Does blocking affect experimental efficiency on sand-based putting greens?

Past experiments on sand-based putting greens have frequently used randomized complete blocked designs (RCBD), even though these experimental areas are relatively uniform with regard to external variables. Consequently, completely randomized designs (CRD) may have had better precision with which to estimate treatment effects compared with RCBD. The objective of this study was to estimate the relative efficiency (ERE) of a RCBD compared with a CRD when evaluating common parameters on sand-based putting greens. Uniformity trials were conducted in Arkansas and Nebraska on sand-based putting greens established with creeping bentgrass (Agrostis palustris Huds.). Estimated relative efficiency values were calculated for varying blocking schemes when measuring canopy temperature, soil temperature, soil moisture, clipping yield, and macronutrient content in plant tissues. Since canopy temperatures were time dependent, when those measurements were collected by a blocking scheme, the associated RCBD was approximately nine times more efficient than a CRD. For the remaining parameter and blocking scheme combinations, ERE values indicated that the precision between RCBD and CRD was similar. Therefore, it is likely that the precision with which treatment effects are estimated is not compromised from the use of RCBD on sand-based putting green trials.