Wednesday, November 7, 2007 - 12:00 PM
318-10

Determining Critical Phosphorus Levels for Cool Season Seedlings Established on Calcareous Soil.

Jared Nemitz, Cale Bigelow, Jim Camberato, Brad Joern, and Doug Smith. Purdue University, Lilly Hall of Life Sciences, 915 W. State Street Office #2414-D, West Lafayette, IN 47907

Sufficient soil phosphorus (P) is critical for rapid seedling establishment. P-deficient seedlings lack vigor and form low density turf areas which are more susceptible to soil erosion and nutrient loss. A greenhouse study was conducted to determine the critical soil P-levels necessary to establish Kentucky bluegrass (KBG) and endophyte infected (E+) and non-endophyte (E-) turf-type tall fescue (TF) from seed. A calcareous, low-P, sub-soil typical of urban environments in Indiana was amended with (0, 3, 9, 15, 25, 45 and 75 mg kg-1) mono-calcium phosphate to generate a range of soil concentrations. Turf was seeded at recommended lawn rates in 15 cm diam. x 10 cm deep pots with nitrogen and moisture not limiting throughout establishment (12 weeks).Turfgrass performance was measured both visually and quantitatively as appearance, density, color and growth. Days to germination, establishment, and canopy cover using digital imaging techniques were measured. As expected turfgrass seed generally established more quickly at higher P concentrations (³ 45 mg kg-1). Additionally there were significant species and endophyte differences with TF establishing more quickly than KBG. Among TF, E+ reached 50% cover (36 days) more rapidly compared to E- (43 days). TF recorded higher clipping yield than KBG while E+ (180.4 g) recorded higher overall clipping yield than E- (159.4 g). This study demonstrates that in addition to sufficient soil P, endophyte infected seed may impact seedlings nutrient uptake, resulting in a healthy dense turf and reduce potential soil and nutrient loss during establishment.

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