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Summary Concentrations of proline, sodium and potassium in shoot tissues of five turfgrass species were measured following exposure to 170 mM NaC1 salinity stress. Salt tolerant 'Fults' alkaligrass and 'Dawson' red fescue restricted the accumulation of Na-ions to significatnly low levels compared to the salt sensitive Kentucky bluegrasses ('Adelphi' and 'Ram I') and 'Jamestown' red fescue. Accumulation of proline began in all species within 24 h of initiation of salt stress but at a more rapid rate and higher overall concentration for 'FuRs' alkaligrass. Proline levels were variable and too low in relation to sodium accumulations to have any significant osmoregulatory role in salt tolerance among all cultivars tested with the possible exception of alkaligrass.

Nitrogen applied to turfgrass stands can be lost through leaching, denitrification, or ammnnia (NH)) 'olatilization. Tbe purpose of this in,estigation was to e,aluate tbe effects of N carrier and mode of application on NH) ,olatilization from a Kentucky bluegrass (POfl prfltensis L.)turf growing on an acidic (pH 6.4) Flanagan silt loam (fine, montmorillonitic, mesic Aquic Argiudoll) soil. The NH) wbicb 'olatilized after .application of any of senral sulfur-coated ureas (SCU), prilled urea, spray-applied solubilized urea, and two liquid N products was measured by passing tbe airstream from microecosystems, in whicb tbe treated turfs were growing, througb an indicating boric acid solution to trap NH). Ammonia-N losses after sulfur-coated urea fertilization ranged from 0.2% of tbe applied N wben tbe fertilization rate was 98 kg NI ba to 2.3 % of tbe applied N wben tbe fertilization rate was 293 kg NI ba. Wben prilled urea was applied at a rate of 293 kg N/ba, NH)losses averaged 10.3% of tbe applied N wbereas 4.6 and 1.6% of tbe applied N was lost after turf was fertilized witb 49 kg NIba from spray-applied solubilized urea and prilled urea, respectively. Ammonia losses from turf treated with liquid N sources ranged from 3.2 to 4.5% of the applied N. Tbe results of tbis researcb indicate tbat ammonia volatilization occurs to a limited extent in turfgrass stands growing on an acidic soil.

Denitrification may represent an important mechanism in the fate of N applied to turf. Denitrification losses were directly measured from fertilized 'Baron' Kentucky bluegrass (Poa pratensis L.) sod samples sealed in acrylic chambers using the acetylene inhibition technique. Losses were correlated with soil texture, percent soil sat· uration (SAT), and temperature. Losses from turf on a Hadley silt loam soil and Hadley silt soil (both coarse-silty, mixed, nonacid, mesic Typic Udifluvents) incubated at 2rC did not exceed 0.4 and 0.1 %, respectively, of the applied potassium nitrate fertilizer (4.5 g N m-2 ) when soil water levels were less than 75% saturated. Soil saturation increased denitrification losses from the silt loam and silt soils to 2.2 and 5.4% of the applied N, respectively. The relationship between percent soil saturation and denitrification loss was quadratic and highly significant for both soils. .70] existed between denitrification losses and soil temperatures between 22 and 30°C in the silt soil at 75% of soil saturation. Soil temperatures of 30°C or greater coupled with saturated soil conditions resulted in the greatest losses, equiv alent to 44.6 and 92.6% of the applied N to the silt loam and silt soils, respectively. Denitrification losses did not increase at soil tem peratures above 30°C. These results indicate that denitrification loss from fertilizers applied to turfgrasses may not be a serious problem unless the soils are saturated and at higher soil temperatures.

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