Open‐field burning provides effective, economical post‐harvest residue management in Kentucky bluegrass (Poa pratensis L.) seed crops, but public concern over air quality necessitates the identification of nonthermal management strategies. On‐farm trials were conducted in Oregon's Grande Ronde Valley to investigate the effect of nonthermal management in two cultivars of Kentucky bluegrass on crop regrowth, seed yield, and seed quality. Residue treatments imposed after the first, second, and third seed harvests included (i) removal of straw by baling (Bale), (ii) baling, flailing with a rotary scythe, followed by residue removal with a needle‐nose rake (Rake), (iii) baling, followed by removal of the residue by vacuum‐sweeper (Vacuum), (iv) flail‐chopping residue three times with no removal (Flail 3X), and (v) open‐field burning (Burn). Tillers were etiolated at the cessation of fall regrowth in Flail 3X (stubble height reduced, no straw removal) and Bale (no stubble height reduction, 75% straw removal) treatments. Fertile tiller number was lower in the following spring with Flail 3X and Bale treatments compared with Burn. Seed yield averaged across the 3‐yr period was reduced 38% when managed with Flail 3X and 10% when managed with Bale compared with Burn. Crop regrowth, fertile tiller production, and seed yield resulting from Rake and Vacuum treatments were equivalent to the Burn treatment. Rake and Vacuum treatments reduced stubble height and removed at least 90% of the straw. High seed yield and seed quality can be maintained in Kentucky bluegrass without open‐field burning when straw removal is thorough and stubble height is reduced prior to crop regrowth.

The allelopathic potential of hoary cress was evaluated by exposing the seeds and the germinated seeds of winter wheat, alfalfa, crested wheatgrass, bluebunch wheatgrass, and hoary cress to a water extract of dried, hoary cress roots under controlled conditions in an environmental chamber. Germination for all species was reduced in the hoary cress root extract when compared with distilled water, with winter wheat and hoary cress being more tolerant than the other species. Root length of all species was reduced by the extract when compared with distilled water. These data show the presence of phytotoxic chemical(s) that may inhibit germination and initial seedling growth in natural environments. Three glucosinolate compounds were identified in hoary cress root extracts.

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Sewage sludge application rates on grasses are mainly determined by N availability and concentration of toxic metals in sludge. The exact availability of N in sludge is difficult to predict. A 3-yr study was conducted to determine which sludge rates would give yields of tall rescue (Festuca arundinacea Shreb. 'Alta') comparable to yields obtained from inorganic N application. Sludge and NH4NO3 were surface applied at annual rates of 0, 110, 220, 440, and 880 (sludge only) kg N/ha. Dry matter yield of tall rescue from sludge-treated soils was 36, 56, and 50% of that on NH4NO3-treated soils for 1976, 1977, and 1978, respectively. Sludge was 27, 41, and 44% as effective as NH,NO3 as a source of available N in 1976, 1977, and 1978, respectively. Ammonium-N in the sewage sludge apparently provided most of the available N for fescue growth. Concentrations of Zn, Cd, and Cu were higher and Mn lower in tall fescue grown on sludge-treated soil with NH~NO3 and usually increased toward the end of the growing season. However, plant concentrations of these heavy metals never reached toxic levels at any time. Sewage sludge was an effective and safe nutrient source for tall fescue. Additional index words:Nitrogen availability, Tall fescue, Festuca arundinacea Shreb., Nutrient source. Kiemnec, G.L., T.L. Jackson, D.D. Hemphill, Jr., and V.V. Volk. 1987. Relative effectiveness of sewage sludge as a nitrogen fertilizer for tall fescue. J. Environ. Qual. 16:353-356.

Hoary cress germination decreased with lower osmotic potential. Knapweed germination was greatest at 0.0 and −0.5 MPa of osmotic potential. Salinity increases up to an electrical conductivity (EC) of 12 dS m-1 had no effect on germination of either species. Hoary cress and knapweed root growth were reduced by decreases in osmotic potential. Hoary cress root growth was not affected by increasing salinity up to an EC of 12 dS m-1. Knapweed root growth was reduced by the initial increase in salinity (4 dS m-1), but not by higher salt concentrations.