English: On August 13, 2018, NASA’s Aqua satellite passed over Paraguay, allowing the Moderate Resolution Imaging Spectroradiometer (MODIS) on board to acquire a true-color image of fires burning in agricultural fields.

The light tan, rectangular-shaped areas mark agricultural activity. Neatly-edged fields typically indicate cropland although smaller pastureland may appear similar. The edges of these fields are bordered by dark green forests. Red areas mark “hot spots”, which are areas where the thermal bands on the MODIS instrument detected high temperatures. The gray smoke rising from the hot spots indicate that the heat arises from actively burning fires.

Farmers have long used fire to manage land. It can be used to clear stubble prior to planting, to open new land for use, and to refresh pasture, and to burn agricultural waste. The fires in this image appear to be on the edge of fields and next to or in the edge of forest. At times this pattern is seen with slash-and-burn clearing of forest, but in most cases the fires affect the straight edges of the fields and are in areas where substantial forest is available for clearing. In Paraguay, mid-August is the preferred time for planting maize, potatoes, and sweet potatoes. Although it is not possible to discern the reason for a fire from satellite imagery, it is likely that these fires are being used to burn stubble and ready the ground for planting these crops.

The regular and periodic burning of cultivated fields for the purpose of cheaply and quickly removing excess vegetation – including crop residue such as straw, weeds, and waste – prior to planting a new crop is known as “open burning”. Many farmers believe this enriches the soil; however, in reality such scorching damages soil and decreases productive capacity by destroying the organic matter and soil structure. Over time, burned soils become less fertile, retain less water, and are prone to erosion.