Sugarcane is an important crop in tropical regions of the world and especially for Brazil, the largest sugar supplier in the market, also running a domestic fleet of flex-fuel driven vehicles based on ethanol. Site specific production management can impact sugarcane production by increasing yield and reducing cost. Sugarcane fields are planted each five years, in average, and an important parameter that is measured after the planting operation is the gaps caused by problems during planting operation. But its economic return greatly depends on a good stand along the years. Especially in the harvest operation rhizomes can be removed by the base cut disks of the harvester if the sugarcane root system is too shallow. In the same way trailers and tractor may cause damages to the crop by traffic over the harvested rows causing injuries and soil compaction as tractor and harvester sequentially cross the area. Distances above 0.5 m between two consecutive stalks along the sugarcane row, measured at the soil level from stalks centers are considered gaps. It is usually measured manually by a team witch walks through the fields measuring gaps in predetermined points (field samples) and expressing results as a percentage of gaps in relationship with the total sugarcane row distance. Gaps on sugarcane can be measured and georeferenced to provide spatial information to managers related to planting quality and on evaluation of replanting requirement. We developed a study involving a technique to measure and locate gaps in the field by using a photoelectric sensor horizontally positioned underneath a vehicle. This sensor was connected to an encoder and a GNSS receiver to compute gaps measure and the distance between these gaps. Initial tests under controlled conditions were conducted by using regular stakes as obstacles with varying widths, standing in the ground with varying distances between each other, indicating a reading inaccuracy of less than 0.03 m. Field tests were conducted on newly planted and first ratoon areas. Plots were established to measure gaps by hand and compare it to the sensors readings. Results obtained from the statistical tests shown that there is not statistical difference between manual and sensor measuring methods (t-test) and the R2 were 0.60 by the planted field and 0.48 to the first ratoon comparison. With this method it is possible to georeference the measurements allowing the generation of maps representing the spatial distribution of gaps, giving to the user an information about the occurrences and their locations.