Verdure: ‘You can’ doesn’t mean ‘you should’

Hoping to hasten putting green establishment by applying more fertilizer? Consider this research first.

|

Sometimes, people think that putting green establishment can be hurried along by applying more fertilizer. Given that high-sand greens can have issues with nutrient retention, especially in the first year of establishment, is adding more nutrients necessary?

Turfgrass faculty at the University of Nebraska set out to answer this question by designing an experiment that studied combinations of root-zone mix, fertilization and putting green age.

Each year for four years (1997-2000), experimental putting greens were built, with two different greens mixes as the first variable. Greens mixes were either 80/20 (v/v) sand/peat (calcareous sand and sphagnum peat) or an 80/15/5 (v/v/v) mix of sand, sphagnum peat and soil (Tomek silty clay loam).

The second treatment was two different nutritional programs for establishment. First was a “controlled” treatment that was pre-plant nitrogen (N) at 3 pounds/1,000 square feet (15 grams/square meter), phosphorus (P) at 0.7 pound/1,000 square feet (3.3 grams/square meter) and potassium (K) at 1.7 pounds/1,000 square feet (8.3 grams/square meter), along with a micronutrient blend — magnesium (Mg), sulfur (S), copper (Cu), iron (Fe), manganese (Mn) and zinc (Zn) — at 11 pounds/1,000 square feet (55 grams/square meter).

The “accelerated” pre-plant treatment doubled the amounts of N, P and K applied, along with 16 pounds/1,000 square feet (80.0 grams/square meter) of the micronutrients. The controlled and accelerated treatments were continued for post-plant treatments, too, with N, P and K applied at 1.2, 0.9 and 0.8 pounds/1,000 square feet (6.0, 4.2 and 3.8 grams/square meter) every two weeks in the controlled treatment, plus 1.4 pounds/1,000 square feet (7.0 grams/square meter) of micronutrients. The total applied post-plant in the accelerated treatment was four times that of the controlled treatment, except for the micronutrients, which were applied at 2.4 pounds/1,000 square feet (11.5 grams/square meter). These materials were all applied as granular fertilizers during the growing season, starting with the May seeding of Providence creeping bentgrass.

After four years of construction, there was a group of replicated putting greens, established with the same fertilization regimes but differing in age. Each year, samples were collected from each plot at a 3-inch (7.6-cm) depth and analyzed for soil pH, total soluble salts, soil organic matter, soil nitrate-N, and soil P, K, Ca (calcium), Mg, Fe, Zn, Cu and B (boron).

In the establishment year, there were few differences in soil nutrient content due to the root-zone mix. Inclusion of soil in the one root-zone treatment did not affect levels of NO3-N, P, K, Ca, Mg, S, Zn, Mn, Cu or Na (sodium). Soil organic matter content, soil pH and total soluble salts were also unaffected by the type of greens mix.

The fertility program, however, did affect measured soil variables. With the accelerated program, there were higher amounts of NO3-N, P, K, Ca, Mg, S, Zn, Fe, Mn and Cu in greens. Soil pH was significantly decreased by the extra fertilizer (6.73 in the accelerated program, 7.40 in the controlled). Boron, soil organic matter, sodium and total soluble salts were unaffected by fertilization rate.

As the greens aged from one to four years, the greens mix had little effect on their nutrient retention and chemical properties. Greens mix also had little effect on establishment of the bentgrass or on bentgrass quality throughout the study. The type of greens mix did not matter for nutrients, growth or quality. Only one nutrient of the fertilization regime affected longer-term performance: phosphorus, which accumulated in the accelerated fertilization program.

Adding extra fertilizer in the accelerated program did not increase establishment or improve quality. In fact, quality often decreased as a result of Pythium foliar blight in treatments that received the accelerated fertilizer treatment. So, increased fertilization during the year of establishment had no positive benefits on soil nutrients or bentgrass establishment or quality.

Sources: McClellan, T.A., R.C. Shearman, R.E. Gaussoin, M. Mamo, C.S. Wortmann, G.L. Horst and D.B. Marx. 2007. Nutrient and chemical characterization of aging golf course putting greens: establishment and rootzone mixture treatment effects. Crop Science 47:193-199. doi:10.2135/cropsci2006.02.0123

Lewis, J.D., R.E. Gaussoin, R.C. Shearman and L.J. Giesler. 2007. Golf course putting green rootzone and establishment effects on pythium foliar blight on creeping bentgrass. Applied Turfgrass Science 4. doi:10.1094/ATS-2007-0806-01-RS


Beth Guertal, Ph.D., is a professor in the Department of Crop, Soil and Environmental Sciences at Auburn University in Auburn, Ala., and president-elect of the Crop Science Society of America. She is a 20-year member of GCSAA.

You may also like: Verdure: Bentgrass establishment