Forage Biomass and Nutritive Value of Grasses and Legumes Grown Under Agrivoltaic Systems

Abstract

Forage crops grown underneath ground-mounted photovoltaic systems (PV) may provide a feed source for livestock production. The objective was to evaluate forage biomass and nutritive value of crops, grasses and legumes grown under different PV conditions. Forages were planted underneath a 30-kilowatt PV site (30kW), a 50-kilowatt PV site (50kW) and one control site without PV (CON) in May 2022 with four replicates per site. Forage crops included alfalfa, field peas, meadow fescue, orchard grass, red clover, brown midrib sorghumsudan grass, white clover and 3 grass and legume mixes with either alfalfa, red clover, or white clover. Biomass samples were clipped at appropriate maturity levels for grazing. Samples were sorted for botanical composition and analyzed for nutrient value. Crop biomass, dry matter and nutrient values were analyzed with PROC Mixed of SAS with the fixed effects of site (30kW, 50kW, or Con), crop nested within site, and cutting (1st or 2nd) and the random effect of replicate nested within site. Forages produced less biomass at the 30kW (563.7 kg/ha) and 50kW (446.4 kg/ha) solar sites compared to CON (1099.7 kg/ha). The 50kW forages had greater crude protein on a dry matter basis (25.8%) than the 30kW (21.4%) and CON (20.9%). The 50kW (57.1%) forages also had greater total tract neutral detergent fiber (NDF) digestibility than the 30kW (52.5%) and CON (51.0%). Additionally, the 50kW forages had greater percent calcium (1.05%) compared to the 30kW (0.75%) and CON (0.84%). Forage biomass and nutrient values varied based on the solar array design and amount of sun exposure.