OSU study: Combining solar panels and lamb grazing boosts land productivity

CORVALLIS, Ore. (KTVZ) – New research from Oregon State University scientists suggests that combining sheep grazing and solar power generation on the same land could significantly increase land productivity.

It is believed that this will be the first study to examine livestock production under agrivoltaic systems that combines solar energy production with agricultural production, for example by growing agricultural crops or grazing animals.

The researchers compared lamb growth and pasture production on pasture using solar panels and traditional open pasture. Overall, they found less high-quality feed in the sunny pastures, and the lambs raised in each type of pasture gained a similar amount of weight. The solar panels, of course, add value in terms of energy production, which increases the overall productivity of the country.

Solar panels also benefit the lambs by providing shade, which allows the animals to save energy. Lamb grazing also reduces the need to control plant growth under the solar panels with herbicides or regular mowing, which requires additional labor and expense.

“The results of the study support the benefits of agrivoltaics as a sustainable farming system,” said Alyssa Andrew, an Oregon graduate student who is the lead author of the paper published in Frontier in Sustainable Food Systems.

The US solar photovoltaic system has grown an average of 48% per year over the past decade, and current capacity is expected to double again over the next five years, the researchers say.

Previous research has found that grasslands and farmlands in temperate regions are the best places to install solar panels for maximum energy production. However, generating energy in photovoltaic systems requires large areas, which can potentially lead to competition between agricultural uses.

Agrivoltaics seeks to dispel this competition by measuring the economic value of energy production and agricultural use in the same country. Previous research has focused on plants and solar panels and found that some plants, especially species that like shade, can be more productive when combined with solar panels.

Another recent Oregon state study found that the shade provided by the solar panels increased the number of flowers under the solar panels and delayed the timing of their flowering. Both outcomes could help the farming community.

The just published study of lambs and solar panels was conducted on the Oregon state campus in Corvallis in 2019 and 2020. Results include:

  • The lambs gained almost the same weight on both types of pasture in both years.
  • The daily water consumption of lambs in the two pasture types in spring 2019 was similar in spring, but lambs in open pastures consumed more water than those grazed under solar panels in late spring. In spring 2020, no difference was observed in the lambs’ water intake.
  • In the two years, solar pastures produced 38% less forage than open pastures.
  • The total grazing yield on open pastures was $ 1,046 per hectare (one hectare equals 2.47 acres) per year and on pastures with solar panels, it was $ 1,029 per hectare per year.

“The total return is about the same, and that doesn’t take into account the energy the solar panels produce,” said Serkan Ates, assistant professor in the Oregon Department of Animal and Rangeland Sciences and co-author of the paper. “And if we designed the system to maximize production, we’d probably get even better numbers.”

Andrew is currently working on a follow-up to this study, in which she quantifies feed and lamb production from three different types of pasture under solar panels.

In addition to Andrew and Ates, several colleagues from Oregon State College of Agricultural Sciences co-authored the paper: Mary Smallman from the Department of Animal and Rangeland Sciences and Chad Higgins and Maggie Graham from the Department of Biological and Ecological Engineering.

The Agricultural Research Foundation in Oregon State funded the research.

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