This video explains the soil water balance equation and demonstrates how to use it to estimate the amount of irrigation to apply to a cropped field. This video was produced by Harsanjam Singh, a student in "Soil, Water, and Weather" and Oklahoma State University. The free etextbook used in that course, "Rain or shine: An introduction to soil physical properties and processes" by Tyson E. Ochsner, is available at https://osf.io/z4rbt/.