A field experiment comparing irrigation treatments of 100% of predicted ETCrop applied with subsurface drip irrigation with 50%, 75% and 125% ETCrop was conducted at Warren in the 1999/2000 season. Cotton yield of 7.8 bales/ha was greatest in the 100% treatment followed by the 75% and 125% treatments with lowest yield coming from the 50% treatments. This yield trend, combined with similar soil moisture contents in the 100% and 125% treatments indicated that the 100% treatment was supplying adequate water to satisfy crop demand. Neutron probe readings showed that treatments receiving insufficient water to satisfy crop demand were able to extract water from part of the soil profile that was not wet by irrigation. Use of this water allowed the 50% and 75% treatments to grow at similar rates to the 100% and 125% treatments for I month in peak growing conditions after the soil was saturated by rain moisture in late December.