Turfgrass Soil Management1986 Research Report

P.E. Rieke, M.T. McElroy and J.A. MurphyCrop and Soil Sciences, M.S.U.

SULFUR STUDIESThree studies were initiated in 1986 to study the response of

turfgrasses to sulfur applications. These studies were initiated in July.The first was applied on a Kentucky bluegrass turf which had been seeded in1980. The soil was compacted clay loam subsoil. Plot size was 6 feet by10 feet with 3 replications for each treatment. Treatments applied aregiven in Table 1. Data for this study are given, in Tables 1 and 2. Ratesof sulfur application were 10 and 20 pounds of sulfur carrier depending ontreatment.

The most striking responses were to treatments with Cleary's flowablesulfur. There was a significant response in turf density and clippingweights (Table 1) as well as in color and turf quality ratings (Table 2).Note the dramatic increase in weight of clippings as an indicator growthresponse. In one month after application the 10 and 20 pound rates ofapplications gave comparable growth responses, while after two months the20 pound rate resulted in significantly more growth than the 10 pound rate.

There were few responses to other sulfur carrier applications exceptfor Thiolux which showed some tendency to result in a darker green color.Although there was a significant response to the flowable sulfur inparticular, the rates applied were quite high and injury could easilyresult from such application rates. In this regard, there was reduction incolor ratings taken in October on both and 20 pound treated plots.

Soil pH tests taken in October indicated there was no change in pHwhen sampled to the 1.0 inch depth. pH values ranged from 7.2 to 7.5.Injury from sulfur applications will occur because of rapid pH change inthe very soil surface. This pH change can be very dramatic and can causeinjury to plant tissue (roots and crowns). Gradually the acid releasedwill leach downward to change the pH a little deeper in the soil. In thisstudy the reduction in turf color is not understood. It could result fromtoo much acidity in the surface 1/4 inch or so (although there was noindication of this in the pH test) or from some other nutritional response.

Responses to the sulfur applications on annual bluegrass fairwayheight turf at the Hancock Turfgrass Research Center were quicker than onthe Kentucky bluegrass. There was very clear growth and density responseto both the 5 and 10 pound rates used in this study (see Table 3), within aweek or so although no clipping weights were taken because of smaller plotsize. Turf color response was different than with Kentucky bluegrass.There was a short term response in turf color causing a darker green on theflowable sulfur plots but after one month the turf was lighter green thanon the untreated plots. This was very noticeable two months after

2

treatment in September when all other plots had a darker green color. InSeptember the turf density on the flowable treated plots was more openespecially at the 10 pound rate (compared to the 5 pound rates). Clearlythere was weakening of the turf during the fall due to treatment. Againsoil test did.not reflect a meaningful change in pH at least in the 1.0inch depth.

It should be noted that there was some response of annual bluegrass tothe Thiolux treatments. There was darker green color, an improvement inquality ratings and relative growth compared to the untreated control forabout a month (Table 3). There was also some indication of injury whichoccurred on small spots at the edges of plots where a little extra productfell during application of Thiolux. To a lesser degree this occurred withthe flowable product. No indication of this occurred with other products.

A second study on annual bluegrass was initiated in August as outlinedin Table 4. There was no indication of any response to any of thesetreatments with Thiolux or Cleary's flowable sulfur. Apparently there areother factors involved in the nature of this response. It is not known ifthese are related to physiological, environmental, or soil conditions.

On July 19 a small study on sulfur response of Penncross creepingbentgrass under greens conditions was begun. After about a month there wassignificant turf color response to the flowable sulfur that persistedthrough the end of the growing season. There was no apparent response inturf density or growth rate although no clipping weights were taken becauseof small plots size.

Table 1. Effect of sulfur applications on turf density and clipping weightsof Kentucky bluegrass growing on clay loam subsoil. Treatmentsapplied July 12, 1986 at rates shown pounds product per 1000 squarefeet. Averages for 3 replications. Hancock Turfgrass ResearchCenter. A density rating of 9 - highest density.

Treatment Turf density Clipping weight gmCarrier Rate 8/14 9/8 8/14 9/10

Thiolux 10 8.0 a 7.5 bc 21 40 c20 6.3 b 7.2 cd 6 b 39 c

LESCO Microprill 10 6.3 b 6.0 d 7 b 25 de20 6.7 b 6.5 cd 10 b 21 e

LESCO Water 10 6.5 b 6.3 cd 9 b 23 edegradable 20 6.5 b 6.7 cd 11 b 38 cd

Frit-Sul-Ate 10 6.7 b 6.7 cd 11 b 29 cde20 6.3 b 6.8 cd 5 b 31 cde

Cleary Flowable 10 8.5 a 8.5 ab 47 a 75 b20 8.7 a 9.0 a 49 a 143 a

Check 6.7 b 6.0 d 5 b 20 e

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Table 4. Effect of sulfur applications on annual bluegrass turf growing onloam soil -- Study II. Treatments applied August 22, 1986 atrates shown in pounds per 1000 square feet. Averages of 3replications. Hancock Turfgrass Research Center. A rating of 9is best.

Treatment Color ratingCarrier Rate 9/8 9/19

Thiolux 1 6.7 ns 6.0 ns2 6.7 5.85 6.8 5.8

Cleary 1 7.3 5.02 7.0 5.85 6.8 5.3

Check 6.8 5.3

Table 5. Effects of sulfur applications on Penncross creeping bentgrassturf growing on loamy sand soil. Treatments applied July 19, 1986at rates shown in pounds product per 1000 square feet. Averagesfor 3 replications. Hancock Trofgrass Research center. A ratingof 9 is best.

Treatment Color rating C9=dark green)carrier Rate 8/8 8/14 9/8 9/19 10/16Cleary 5 6.7 ab 7.5 a 7.0 b 7.3 a 7.5 a

Flowable 5 + 5 7.2 a 6.8 a 7.5 a 7.5 a 7.5aIESCO 5 5.7 b 5.7 b 5.5 c 5.5 b 6.3 b

Microprill 5 + 5 6.2 ab 5.7 b 5.5 c 5.5 b 6.3 bCheck 6.5 ab 5.7 b 5.5 c 5.7 b 6.3 b

6

EFFECTS OF PHOSPHORUS AND POTASSIUM APPLICATIONS ON SOIL TEST AND TURFRESPONSE

In an ongoing study at the Hancock Turfgrass Research Centerapplication rates of P205 and K20 are made as shown in Tables 6 and 7,respectively to Penncross creeping bentgrass growing on three differentsoils. These soils are a dune sand (built to PurrWick specification), a2NS sand with 25% peat mixed into the surface 4 inches; and a native sandyloam soil. The ability to hold applied phosphorus (Table 6) is evident inthe sandy loam and sand/peat soils. There is already a high phosphoruslevel in the untreated sandy loam soil while the phosporus test in thesand/peat untreated soil is only 10 pounds per acre. This should be lowenough to result in a lack of growth although this is not evident on theplots. The sand does not hold the phosphorus as well and some leaching hasobviously occurred. It has become evident that more frequent applicationsof phosphorus at lighter rates are necessary on sands.

A similar response has occurred with potassium (Table 7) except thesand holds essentially no potassium. There is no difference in soilpotassium tests between the untreated check and the highest K20 rate. Whatis applied is either being removed with the clippings or is leached due tovery low cation exchange capacity. The addition of some peat to sanddramatically increase the potassium holding capacity of the soil. Forthose turf managers growing turf on pure sands or where sand topdressing isbuilding a sand layer, potash should be applied several times a year, justas with nitrogen.

Phosphorus deficiency can also occur on fine textured subsoils. Astudy was initiated in 1984 on an apartment complex in Novi to determinethe phosphorus response on a soil testing very low in phosphorus.Phosphorus was applied as 0-46-0 at rates shown in Table 8. Initiallythere was visual evidence of response to the phosphorus with improveddensity and growth but the data collected did not indicate significantdifferences. Extra nitrogen was applied in 1986 after which the turfquality ratings and density ratings were significantly improved (see Augustand September ratings). Soil tests did not reflect a significant increasein available soil phosphorus levels even at the 8 pounds per 1000 squarefeet application rate. The thatch was discarded before testing was done.Since the thatch is very thick on the site (over 1 inch) the phosphorus islikely still in the thatch layer. Obviously, further study is necessary.The bottom line is that lawn care companies and others who are treatingsodded turfs on compacted subsoils should be sure to include somephosphorus in their fertility programs. We cannot afford to have poor turfresponse to nitrogen because phosphorus or some other element is deficient.

7

Table 6. Effect of phosphorus applications on phosphorus soil tests ofthree soils maintained under greens conditions. Treatmentsinitiated in 1983. Hancock Turfgrass Research Center.Averages of 3 replications.

P205 annually Phosphorus soil tests. 1bs/acre

1bs/1000 sand sand/peat sandy loam

0 12 10 116

0.5 18 45 136

1.0 47 94 173

2.0 89 166 290

Table 7. Effect of potash applications on potassium soil tests of threesoils maintained under greens conditions. Treatments initiatedin 1983. Hancock Turfgrass Research Center. Averages of 3replications.

K20 annually Potassium soil tests. Ibs/acreIbs/1000 sand sand/peat sandy loam

0 32 91 830.5 35 123 1121.0 40 144 1412.0 35 236 221

8

Table 8. Effect of phosphorus applications on Kentucky bluegrass sodgrowing on a compacted clay loam subsoil testing very low inphosphorus.

Treatment Turf quality rating (9....best) Turf density (9=best)Prate 7/3 8/19 9/26 7/3 8/19

1bs/1000

0 4.8 a 5.2 b 5.5 b 6.5 a 5.3 b

1 5.7 a 8.8 a 8.2 a 6.8 a 8.8 a

2 6.7 a 8.8 a 8.7 a 7.7 a 9.0 a

4 6.5 a 8.5 a 8.2 a 7.3 a 8.7 a

8 6.3 a 8.5 a 8.7 a 7.7 a 9.0 a

9

TOPDRESSING STUDIES ON GREENS

A new study on topdressing of a Penncross creeping bentgrass green wasinitiated in 1986 utilizing sand and sand/peat mixes prepared by the GreatLakes Minerals Co. The objective is to determine if the addition of peator peat and soil into the mix will result in an improved soil medium forgreens. The treatments applied are given in Table 9. The TDS-50 is thesand used in the study. The 80:20 mix is 80% TDS-50 sand and 20% peat on avolume basis while the 60:20:20 mix is 60% sand, 20% peat and 20% soil.The hypothesis is that the 80:20 or the 60:20:20 mixes will result in equalquality turf (or improved) with a soil medium that will be easier to managethan sand alone because of increased water and nutrient holding capacities.Of necessity this is a long term study to allow a buildup of thetopdressing material. Data taken this first year indicate there were fewconsistent, major differences, although there seems to be an improved turfquality following topdressing applications. Note particularly the improvedturf ratings after the heavier topdressings applied in the fall compared tothe ratings on the light and frequent (every 3 weeks) topdressingtreatments. Since this study has just begun, we cannot yet make arecommendation based on results.

The long-term sand topdressing study which has several frequencies andrates of sand topdressing and two nitrogen rates was continued. This hasbeen reported on in past years so no new data will be presented here. Golfcourse superintendents are strongly encouraged to follow their sandtopdressing program faithfully to prevent any development of layers in thegrowing medium.

Table 9. Effect of topdressing a Penncross creeping bentgrass green mowedat 3/16 inch with Great Lakes Minerals topdressing mixes. Studyinitiated Spring, 1986. Hancock Turfgrass Research Center.Averages of 3 replications.

Treatment Quality rating C9=best)mix Rate Frequency Jul 7 Sept. 21 Nov 3

cu ft/m

TDS-50 3 3 weeks 5.7 bd 5.7 bc 6.2 c12 Spr, Fall 6.3 b 5.7 bc 7.0 b

80:20 3 3 weeks 5.3 cd 7.3 a 6.2 c12 Spr, Fall 7.2 a 5.7 bc 7.8 a

60:20:20 3 3 weeks 5.5 cd 7.5 a 6.2 c12 Spr, Fall 7.5 a 5.7 bc 7.8 a

Check 5.2 d 5.5 c 6.0 c

TDS-50 12 Spr, Fall 6.0 bc 6.0 b 7.0 b(Cored)

10

COMPARISON OF SEVERAL AERIFIERS

A comparison of several aerifiers was made in September. The study wasdone on two sites: one on a perennial rye grass turf growing on a heavysandy loam soil at the Hancock Turfgrass Research Center and the other on amodified sandy loam student athletic field on campus at M.S.U., which ishighly compacted. Aerifiers utilized in the study were those which couldbe gathered from several companies at the same time. Unfortunately, somecommercially available units were not available at the time of the study sothese could not be ~ncluded in the study.

Data collected were limited because of extended rainfall aftertreatment. The amount of soil removed by hollow tine units is given inTable 10. As would be expected, the Verti-Drain unit removed the most soilbecause of depth of tine, spacing at 2.5 inches longitudinally and diameterof tine. The new Taro aerifier was also very effective. The Salsco unitis much smaller and naturally removes less soil. These data represent soilremoved from a plot area of 4 square feet and 2 samples per plot.

Data were also collected on penetrometer readings to determinerelative ability of the various units to loosen the surface soil. Thesedata are still being analyzed. Other units included in the study were theAer-Way and Verti-Drain solid tine aerifiers.

Table 10. Weight of soil removed from 4 square feet by aerifiers. Loamsoil. Hancock Turfgrass Research Center. September, 1986.Averages of 4 replications and 2 measurements per replication.

Aerifier Dry soil wt.grams

Verti-Drain, 2.5 inchVerti-Drain, 4 inch

935 a639 b

TaroSalsco

727 ab121 c

11

LONG TERM NITROGEN FERTILITY STUDIES

Two long-term nitrogen fertility studies were evaluated in 1986.Treatments for these studies are outlined in Table 11 and data shown inTables 12 and 13. These studies evaluate nitrogen fertility programscomparing carriers, rates and frequencies. These studies have been set upcooperatively with J.M. Vargas, Jr., and the first has been conducted on aPenncross creeping bentgrass green at the Hancock Turfgrass ResearchCenter. Turfgrass Quality ratings data are given in Table 12. Results areabout as expected from these treatments. Late fall applications ofnitrogen (treatments 1,3,5,7,9 and 11) give better spring color. The 18-4-10 is provided by the Lebanon Chemical Col. and is used as representativecomplete fertilizer containing some slow release nitrogen. In May 1986 aspotty response was noted to the application of urea, ammonium nitrate andsulfur coated urea. This has been observed in the past. In all otherstudies with urea or ammonium nitrate we have found it necessary to applythese materials as a spray to prevent this spotty response which occurs inspite of watering immediately after app1icati~n. The spottiness is causedby a high concentration of soluble nitrogen being released around thefertilizer granular giving greener spots on the greens. This is seenoccasionally of annual bluegrass fairway height turf but has not beenobserved on turfs which are mowed higher.

The residual effects of the treatments outlined in Table 11 are givenin Table 13. The study was discontinued in 1986 but some residual datawere taken. The most striking response was the dramatically higherincidence of annual bluegrass seedheads for certain fertility treatments.The higher the nitrogen rate the more seedheads developed. Comparetreatments 16 through 20 with rates of nitrogen ranging from 1.0 to 7.5pounds N per 1000 square annually. Of further interest is the tendency forlate fall N applications of certain carriers to result in more seedheads.

Another long term study is the effect of nine different nitrogenfertility programs on three creeping bentgrasses, Emeralds, Penncross andPenneagle. Treatments applied to these turfs which were maintained undergreens conditions are given in Table 14. Turfgrass quality ratings aregiven in Tables 15 through 17 for the three grasses while color ratings aregiven in Tables 18 through 20. Responses are as would be expected fromthese treatments. This study will be terminated in 1987.

12

Table 11. Treatments applied on a Penncross bentgrass green and on annualbluegrass in a fairway nitrogen carrier fertility study at theHancock Turfgrass Research Center. Treatments initiated in 1982 andrevised in 1985. Plot size is 6 feet by 6 feet. Four replications.

Treatment Month of applicationNo. N Carrier Nov Apr May June July Aug Sept Total

- - - - Pounds N per 1000 sq. ft. - - - -1 IBDU 1.0 0.5 0.5 0.5 1.0 3.52 IBDU 1.0 1.0 1.0 1.0 4.03 S.C. Urea 1.0 0.5 0.5 0.5 1.0 3.54 S.C. Urea 1.0 1.0 1.0 1.0 4.05 Urea 1.0 0.5 0.5 0.5 1.0 3.56 Urea 1.0 1.0 1.0 1.0 4.07 Am. Nitrate 1.0 0.5 0.5 0.5 1.0 3.58 Am. Nitrate 1.0 1.0 1.0 1.0 4.09 Mi10rganite 1.0 0.5 0.5 0.5 1.0 3.5

10 Mi10rganite 1.0 1.0 1.0 1.0 4.0

11 18-4-10 1.0 0.5 0.5 0.5 1.0 3.512 18-4-10 1.0 1.0 1.0 1.0 4.013 18-4-10 1.0 1.0 2.014 18-4-10 0.5 1.0 0.5 0.5 0.5 1.0 4.015 18-4-10 1.0 1.0 1.0 1.0 1.0 1.0 6.016 Urea 0.5 0.5 1.017 Urea 1.0 1.0 2.018 Urea 0.5 1.0 0.5 0.5 0.5 1.0 4.019 Urea 1.0 1.0 1.0 1.0 1.0 1.0 6.020 Urea 1.5 1.5 1.0 1.0 1.0 1.5 7.5

13

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14

Table 13. Effect of residual nitrogen carrier fertility treatments asoutlined in Table lIon visual turf quality ratings and relativeseedhead production of annual bluegrass. Hancock TurfgrassResearch Center. Averages of 4 replications.

Treatment Quality rating (9=best) Relative seedheads (9=most)

No. N Carrier Apr 4 May 16

1 IBDU 2.8 ce 4.6 bf2 IBDU 2.3 ef 6.6 gi3 s. coated urea 3.4 ac 4.6 bf4 s. coated urea 2.1 ef 6.1 fh5 urea 3.9 a 5.0 bf6 urea 2.1 ef 5.8 eg7 ammonium

nitrate 3.6 ab 4.4 bf8 ammonium

nitrate 2.3 ef 4.1 be9 milorganite 3.1 d 3.5 bc

10 milorganite 2.1 ef 4.4 bf

11 18-4-10 3.3 ac 4.5 bf12 18-4-10 2.4 ef 4.0 bc13 18-4-10 2.5 df 2.9 ab14 18-4-10 2.3 ef 3.4 ac15 18-4-10 2.0 f 5.4 dg16 urea 2.8 ce 1.9 a17 urea 2.6 df 4.4 bf18 urea 2.3 ef 5.3 dg19 urea 2.3 ef 7.4 hi20 urea 2.5 df 7.9 i

15

Table 14. Long-term nitrogen fertility program treatments which have beenapplied to Penncross, Penneagle or Emerald creeping bentgrassturfs mowed at 3/16 inch. Treatments initiated in 1982. Allplots receive 2 pounds K20 per 1000 sq. ft. annually. HancockTurfgrass Research Center. Averages of 3 replications.

TreatmentNo. Carrier N rate Month of application

lbs/lOOO Apr May June July Aug Sept Nov

1 Urea 1 0.5 0.52 Urea 2 1.0 1.03 Urea 3 1.0 0.5 0.5 1.0

4 Urea 4 1.0 1.0 1.0 1.05 Urea 6 1.0 1.0 1.0 1.0 1.0 1.06 Urea 8 1.25 1.25 1.25 1.25 1.25 1.25

7 Urea 4 1.0 0.5 1.0 1.58 Mi10rganite 4 1.0 0.5 1.0 1.59 Ammonium 4 1.0 1.0 1.0 1.0

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