultural purposes and may affect crucial ecosystems services. Despite the large widespread deployment of photovoltaic plants, their potential effect on soil properties has been poorly investigated. The aim of this study was to assess changes of soil physical, chemical and biochemical properties seven years after the installation of the panels. For this purpose, the soil under photovoltaic panels was compared with the GAP area between the panels’ arrays and with an adjacent soil not affected by the plant. The main results showed that seven years of soil coverage modified soil fertility with the significant reduction of water holding capacity and soil temperature, while electrical conductivity (EC) and pH increased. Additionally, under the panels soil organic matter was dramatically reduced (-61% and -50% for TOC and TN, respectively compared to GAP area) inducing a parallel decrease of microbial activity assessed either as respiration or enzymatic activities. As for the effect of land use change, the installation of the power plant induced significant changes in soils’ physical, chemical and biochemical properties creating a striped pattern that may require some time to recover the necessary homogeneity of soil properties but shouldn’t compromise the future re-conversion to agricultural land use after power plant decommissioning.



GeoREG2022

By: Mariah Rogers, Graduate Student, University of Arizona

Do plants taste different under solar panels? Do they taste better? At the Biosphere 2 Agrivoltaics Learning Lab, we studied just that.

Why Should We Use Agrivoltaics?

Agrivoltaics—the production of agriculture and solar photovoltaic energy on the same parcel of land—is gaining attention as farmers are facing new struggles amid the climate crisis. With agrivoltaics, farmers can reduce water consumption, produce renewable energy, and continue to cultivate their land. However, there is skepticism toward growing crops under solar panels, as farmers may have to change the types of plants that are more shade tolerant.

The Biosphere 2 Agrivoltaics Learning Lab

At the Biosphere 2 Agrivoltaics Learning Lab (B2AVSLL), we study the microclimate—that localized environment under the solar panels— and how plant adaptations occur in the shade of the agrivoltaic system. Some of the adaptations that plants make in the agrivoltaic microclimates include differences in yield, changes to plant morphology (leaf size, fruit shape and color), and alterations in metabolites. These adaptations may cause differences in how people perceive these crops. To study these differences, we grow a slew of different crops underneath solar panels.

We grow tomatoes, basil, potatoes, beans, squash, and lavender, just to name a few. While some of the plants grown at B2AVSLL are heat tolerant, crops grown in this region of the U.S. still require a lot of water. With agrivoltaics, we can reduce water consumption and still have a good yield. So, it is in our best interest to figure out if they would be successful both for the environment and in the market.

The Study Goals

To understand how these crops would do in the market, we conducted a consumer sensory study at the University of Arizona. The three goals of the study were to: (1) to understand if people perceived a difference between agrivoltaic-grown crops vs. crops grown in full sunlight (control); (2) determine if people preferred agrivoltaic-grown crops compared to control; and (3) discover if people were willing to pay more for crops grown in agrivoltaic conditions.

A total of 105 people participated in the study. Panelists were subjected to different conditions and samples, based on the site and the day they were tasting samples. Tomato and basil, potato and bean, and potato and squash were tasted by panelists.

Does Agrivoltaics Change the Flavor of Plants?

To understand if there was a difference between agrivoltaic- and control-grown samples, we used a triangle test where participants were given three samples with a random three-digit code; two of the samples were the same and one was different. We then asked the participants to pick which sample was the “odd one out.”

So, did agrivoltaics change the flavor of the crops? Yes and no. Tomato, bean, and squash samples (all fruits) were perceived as different by tasters. Basil and potato samples were not perceived as significantly different by tasters.

Does Agrivoltaics Make Plants Taste Better?

To understand if there was a preference between samples from the two growth conditions, we then conducted a paired preference test. We gave tasters two samples with random three-digit codes and asked if they preferred one sample more than another, or if they preferred neither sample.

Unsurprisingly, the results were mixed. People significantly preferred beans grown in the control setting over those grown in agrivoltaics. In addition, agrivoltaic-grown basil, potato, and squash samples were preferred by tasters.

Are People Willing to Pay More for Agrivoltaic-grown Produce?

After the triangle and preference tests, we asked participants if they would be willing to pay more or less for their favorite samples. Overall, we found that participants were willing to pay the same or more for all samples after they knew that their favorite samples were grown in agrivoltaic systems.

What Does This Mean for Farmers and Investors?

Because consumers can’t tell a significant difference in vegetable samples, and they preferred basil, potato, and squash, it may be in farmers’ best interest to grow these crops, especially in the desert. By marketing the produce as grown under solar arrays, and educating consumers about agrivoltaics, farmers may be able to sell their produce for slightly more at farmers markets.

What Does This Mean for You as a Consumers?

Buying for foods that are grown using agrivoltaics means supporting solar energy generation through purchasing fruits or vegetables. If you already go to the farmers market to buy fruits and vegetables, you may want to consider buying agrivoltaic-grown produce. If you want something that tastes like what you already buy from the farmers market, then you may want to buy vegetables. If you are looking for a different tasting product, you may want to buy fruits grown under agrivoltaics. You can be the judge whether you prefer one growth condition over another.

Cannon Valley Graziers is a vegetation-management company based in Southeastern Minnesota. Since 2018, Arlo Hark and Josephine Trople have been using their flock of sheep to manage vegetation in a variety of environments, working closely with customers to meet their management goals. Cannon Valley Graziers provides vegetation-management services for solar developers throughout southern Minnesota. The vegetation on community and utility solar sites is traditionally mowed multiple times per year, incurring high operations/maintenance costs. By applying adaptive-grazing strategies on these solar sites, Cannon Valley Graziers can reduce the annual maintenance costs for developers, while also having a positive impact on the soil health and water quality of southern Minnesota. 

Photo Courtesy of Cannon Valley Graziers

The principles of adaptive grazing are well-suited for vegetation management. By mob grazing—introducing a large number of sheep into a small area for a short amount of time—Hark is able to deploy his flock with surgical precision to meet the needs of each site. After the desired objectives are met, he moves the flock to the next site. Meanwhile, the vegetation is allowed to recover, strengthen its root systems, and grow more resilient. Hark says these root systems are key for soil regeneration and water quality. Deeper roots build organic matter and allow for the transfer of minerals deeper into the soil. Strong root systems also improve the soil’s ability to store and maintain water, which reduces soil erosion and chemical runoff into nearby waterways. 

Photo Courtesy of Cannon Valley Graziers

Growing a sheep-powered vegetation-management company is not without challenges. Large flocks require large trucks and trailers to move from site to site. In addition, most sites do not have water, so water must be supplied by the grazier. But to Hark, the effort is worth it. “It makes sense to stack benefits on these sites,” he explains. “We are providing a top-notch service to our customers, improving soil and water quality, and providing meat and fiber to our community. It just makes sense.”

Written By: Amanda Gersoff (M.Sc. student), Dr. Seeta Sistla

Natural Resources Management and Environmental Sciences Department, Cal Poly, San Luis Obispo

Our team is studying the ecological aspects of utility-scale solar arrays set on former agricultural land whose understory is maintained by sheep grazing. By gaining a better understanding of the ecological implications associated with panel shading coupled with grazing by sheep, we hope to develop insights into agrivoltaic development that can maximize positive environmental effects while reducing negative externalities. We are currently focusing on two utility-scale solar energy sites located in San Luis Obispo County, California. At these sites, we conduct weekly monitoring to measure surface microclimatic features, soil nutrient cycling processes, and plant community composition.

Collecting soil cores at Topaz Solar Farm. Photo: Amanda Gersoff
Collecting aboveground biomass samples at Topaz Solar Farm. Photo: Amanda Gersoff

We hypothesized that the novel shading caused by the arrays will affect plant and soil dynamics, including decomposition, biomass production, plant moisture content, the timing of plant community events (like flowering duration and time to senescence) and plant nutrient content. Our work has suggested that placing arrays in arid grazing landscapes that are emblematic of the western U.S. can confer synergistic benefits for the plant community and their grazers. For example, our work has found that the plant mass beneath the array rows has high water content, greater nitrogen content (correlated with higher soil plant-available nitrogen), and lower non-digestible fiber content than areas that are grazed but outside the arrays’ direct shading influence. We are currently tracking phenological patterns of greenness and flowering time/duration in the array, to better understand if the traits we are observing correlate with an extension of the growing season for the community with the array’s shading area.

Over the next year, we will continue monitoring to gain a more comprehensive understanding of how exactly spatial heterogeneity created by panel shading influences ecological systems. At both sites, the practice of solar grazing, in which sheep are used to maintain vegetation under solar panels, has been implemented. By combining agricultural and renewable energy production, also known as agrivoltaics, multiple benefits can be realized. Utilizing rotational grazing by sheep is beneficial because it can reduce the costs of mowing and maintenance, support local shepherds, cultivate biodiversity, cycle nutrients into the soil, and decrease the risk of sparks igniting dried grasses. As utility-scale solar energy grows, it is important to look to dual-use solar for increasing efficiency and maximizing environmental benefits.

Rotational grazing by sheep at Goldtree Solar Farm. Photo: Amanda Gersoff
Patterns of phenological differences  vegetation due to shading at Topaz Solar Farm.  Photo: Amanda Gersoff
Owl’s clover (Castilleja exserta): An annual native wildflower common in the rows adjacent to panels at Topaz solar Farm. Photo: Amanda Gersoff

This is a one-page overview of contour buffer strips, their application, and their effectiveness.