A three-year study conducted at Cornell University revealed that the impact of sheep grazing on land where solar panels are located varies with the number of animals. According to the results of the study, the total abundance of beneficial insects in the area grazed by two sheep per hectare was 38 percent higher than in the control area using the mowing method. But more intensive grazing did not produce the same results. At eight sheep per hectare, the number of honey bees decreased by 45 percent compared to the control area.
The team compared different grazing densities on the Cascadilla Community Solar Farm in Dryden, New York state. Researchers evaluated wild bees, honeybees and ladybugs. Honeybees were the main source of the total increase in the two-sheep group. The abundance of honeybees in this group increased by 83 percent.
In the section where four sheep were used per hectare, the total abundance of beneficial insects remained at a similar level to the mowed control area. In contrast, four sheep controlled vegetation more effectively than two sheep. While weed control was at its highest level in the group of eight sheep, the health of the flock remained good. But the decline in honeybees showed that plant management and insect life do not always go in the same direction.
These results are based on a specific terrain and a three-year monitoring period. Therefore, two sheep per hectare should not be read as an immutable prescription for every country, climate and solar power plant. The concrete contribution of the research is that not only grass height but also insect communities are taken into account in maintenance decisions. The study was published Oct. 7 in the journal Environmental Research Letters.
Researchers develop tool to plan herd size
In addition, a separate team of the university prepared a decision model for businesses grazing in solar fields. The spreadsheet-based tool evaluates target herd size, animal purchases and sales, expected revenue and costs together. Vegetation expected to grow on particular sites is also taken into account. Since there is still a need for other mowing methods in insufficient herds, the model also makes this gap visible.
The model developed by Vincent Slaugh, Linwei Xin and Shane Henderson aims to help farmers and power plant operators evaluate contract terms. United Agrivoltaics reports that it is incorporating the tool into its process of working with new participants. The research explaining the economic model was published Sept. 28 in the journal Manufacturing & Service Operations Management. Thus, two separate studies address the maintenance, income and ecological needs in the same field from different perspectives.