Analyzing Trend in Modis Derived Crop Phenology for Corn and Soybean in Comparison with Field-Based Crop Progress Data

Crop phenology is helpful for the sustainable management of agricultural resources. It provides crucial indicators for improving decision-making regarding the application of fertilizers, irrigation, pesticides, and timely harvesting. The aim of this study was to analyze and compare the long-term trend of corn and soybean phenological transition dates using MODIS-derived crop phenological parameters (MCD12Q2) and ground truth crop progress data reported weekly by National Agricultural Statistics Service (NASS) in major crop growing states within United States from 2001 to 2021. Moderate Resolution Imaging Spectroradiometer MODIS phenology product (MCD12Q2) was downloaded and mosaicked. Pure crop pixels were identified using Crop Data Layer (CDL) and CornSoy data layers (CSDL). Crop phenometrics derived from MODIS were compared with Ground truth data on crop progress data at key phenological stages reported by NASS. Trends for phenological transition dates for corn and soybean crops were generated for the study area using median value within the state. Similarly, spatiotemporal patterns at pixel level for trends in greenup and maturity stages of corn and soybean were produced. The results showed that MODIS derived crop phenological dates were comparable with field-based phenology data. Substantial interannual variation was observed in phenological transition dates for both crops from 2001 to 2021.