Manipulating Tillage to Increase Stored Soil Water and Manipulating Plant Geometry to Increase Water-Use Efficiency in Dryland Areas

Abstract

This paper briefly summarizes some of the practices being used in the semiarid U.S. Great Plains to grow crops without irrigation. Fallow periods are commonly used to increase the amount of plant-available water in the soil profile at the time of seeding a crop because growing-season precipitation is nearly always insufficient to produce economic grain yields. Maintaining plant residues on the surface as mulch has been very beneficial for this purpose. The most successful practices depend mostly on herbicides for controlling weeds during the fallow period and eliminating as much tillage as feasible. Reduced plant populations and, more recently, seeding plants in clumps rather than uniformly spacing plants in rows show some promise as useful strategies for reducing early vegetative growth so that more soil water is available during the grain-filling period late in the season. While these practices may not be applicable to other semiarid regions because of differences in soil, climatic, social, and economic conditions, some of the principles may apply and useful technologies can be developed.

KEYWORDS:

• Fallow
• clumps
• grain sorghum
• evapotranspiration
• no-tillage