Phosphorus Effect On Turfgrass Growth and Soil Moisture During Drought and Post-Drought Recovery.

The use of phosphorus fertilizer is being more regulated for lawn care and golf industries in North America with the concern of ground water contamination. At the same time, water availability for irrigation of turfgrass is increasingly limited by less rainfall due to climate change, and by water use regulations for the green industry.  Objective of this research is to investigate turfgrass performance with limited phosphorus availability under water deficit condition. Three turfgrass species including creeping bentgrass (CB), velvet bentgrass (VB), and annual bluegrass (AB) were maintained with different phosphorus fertilization before being exposed to drought stress by withholding water for 21 days. Water was then resumed to start the drought recovery period. Turfgrass growth, quality, root development, and soil moisture were measured during drought and post-drought recovery. Turfgrass species responded differently for the two periods. CB had better turfgrass color than AB and VB during the drying out period. However, VB had the best color recovered during post-drought recovery. Pencross had better color than L93 after 16 days of drought recovery. In addition, the water-withheld treatment resulted in larger clipping dry weight for SR7200 and Pencross. Water-withheld treatment resulted in shorter total root length for SR 7200. Phosphorus showed adverse effects on SR7200 color rating and root weight, and had lower soil moisture levels for CB at 15, 20 and 25 cm rootzone depth. However, phosphorus resulted in higher soil moisture levels for AB at these rootzone depths.