Share | 10/26/2020
The effects of climate change are heavily impacting the agricultural industry in Chile. Once ideal for citrus cultivation, the country is now declared as “under agricultural emergency” as a rainfall deficit of more than 90% compared to the previous decade contributes to water scarcity. Thus, water monitoring is vitally important for the industry and presents a new challenge in using the least amount of water for plants to thrive without wasting any of this already scarce resource.
Proper irrigation is key to quality mandarin production. Excessive water inputs may translate into higher vegetative growth, but other important fruit quality parameters could be negatively impacted, such as total soluble solids content, acidity, pigments, or fruit size.
On the other hand, low water inputs are manifested as delayed vegetative growth, uncertainty in flowering, fruit size, and plants more sensitive to abiotic and biotic factors that impede their growth and development.
The Crop Water Stress Index (CWSI) is the most frequently used index to quantify crop water stress based on leaf temperature. It ranges from 0 to 1, with the numbers closest to 1 being those with a higher degree of water stress.
NutriGIS, an agricultural service provider in Chile uses both the multispectral and thermal capabilities of the MicaSense series Altum to obtain data for the CWSI and analyze the water status of orchards in the region.
In this particular mandarin orchard, located in Santiago at 290 meters above sea level, NutriGis flew a Matrice 200 equipped with the Altum. Their goal was to evaluate the drip irrigation system in place aiming to use less water without impacting fruit production quality.
The multispectral bands and thermal sensor included on Altum provided a key tool to identify rows presenting some level of hydric stress, according to the CWSI obtained. The plants highlighted in figure 4 received less water which translated into a higher temperature due to the stress caused by the lack of moisture at the root level.
However, manual surveys determined that the lack of moisture was not due to drips or leaks, but rather soil management. The rows with some level of hydric stress presented sandy-loam soils in contrast to loam soils in low-stress areas.
This information led the NutriGIS team to recommend changes in the irrigation system, including adjusting the pipe sizes to apply more pressure in high-stress areas. NDVI and red edge indices were also used to determine a new irrigation program based on the vegetation coverage, reducing the amount of water needed to irrigate the orchard by 15-20%.
Altum’s multispectral and thermal data has the potential to greatly contribute to the sustainability of mandarin orchards, helping managers use only the necessary resources for a successful harvest. This will ultimately have a greater impact on farmer’s bottom lines and the sustainability of the industry.
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