Effect of P, K, and Lime on Growth, Composition, and ³²P Absorption by Merion Kentucky Bluegrass¹

Abstract

ABSTRACTthis isotope satisfactorily reflected the absorptive caInformation is needed concerning the effects of differcllt soil fertility IcveI.~ on the activity of turfgrass roots in that part of the soil profile sampled for routine soil tests. In Pennsylvania, a sampling depth of 5 to 7.5 em is suggested for established turf. A study was cond ucted on 'Merion' Kentucky bluegrass (Poa pratensis L.) to determine relationships among lime, phosphorus, and potassium applications; soil test results; foliar growth and elemental analysis; and mot activity as determined by ""P uptake from three soil depths. In the field, soil pH values were 5.8 and 7.0, P ranged from 13 to 137 ppm, and K ranged from 0.14 to 0.43 meq./loog. Liming increased the Ca content in clippings fwm 0.35 to 0.42%. Phosphorus treatments increased P from 0.32 to 0.44%, and K was increased from 2.00 to 2.45% by K fertiliza· tion. Clipping yield was increased by P treatments. Sod plugs from the field were used in the greenhouse to detennine root activity. Agar discs containing :l2p were placed at a depth of 1.3, 3.8, or 6.4 em, and clippings were assayed for B2p after 20 and 33 days. Shallow placement of "'P resulted in more absorption. A soil P X depth interaction was found for "'P absorption. A significant positive correlation between soil P and "2P absorption was obtained for the 1.3 em depth, whereas a nonsignificant correlation was found for the 6.4 em placement. Results indicated that P enhanced rooting, and the magnitude of absorption from the I.3·cm depth exemplified the need fm· P lIear the soil surface for optimum turf establishment..4dditiOllal index

Shoot and Root Growth Response of Perennial Ryegrass to Fertilizer Placement Depth

“…Except for P, nutrient accumulation in the shoot tissue of subsurface-fertilized plants matched or exceeded that in surface-fertilized plants. Phosphorus absorption by Kentucky bluegrass roots has been shown to be greater at the 1.3-cm soil depth compared with 3.8-and 6.4-cm depths (Watschke et al, 1977). Furthermore, P absorption from the 1.3-cm depth increased as soil P levels increased, but greater P absorption did not occur at lower soil depths of 3.8 and 6.4 em when soil P levels were increased (Watschke et al, 1977).…”

“…Phosphorus absorption by Kentucky bluegrass roots has been shown to be greater at the 1.3-cm soil depth compared with 3.8-and 6.4-cm depths (Watschke et al, 1977). Furthermore, P absorption from the 1.3-cm depth increased as soil P levels increased, but greater P absorption did not occur at lower soil depths of 3.8 and 6.4 em when soil P levels were increased (Watschke et al, 1977). Powell (1977) concluded that P uptake occurs primarily through new root growth into soil volumes having nonlimiting P levels.…”

Long‐term Effects of Nitrogen and Potassium Fertilization on Perennial Ryegrass Turf

“…Petrovic et al (2005) and Fitzpatrick and Guillard (2004) have also reported similarly low soil test K levels of 50 to 60 mg kg −1 , with no CY response observed despite testing low for soil K. They have attributed this lack of a response in shoot growth to K fertilization to be related in part to the important role that N contributes to soil test K interpretation. In addition, many have suggested the need to reevaluate current soil test K recommendations because they may be too high for turfgrass (Watschke et al, 1977;Sartain, 2002;Fitzpatrick and Guillard, 2004;Petrovic et al, 2005). However at 343 kg N and year 2008 (Table 4), soil test K levels of 80 mg kg −1 were associated with a positive CY response to K fertilization (P = 0.063) and CY increased from 3.3 to 5.2 g dry wt.…”

“…No response in CY to K fertilization have been observed in numerous field studies where typical N rates have been applied to turf (49-245 kg ha −1 yr −1 ) (Watschke et al, 1977;Snyder and Cisar, 2000;Johnson et al, 2003;Fitzpatrick and Guillard, 2004;Webster and Ebdon, 2005;Petrovic et al, 2005;Hoffman et al, 2010). In such cases it is assumed that soil K levels are adequate for growth.…”

“…In such cases it is assumed that soil K levels are adequate for growth. However, where soil test K levels have been categorized as low, it has been suggested that the soil test K interpretations may be too high and need to be readjusted (Watschke et al, 1977;Sartain, 2002;Fitzpatrick and Guillard, 2004;Petrovic et al, 2005). Researchers have suggested that the release of nonexchangeable forms of K from primary minerals may be partially responsible for meeting the K requirements of turfgrass; therefore, soil test exchangeable K may overestimate the true K requirements of turf (Dest and Guillard, 2001;Fitzpatrick and Guillard, 2004;Woods et al, 2006).…”