The proposed field trial was established in a commercial citrus grove on 22 acres of a typical SW Florida flatwoods-type site in Hendry County (Lat/Lon: 26° 34′ 28.3518″ N, 81° 30′ 34.3772″ W). A total of 3232 trees were planted in 32 rows on 16 beds, each separated by furrows, at a spacing of 12 ft within rows and 25 feet between rows (145 trees per acre). Each row contained 101 trees. Trees were composed of Valencia scion (clone 1-14-19) on four different rootstocks: 1) X-639, a high-vigor inducing cultivar; 2) US-802, a high-vigor inducing cultivar; 3) US-812, a moderate-vigor inducing cultivar; and 4) US-897, a low-vigor inducing cultivar. Except for US-802, which is a pummelo × trifoliate hybrid, rootstocks are mandarin × trifoliate hybrids. Trees were arranged in a randomized split-plot design with treatment (compost or no compost) as the main plot and rootstock (X-639, US-802, US-812, US-897) as the subplot. Plots were arranged in eight blocks (16 beds) across the experimental site with each block containing two beds either treated with compost or without compost. Each bed contains 200 experimental trees, 100 per row, arranged in sets of 50 trees of each rootstock cultivar and separated by a non-experimental tree in the center of each row. OMRI certified compost (Green Care Recycling, Ft Myers, FL) was applied at a rate of 5 tons per acre and tilled into the soil. A subset of trees in each experimental unit was selected and tree heights and trunk diameters (above and below the graft union) were measured. Soil samples were collected from each experimental unit and divided for nutrient analysis and soil microbial analysis.