Efficient Irrigation for Recreational Turf In the Cool-Humid Northeast: ET and Crop Coefficients.
Poster Number 502
Tuesday, November 5, 2013
Tampa Convention Center, East Hall, Third Floor
James William Poro, University of Massachusetts-Amherst, Amherst, MA, Jeffrey Ebdon, Stockbridge School of Agriculture, University of Massachusetts Amherst, Amherst, MA and Michelle DaCosta, Stockbridge School of Agriculture, University of Massachusetts-Amherst, Amherst, MA
Scheduling irrigation
according to actual turfgrass evapotranspiration rates (ETa) reduces
waste and increases irrigation efficiency. Crop coefficients (Kc values) are used in
association with weather station reference ET (ET0) to predict ETa.
Experimentally-derived Kc
values need to be developed at the local level to ensure optimum turf function
and effective irrigation efficiency. The objective of
this study was to measure ETa and Kc values
comparing golf species (creeping bentgrass, Agrostis
stolonifera L. ‘Memorial') maintained as green
and fairway turf with sports grass species (Kentucky bluegrass, Poa pratensis L. ‘Touchdown' and
perennial ryegrass, Lolium perenne L.
‘Exacta'). Reference ET0 values were computed
using the FAO 56 equation. Studies were
initiated in 2010 at the Joseph Troll Turf Research Center,
South Deerfield, MA. Species main plots were arranged as a complete factorial
with two nitrogen (N) levels, 98 and 196 kg N ha-1 yr-1,
with four replicates arranged as a RCB. All
species by N main plots were split according to two heights of cut (HOC) with
sports grass maintained at 31.25 and 62.5 mm while golf main plots were mowed
at 3.125 and 9.375 mm. Twenty-three daily ETa (using weighing
lysimeters), ET0
and Kc values
(calculated as ETa/ET0) were made during the summer months beginning in late June
and ending late August in 2010 and 2011. Reference ET0 values were effective in
predicting daily ETa accounting for 60% of the total variation. FAO 56 over estimated
ETa in 2010 (Kc=0.95) and under estimated ETa in 2011 (Kc=1.15). Within the same
species, HOC had no significant effect on ETa and Kcs. Daily ETa and Kcs
increased with leaf area (leaf growth rate and HOC). In 2010 and 2011, summer
Kcs were significantly lower with golf turf than sports grass averaging 0.90
and 1.10, respectively. Fertilizing in summer with 49 kg N ha-1 (42% as SRN) caused
significantly higher ETa and Kcs on only 3 dates in 2010 and 2011. Two more
years of field testing are planned.
