Green Canopy Cover Percentage as a Method for Quantifying \u3ci\u3eAndropogon virginicus\u3c/i\u3e (Broomsedge) Reduction through Fertilizer Applications in a Cool Season Hay Production System
Remote sensing has been used to measure green canopy cover for a variety of agronomic purposes. This study explores the use of digital imagery as a method to quantify warm and cool season grasses in a hay production system. Due to alternate growth periods, cool and warm season grasses show greener color in different seasons. These seasonal color shifts provide an opportunity to measure their respective percentages when growing together in a system. This study was conducted in a hay field that was originally dominated by cool season grasses including tall fescue (Festuca arundinacea) and Kentucky bluegrass (Poa pratensis), but had been invaded by broomsedge (Andropogon virginicus), a native, warm season grass that is known to be an indicator of poor soil fertility. Soil tests for this field revealed a severe potash deficiency. Plots with high percentages of broomsedge would only be greener during the peak times for warm season grasses, and have a lower percentage of green canopy cover throughout the rest of the year, leading to a lower average green canopy cover percentage for the entire year. Thirteen different fertilizer regimens were applied with four replications each in a randomized complete block design (N-P-K kg/ha: 0-0-0, 0-0-202, 0-0-404, 0-45-0, 0-45-202, 0-45- 404, 202-0-0, 202-0-202, 202-0-404, 202-45-0, 202-45-202, 202-45-404, 43-43-43). Images were captured with a Nikon D750 DSLR camera and a DJI Phantom 4 Pro V2.0 drone throughout 2020, and analyzed for green canopy cover percentage using the Canopeo application in MATLABR2020b.The two fertilizer treatments showing the highest yearly averages for green canopy cover were those that contained the highest levels of N, P, and K (202-45-202 kg/ha and 202-45-404 kg/ha). This method of collecting data was both time and labor efficient and yielded adequate and useful data
