Monitoring of Grass Weight Dynamics Based on Satellite Remote Sensing Using State-Space Model: A Case Study of Grassland in Kochi University

Abstract

Cattle raising method using grazing is useful for saving labor, maintaining abandoned land, and improving cattle health. Japanese brown cattle-Kochi, which are suitable for grazing, are breed in grassland in the campus of the Faculty of Agriculture and Marine Science, Kochi University from March to November every year. In this study, we developed a method for estimating dry grass weight (mean absolute error: 0.05 to 0.15 kg･m⁻²) that can be used over a long grazing period. By applying this method to satellite images taken in 2022 and 2023, we attempted to visualize and compare the dynamics of dry grass weight, and to extract issues or knowledges on grassland management. The results suggest that for improving the efficiency and effectiveness on grassland use, it is necessary to pay attention to grass cultivation before the grazing period, rotation planning of grassland fields based on the topographical and geographical characteristics of each field, and environmental design considering the behavioral characteristics of cattle.