Polyacrylamides (PAM) and polysaccharides can be used as soil amendments to improve soil physical properties, including infiltration of water into soil. Mucilage from prickly pear cactus contains large polysaccharides. Two experiments were done to test the hypothesis that pretreating columns of soil with cactus extract would improve subsequent falling‐head ponded infiltration of water. One experiment tested samples from a loamy Alfisol, the other from a Vertisol. In both experiments we compared effects on infiltration between pretreatments of cactus extract, PAM used as a reference, and water as a control. In both experiments treatment effects were significant (P<0.05). Both cactus extract and PAM improved infiltration compared to the control. This is the first known report that cactus extract can be used to improve infiltration. Many questions remain regarding the mechanisms involved and the potential for practical use of cactus extract as a soil conditioner.