Delineating crop management zones within alfalfa fields using Landsat images

Alfalfa is one of the largest agriculture commodities produced in Wyoming. If information about crop growth variability within their fields is available to producers they can make informed decisions about how much water and fertilizer to use. The objective of this project was to identify areas of low/high growth within alfalfa fields under pivot irrigation systems in Southeastern Wyoming. Crop growth in these fields were measured using Landsat Thematic Mapper images acquired in 2008, 2010 and 2011. Normalized Difference Vegetation Index (NDVI) values of each pixel were computed from these Landsat images. NDVI values are higher when crop growth or vigor is higher and lower values can be associated with poor growth. Pixels were then assigned to high, medium and low growth based on their NDVI values. Data from these three years were combined to identify growth patterns over time and delineate management zones.