Nitrogen and Irrigation Interactions in Water-Stressed Turfgrass Species.

Turfgrass is the leading irrigated crop in the U.S. and is under scrutiny with regard to water conservation. Perennial ryegrass (Lolium perenne L.) was evaluated with all combinations of two irrigation and three N rates. The grass was seeded under glasshouse conditions for 42 d in 0.09 m wide square pots with a depth of 0.3 m in a sand/peat (90/10 v/v) rooting media (meeting ASTM specifications for sand based sports fields). The irrigation treatments included a full replacement of average daily evapotranspiration achieved by daily irrigation to field capacity and a limited irrigation treatment achieved by daily irrigation to 60% of the field capacity. The N rates were 10, 50, and 250 kg ha-1 for the deficient, optimum, and excessive treatments, respectively. Nitrogen application was split-applied weekly as liquid ammonium nitrate —adding any captured leachate back to each pot to eliminate N loss. Generally, plants appeared healthier and had higher NDVI with full irrigation and optimum N rate. Excessive N resulted in reduced root growth relative to the optimum rate. During the first 15 d of water stress, the water use for the fully irrigated treatment at the optimum N rate was 18.0% less and 3.5% more than the excessive and deficient N treatments, respectively. The water use for the drought stressed plants at the optimum N rate was 3.8% less and 8.5% more than the excessive and deficient N treatments, respectively. However, the effect reversed after 15 days for the low N rate, with 11.0 and 18.8% increased water use for the drought stressed and fully irrigated plants, respectively. These results indicate that N management influences ET in perennial ryegrass. Water conservation will be achieved by optimizing the N rate and avoiding excessive or deficient N.

See more from this Division: Students of Agronomy, Soils and Environmental Sciences (SASES)
See more from this Session: Undergraduate Research Contest - Poster Section III

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