Methods and systems for estimating volumes of agricultural crops are provided. A geographic position sensor (644, 1154) provides positions of a harvesting machine (608) as it gathers an agricultural crop (606) and places the crop on the ground in a windrow (610). A speed of the harvesting machine is determined using the geographic position sensor (644, 1154). Signals are received from a sensor system (622, 1152) disposed at a bottom of the harvesting machine (608). The signals are indicative of profiles of segments of the windrow (610) on the ground. Cross-sectional areas of the windrow (610) are estimated using the signals. Volumes of the agricultural crop are estimated using the speed of the harvesting machine (608) and the estimated cross-sectional areas of the windrow (610).
