TURFGRASS SOIL MANAGEMENT RESEARCH REPORT P.E. Rieke and S. L. McBurney Crop and Soil Sciences, M.S.U.

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1 TURFGRASS SOIL MANAGEMENT RESEARCH REPORT P.E. Rieke and S. L. McBurney Crop and Soil Sciences, M.S.U. This report summarizes turf research conducted at the Hancock Turfgrass Center in 1984 and was supported in large part by the Michigan Turfgrass Foundation. The financial and moral support of the Michigan Turfgrass Foundation and its members is gratefully acknowledged. IRRIGATION AND NUTRIENT BALANCE EFFECTS ON ADELPHI KENTUCKY BLUEGRASS The data in Table 1 give the quality ratings on these plots during the growing season. As has been reported in the past the responses to nitrogen were reduced when the plots were irrigated daily at noon. Even the untreated check plot ranked highly under regular irrigation. But higher nitrogen rates were necessary to give acceptable quality ratings when limited moisture was applied. When the entire plot area was subjected to severe moisture stress in late June-early July due to a pump failure, the plots which received the higher N rates gave the highest susceptibility to wilt. If one is growing turf on sand and/or the area is unirrigated, then lower N rates are appropriate to keep the turf less susceptible to wilt. The lower summer quality ratings would be expected on turfs treated with lower nitrogen, even though they are less susceptible to wilt. A further observation is the lack of response to potassium on these marginally low potash soils. With the clippings returned to the plot area, this may return enough potassium to prevent serious stress induced by the low potassium level in the soil. This is a cooperative project with J. M. Vargas, Jr. and Bruce Branham. EFFECT OF NITROGEN FERTILIZATION PROGRAM IN THE TURF QUALITY OF 3 CREEPING BENTGRASSES MAINTAINED AT PUTTING GREEN HEIGHT After 3 years of treatments shown in Table 2, the quality ratings of Penncross and Penneagle creeping bentgrasses continue to be higher than with Emerald. At the low N rates Emerald provides a very open, poor quality turf, while the others are acceptable. At the higher rates of N all grasses become thatchy and puffy resulting in scalping. NITROGEN FERTILITY PROGRAMS ON PENNCROSS CREEPING BENTGRASS This cooperative study with J.M. Vargas, Jr. was established in The treatments are outlined in Table 3. Data for 1984 are given in Table 4. 1

2 The programs which provide modest N in the summer ( pound N per 1000 sq. ft. per month in June, July and August with 1 pound in September and 1 in November) provide the most uniform quality turf. The total N application for the year is 3.5 pounds per 1000 sq. ft. The program which gives 4 pounds N annually with 1 pound applications in April, May and June results in ratings which are too high and would make the turf more susceptible to stresses of traffic, high temperature and moisture limitations. WETTING AGENT STUDIES Several wetting agents were applied to Penncross creeping bentgrass greens at the Hancock Turfgrass Research Center and on two predominantly Kentucky bluegrass fairways growing on light sandy loam soils at the Candlestone Golf Club at Belding. Appreciation is expressed to the LESCO company for financial support and Superintendent Rick Krampe for use of the fairway areas. The objective was to evaluate LESCO'S Lescowet with several other wetting agents on the prevention of localized dry spots. Although there was imminent development of localized dry spots on the two fairways at Candlestone at the time of treatment (mid July) environmental conditions were not conducive for further development of the problem subsequent to treatment. As a result, there were no differences to record either in turf quality, wilting tendency or in soil moisture in samples taken from the fairway. Other studies were established at the Hancock Turfgrass Research Center on Penncross creeping bentgrass greens growing on a loamy sand soil. Treatments were applied in late July and repeated as shown in the accompanying tables two weeks later in early August. Again climatic conditions were not conducive to development of the localized dry spot conditions so no differences were recorded among the various treatments in terms of localized dry spots or in wilting tendency. There was a significant response in dew control, however. The treatments were applied either to plot areas which were irrigated to replace approximately 80% of open pan evaporation or which received no irrigation except at the time of application to prevent burn. The irrigated plots received irrigation during early morning which reduced dew formation to some degree. As a result, differences were smaller than on the plots which were irrigated only on wilt. The plots which received irrigation to replace 80% of open pan evaporation (Table 5) manifested some differences among wetting agents with Lescowet and AquaGro reducing dew the most. Without the supplemental irrigation, dew formation differences were highly significant (Table 6). After 1 day only AquaGro-Dry showed no difference from the check. After 2 days, differences were still evident, but smaller in magnitude. After 5 days, only Lescowet and AquaGro gave meaningful differences. After 2 weeks, differences were very small and not meaningful. In a second study (Table 7) similar data were obtained. Of interest were the responses to AquaGro-Dry. Although there was little response in dew control from the dry material within a day or two of treatment, after 2 weeks there were lower dew ratings compared to the check. This would be expected as the material is applied dry. It must be dissolved into applied water and then diffused into the turf. This gives a longer term release pattern, but will 2

3 not provide as much active ingredient in the turf at the time of the application, of course. In the above study, the treatments were not watered in to determine the degree of phytotoxicity of each of the materials. Obviously this would not be a recommended practice, but this does provide some idea of the relative potential for phytotoxicity. The phytotoxicity data are given in Table 8. AquaGro and Lescowet caused the greatest phytotoxicity when not watered in. Our general recommendation is to apply wetting agents to turf which are not in a condition of moisture stress, then water in immediately. Unless absolutely necessary, it is best to never apply wetting agents when temperatures are going to be above 85, and it is best to treat in the evening. It may be necessary to irrigate the area lightly before treatment so the grass is not in a condition of wilt. SOIL ph CONTROL The plots treated with lime and sulfur in 1981 continue to show some changes with time. Of particular note is the increase in soil ph on the sulfur treated plots as well as on the check. Apparently the major factor is the hardness of the irrigation water applied to the turf. The ph data are in Table 9. Further, the loss in the bases, calcium and magnesium are dramatically increased from the high sulfur plots (Table 10). If the turf manager wants to achieve and keep a low ph, more frequent soil testing should be practiced to prevent a deficiency of magnesium. Also, the ph change occurs first in the surface layer and gradually moves downward. This surface acidification could lead to stress on the turf so the use of sulfur to acidify soils should be done cautiously. PHOSPHORUS AND POTASSIUM SOIL TEST IN RESPONSE TO FERTILIZER APPLICATIONS The effect of P2O5 and K2O applications to several soils are summarized in Tables 11 and 12. As observed previously, the dune sand does not hold applied potassium (Table 11). Effective Potash application on sandy soils requires regular applications, a minimum 3 or 4 times a year. When some peat is mixed with the soil the potash holding capacity of the soil media is increased somewhat over the sand, but not as strongly as on the topsoil green (fine sandy loam). Phosphorus is apparently leached from the dune sand as well (Table 12). After 2 years of application of P2O5 to this dune sand, the phosphorus soil tests are still moderately low. There was a very clear deficiency of P on the check plots throughout the year, while deficiency symptoms appeared on the 1 pound application rate per year late in the fall when soils became colder and the uptake of P was not as efficient. Soil tests on the sands should be taken more frequently than on other soils because of the low cation exchange capacity and the higher susceptibility to rapid chemical change and leaching. 3

4 Table 1. Effect of irrigation regime and nitrogen and potassium levels on turfgrass quality ratings and wilting susceptibility of Adelphi Kentucky bluegrass. Hancock Turfgrass Research Center. Fertilizer applications made May 11, June 16, August 9 and September 14, Averages for 3 replications. Irrigation N Rate K20 Rate Wilt* Quality Rating (9=best) regime lbs/1000 sq ft July 2 June 13 July 15 Aug 25 Daily 2 0 jz 6.2 ce 7.3 cft! 7.0 bd 80% Pan i 4.0 kn 5.5 jm 3.8 ik None de 3.3 mp 4.7 np 2.8 jm Daily 4 0 j 6.7 ac 8.0 ac 7.5 ac 80% Pan de 5.2 fi 6.5 fh 5.0 fh None b np 3.5 il Daily 6 0 j 7.3 ab 8.5 a 7.8 a 80% Pan gh 6.0 cf 7.0 dg 5.8 cf None a 4.8 gk 6.2 gi 4.8 fi Daily 2 1 j 6.0 cf 7.0 dg 6.8 be 80% Pan gh 4.2 jrn 4.8 rno 3.8 ik None fg 2.8 pq 3.5 r 2.5 1m Daily 4 1 j 6.2 ce 7.5 ce 7.2 ac 80% Pan gh 4.8 gk 5.3 kn 4.8 fi None hi 3.7 lp 4.2 or 3.3 jl Daily 6 1 j 7.5 a 8.5 a 8.0 a 80% Pan ed 5.7 dg 6.8 eh 5.5 df None de 4.8 gk 5.7 il 4.5 gj Daily 2 2 j 6.5 bd 7.3 cf 7.2 ac 80% Pan 2 2 j nq 3.5 il None gh 3.0 oq 3.7 qr 2.7 km Daily 4 2 j 6.5 db 7.3 cf 7.0 bd 80% Pan gh 4.8 gk 5.8 hi 4.3 hj None ef 4.3 il 5.5 jm 4.0 hk Daily 6 2 j 7.4 ab 8.0 ac 7.5 ac 80% Pan gh 5.5 eh 7.2 cf 5.2 eh None a 5.2 fi 6.8 eh 4.5 gj Daily 2 4 j 6.2 ce 7.3 bd 7.3 ac 80% Pan gh 4.6 hi 5.8 hi 4.2 hj None b 2.8 pq 4.7 np 2.5 1m Daily 4 4 j 6.5 bd 7.8 bd 7.0 bd 80% Pan i 4.8 gk 6.0 hj 4.5 gj None ef 4.2 jm 5.5 jm 4.2 hj 4

5 Daily 6 4 j 7.2 ab 8.2 ab 7.8 ab 80% Pan cd 5.3 eh 6.8 eh 5.3 eg None bc 5.2 fi 6.0 hj 4.8 fi Daily 0 0 j 6.0 cf 7.3 cf 6.8 be 80% Pan hi 3.2 np 4.2 or 2.8 jm None bc 2.2 cf 4.0 pr 1.8 m Daily 4 1 j 6.5 bd 7.8 bd 7.0 bd 80% Pan b 5.2 fi 6.3 fi 4.8 fi None b 4.0 kn 5.3 kn 3.0 ik Daily 4 2 j 6.5 bd 7.8 bd 7.2 ac 80% Pan ef 5.0 gj 5.8 hi 4.7 hi None de np 3.5 il * Wilt rating based on 1 = no wilt; 5 = severe wilt. # Rating taken 1 week after a 1 inch rain Z Means in columns followed by the same letter are not significantly different from each other at the 5% level using DMRT. 5

6 Table 2. Effect of N fertilization program on turfgrass quality ratings of Emerald, Penneag1e and Penncross creeping bentgrasses maintained under putting green conditions. Nitrogen applications are made in May, June, July, August and September except as noted. Averages of 3 replications. Treatment, 1bs/1000 yr Turfgrass quality rating (9 = greenest) N Carrier May 16 June 5 August 2 Sept 20 Emerald 1 Urea 3.3 kx 3.5 j 2.5 n 3.1 k 2 Urea 3.7 jk 4.6 hi 3.1 mn 3.8 jk 3 Urea 4.2 hj 4.5 i 4.6 jk 5.1 hi 4 Urea 4.4 fj 5.1 ei 5.2 ij 5.5 fh 6 Urea 5.0 di 6.2 bd 6.3 dg 6.6 ce 8 Urea 5.3 cf 6.6 ac 6.6 ce 7.1 bd 4Y Urea 6.1 ac 5.7 dg 5.5 gi 5.9 eh 4Y Mi10rgani te 5.7 bd 5.5 dg 5.4 hi 5.3 gh 4Y Am. Nit. 4.3 gj 5.1 ei 5.3 hj 5.9 eh Penneag1e 1 Urea 4.1 ik 4.8 gi 3.7 1m 4.1 j 2 Urea 4.3 gj 5.4 dh 4.4 k1 5.4 gh 3 Urea 4.7 ei 5.4 dh 5.7 fi 6.1 dg 4 Urea 4.7 ei 5.6 dg 6.1 dh 6.5 ce 6 Urea 5.2 cg 6.6 ac 6.9 bd 7.4 ac 8 Urea 5.4 ce 6.9 ab 7.4 ab 8.3 a 4Y Urea 6.4 ab 6.0 ce 6.3 dg 7.1 bd 4Y Mi10rganite 6.0 ac 5.9 ce 6.3 dg 6.5 ce 4Y Am. Nit. 4.7 ei 5.5 dg 6.5 cf 7.0 bd Penncross 1 Urea 4.3 gi 4.9 fi 4.2 kl 4.3 ij 2 Urea 4.6 ei 5.3 di 4.6 jk 5.3 gh 3 Urea 5.1 dh 5.6 dg 5.6 gi 6.4 cf 4 Urea 5.2 eg 5.8 cf 6.0 ei 6.5 ce 6 Urea 5.3 cf 6.9 ab 7.2 ac 7.6 ab 8 Urea 5.7 bd 7.3 a 7.8 a 8.3 a 4Y Urea 6.6 a 6.2 bd 6.3 dg 7.3 bc 4Y Mi10rganite 6.1 ac 6.1 bd 6.5 cf 6.6 ce 4Y Am. Ni t. 5.3 cf 5.9 ce 6.3 dg 7.1 bd XMeans in columns followed by the same letter are not significantly different YNitrogen program includes 1 pound N per 1000 sq. ft applied on November 5. 6

7 Table 3. Treatments applied in Penncross bentgrass nitrogen carrier fertility study at the Hancock Turfgrass Research Center. Treatments initiated in Plot size is 6 feet by 6 feet. Four replications. No. Treatment N carrier Nov Apr Month of May June application July Aug Sept Pounds N per 1000 sq. ft IBDU (coarse) 2 Sulfur coated urea 3 Powder blue Urea Powder Urea blue Urea 6 CheekY 7 Urea 8 Urea 9 Urea IBDU (coarse) 11 Sulfur coated urea 12 Powder blue Urea Urea 14 Ammonium nitrate 15 Ammonium nitrate 16 Milorganite 17 Milorganite 18 Oxamide 19 Oxamide YCheck plots received 1 pound N per 1000 square feet as urea in July and September. 7

8 Table 4. Effect of nitrogen carriers on quality of a Penncross creeping bentgrass green at the Hancock Turfgrass Center. Averages for four replications. TreatmentY Turfgrass Quality Rating (9 = best) No. Carrier April 16 June 5 July 2 Aug. 1 Sept IBDU 5.3 bcx 6.3 be 6.4 bd 5.9 bd 6.2 cg 2 s.c. urea 4.7 c 5.2 eg 5.3 eh 5.4 cd 6.1 cg 3 P.B. + Urea 5.1 c 5.5 df 5.6 cg 5.3 cd 5.7 dg 4 P.B. + Urea 4.5 cd 5.7 cf 5.8 cg 5.5 bd 6.5 ce 5 Urea 4.7 c 5.2 eg 5.4 db 5.4 ed 6.3 cf 6 Check 2.5 c 3.6 h 4.1 i 3.8 e 4.5 h 7 Urea 3.5 dc 4.6 fh 4.4 hi 4.1 e 5.2 gh 8 Urea 6.3 b 7.1 b 7.4 ab 6.5 ac 7.6 b 9 Urea 7.5 a 8.5 a 8.3 a 7.4 a 8.5 a 10 IBDU 5.0 c 6.2 be 6.4 bd 5.8 bd 6.2 cg 11 s.c. Urea 4.6 cd 5.7 cf 6.4 bd 6.1 bd 6.7 bd 12 P.B. + urea 5.5 be 6.1 be 6.2 cf 5.7 bd 6.3 cf 13 Urea 5.2 be 6.9 be 6.3 ce 5.6 bd 6.9 be 14 Am. Nitrate 6.3 b 6.0 be 5.9 cg 6.0 bd 7.1 be 15 Am. Nitrate 5.6 be 6.7 bd 7.4 ab 6.7 ab 6.6 cd 16 Milorganite 4.5 cd 5.0 eg 5.2 fg 5.5 bd 6.9 be 17 Milorgani te 3.0 e 5.6 df 6.5 be 6.1 bd 6.2 cg 18 Oxamide 3.3 e 4.7 fh 5.1 gh 5.2 d 5.5 eg 19 Oxamide 3.0 e 4.0 gh 5.7 cg 5.5 bd 5.4 fb xmeans in columns followed by the same letter are not significantly different YFor treatment details, see Table 3. 8

9 Table 5. Effect of several wetting agent materials on Penncross creeping bentgrass maintained with irrigation at replacement of 80% of evaporation. Hancock Turfgrass Research Center. Averages for 3 replications Treatment Dew Accumulation Days after (l=least; 9=most) treatment Material July Aug Rate oz/1000 Lescowet 4 0 Lescowet 4 4 Lescowet 8 a Lescowet 8 8 Lescowet 16 0 Lescowet Aqua Gro 8 a Aqua Gro 8 8 HydroWet 8 0 HydroWet 8 8 Basic H 8 0 Basic H 8 8 NAIAD 4 a Aqua Gro-Dry Aqua Gro-Dry 7 7 Control a a ax 1.5 ab 2.5 bd 4.5 de a 1.3 ab 2.3 bc 4.3 cd a a 2.0 ac 4.0 bc a a 1.7 ab 4.2 bc a a 1.3 a 3.8 ab a a a 3.7 a 1.3 ab 1.3 ab 1.7 ab 4.2 bc 1.3 ab 1.2 a 1.7 ab 4.2 bc 1.2 ab 1.8 ac 3.5 cd 4.5 de 1.3 ab 1.8 ac 3.7 cd 4.7 ef a 1.8 ac 3.7 cd 4.7 ef 1.3 ab 1.8 ac 4.0 d 4.5 de 1.2 ab 2.3 bc 4.0 d 4.8 f 2.3 c 3.5 d 4.3 d 4.5 de 1.8 bc 2.8 cd 3.7 cd 4.2 bc 3.8 d 4.7 e 4.3 d 4.7 ef XMeans in columns followed by the same letter are not significantly different 9

10 Table 6. Effect of several wetting agent materials on Penncross creeping bentgrass maintained with irrigation at replacement upon wilt. Hancock Turfgrass Research Center. Averages for 3 replications Dew Accumulation (1 = least; 9 = most) Treatment Days after treatment Material July Aug Rate, oz/1000 Lescowet bdx 3.3 b 3.8 b 6.5 bd Lescowet bc 3.7 b 5.0 bd 6.7 bd Lescowet a 3.5 b 4.0 bc 5.8 ac Lescowet ab 3.0 b 3.8 b 6.0 bc Lescowet 16 0 a 1.7 a a 5.5 ab Lescowet a 1.7 a 1.5 a 5.3 a Aqua Gro bd 3.5 b 3.8 b 6.0 bc Aqua Gro bd 3.2 b 4.0 bc 6.0 bc Hydro Wet bd 4.0 b 5.5 cd 6.5 bd Hydro Wet bd 3.8 b 5.7 d 6.8 cd Basic H cd 4.0 b 6.2 d 6.8 cd Basic H cd 4.0 b 5.5 cd 7.0 d NAIAD e 5.7 c 5.5 cd 6.8 cd Aqua Gro-Dry g 7.2 de 6.0 d 6.8 cd Aqua Gro-Dry ef 6.2 cd 4.0 bc 6.3 bd Control 7.8 fg 7.5 e 6.5 d 7.0 d xmeans in columns followed by the same letter are not significantly different 10

11 Table 7. Effect of several wetting agent materials on dew accumulation on Penncross creeping bentgrass maintained under putting green conditions. Treatments were not watered in following application. Averages for 3 replications Material Treatment July Dew Accumulation 1 = least, 9 = most Days after treatment Rate oz/1000 Lescowet 8 Lescowet 8 Lescowet 16 Lescowet 16 Lescowet 32 Aqua Gro 8 Aqua Gro 16 HydroWet 8 HydroWet 16 Basic H 8 Basic H 16 Aqua Gro-Dry 3.5 Aqua Gro-Dry 7 Aqua Gro-Dry 1 NAIAD 8 Control 3.7 bdx 6.3 cf 8.3 cd 8.8 de 3.3 bc 6.0 ce 8.3 cd 8.7 ce 1.7 ab 4.3 bc 8.0 cd 8.3 cd 1.7 ab 4.3 bc 7.3 bc 8.2 c a 2.0 a 6.3 ab 7.3 b 3.7 bd 5.0 bd 8.3 cd 8.7 ce 3.0 ac 4.3 bc 7.7 cd 8.2 c 6.0 ef 6.7 df 9.0 d 8.8 de 4.0 ce 6.3 cf 9.0 d 9.0 e 7.0 fg 8.0 eg 9.0 d 9.0 e 6.0 ef 8.0 eg 9.0 d 9.0 e 6.7 ef 6.0 ce 8.7 cd 8.8 de 6.0 cf 5.0 bd 7.3 bc 8.5 ce 5.0 df 3.7 ab 5.7 a 6.7 a 5.7 f 8.3 fg 9.0 d 9.0 e 8.7 g 8.7 g 8.7 cd 9.0 e XMenas in columns followed by the same letter are not significantly different 11

12 Table 8. Effect of several wetting agent materials on turf discoloration of Penncross creeping bentgrass maintained under putting green conditions. Treatments were applied July, 1984 and were not watered in following application. Averages for 3 replications. Treatment Material Rate 2 Turf Discoloration Days after treatment oz/1000 Lescowet 8 Lescowet 8 Lescowet 16 Lescowet 16 Lescowet 32 AquaGro 8 AquaGro 16 HydroWet 8 HydroWet 16 Basic H 8 Basic H 16 AquaGro-Dry 3.5 AquaGro-Dry 7 AquaGro-Dry 1 NAIAD 8 Control 2.17 dex 2.00 ab 1.17 a 1.17 a 3.50 cd 3.83 ce 1.17 a 1.17 a 5.33 ef 5.33 ef 2.50 bd 2.33 bc 5.67 f 4.67 de 2.67 cd 3.00 c 7.50 g 7.33 g 4.17 e 4.00 d 3.50 cd 3.50 bd 1.67 ad 1.67 ab 5.70 ef 5.00 df 2.83 d 2.67 c 2.00 ac 2.00 ab 0 a 1.17 a 2.00 ac 3.00 bc 0 a 0 a 2.00 ac 0 a 1.33 ab 1.17 a 2.33 ac 2.33 ac 0 a 0 a 1.17 a 3.17 bc 1.50 ac 1.33 a 1.67 ab 4.83 de 2.83 d 2.67 c 2.83 bd 6.33 fg 5.33 f 4.67 d 2.00 ac 2.50 ac 0 a 0 a 0 a 0 a 0 a 0 a XMeans in columns followed by the same letter are not significantly different 12

13 Table 9. Soil ph control study on sandy loam at the Hancock Turfgrass Research Center. Treatments applied August, Averages for three replications. Sampled August, Incorporation Treatment Chemical Rate, t/a Depth of sampling, inches Limestone a 7.6 a 7.5 a 7.0 ab 7.3 a 6.9 a Limestone a 7.3 ab 7.6 ab 6.6 bc 6.7 b 6.5 b Limestone ab 7.0 b 6.9 b 6.1 cd 6.5 b 6.5 b Control 6.0 cd 6.4 c 6.9 b 5.5 d 5.8 c 6.4 b Sulfur 4.1 ef 4.8 d 5.2 c 4.6 c 4.6 d 5.3 c Sulfur 3.4 g 4.3 e 5.0 c 3.8 fg 4.1 d 4.8 c xmeans in columns followed by the same letter are not significantly different Table 10. Effect of sulfur and dolomitic limestone applications on soil tests. Treatments applied August, 1981 at the Hancock Turfgrass Research Center on a sandy loam soil. Sampled September Incorporation Material Treatment Rate TIA Sample depth inches ph Available soil test levels, poundsla P K Ca Mg Limestone ax 6.9 bc 52 Y Y b 1520 bc 325 bd 395 bc Limestone ab 6.9 bd a 1360 bc 453 ab 547 a Limestone bd 6.5 cd bc 1253 c 306 cd 301 cd Control bd 6.4 d bc 1227 c 299 cd 269 de Sulfur e 5.3 e d 667 d 125 c 133 e Sulfur e 4.8 e d 373 d 157 e 75 e XMeans in columns followed by the same letter are not significantly different Yindicates there was no significant difference among means. 13

14 Table 11. Potassium soil testx responses on Penncross creeping bentgrass greens growing on 3 soils. Hancock Turfgrass Research Center. Averages for 3 replications. Studies initiated September 30, Samples taken September, K20 Applied Dune Sand Sand/Peat Topsoil Ibs/1000 sq. ft. 0-3" 0-3" 0-3" 0 23 c 47 d 126 b 47 bc 94 c 132 b 67 b 161 b 189 ab a 247 a 275 a XAvailable Potassium (K) determined with neutral normal ammonium acetate. YMeans in columns followed by the same letter are not significantly different Table 12. Phosphorus soil test responses on Penncross creeping bentgrass growing on dune sand. HTRC. Treatment P Soil test Quality rating (9-best) lbs P205/M time lbs/a Jul 8 Aug 14 Sep c 1.7 c 1.2 d 1.3 d 1 spr 14 c 3.7 b 3.0 c 3.2 c 2 spr, fall 21 b 4.3 a 3.5 b 3.8 b 4 spr, fall 34 a 4.5 a 4.2 a 4.7 a Spring treatments on April 20, fallon September 25. Study initiated July