Optimum Fertility Regimes During Late Spring

2007, Univeristy of Tennessee, TN

Research Topic: Optimum Fertility Regimes During Late Spring Creeping Bentgrass Putting Green Establishment (2007) -- J. Sorachan, Univeristy of Tennessee

Creeping bentgrass (Agrostis stoloniferous) planting requires adequate fertility to maximize grow-in time and speed to establish a mature turfgrass sward. Cool-season turfgrasses also have different fertility requirements during establishment. The objective of this experiment was to evaluate the use of granular, foliar, a combination of granular and foliar fertilizers, or urea for creeping bentgrass establishment on a sand-based green built to USGA

specifications. All plots received 0.5 lb P/M of a 25-13-12 started fertilizer prior to planting. The six (6) fertilizer treatments consisted of:

  • Green Spec® (0.5 lb N/M) Seven Iron™ 7-7-7 applied every 14 days after germination
  • Milorganite (0.5 lb N/M) 6-2-0 applied every 14 days after germination
  • NuBlade (12 oz/M) applied at germination then Gary’s Green® (4 oz/M) + P-K Plus® (6 oz/M) applied every 7 days
  • NuBlade (12 oz/M) applied at germination then Gary’s Green (6 oz/M) + P-K Plus (6 oz/M) every 14 days
  • Urea (0.013 lb N/M) applied at germination then urea (0.14 lb N/M) applied every 14 days
  • NuBlade (12 oz/M) applied at germination 7 days (6 oz/M) then Green Spec Seven Iron 7-7-7 (0.05 lb N/M) after 14 days then Gary’s Green (6 oz/M) + P-K Plus (6 oz/M)

Plots were arranged in a randomized complete block design and replicated 3 times and ‘A4’ creeping bentgrass was seeded on 3 April. Visual ratings and analysis of percent (%) turf cover were taken weekly starting on 7 May. Consistent temperatures above 90 F occurred from mid-May through 18 June resulting in persistent Pythium blight pressure during July and August. In general, creeping bentgrass treated with Green Spec 7-7-7 resulted in faster establishment and the greatest overall turf cover after 8 weeks on 31 May (Figure 1). Initially and until 22 May, the

NuBlade (12 oz/m) applied at germination followed by Gary’s Green (4 oz/M) + PK Plus (6 oz/M) applied every 7 days provided a high level of percent turf cover. In fact, the foliar program applied at lower rates and on a 7 day interval performed consistently better than the foliar program using higher rates (6 oz/M) and on a 14 day interval (Figure 1). All GRIGG foliar programs resulted in higher percent creeping bentgrass cover during establishment than an equivalent nitrogen (N) rate of urea (Figure 1).

‘A4’ creeping bentgrass establishment from seed during the late spring should be avoided in the transition zone. However, if you are going to establish a sand based creeping bentgrass putting green from seed in the transition zone during late spring and early summer fertility, treatments with Green Spec Seven Iron 7-7-7 will provide the best success versus common Milorganite and urea fertility establishment programs. Green Spec Seven Iron 7-7-7 combined with foliar treatments did not perform significantly better than Green Spec Seven Iron 7-7-7 applied alone. Lower dose (4 oz/M) and more frequent (7 day interval) foliar fertilizer treatments were more effective than higher dose (6 oz/M) and less frequent (14 day interval) application, however, all foliar treatments were more effective than urea treatments applied at an equivalent N rate.

Figure 1. Percent (%) turf cover after treatment with various granular and foliar fertilizers during creeping

bentgrass establishment.

*All plots received 0.5 lb P/M of a 13-25-12 starter fertilizer prior to planting.