Driven by soaring international demand, extensive areas of grasslands, and forests across South American plains have rapidly been converted to the production of annual crops, such as soybean and maize. This agricultural expansion has been taking place at a staggering rate of 2.1 million hectares a year. A new study shows how these shifts to annual crop agriculture, which relies on rainfall rather than irrigation, is also rapidly disrupting the water table across the large flat regions of the Pampas and Chaco plains and contributing to significantly increased risks of surface flooding.