Diverse Agroecosystem Soil Sampling

A total of 90 soil samples were used for this research. Soils were collected in five different plots under different land uses in the Everglades Agricultural Area (EAA) including an unmanaged native plot (plot 1), a sugarcane-spinach-fallow-sugarcane rotation plot (plot 2), a sugarcane-sweetcorn-rice-sugarcane rotation plot (plot 3), a sugarcane-sweetcorn-fallow-sugarcane rotation plot (plot 4), and a year-round sugar cane plantation plot (plot 5). Plots 2–5 had been historically cultivated with sugar cane for 2 (plot 5) or 3 (plot 2–4) years. Starting from January 2017, plot 2 was planted with spinach till May 2017, followed by a 28-week fallow period before sugar cane plantation in December 2017. Plot 3 was planted with sweet corn from January to May 2017, followed by rice cultivation from May to October 2017 and an 8-week fallow period before sugar cane plantation in December 2017. Plot 4 was planted with sweet corn from January to May 2017, also followed by a 28-week fallow before sugar cane plantation in December 2017. Plot 5 was cultivated with sugar cane for a third consecutive year. Soils were collected during May 2017 to April 2018 at 2–3-month intervals. The area of each plot is ~20,000 m² (~100 × 200 m square). Biological triplicates were sampled in each plot, each containing 9 random cores of 10-cm topsoil within a subplot of ~10 × 10 m square, and the samples were immediately transported to the laboratory on ice. Part of the soil samples were stored in –20°C before DNA extraction.