Normal and Flush Irrigation Effects On Phosphorus Leaching from Simulated Golf Greens in the Greenhouse

Abstract

Fertilizer nutrients have the potential to leach from porous golf greens, especially when “flushing” is practiced where 8 or 10 cm of irrigation is applied. A greenhouse experiment was carried out with 52 cm columns (15 cm diameter) made to United States Golf Association green specifications and sodded to ‘Tifdwarf’ bermudagrass to determine the amounts of phosphorus leached for two fertilizer sources (20–20–20 and superphosphate) at three rates (0, 5, and 11 kg ha−1 added every other week for a total of 6 weeks) and two irrigation schemes (normal irrigation at 6.3 mm day−1 and the same irrigation with an additional four flushes of 8 cm each). Weekly leachate collections for 29 weeks were analyzed for soluble P. Flushes resulted in higher P concentrations in the leachate where as much as 40% of the added P was recovered in the leachate. In contrast, normal irrigations resulted in less than 10% of the P applied moving through the columns. The two fertilizer sources gave essentially similar results. The higher P rate caused higher concentrations of P in the leachate, but P concentrations for the low rate for normal irrigation were not different than the control. For flushes, the extractable P in the top 15 cm of the rooting media was lower than for normal irrigation and the extractable P in the columns was higher. Results indicate that low rates of P should be applied to golf greens and, if flushing is practiced, it should be done when little P is in the rooting media.