Elevated soil nitrogen pools after conversion of turfgrass to water-efficient residential landscapes

Hannah Heavenrich, Sharon Hall

Research output: Contribution to journalArticle

Abstract

As a result of uncertain resource availability and growing populations, citymanagers are implementing conservation plans that aimto provide services for people while reducing household resource use. For example, in theUS,municipalities are incentivizing homeowners to replace their water-intensive turfgrass lawns with water-efficient landscapes consisting of interspersed drought-tolerant shrubs an treeswith rock ormulch groundcover (e.g. xeriscapes, rain gardens,water-wise landscapes).While these strategies are likely to reducewater demand, the consequences for other ecosystemservices are unclear. Previous studies in controlled, experimental landscapes have shown that conversion fromturfgrass to shrubsmay lead to high rates of nutrient leaching fromsoils.However, little is known about the longtermbiogeochemical consequences of this increasingly common land cover change across diverse homeownermanagement practices.We explored the fate of soil nitrogen (N) across a chronosequence of land cover change fromturfgrass to water-efficient landscapes in privately owned yards in metropolitan Phoenix, Arizona, in the aridUS Southwest. Soil nitrate (NO3-N) poolswere four times larger inwater-efficient landscapes (25F4 kg NO3 -N/ha; 045 cmdepth) compared to turfgrass lawns (6F7 kg NO3 -N/ha). Soil NO3 -Nalso varied significantlywith time since landscape conversion; the largest pools occurred at 913 years after turfgrass removal and declined to levels comparable to turfgrass thereafter.Variation in soil NO3 -Nwith landscape agewas strongly influenced bymanagement practices related to soil water availability, including shrub cover, sub-surface plastic sheeting, and irrigation frequency.Our findings showthat transitioning fromturfgrass to water-efficient residential landscaping can lead to an accumulation of NO3 -Nthatmay be lost fromthe plant rooting zone over time following irrigation or rainfall.These results have implications for bestmanagement practices to optimize the benefits of water-conserving landscapeswhile protectingwater quality.

Original languageEnglish (US)
Article number084007
JournalEnvironmental Research Letters
Volume11
Issue number8
DOIs
StatePublished - Aug 5 2016

Keywords

  • alternative landscape
  • drought
  • nitrate leaching
  • turfgrass
  • urban ecosystem
  • water quality and conservation
  • xeriscape

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Environmental Science(all)
  • Public Health, Environmental and Occupational Health

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