Irrigating recreational turf requires ET (evapo-transpiration) replacement for water conservation and to sustain optimal leaf growth and turf function under traffic stress. Lysimeter measured actual ET (ETa) can be estimated using a reference crop ET (ETo) from meteorological data adjusted using a crop coefficient (Kc, ETa/ETo) to correct for cultural affects on ETa. Previous studies have not fully investigated the effects of turf culture on Kc. The objective of this research was to develop reliable Kc when ETo is computed using the FAO-56 Penman-Monteith equation, with Kc adjusted according to the effects on ETa of two mowing heights of cut (HOC), two N rates, and three species. Creeping bentgrass (CB) as golf turf and Kentucky bluegrass (KB) and perennial ryegrass (PR) as sports-lawn turf were planted in South Deerfield, MA. Species and two N rates (98 and 196 kg N ha–1 yr–1) were arranged as main plots (3.12 by 1.56 m). Main plots were split according to HOC, with KB and PR mowed at 3.125 and 6.25 cm and CB mowed at 0.3125 and 0.9375 cm. Crop coefficients were calculated as ETa:ETo ratio and using linear regression (slope) estimates during July and August from 2011 to 2013. Results were similar between the two Kc methods. Adjustments to Kc values are necessary to account for variations in leaf growth rates (r = 0.66, n = 48, P £ 0.001) caused principally by HOC, with N having some influence on PR. Golf HOC (CB) ranged from 0.90 to 1.00 in Kc while sports-lawn turf HOC (KB and PR) ranged from 1.15 to 1.25.
ASJC Scopus subject areas
- Agronomy and Crop Science