Alternative planting geometries reduce production risk in corn and sorghum in water‐limited environments

Conserving soil water and making it available to plants, especially during reproduction and grain-filling periods, is one of the most challenging aspects of crop production in water-limited areas. In such areas, adoption of suitable planting geometry may play a key role in determining plant growth and yield. We reviewed the effect of different planting geometries, namely evenly spaced planting (ESP), clump (three plants close together), cluster (five plants close together), and skip-row (one row planted, one row skipped) in corn (Zea mays L.) and grain sorghum (Sorghum bicolor L. Moench) in different agro-ecological environments and crop management practices. All other planting geometries are called "alternative planting geometries" in this paper. Most studies were conducted in the U.S. Southern Great Plains region, where annual precipitation is less than the potential evapotranspiration and the summer season is usually hot and dry. Results clearly showed the potential benefits of alternative planting geometries, such as reduced canopy temperature, improved microclimate within the crop canopy, less vegetative growth, comparable or greater grain yield, and higher harvest index compared with standard ESP. However, there is much to learn about the feasibility, other benefits, and risks associated with alternative planting geometries for sustainable dryland farming. More studies on weed dynamics, soil evaporation, root penetration, soil water extraction, and water use efficiency are required to complement the existing knowledge on alternative planting geometries.