Topdressing Kentucky Bluegrass with Compost Increases Soil Water Content and Improves Turf Quality During Drought

Management practices that reduce landscape water consumption will become more important as potable water supplies diminish. Currently, a significant portion of urban water in hot, dry climates is used for landscaping purposes. Little information is available concerning the effects of compost topdressing after core cultivation on turfgrass drought response. The objectives of this study were to evaluate the effects that core cultivation and topdressing compost onto established Kentucky bluegrass (Poa pratensis L.) have on: i) soil water content, and ii) turf canopy temperatures and quality responses during periods of drought. Following core cultivations in May and September 2003 and May 2004, compost treatments [0 (control), 33, 66, and 99 m³ ha^?1, i.e. 0, 31, 62, 93 Mg ha^?1] were topdressed onto established ‘Nuglade’ and ‘Livingston’ Kentucky bluegrass in the field (Experiment I). In Experiment II, ‘Kenblue’ Kentucky bluegrass was topdressed with 0 (control), 66, and 99 m³ ha^?1 compost after core-cultivation. In addition, a non-core-cultivated and no-compost-topdressed treatment was included. Three 10-d dry down periods were imposed during the summers. During the dry down periods, compost treatment increased SWC in the 15-30 cm soil depth during the first four days of dry down and in the 0-15 cm depth 7-10 days into the dry down period. Compared to the control, compost treatments at 66 and 99 m³ ha^?1 reduced turf canopy temperature by 1.2-3.3°C during 4-10 days of dry down, indicating less drought stress. While ‘Nuglade’ and ‘Livingston’ turf quality of control (no compost treatment) declined to an unacceptable level on day 8 of dry down, plots with 66 and 99 m³ ha^?1 compost treatments maintained acceptable turf quality during the entire dry down periods. In Experiment II, turf quality of ‘Kenblue’ declined to below 6 on day 3 for the non-cultivated and no-compost-topdressed treatment, on day 5 for the core-cultivated but no-compost-topdressed control and on day 9 for 66 and 99 m³ ha^?1 compost treatments. Our results suggested that compost topdressing after core cultivation is a management practice that could reduce turfgrass irrigation requirements.