Agronomic Practices for Improving Water Use in Rainfed Production.

Precipitation is often limiting at some time during the growing season for rainfed crops in most growing seasons. Consequently, growers should adopt agronomic practices that maximize available soil water, especially during critical growth stages of the crop. Most agronomic management practices, such as crop rotation, choice of tillage, selection of hybrid traits and relative maturity, planting date, plant densities, timing of weed management, control of insects, and timing of fertilizer application can have an impact on available soil water. For example, crop rotations improve soil health, which promotes root growth and allows the crop to deplete soil water from the deeper soil depths during periods of limited precipitation. Likewise, no-till or reduced tillage reduces soil evaporation losses, which allows the crop to utilize more soil water in a rainfed environment. Selecting earlier hybrids or cultivars allows a crop to reduce the probability of encountering severe drought during critical growth stages and selecting new genetic traits, such as Bt corn or cotton, can mitigate the effects of severe drought during the growing season. Lower plant densities can delay the onset of drought during dry periods, whereas timely weed removal can eliminate weed competition for available soil water, especially during late vegetative and reproductive development of the crop. Timing of fertilizer application can also affect root/shoot ratios, which also impact water use of a crop during dry periods. Specific examples of each management practice for some of the major crops, including corn, soybean, wheat, and cotton, will be presened.