Performing Department
(N/A)
Non Technical Summary
Ground-mounted solar arrays on farmland will increase significantly in number in the US Northeast in the coming years and offer opportunities for co-location with sustainable animal production agriculture. This research project will explore how renewable energy can be co-located with sheep grazing to achieve multiple positive ecosystem outcomes: Sheep will be grazed in a 54-acre, ground-mounted solar array to test the impact of 6 different stocking densities. Research will investigate aspects of animal, habitat, and soil health, including sheep welfare, health, and nutritional status, as well as forage biodiversity, pollinator habitat, and soil organic carbon sequestration. Generated data will help identify underlying scientific concepts connecting sheep grazing density with ecosystems impacts relating to climate change and habitat decline.Findings will establish best management guidelines that can be implemented for managing the vegetation in ground-mounted solar arrays with sheep. These established best management practices will produce multiform positive outcomes for ecosystems, livestock, farmers and the public. For example, these practices will allow for increased biodiversity of foraged habitat and increased pollinator abundance in ground-mounted solar arrays. Best management practices will also allow for optimal amounts of sequestered carbon and provide optimal nutrition for sheep. Additionally, these practices will help produce high quality, locally-raised meat with the benefit of increased farm financial viability gained through vegetation management contracts. In all, this research project will promote sustainable land use and provide a strategy for grass-based ruminant agriculture to help mitigate climate change and habitat decline.
Animal Health Component
80%
Research Effort Categories
Basic
10%
Applied
80%
Developmental
10%
Goals / Objectives
This project will quantify the impact of grazing density (sheep per acre) on soil organic carbon sequestration, pollinator species abundance and diversity, as well as forage plant species diversity and pest-suppressing insect behavior. It will be carried out at the 54-acre Cascadilla Community Solar Site between Turkey Hill Rd and Dodge Rd adjacent to the Cornell University campus and commissioned on marginal native pastureland not in agricultural production for 10+ years.It will be investigated how US Northeast pastures can be managed to support sheep, pollinator habitat, and carbon sinks. The Cascadilla Solar Farm vegetation will be managed with sheep to test 6 grazing densities. Pollinators and forage will be quantified and identified within each grazing density level, as will soil organic carbon, nitrogen levels, and bulk density.The goals of this research are to answer:How solar sites should be managed with sheep to ensure on par vegetation management and high animal welfare and flock productivity.If pollinator habitat and grazing sheep can be co-located, providing valuable habitat for pollinator species, particularly those of conservation concern, while meeting nutritional requirements for sheep.What grazing intensity and stocking density creates the best habitat, and how plant species biodiversity and legume inclusion in the pasture influence pollinator diversity and forage quantity for bees and pest surprising insects.How grazing intensity and stocking density are connected to soil health and soil organic carbon sequestration, and how high legume inclusion alters soil health and soil organic carbon sequestration.What the fundamental scientific mechanisms are that connect grazing intensity to carbon sequestration.Our objectives are designed to observe and measure which sheep grazing density is best suited to:Prevent panel shading and achieve high quality vegetation management on par with traditional vegetation management?Benefit communities by increasing (sheep) farm viability and access to local meat?Achieve high animal welfare, health, and nutritional status for sheep under solar panels and achieve high flock productivity?Provide thriving habitat for bee pollinators and pest suppressing insects (ladybugs)?Support pastures with native, highly diverse vegetation?Find and sequester, over time, high amounts of soil carbon, and identify what role additional legume nitrogen plays?
Project Methods
The 54-acre solar site where the experiment will be taken out is fenced into 5 separate solar arrays varying from 8 to 12 acres each. Each array is divided into 6 paddocks of equal size. The paddocks within each array are randomly assigned to 6 grazing densities, including a control paddock. These densities are 0 (mowed) 4, 8, 12, 16, and 20 sheep per acre. Within each paddock, legume and control halves were established by seeding half of the paddock with additional King Argriseed Pollinator Pasture mix. The sheep have unrestricted access to both half paddocks at the same time. For sampling purposes, the plots are spatially divided into areas under the panels, and areas between panels resulting in:5 individually fenced arrays serving as experimental blocks6 equally sized paddocks within each array of the 5 arrays (grazing densities of 0 (mowed) 4, 8, 12, 16, 20 sheep per acre)2 stratified randomly assigned seeding treatments plots (clover pollinator seeding vs control)2 subplots per seeding treatment plots (areas below and between the panels)This results in a total of 120 subplots for sampling and measuring forage and soil, and 60 plots for entomological investigations, for which the areas below and between the panels are not investigated separately. Replication will be given by 5 total grazing rotations per year. Sheep will move from array S1 through S5 in every rotation and thus graze each paddock 5 times per grazing season. Seasonal replication (3 grazing seasons) will be given by adding 2 additional grazing seasons to the current season. The data will be analyzed as a split-plot design with years and arrays serving as blocks, grazing densities as levels, and legume inclusion as a stratified split plot.Grazing rotation, animal welfare, and health Prior to each grazing season, the sheep flock is weighed and sheep are assigned to grazing density groups. The sheep will be weighed, FAMACHA and ADG scored 5 times during the grazing season to establish nutritional and health/welfare status. The sheep will be moved among arrays (S1 to S5, in consecutive order) every 5 days in Spring and Fall (rotations 1 and 5) and every 10 days in rotations 2, 3, and 4. This results in rest periods for each array of 28 days in Spring and Fall, and 40 days in Summer, and a total of 200 grazing days per season between mid-April and mid-November, depending on weather conditions.Forage sampling Forage (above-ground biomass, composition, dry matter) will be sampled at every sheep move from array S1 to S5 in each grazing rotation 1 through 5, or a total of 25 times per grazing season. Maximized above ground biomass of forage are sampled in the 24 subplots of each array prior to grazing and clipped at 0.5 inches above ground, pooled, and weighed. Subsamples are dried until stable weights at 65 C are reached for dry matter determination; then they are ground, and frozen for later analysis. Wet lab chemistry (NDF, starch, sugar, protein, and ash) will be performed on pooled subsets per subplot at three timepoints per year (May, July, September) for chemical composition and nutrient density. Pooled portions will be kept for total C and N determination with dry combustion analysis for LCA of C and N. The rest of the sample is sorted into grasses (including sedges and rushes), legumes, and forbs, weighed and expressed as proportions for forage composition.Digestion trial Three times in each grazing season, a combination of 20 rams, wethers, and vasectomized rams will be accustomed to the grazing diet pertinent on the solar arrays for 10 days prior to the digestion trial. The animals will then be housed in individual metabolism crates. Forage will be mowed in randomly allocated plots in the 5 grazing density paddocks stocked with sheep daily and fed to 4 rams per each.Pollinators and pest suppressing insects At each sheep moving timepoint (from array S1 to S5 in each grazing rotation 1 through 5, or a total of 25 times per grazing season) each of the 60 plots (we will not differentiate between under or between panels for insect sampling) will be sweep netted. Insect samples will be collected in labelled bags and frozen until identification. All bees will be identified in the McArt lab, and subsequently digitized and added to the Cornell University Insect Collection to serve as a resource for future studies. All pest suppressing insects (ladybugs) will be identified in the Losey lab and added to the Cornell University Insect Collection to serve as a resource for future studies.Soil, plant litter, and below-ground biomass Plant litter samples will be obtained at three timepoints (May, July, September) throughout each grazing season in each of the 120 subplots. Samples will be dried, ground, and analyzed for C and N with dry combustion. Below-ground biomass will be sampled by establishing randomly allocated sampling plots at three timepoints (May, July, September) throughout each grazing season in each of the 120 subplots. Root matter will be collected, washed, dried at 45 C, ground, and subsequently analyzed for C and N by dry combustion. Random soil samples (hand-operated soil bulk density sampler at 7 cm diameter and 15 cm depth) will be collected in each of the 120 subplots at the end of each grazing season to establish bulk density and volume-weighted equivalent soil mass. Subsamples will be dried until constant weight for soil dry matter determination. Soil will be sifted through a 2 cm sieve and air dried for storage and analysis. Stone weight and volume will be determined. Soil samples will be analyzed for C and N with dry combustion. Total organic C stocks will be calculated using bulk density and concentrations. grazing density. Amounts fed (2x expected intake to allow for sorting and simulation of grazing environment) and refused will be quantified, subsamples will be analyzed for dry matter concentrations as well as dried, ground, and frozen for chemical nutrient content and dry combustion analysis for C and N content. Feces and urine will be collected in metabolism crates for a 4-day period after a 5-day adaptation period to the crates. Fecal samples will be dried, ground and frozen, urine will be collected and frozen. Dry combustion analysis will be performed to quantify total C and N of feces and urine. C and N content in feces and urine will be related to feed nutrient content and expressed in % bodyweight to allow for quantification of fecal and urine C and N deposited onto the solar site.Forage (plant) biodiversity Modified Whittaker sampling plots will be used to quantify forage biodiversity three times per year (May, July, and September) in all 120 subplots of the 5 trial arrays. Plant percentage cover, height, and stage will be recorded for every species identified.Evaluation:To evaluate the project plan, the 2-year timeline can be structured in field trial, lab analyses, administrative, and analytical tasks and structured in reachable milestones for evaluation:Milestones to be completed:Field trialGrazing trial and forage/insect sample collection: May, July, August, September, October 2021 & 2022Digestion trial: May, August October 2021 & 2022Plant litter, below-ground biomass sampling, Spring: May, August, October 2021 & 2022Soil sampling, bulk density, dry matter concentration: November 2021, November 2022Laboratory analyses, administrative, and analytic milestones Forage, feces, urine chemical composition, C and N content: February 2022, January 2023Bee pollinator and ladybug identification and quantification: February 2022, January 2023Soil, plant litter, root mass C and N analyses: February 2022, January 2023Preliminary data analyses for posters and abstracts: Fall 2021, Fall 2022Data analyses for publication(s): Fall 2021, Fall 2022Final data analyses for publication(s): March 2023Advisory group meetings: May, December 2022 & May, December 2023Data sharing, reports, and final publication: April 2023