Furrow‐irrigation application efficiency in mid‐southern U.S. conservation tillage systems

Approximately 80% of mid-southern U.S. irrigation requirements are supplied through gravity flow delivery systems with inherently low application efficiency. This research was conducted to determine whether the efficiency of furrow-irrigation systems could be manipulated through conservation tillage systems. Three experiments were conducted near Stoneville, MS, on a Dubbs silt loam to determine the effects of reducing tillage and increasing ground cover residues on irrigation application efficiency and irrigation water use efficiency. In Exp. 1, transitioning from conventional tillage to a conservation tillage system had no adverse effect on irrigation application efficiency and irrigation water use efficiency when subsoiling was included. For Exp. 2, replacing subsoiling with a cereal rye (Secale cereale L.) or tillage radish (Raphanus sativus L.) cover crop in a conservation tillage system either had no effect or reduced irrigation application efficiency and irrigation water use efficiency up to 10%. In Exp. 3, independent of cover crop, reducing tillage to only furrow creation had no adverse effect on irrigation application efficiency or irrigation water use efficiency relative to a conservation tillage system with subsoiling. Conservation tillage systems that include subsoiling maximize irrigation application efficiency and irrigation water use efficiency while minimizing adverse effects on yield and net returns relative to conservation tillage systems that further reduce tillage and/or increase ground coverage with cover crops. Our data indicate that soybean [Glycine max (L.) Merr.] producers in the mid-southern United States maximize furrow-irrigation functionality, yield, and profitability while minimizing risk by transitioning from a conventional tillage system to a conservation tillage system with subsoiling.