Summer means attention to lawn care.\u00a0 Mid-summer drought leads to frequent repositioning of garden hoses to ensure a green lawn. \u00a0Water bills skyrocket. \u00a0Is this mindless?<\/p>\n
Just how much water does a lawn use?\u00a0\u00a0 Noortje Grijseels and her collaborators have examined water use in six suburban areas across the United States, reporting rates of 0.9 mm\/day (=0.035 inches\/day) in the eastern U.S. and 2.9 mm\/day (=0.114 inches\/day) in arid cities of the West.\u00a0 This consumption of water accounts for both the uptake of water by plants, known as transpiration, and the evaporation of water from the surface of the soil, which normally extends to about 10-cm depth.\u00a0 Globally, evapotranspiration returns about 65% of precipitation to the atmosphere, with plants contributing slightly more than half of this portion and evaporation the remainder.\u00a0 (Runoff accounts for 35%).<\/p>\n
In a comparison among cities, climate, particularly solar radiation, was the major driver of water loss from lawns. \u00a0In arid regions, these researchers found little difference in water use between traditional lawn management, with irrigation, and xeriscaping.\u00a0 This surprised me until I remembered one of my research projects in the Chihuahuan desert nearly forty years ago.\u00a0 We found that desert vegetation transpires about 72% of incident precipitation, and when it was removed from some experimental plots that we kept bare, the soil moisture content below about 10 cm accumulated to field capacity.<\/p>\n
In traditional suburban lawns with scattered trees, the grass dominates evapotranspiration, since its total leaf area is so much larger than the trees. \u00a0Irrigated golf courses in arid regions are among the most water-intensive landscapes. Lawns with xeriscaping tended to be smaller, reducing total water use.<\/p>\n
It is time to rethink the need for a turfgrass lawn.\u00a0 Indeed, we have no lawn at all and have left our property fallow for a diverse and colorful meadow to return.<\/p>\n
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References<\/p>\n
Grijseels, N.H. et.al. 2023.\u00a0 Evapotranspiration of residential lawns across the United States.\u00a0 Water Resources Research doi: 10\/1029\/2022WR032893<\/p>\n
Litvak, E., N.S. Bijoor and D.E. Pataki. 2014.\u00a0 Adding trees to irrigated turfgrass lawns may be a water-saving measure in semi-arid environments.\u00a0\u00a0 Ecohydrology 7: 1314-1330.<\/p>\n
Schlesinger, W.H., P.J. Fonteyn, and G.M. Marion.\u00a0 1987.\u00a0 Soil moisture content and plant transpiration in the Chihuahuan Desert of New Mexico.\u00a0 Journal of Arid Environments 12: 119-126.<\/p>\n
Schlesinger, W.H. and S. Jasechko. 2014.\u00a0 Transpiration in the global water cycle.\u00a0 Agricultural and Forest Meteorology 189: 115-117.<\/p>\n
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