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Using Biomass and LAI to Guide Decisions

14/03/2025 The Biomass Index and Leaf Area Index (LAI) provide valuable insights into crop condition and development through remote sensing. Farmers can use these indicators to optimize fertilization, crop protection, and harvest timing – even without advanced precision farming equipment. Much of this data is freely available and helps save time and resources.


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Introduction:

Modern agricultural operations increasingly use vegetation indices such as biomass indices and the Leaf Area Index (LAI) to monitor the condition of their crops and make informed decisions. These metrics make it possible to objectively quantify plant growth, stand density, and vitality. The following sections define these indices and explain how they are collected, interpreted, and practically applied—both for highly technological precision farming operations and for farmers without digital high-tech equipment. In doing so, the relevance of biomass and LAI data for modern agriculture is highlighted, and the concrete advantages that result in practice are presented.

1. Definition and Explanation of Biomass Index and Leaf Area Index (LAI)

Biomass Index:
The biomass index is a vegetation index that provides insights into the existing plant biomass and the condition of the crop stand. A commonly used biomass index is the NDVI (Normalized Difference Vegetation Index). It is calculated from reflectance measurements in the red and near-infrared (NIR) spectrum and serves as a measure of the “greenness” or density of vegetation (earthobservatory.nasa.gov). Healthy, dense stands absorb a lot of visible light (red) and strongly reflect near-infrared light—the more leaf mass present, the higher the NIR reflectance (earthobservatory.nasa.gov). The ratio of this reflected radiation is converted into an index; for NDVI, the resulting value lies between -1 and +1, with values near +1 indicating high leaf density (earthobservatory.nasa.gov). In general, biomass indices use combined reflectance measurements (typically red and NIR) to make the condition and vitality of plants measurable (dlg.org). Such vegetation indices closely correlate with plant parameters—in scientific studies, NDVI values have been shown to be related to above-ground biomass, LAI, water content, and chlorophyll content of stands (literatur.thuenen.de). Sensors measure the light reflected by the plant canopy and convert the signals into indicator values, allowing indirect estimation of characteristics such as biomass and nitrogen supply status of the crop (dlg.org).

Leaf Area Index (LAI):
The LAI is a dimensionless metric for the foliage density of a plant canopy. By definition, the LAI corresponds to the total leaf area of all leaves per ground area (typically given as one-sided leaf area in m² per m² of ground) (lpvs.gsfc.nasa.gov). In other words: an LAI of 3 means that the leaves of a crop cover the ground with three times the area of the underlying surface. In practice, the LAI is a measure of the green leaf mass and thus the photosynthetically active surface of a crop. It reflects how efficiently a plant canopy can absorb light, which is linked to growth and biomass production (agrarraum.info). A higher LAI indicates a denser, more vigorous crop, while a lower LAI suggests sparse vegetation. LAI is regarded by scientists and authorities as an important indicator—it is considered, among other things, an Essential Climate Variable in climate models and a key metric for assessing ecosystems and agricultural structures (agrarraum.info). Modern remote sensing methods make it possible to derive LAI over large areas from satellite data by converting spectral reflectance values into corresponding LAI estimates (sdi.eea.europa.eu). Overall, both biomass indices (such as NDVI) and LAI provide a quantifiable description of plant stands that can serve as a basis for further analyses and decisions.

2. Methods for Capturing These Indices (Satellites, Drones, Sensor Systems)

The recording of biomass and LAI indices today is predominantly carried out using remote sensing technologies. Depending on the specific application, satellite imagery, drone footage, or sensors mounted on agricultural machinery are used. What they all have in common is that they provide contactless information about the crop stand.

In summary, farmers today have access to several methods of data collection: satellite images offer wide-ranging and regular data, drones provide flexible and high-resolution detail images, and machine sensors enable immediate data use during fieldwork. In many cases, these technologies are used in combination to leverage the strengths of each layer.

3. Interpretation of the Indices and Economic Conclusions

The biomass and LAI data obtained must be correctly interpreted in order to derive practical decisions from them. In general, high vegetation index or LAI values reflect a lush, vital crop stand, while low values indicate gaps, growth problems, or reduced stand density. This information can be used economically by identifying management zones and optimizing interventions.

From an economic perspective, farmers derive concrete measures from interpreting these indices (see Section 6). However, it is important to always consider indices in context (weather conditions, growth stage, crop type) and—especially in the case of anomalies—conduct field inspections and possibly sampling to verify the cause.

4. Applications in Precision Farming – Advantages for Digitally Equipped Operations

Farms equipped with modern digital technology (Precision Farming) can fully automate the integration of biomass and LAI data into their operational workflows and derive significant benefits from it. By linking data acquisition, data processing, and machinery, the indices are directly translated into action in the field, optimizing work processes and conserving resources.

In summary, Precision Farming technologies, in combination with biomass/LAI data, enable a new quality of farm management. Decisions are data-driven and often automated, which saves labor time and increases the precision of operational measures. Larger farms with the appropriate technology especially benefit from these advantages, as they are capable of analyzing and directly implementing the abundance of data (gdi.bmel.de). The investment in digital equipment pays off through more efficient production and higher yields or savings in operational resources.

5. Benefits for Farmers Without Precision Farming Technology

Even without high-tech equipment, farmers can practically benefit from biomass and LAI data. Not every farm has real-time sensors or automated fertilizer spreaders—but thanks to freely available remote sensing data and easily accessible services, the entry barrier into data-driven farming is low. Here are some of the practical advantages for traditionally operating farms:

In short: Farmers without their own Precision Farming devices can use biomass and LAI information as an additional decision-making tool. They improve their field observation skills, can time and adjust measures more accurately, and indirectly benefit from digital insights—all at low cost. This allows them to take first steps toward “Smart Farming,” which often already brings noticeable operational improvements.

6. Application Possibilities in Agriculture (Fertilizer Optimization, Yield Forecasts, Crop Management)

Biomass and LAI data are used in many areas of agricultural practice. Some key fields of application—with their associated benefits—include:

As the above points illustrate, the range of applications is extensive. Whether it's fertilizer management, crop protection, irrigation, or harvest planning—nearly every aspect of arable and crop farming can be improved with information derived from biomass and LAI data. What's crucial is integrating this information into the farmer’s decision-making process: the data alone yield no benefit—it is only when translated into concrete actions that they enhance the efficiency and sustainability of farming operations.

7. Availability of Data – Platforms and Sources (DLG, ESA, BMEL, EU, etc.)

One of the great advantages of our time is that biomass and LAI data are becoming increasingly accessible. Various organizations and platforms provide such data either free of charge or at low cost, allowing farmers and advisors to use them easily. Below are some key sources and initiatives:

Conclusion on Data Sources:

There is no shortage of data today—much of it is publicly available. The challenge lies more in filtering the relevant information from the data flood and making it useful for individual farm operations. Thanks to initiatives by the EU, BMEL, and others, access barriers are being continuously lowered. Every farmer—whether digitally equipped or conventional—can at least view basic biomass and LAI data for their fields and benefit from them.

This clearly shows: Biomass indices and LAI are highly relevant indicators in modern agriculture, and the widespread availability of this data enables all types of operations to monitor their crops more precisely and make informed, practical decisions—a development that continues to enhance the efficiency and sustainability of farming.


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