SIMULATING NATURAL DRAINAGE UNDER TURFGRASS IN CHEMICAL FATE STUDIES

Simulation of field conditions is important when conducting solute mov ement research in the greenhouse. A study was initiated to develop and test a solute movement system with intact turf-soil columns subjected to suction approximating field capacity and typical irrigations. Inta ct soil columns from a Sharpsburg soil (fine montmorillonitic, mesic T ypic Argiudoll) planted to Kentucky bluegrass (Pea pratensis L.) were encased in concrete, excavated, and brought to the greenhouse. Porous ceramic plates were attached to some column bottoms and suction (50 kP a) was applied to simulate soil water matric potentials at field water capacity and eliminate perched water tables. Under 2.5-cm irrigations , evapotranspiration (ET) was 15% greater (P = 0.09) from columns with out suction than from columns with suction. Drainage was 460% greater (P = 0.08) from columns under suction receiving 2.5-cm irrigation. Vol ume of drainage water and total bromide collected was significantly gr eater (P = 0.01 and 0.02) from columns under suction receiving 5.0-cm irrigations than from columns receiving 2.5-cm irrigations. Averaged b romide concentrations in the drainage did not differ among treatments. Water and solute movement may be underestimated in greenhouse studies using containers without suction plates to eliminate perched water ta bles.