Detecting trends in cereal crop sowing dates using Landsat

Agronomic research suggests Australian farmers may increase wheat yields by 13 to 47% and reduce risk of crop failures by sowing crops earlier than is currently practiced. This study investigated the potential to use remote sensing to assist in evaluating changes in farmer sowing date practices in response to research recommendations, using study paddocks in the southern Australian cropping region. Vegetation Indices (VIs) derived from Landsat imagery were utilised by fitting a 5 parameter logistic curve (5PL) to the VIs from days 50 to 250 of each year, encompassing the crop green-up period. This method was applied to 10 co-located paddocks with sowing time records spanning years 1988 to 2014, and 17 dispersed paddocks with two years of sowing history. The method shows promise in detecting crop green-up, but only in years and locations where cloud cover does not prevent successful image capture at key crop growing times.