A Review on Crop Residue Measurement and Sensing

Crop residue plays a crucial role in diverse areas of soil, biomass, crop yield, and the environment by impacting aspects such as soil organic matter, erosion, nutrient leaching, soil moisture and temperature, plant emergence, in turn influencing plant biomass and crop yields. Measuring crop residue coverage has been a long-term practice, primarily for monitoring purposes by agencies for various programs. More recently, increased research effort has been focused on improving the means and mechanisms of measuring and sensing crop residue efficiently and on large scales for both monitoring and improved agricultural decision-making insights. This review attempts to provide an overview of crop residue measurement and sensing, presenting a holistic review of the different measurement techniques available. It also highlights how research has shifted from field-based measurement to the use of diverse sensing approaches and future directions. Traditional methods of crop residue measurement are reviewed and the literature on more modern sensing approaches is summarized through categorization of the approaches based on sensing scale of satellite-, UAV-, and ground-based systems. Key findings highlight the growing shift toward high-resolution UAV sensing and the increasing use of machine learning models for improved classification. Identified critical challenges, particularly in satellite sensing, include spectral similarity between residue and soil, influence of moisture, and limited real-time application. The review aims to provide a summary of the current state of crop residue sensing with insights into potential areas for opportunities, especially through on-machine sensing systems, emphasizing the need for real-time, integrated, and adaptive residue coverage sensing solutions.