HEAVI NITROGEN FERTILIZATION OF COOL SEASON TURF GRASSES

A Thesis

Submitted to the Faculty

of

Purdue University

by

NormanRichard Goetze

In Partial Fulfillment of theRequirements for the Degree

ofDoctor of Philosophy

January 1960

ii

ACKNMEDGMENTS

The author expresses his appreciation to the following for their

support, inspiration, guidance, and assistance in the completion of this

work.

To Dr. W. H. Daniel, the major professor, for his untiring counse L

and inspirational attitude toward research;

to Dr. J. L. White and J. L. Ahlrichs far their patient assistance

in organizing several of the sampling and labor atory procedures;

to Jam s Beard, Stephen Frazier, Edward Jordan, and Robert Montgomery

tor their cooperative support in both' the planni~ and execution of the

study;

to Monty Aldefer, ThomasHodges, Eugene Johanningsmeier,' OwenLewis,

and Paul Morgan for their unselfish devotion to many of the routine

operations;

to Dr. E. H. Barnes for his constructive cri.ticisms of ,the manu-

script;

to Allied Chemic I C any, rican Cyanamid Company,Bordens Chemi-

cal Company,Corn Products Refining Company,E. I. du ont de Nemours and

Company,Milwaukee Sewerage Commission, and Nitroform Agricultural Chemi-

cals for t 1r financial support; to all these a sincere debt of gratitude

is aclmowledged.

While this obligation cannot be repaid to th individual creditors,

it is the author's fervent wish that he may in like manner help other rem-

bers of the scientific agricultural community whenever possible.

lli

TABLE OF CONTENTS

Turf Quality •Height of Growth •Turf Density •Mechanical Support~ Weight of Clippings.Percent of Nitrogen in Clippings.Nitrogen Reoovery.Soil Nitrogen •Soil Carbon. •Carbon-Nitrogen Ratio

..

Pageiv

v

vii133577

9

., . 91417172323283137424751546063646875

LIST OF TABLESLIST OF FIGURES .ABSTRACT •

DlTRODUCTION •:LITERATURE REVIFM •

Changes in Soil Organic Matter and Nitrogen •Mechanism of Soil Nitrogen Volatilization.Turf' Fertilization Research' •Ureaformaldehyde Fertilizers ~

METHODS AND MATERIALS.Turf Response •Soil Re sponse •

RESULTS AND DISCUSSION.

SUMMARY OF RESULTS AND DISCUSSION •CONCLUSIONSBIBLlOORAPHYAPPENDICESVITA.

iv

LIST OFTABLES

Table Page

1. 'Properties and Source of Fert~lizers Studied . 11

2. Plan of Putting Green Fertilizer Treatments . IS

3. Creeping Bentgrass Turf Quality during the FirstSeason after Fertilization . . 21

4. Average Annual Requdz-emerrt of Nitrogen and Numberof Applications to Maintain Desirable Turf Qualityover a Three-Year Period • • 22

S• Relative Dry Weight Yields of Clippings from theCreeping Bentgrass Trials at Various Times . . 36

6. Nitrogen Content of Clippings from Creeping Bentgrass . 43

v

LIST OFFIGURES

Figure•

Page

1. Visual Ratings of Ryegrass Turf Quality afterTreatment with 2 Rates of Organic and UreatormFertilizers • 18

2. Visual Ratings of Ryegrass Turf Quality afterTreatment with Various Formulations at 8 Poundsof Nitrogen per 1,000 Square Feet •

3. Height of Seven Days of Growth of Ryegrass Turfafter Treatment with 2 Rates of Organic andUreaform Fertilizers

· 19

• 24

4. Density of Ryegrass Turf after Treatment with2 Rates of Organic and Ureaform Fertilizers.

S. Density of Ryegrass Turf after Treatment withVarious Formulations at 8 Pounds of Nitrogen per1,000 Square Feet

6. Mechanical Support by Ryegrass Turf after Treatmentwith 2 Rates of Organic and Ureaform Fertilizers ·

• 2S

• 27

• 297. Mechanical Support by Ryegrass Turf after Treatrrent

with Various Formulations 8 of Nitrogenper 1,000 Square Feet •

8. Dry Weight Yield of Ryegrass Clippings from WeeklyHarvests after Application of 2 Rates of Ureaformand Organic Fertilizers

• 30

· 329. ,WeeklyDry Weight Clipping Yields from Ryegrase

Turf atter TreatlTSnt with Various Formulations at8 Pounds of Nitrogen per 1,000 Square Feet • · 34

10. Weekly Ryegrass Dry Weight Clipping Yields afterTreatIrent with Different Ureaform Fertilizers at8 Pounds of Nitrogen per 1,000 Square Feet ·

11. Nitrogen Content of Ryegrass Clippings afterTreatment with 2 Rates of Organic and Ureaf'ormFertilizers

• 3S

· 38

vi

Figure

12. Nitrogen Content of Ryegras Clippings afterTreatment with Various Nitrogen Materials at8 Pound,s of Nitrogen per 1,000 Square Feet •

13. Nitrogen Content of Ryegrass Clippings afterTreatment with Different Ureaform Fornmlationsat 8 Pounds of Nitrogen per 1,000 Square Feet.

1.4. Nitrogen Recovered in Ryegrass Clippings afterTreatment with Different Nitrogen FornD.l1ationst 4 Pounds of Nitrogen per 1,000 Square Feet •

IS. Nitrogen Recovered in Ryegrass Clippings afterTreatment with Different Nitrogen Formulations.

16. Soil Nitrogen at 0"-1" Depth after 3 AnnualTreatments of Nitrogen Fertilizers on MerionBluegrass Turf

17 . Soil Nitrogen at 2 Depths after 3 Annual Treatmentsor Nitrogen Fertilizer on Merion Bluegrass Turf

18. SoU Carbon at 2 Depths after 3 Annual Treatmentsof Nitrog n Fertiliser at MediumRates on MerionBluegrass Turf

19. Soil Carbon at 2 Depths atter 3 Annual Treatmntsof trogen Fertilizer at Higher Rates on MerionBlu "grass Turf

20. Carbon- itrogen Ratio of the Upper Soil Inch afterTreatment. of Merion Bluegrass Turf with 3 AnrmalApplications of Nitrogen Fertilizer at High Rates

21. Carbon-Nitrogen Ratio of the Upper Soil Inch afterTreatment or Merion Bluegrass Turf' with 3 AnnualApplications of Nitrogen at MediumRates.

Page

• 39

.41

· 4,· 46

· 48

· ,0

• ,2

· ,3

· "· ,6

22. Carbon-Nitrog n Ratio of th 7"-13" Soil Depth afterTreatment of Merion Bluegrass Turf with 3 AnnualFertilizatims at MediwnRates. · S7

23. Carbon-Nitrogen Ratio of the 7"-13" Soil Depth afterTreatment of Merion Bluegrass Turf with 3 AnnualFertilizations at High Rates. · ,8

vii

ABSTRACT

Goetze, NormanRichard. Ph.D., Purdue University, January 1960.

HeavyNitrogen Fertilization of Cool Season Turf Grasses. Major Pro-

tessor: William H. Daniel.

Greenhouse and field comparisons of representative types of nitrogen

fertilizers at heavy rates of application to turf were made. Objective

measur'emant.sof turf response, as well·.~ changes in soil carbon and

nitrogen levels, were measured.

A greenhouse ryegrass turf experiment clearly portrayed the changes

in turf responses at 28-day intervals over a 24 week period. The turf

was mowedat weekly intervals and detailed observations of plant response

to 4, 8, and 16 pounds of actual. nitrogen per 1,000 square feet were made.

Similar materials were evaluated on a creeping bentgrass putting

green. Turf reactions to nitrogen were kept nearly equal and the amount

of nitrogen required from different sources was measured as the dependent

variable.

The long term effects of repeated annual applications of 4, 8, and

20 pounds of nitrogen per 1,000 square feet on Merionbluegrass turf and

aod.L were studied.

Natural organic materials produced better visual estimates of rye-

grass turf' quail ty than e1ther soluble or ureaformaldehyde fertilizers at

comparable rates. Less soluble and organic fertilizer nitrogen was re-

quired to produce putting green turf quality equivalent to ureaformaldehyde.

viii

Under the conditions of this experiment, no differences in Merion blue-

grass turf quality were observed.

Density of ryegrass turf was not affected by differences between

materials, .but was improvedwith increased rates of ni.trogen. No density

differences in Merion bluegrass turf' occurred.

Amethod fo'r objectively measur'Lngthe amountof mechanical support-

ing ability of turf was developed. The height of a constant weight tennis

ball supported by the turf above a standard plot mountedring was measured.

Organic materials gave better mechanical supporting ability to ryegrass

turf than other tertilizers •

Dry weight yields of ryegrass clippings r-esponded directly to the

amountof nitrogen applied with the organic materials giving a higher re-

sponse at comparable rates. Anexperimental material, .UF-80, produced a

consistently high yield of clippings. Ureaformaldehyde-~terials produced

a more uniform yield than other materials. No differerees in yield of

Merionbluegrass turf clippings were found between 4, 8, and 20 pounds or

nitrogen per 1,000 square feet.

The nitrogen content of ryegrass clippings decreased steadily atter

an early peak in direct relationship to the nitrogen availability. Putting

green clipping nitrogen content also varied with fertilizer r-ates; .Nttro-

gen deficiency symptomsappeared when the ryegrass clippings dropped to

3% nitrogen and when the putting green clippings dropped to 2.8%nitrogen.

Merion bluegrass clippings varied from 3.4% to 4.6% in their nitrogen

content.

The amountof nitrogen recovered in the clippings ot ryegrass varied

from 33% of that applied in the soluble· form to only l7t of the ureaformalde-

by'de applied. At the end of a five we.ekleaching period, the soluble ma-

ix

terial had lost 19%of the nitrogen applied, whereas the ureaforma1dehyde

lost only 2.2%. Little additional nitrogen was removedby further leaching.

Atter three years of heavy nitrogen fertilization, Merion'bluegrass

turf soils were found to have accumulated large amountsof nitrogen in the

top inch, especially from ureaformaldehyde materials. Increases in nitro-

gen content at lower depths were related to solubility and b:reakdownrate.

Merionbluegrass soil carbon content at the surface level was not in-

fiuemed by fertilizer. Carbon content 'at the lower depths was reduced

quite generally.

The carbon-nitrogen ratio of Merionbluegrass turf soils was reduced

at all depths as a result of higher amountsof nitrogen in the upper depths

and lesser amounts of carbon at the deeper depths.

1

INTRODUCTION

Recent trends in shorter working hours for the average Americanworker

have created more possibilities for family recreation. This, coupled with

an expanding and more efficient motor vehicle transportation industry,

has been one of the prime factors in the development of the modernAmerican

outdoor living attitude.

As Ii ving, recreational, and blsiness areas becone lOOrespacious, turf

assumes a more important place. To meet the demandfor better quality turf

for larger areas with an efficient expend!ture, contirmed improvementin

managementand materials is needed.

Nitrogen fertilizers for turf in the past have been either of the con-

ventional agricultural type, or of residual waste from naturally occurring

organic substances. Only in the last two decades has any interest been

shownin improving fertilizer for ation sp ially for turf. Conven-

ience of the user centered on higher analysis and better handling properties

has been of importance in marketing developIOOnt. A more long lasting re-

sponse and greater safety in applying higher rates of nitrogen have also

been sought.

The importance of fertilization to a good turf managenarrtprogram has

been well recognized. A mediumor poor quality turf can be readily im-

proved by increased usage of nitrogen fertilizer. However,afte~ several

nitrogen applications, a peak is reached and further improvenent is some-

what limited. Factors other than nitrogen becomelimiting, or the applied

ni trogen is not as readily available to the turf plants.

2

This study was designed to compare various turf responses from repre-sentative formulations of several types of nitrogen fertilizers. Also,the possible explanations for la~k of continued high responses from heavyamounts of fertilizer over a prolonged period are investigated.

3

LITERATUREREVIEl\T

Soil is a qynamie system and its properties are the result of sev-

eral variables. JeIllV' (20) lists the independent variables: climate,

organisms, topography, parent material, and time. His classification of

independent variable is not meant to imply that inter-dependence is not

possible, but rather that it is not necessary. Most concepts of soil

formation have been derived from studies of changes in soil properties

under natural vegetation. If we include manin Jenny's variable, organ-

isms, and study the effect of cropping on soils, we find similar changes

in soil properties occurring. Generally, however, the rate of change is

accefer ated,

It is not intended that this review be an exhaustive coverage of

soil nitrogen R nt r vi (2, 7, 10, 13) give good coverageof American nitrogen fertility research. Only reference to the researchmost applicable to the present work is made.

Changes in Soil Organic Matter ~ Nttrogen

Changes in soil organic mattar and nitrogen whendisturbing nati ve

North Americanprairie are a matter of record. After 75 years of cropping

with corn, oats, and wheat with no additions of any form of fertilizer,

Jenny (20) noted the following changes in a nearly flat loess dark soil

profile:

Prairie, nativeCuI ti vated 75 years

Carbon Nitrogen C!Nvalue% %

2.10 1.97 10.71.)0 0.129 10.1

4

Lysimeter studies involvi~ high rates of nitrogen application have

shownthat nDlchof the soil nitrogen is not used by the plant. Burd and

Martin (9) reported a barley cr-op to removeonly 48% of the total nitro-

gen lost from the soil. Lipmanand Blair (2.5) reported an average anrmal

loss of nitrogen, exclusive of crop reIOOval,of 103 pounds per acre over

a fifteen-year cropping period. Voorheesand Lipman(31) reported re-

cavery by cropping of only 62%from nitrate sources and 43% from anmoni-

cal nitrogen sources. Rothamstedsoils lost 70 pounds of nitrogen per

acre annually over a period of.'O years. Dyer (12) assuned most of that

loss to be by leaching. Snyder (30) reported a loss of 1400 pounds of

nitrogen p r acre over an eight-year period of continuous wheat above

that reroovedby the crop. Heassuned it to have been lost both by leach-

ing and volatilization.

Dodgeand Jones (11) found that fertilizer treatroonts and rotations

increased the rate at which equilibrium was attained as well as the C:N

ratio. Myers~!:l. (27) found that row crops tended to reduce soil ni-

trogen faster than continuous grain or alternate follow systems. White

et!l. (33) reported that unfertilized prairie soils had 68.2%more nitro-

gen than an adjacent area contimously cropped for 72 years. Holley et !!..(19) showedunder Georgia conditions that soil nitrogen could be just as

efficiently maintained with commercialfertilizer as with green marro.re

crops. Broadbent and Norman(8) found that Sudangrass used as green ma-

nure accelerated the deconposition of soil organic matter. Bizzell (.5, 6)

assumeda loss due to volatilization from lysimeters to be 24% of the to-

tal nitrogen used in fertilization over a fifteen-year period. Leachates

were also included in these calculatims. Onan eight-year lysimeter

study, without additional fertilization, from 4 to 21%of the nitro,gen

originally present was assumedto have been volatilized.

Rubin and Bear (29) reco ered tn tops and roots of Sudangrass as

muchas 59% of the nitrogen from organic fertilizers and 88% of the ni-

trogen applied as urea. 'nley found natural organics having. carbon-nitro-

gen ratios higher than 10 were relatively poor sources of nitrogen in

terms of total nitrogen recovery. Allison (2) has summarizedthe results

of several lysimeter experiments: 1. Crops generally remove 40 to 75%

of the added nitrogen. 2. Lower·percentage returns are received from

higher rates of application. 3. Soil nitrogen levels usually decrease

during cultivation. 4. Nitrogen unaccounted for by leaching and cropuse was independent or the form in which it was added.

Woodruff (37) fonnd that during the last 33 yecrs of a 68-year trial,

the soil nitrogen content had reached an equilibrium. Sources of supply

were rainfall and non-symbiotic fixation according to Allison (2). When

irrigation is practiced, larger quantities of nitrogen are used and ni tro-

gen losses both by leaching am volatilization are increased.

Mechanism~ Soil Nitrogen Volatilization

Ammonia

Twenty-five percent or Ilk>reof the total nitrogen 105s m~ be in the

rorm of 8l1IIl0nia. The five factors affecting its importance have been out-

lined by Allison (2) based on the work of Jewitt (21), Lehr (24), Martin

and Chapman(26), and Willis and Sturgis (35):

1. Losses increase as pH rises.

2. A drying soil loses ammoniaif ammoniaprecursors are near the

surface.

3. Losses increase with temperature.

4. Soils with low exchange capacity cause greater Loases,

5. Losses maybe high where rrl. trogenous materials are all owedto

decomposenear the surface.

Heck (18) has shownlosses from barnyard manure application to the

surface to be quite high. Ohlrogge (28) hypothesized rome of the un-

accountable nitrogen lost from dry soils to have escaped as ammonia.

Nitric Oxide

Allison (2), on the basis of the oxide being oxidized to nitrate or

being absorbed on organic matter, has assumed this method of loss to be

unoperative in soil systems.

Nitrogen Gas

The Van Slyke reaction (RNH2 .• HN02 " ROH ~O + N2)

has been suggested as a possible mechanismof soil rri trogan loss thr-ough

either plant or soil reactions. Allen and van Niel (1) and Allison and

Doetsch (3) have shown that low pH values are necessary for the reaction

and that nitrites 'WOuldnot be produced at those pH levels.

Nitrous Oxide and Nitrogen Gas from Bacterial Denitri. ication

Wijler and Delwiche (34) f'ourd these materials to be the major deni-

trification product under artificial conditions.

Organic Subst~es from Plants

Franzke and Hume(14) have reported hydrocyanic acid to be commonly

exuded from someplants. Wilson ()6) reported nitrates, nitrites, andammoniaas commonplant exudates. The volatile materials could escape

from the plant surface, but ultimately the nonvolatile materials would be

returned to the substrate. The quantitative importance of this mechanism

is not known. In most soil conditions, therefore, evolution of nitrogen

gas or ammord.aprobably accounts for most of the volatilization losses.

7

Turf Fertilization Research

Armiger~.:!. (4) found nitrogen content of ryegrass clippings tobe mre variable than dry matter pro

8

Kralovee and Morgan(23) further delineated the factors of environ-

nent which control the rate of release of nitrogen froin ureaform fertili-

zers. They found the highest availability at pH6.1. Additional amount.sI

of phosphorus and potassium stinulated ni. trogen availability. They also

assumedthat increasing lOOistureand temperature would increase the ni-

trifying rate.

In relating the chemical properties of th different fornnlations

to rate of availability, the AI or availability index methodwas devised.

It is based on the percentage of cold water insoluble nitrogen that will

diasol ve in a hot dilute phosphate buffer. The avail abili ty index is

given by the following !ornula:

AI = % IN - % HWINx 100%IN

where AI is the availability index, IN is the cold water insoluble ni tro-

gen,and HWINis the hot dilute phosphate buffer insoluble nitrogen.

9

METHODS AND MATERIALS

~ Response

Ryegrass

The effect of the three commonformulations of nitrogen soluble, ,organic, and ureaform on ryegrass turf was studied under controlled con-

d1tions in the greenhouse (16-hour day and 700 F. temperature). The con-

tainers were I-gallon stone crocks filled to within l~n from the top with

a uniformly mixed Brookston silty clay loam soil. Pots were watered by

the addition of 400 ml, of water uniformly over the sur ace whenever the

soil surface appeared dry during 'an early morning daily check. Previous

experience in earlier experiments had ind1.cated that this system kept

the available soil moisture within tolerable limits.

Perennial ryegrass (Lolium perenne) was seeded at the rate of 10

pounds t>er 1,000 square feet approximately' 6 weeks before the start of

the experiment and harvested at weekly intervals until the experiment be-

gan, During the weekbefore the applicatim of fertilizers, clipping

weights from the individual plots were taken and the plots were arran ed

in descending order of clipping weights and green color to minimize the

variance within individual. replications. At this particular time there

was very little newgrowth, indicating a low re sichlal amountof nitrogen

in the soil. Four replications in a randomizedblock design were used.

nte nitrogen fertilizers for the individual plots were weighed out

and mixedwith an amountof 0-20-20 mixed fertilizer to give P and K levels

10

at 80 pounds per acre so that neither phosphorus nor potassium wculd be

limiting during the experiment.

All materials (Table 1), except cyanamid, were applied at rates of

4, 8, and 16 pounds of nitrogen per 1,000 square feet. Aliquots of thefertilizers were nd.xedwith the 0-20-20, and the mixtures were diluted

with dry sand to facilitate distribution. These were evenly applied over

the surface of the turf and the leaves were immediately washedwith water

from a clothes sprinkler to minind.zethe possible foliar burning effect

from the soluble fertilizers and the 0-20-20.

At seven-day intervals, the ryegrass was clipped at approximately

2" height above the soU. The height of clipping on the irxiivich.1alplots

was kept constant by use of a steel ring whichwas fitted over the top of

the individual crocks. This ring served as a guide in the use of the hand

shears. The hand shears had a small al umirum plate on the back side of

the large blade whichwas used to collect the clippings. At the time of

weekly clipping, the height of the seven-dq growth was measuredby placing

a ruler over the clipping ring and estimating the ava-age might of the,

leaves above the ring. The clippings were dried at 1700 F. for 24 hours

or more and weighed.

Immediately atter clipping, the turf density was estimated by counting

the cut blades of ryegrass boundedby!" by 2" cardboard template.

Turf' quality was estimated visually us:ing a rating scale of 1 to 9,

with increases in ratings denoting decreases in quality.

The 8lOOuntof mechanical support which the turf stubble cou'Ldgive to

constant pressure was estimated by measuring the height in millilooters of

a tennis, ball above a connon reference point (clipping ring).

11

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12

Nitrogen content of the clippings was detennined by use of a modified

Kjeldahl procedure:

1. Digestion for two or more hours using 30 rol. of concentrated sul-

furic acid in the presence of 5 g. of catalyst •.2. Catalyst was compoed of 10 parts of sodium sulfate and 1 part of

copper sulfate. Preliminary trials with additions of mercury or

selenium compoundsgave nc rreduct.Lonsin digestion time, nor dif-

ferences in nitro en content. These compoundswere omitted because

of their hazardous nature. Reduction of ni trates and nitrites by

use of salicylic acid and powdered zinc also did not give increases

in nitrogen values of clippings.

3. Onehundred ten ml, of water were added to the cooled digestion

mixture and the mixture was allowed to reach room temperature.

4. Onehundred ml, of 40% sodium hydroxtde and a liberal arrount of

mossy zinc were added and the "mixture was distilled until 100 rol.

of ammoruawere distilled.

5. The ammoniadistillate was collected in a 4% solution of boricacid, containing a mixture of methyl red and brom-cresol green

indicators.

6. The ammonium-boratecomplexwas titrated with standardized hydro-

chloric acid solution.

7. Normali ty of the hydrochloric acid and quantity of grass clippings

were adjusted so that the amount of acid used in titration fell

somewherebetween 15 and 40 ml,The percentage of nitrogen and dry weight of clippings were used in

the calculation of the total amountof nitrogen recovered from the clip-

pings. Also, the accumulated harvests of nitrogen in the clippings above

13

that of ,the check plot was tabulated, using the quadri-weekly nitrogen

values.

Data from all observations were collected and processed only at 2&.

day intervals strce earlier experieme had failed to showthe necessity

for weekly observations.I

The experiment was contirmed far 2h weeks and data were processed

and statistically analy-zed. Results were graphically prepared only when

"F" values in the analysis of variance were significant at the 5% level.

Creeping Bentgrass

Several formulations of nitrogen fertilizers were tested on putting

green turf. The experiroontal putting green located on the Purdue Univer-

sity ~aI!q)usand composedprimarily of Old Orchard variety of creeping bent-

grass (Agrostis palustris) with someinfestation of Poa annua was used.

Materials were applied with a 36-inch professional model ttLawn Beauty'!,

fertilizer spreader. At least two applications to each plot were given

at each tine of application to insure uniform distril:u td.on, The plot size

was 3 feet by 48 feet, and each treatment was replicated three times in

a randomizedblock design. Visual estimates of turf quality were made

periodically by two or IOOreindividual observers. Clippings were collected

from a putting green moweroperated through the center of the plots. Clip-

pings were dried and weighed. Nitrogen contents of clippings were deter-

minedperiodically as described earlier. During tbe first year, fertilizer

sources were applied at equal rates of nitrogen. Therefore, any differences

in th~ir performance would be observed as differences in turf quality.

During the later two years of the experiment, turf quality was kept

equal and the amount.of nitrogen require d for its maintenance was used as a

14

criterion in measuring differences between the fertilizers. Determining

when to add additional fertilizers was done by fifteen-d~ inspections of

the turf. Anyplots rating 4 or more on the quality scale were given addi-tional amountsof fertilizer as outlined in Table 2.

Merion Bluegrass

The effects of high rates of the different types of fertilizers on

Merionbluegrass (~pratensis) were determined by the applications of

representatives of the materials in Table 1 at rates from 4 to 20.pounds

of nitrogen per 1,000 square feet per year. Applications 'Weremadeto 3

foot by 10 foot plots by hand distribution of the aliquot mixedwith sand

to facilitate better distr:1hution. Six replications in a rancbnti.zedblock

were used.

Duri~ the first year' 5 observation 0n these plots, no damaging effect

was noticed from any rates of application. Consequently, the long term

effect upon soil carbon and nitrogen was studied. Turf quality, clipping

weights, and density ratiq;s were also taken.

~ Response

Leaching

The resistance of the various nitrogen fertilizers to leaching was

estimated in the ryegrass greenhouse fertility work by removing the drain

plugs from the creeks and watering once a week in excess• Nitrogen deter-

minations of the leachate were madeby the previously ouUinad Kjeldahl

procedure lOOdifiedby addition of salicylic acid and zinc to include ni-

trates. This was a phase of a study on differelXes in turf quality and

other plant responses.

I,

Table 2. P1~ of Putting Green Fertilizer 'l'reatnents

Nitrogen/l,OOO Square FeetMaterial Second and Third YearFirst Year

Spring Fall InterimIbs. lbs. Lbs , 1bs.

Urea 3 1.0 1.0 0.5Urea 6 2.0 2.0 1.0Sludge 3 1.0 1.0 0.,Sludge 6 2.0 2.0 1.0Gluten 3 1.0 1.0 0., .Gluten 6 2.0 2.0 1.0

UF 35 9 3.0 3.0 3.0UF 3, 6 4., 4.5 4.,tJF 3, 9 6.0 6.0 6.0UF 56 9 3.0 3.0 3.0

UF 56 6 4., 4., 4.,UF 56 9 6.0 6.0 6.0

16

Soil Nitrogen

Nitrogen content of soils from the putting green trial were deter-

mined at 0"-1", 1"-7", and 7"-13" depths. Sampleswere taken with the

Hoffer tube and dried in a 6,0 C. oven for 24 hours. Total soil nitrogendeterminations were madeby the Kjeldahl procedure. Similar samples were

taken from the Merionbluegrass trial. An additional 13"-20" depth sam-

ple was collected.

Soil Carbon

Samples of soils collected for the soil nitrogen determinations were

analyzed for readily oxidizable organic carbon (32). The procedure en-

tailed the use of 0.3 to 0.6 grams of air day soil, depending upon amount

of organic matter. The carbon and other materials were oxidized by the

addition of 10 ml, of 1 normal potassium dichromate and 20 ml., of concen-

trated sulfuric acid. Heat for the reaction was generated during the mix-

ing of the sulfuric acid and dichromate. No external heat was applied.

The reaction mixture was cooled and 200 mI. of water were added to reduce

concentrations. Twenty-five ml, of ferrous anunoniumsulphate were added

and resulting ferric ion was titrated with 0.2 normal standardized po-

tassium permanganate. The results from this analysis were expressed as

percentage of carbon, using the factor 1.34 as suggested by Walkley (32)

to correct for incomplete oxidation of carbon.

Carbon-Nitrogen Ratio

Carbon-nitrogen ratios of soil samples from Lndf,vidual plots from

both putting green nd Merion bluegrass trials were calculated by dividing

the percentage of carbon by the percentage of nitrogen of the respective

plots.