Vegetation Indices. How to work with historical data.
Agriculture is a crucial sector for providing food, fuel and other resources to meet the increasing demand of the growing population. To enhance the productivity and sustainability of agricultural practices, researchers have developed various indices that help in monitoring crop health and growth. NDVI, NDMI and EVI are some of the most commonly used indices in agriculture.
Vegetation indices (IV's) are equations that combine surface reflectance values from two or more bands of the electromagnetic spectrum in order to evaluate some property of the vegetation. Although they are not able to directly quantify any component of the vegetation, several IV's have great correlation with field variables (e.g. NDVI x green biomass), thus allowing to infer absolute values of a particular component of the vegetation in order to define the guidelines for field operations.Thus, the ability to access historical data of vegetation indices for a particular crop is very valuable as it allows us to have a very clear picture of the current and past state of the crop over the seasons to support various types of agronomic decisions.
EVI (Enhanced Vegetation Index)
The Enhanced Vegetation Index (EVI) is a powerful tool for evaluating the health and productivity of vegetation. By measuring the amount of green vegetation cover and its photosynthetic activity, specially in vegetation areas with high leaf area index (LAI), where the NDVI tends to saturate, EVI can provide valuable insights into the state of crops and forests.
This information can be used to optimize resource management, increase yields, and ultimately create value throughout the entire agricultural value chain. Whether you're a farmer looking to improve crop production, a supply chain manager seeking to ensure sustainable sourcing, or an investor looking to make informed decisions, EVI provides a valuable source of data and intelligence.
NDVI (Normalised Difference Vegetation Index)
For farmers and farmer data providers such as FMS companies – productivity zones will help to locate the areas of field or fields which require attention and allow for a greater understanding of the heterogeneity present of each field, as they provide the historical mean values for the vegetation index data in the form of zones within the fields. Several types of farm operations can benefit from an in-depth understanding of the field's historical heterogeneity, such as fertilisation and seeding.
This information can greatly enhance decision-making on where to apply resources on each field for an effective crop development, creating the potential for increasing yields without increasing field input costs.
NDMI (Normalised Difference Moisture Index)
The NDMI, unlike other vegetation indices, focuses specifically on the moisture content of plants using a combination of spectral bands in the near infrared (NIR) and shortwave infrared (SWIR) ranges, making it a trustworthy indicator of moisture in plants. Also, this index can detect areas where the crops are under stress due to the lack or shortage of water, suffer from field flooding and also areas that are prone to fire, which makes this information useful as well to firefighters and the forestry sector.
The NDMI is particularly useful for arid and semi-arid regions where water resources are limited, and it provides crucial information for optimizing irrigation schedules and improving water management.
How indices will help farmers?
Indices play an important role in helping farmers make informed decisions about their crop management practices. By providing valuable information on crop health, growth, and productivity, indices can help farmers improve yields and sustainability in agriculture.
Indices can also be used to assess crop yield potential. By monitoring the growth of crops over time, farmers can estimate the potential yield and adjust their management practices accordingly. For example, if the NDVI values of a crop are low, farmers may choose to increase irrigation or add fertilizer to improve the health of the crop.
In addition to crop management, indices can also help farmers make decisions about planting and harvesting. By monitoring the growth of crops in different areas, farmers can identify the best planting dates and determine the optimal harvest time. This can lead to improved yields and reduced waste, as crops are harvested at the right time when they are at their peak.
Finally, indices can be used to monitor the impact of environmental stressors on crops. For example, the EVI values of crops can be used to detect the impact of drought, while NDVI values can be used to monitor the impact of pests and diseases. This information can help farmers make informed decisions about pest and disease management, leading to reduced losses and improved yields.