We monitored some soybean crops in Padua using our EarthAlytics cloud platform.
The soybean plants belong to the leguminous class. Bacteria on the roots of these plants take nitrogen from the air and fix it in the soil, so that other plants that require nitrogen can also use it.
This plant helps to improve the nitrogen content in the soil and allows farmers to apply the so-called “crop rotation”.
Light helps us to understand crops health
Thanks to the NDVI index we can describe the vigour level of the crop and have a graphical representation of it and its formula is:
The index is calculated from satellite images produced by sensors that acquire red (R: 0.7 µm) and near infrared (NIR: 0.9 µm).
It evaluates the presence of photosynthetic activity, as it relates the spectrum of red, in which there is absorption by chlorophyll, and that of near infrared in which the leaves reflect light to avoid overheating.
The index values are typically in the range of -1 and +1. The presence of vegetation assumes values greater than 0.2.
Considering a time period of 5 years and working with datasets belonging to the same seasonal period we have calculated the NDVI index for each year.
The interpretation of the absolute value of the NDVI is highly informative, since it allows to immediately recognize areas of the field that could present growth problems or alternatively to precisely evaluate the state of the crops and the effectiveness of the agricultural techniques used.
For ease of analysis all values between -1 and 0 are not considered because they represent typical values of non-cultivated areas such as rivers and only values between 0 and +1 are taken into consideration. This range corresponds to a gradient of colors ranging from RED to GREEN where red stands for almost absent plant cover and green stands for total plant cover with very high vigor.
Crop rotation highlighted thanks to NDVI
Looking at the images and the index in the past 5 years, we were able to state that the crop rotation we mentioned earlier was actually conducted.
The crop rotation is stable for the analyzed field, while this is not the case for the other two fields.
A tool like EarthAlytics can be used by farmers or technicians, allowing them to have clear picture of their crop’s health using these vegetation indexes, being able to promptly react in case of health problems of individual plants. Using remote sensing techniques allows any farmer to optimize crop management with extreme ease thanks to the monitoring of each field throughout the seasonal evolution of the crop.