Researchers note that the population of the planet has grown so rapidly over the past 100 years that 14% of all people that have ever existed are alive today. This growth has put pressure on agricultural production and the gathering of reliable harvest statistics world-wide. Hence, more effective management of agricultural resources is required. Agronomists understand that correct data on the state of fields, and crop conditions at each stage of growth is critical to farmers achieving their goals of optimizing costs, maximizing yield, and increasing sustainability.
Optical satellite sensors allow agronomists to assess the viability of plants and identify potential problems before symptoms become visible to the human eye, measuring the effect of crop canopies in the visible and infrared area of the electromagnetic spectrum.
The spatial resolution of modern sensors can return highly detailed information, allowing, in particular, scanning, diagnosis and localized treatment. Field crops, gardens and tree plantations are complex systems that require constant monitoring, which is often costly and highly subjective.
NDVI is the ratio of the difference between the near-infrared and red reflectance over their sum. It receives values from -1 (no vegetation) to +1 (abundant vegetation).
NIR – reflection in the near-infrared spectrum
RED – reflection in the red range of the spectrum
The NDVI was found to be related to many properties of the plants. It was, and in many cases still is, used to identify the health status of plants, to depict phenological changes, and to estimate the green biomass and crop yield.
Remote sensing allows a farmer or agronomist to determine any differences in crop growth depending on its location within the field. For example, during strong rains, a quick decision can be made if the field is at risk of run-off, but you do not know exactly which part of the crop is affected. In addition, the satellite images help to quickly identify a region infected with weeds which can damage dozens of acres in a short time. In certain cases, some parts of the field are very difficult to access or are surrounded by trees.