Submitted to: International Evapotranspiration Irrigation Scheduling Conference
Publication Type: Proceedings
Publication Acceptance Date: April 12, 1996
Publication Date: N/A
Technical Abstract: Automatic irrigation control on the basis of a threshold canopy temperature has been shown feasible for cotton but has not been tested for corn. Triplicate drip irrigation plots were established on Pullman clay loam for each of seven irrigation treatments including weekly 100% replacement of water use, 67% of the 100% treatment, a dryland treatment, and four automatic irrigation treatments: a 28 deg C threshold applied to two decision intervals (15 min and 3 days), and a 30 deg C threshold applied to the two decision intervals. Corn yield for the 28 deg C, 15 min interval was significantly higher at 1.20 kg m**-2 than for the 100% replacement but irrigation was also significantly higher (906 mm vs. 589 mm) causing deep drainage losses. For the 15 min, 30 deg C and 3 day, 28 deg C treatments irrigation was significantly lower than for 15 min, 28 deg C (625 and 585 mm, respectively) but yields were not significantly lower (1.20 and 1.06 kg/m**2, respectively) and were statistically equivalent to that for the 100% treatment. Water use efficiency was significantly lower for the 15 min, 28 deg C treatment, at 1.23 kg/m**3, than for the 15 min, 30 deg C, 3 day, 28 deg C and 100% treatments (mean of 1.36 kg/m**3). Automatic irrigation using threshold canopy temperature was more responsive to plant stress and showed the potential to outyield manual irrigation based on 100% replenishment of crop water use.