EFFECT OF SULFURIC ACID ON AMMONIAVOLATILIZATION UNDER FIELD CONDITIONS

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Authors Yahia, Taher Ahmed, 1947-

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YAHIA, Taher Ahmed, 1947-EFFECT OF SULFURIC ACID ON AMMONIA VOLATILIZATION UNDER FIELD CONDITIONS.

The University of Arizona, Ph.D., 1977 Agronon\y

Xerox University Microfilms, Ann Arbor, Michigan 48106

EFFECT OF SULFURIC ACID ON AMMONIA VOLATILIZATION

UNDER FIELD CONDITIONS

by

Taher Ahmed Yahia

A Dissertation Submitted to the Faculty of the

DEPARTMENT OF SOIL, WATER AND ENGINEERING

In Partial Fulfillment of the Requirements For the Degree of

DOCTOR OF PHILOSOPHY WITH A MAJOR IN SOIL AND WATER SCIENCE

In the Graduate College

THE UNIVERSITY OF ARIZONA

19 7 7

THE UNIVERSITY OF ARIZONA

GRADUATE COLLEGE

I hereby recommend that this dissertation prepared under my

direction by T a h e r A h m e d Y a h i a

entitled E f f e c t o f S u l f u r i c A c i d o n A m m o n i a

V o l a t i l i z a t i o n U n d e r F i e l d C o n d i t i o n s .

be accepted as fulfilling the dissertation requirement for the

degree of D o c t o r o f P h i l o s o p h y

ssertation Director

J) / f ate

As members of the Final Examination Committee, we certify

that we have read this dissertation and agree that it may be

presented for final defense.

T

-&JI

L A rts 3 J)?77

< . ,/ff 7 ?

/O -^>'7 ~~ts 5

Wmi.

Final approval and acceptance of this dissertation is contingent on the candidate's adequate performance and defense thereof at the final oral examination.

STATEMENT BY AUTHOR

This dissertation has been submitted in partial fulfillment of requirements for an advanced degree at The University of Arizona and is deposited in the University Library to be made available to borrowers under rules of the Library.

Brief quotations from this dissertation are allow­able without special permission, provided that accurate acknowledgment of source is made. Requests for permission for extended quotation from or reproduction of this manu­script in whole or in part may be granted by the head of the major department or the Dean of the Graduate College when in his judgment the proposed use of the material is in the interests of scholarship. In all other instances, however, permission must be obtained from the author.

SIGNED:

ACKNOWLEDGMENTS

The author expresses his sincere gratitude to

his major professor, Dr. Jack L. Stroehlein, for his

advice, interest, encouragement, and patience during this

study.

Sincere appreciation is extended to Dr. Arthur W.

Warrick, Dr. Hinrich L. Bohn, Dr. John L. Thames and

Dr. Martin M. Pogel for their constructive criticism,

assistance, advice and for reviewing the manuscript.

Special thanks are extended to Mr. Ed Hanlon and

Mr. Joe Tram for their help during the fieldwork.

The author also expresses his gratitude to The

University of Libya for sponsoring and financing his

graduate study at The University of Arizona and to the

Arizona Mining Association for assistance in purchasing

the supplies.

To all others who contributed in any way and are

not mentioned here, the author, is deeply grateful.

iii

TABLE OF CONTENTS

Page

LIST OF TABLES vi

LIST OF ILLUSTRATIONS viii

ABSTRACT ix

1. INTRODUCTION * 1

2. LITERATURE REVIEW 4

Potential Production and Availability of Sulfuric Acid 4

Chemical Functions of Sulfuric Acid When Applied to Calcareous Soils 5

Chemical Functions of Sulfuric Acid When Applied to Irrigation Water and Its Effect on Soil Properties 6

The Relation between pH and Ammonia Equilibria in Soil 10

Ammonia and Ammonium Reactions 11 Ammonia Volatilization from Soils 13 Factors Affecting Ammonia Volatilization in Soil 14

3. MATERIALS AND METHODS 21

4. RESULTS 31

Wheat 31 Soil Analysis 31 Plant Analysis 41 Water Analysis 45 Yield 45

5. DISCUSSION AND CONCLUSIONS 50

6. SUMMARY 56

APPENDIX A: PROPERTIES AND HANDLING OF SULFURIC ACID AND ITS USE FOR AGRICULTURAL PURPOSES 57

iv

V

TABLE OF CONTENTS—Continued

Page

APPENDIX B: REPRESENTATIVE SAMPLES OF SOIL, WATER, AND PLANTS 59

APPENDIX C: GENERAL INFORMATION TABLE ..... 64

APPENDIX D: SAMPLE CALCULATIONS 65

REFERENCES 68

LIST OF TABLES

Table Page

1. Per acre yields, costs, and returns of sulfuric acid applied to Arizona cotton farms, 1974 crop year (Ayer, Menzie and Jacobs, 1976) 18

2. Per acre yields, costs, and returns of sulfuric acid applied to Arizona cotton farms, 1973-74 crop year (Ayer, Menzie and Jacobs, 1976) 19

3. Properties of experimental soils collected from the two study areas 23

4. Chemical properties of well waters used for the studies 24

5. Dates of irrigation, H2SO4 and NH, application and soil, water and plant sample collection, Marana Farm 25

6. Dates.of irrigation, H2SO^ and NH? application and soil, water and plant sample collection for the cotton study at Buckelew Farm 26

7. Nitrate-N (NO3-N) in the soils during the season (Buckelew Farm, 1976) 34

8. Total-N (NH4-N + NO3-N) in the soils during the season (Buckelew Farm, 1976) 37

9. The importance of preirrigation in increasing the N availability and redistributing soluble salts at Marana Farm 40.

10. Nitrate-N in the cotton petioles during the season 42

11. Representative water analysis from Buckelew Farm (samples collected July 3-7, 1976) ... 46

12. Effect of H2SO4 on wheat and cotton yields 48

vi

vii

LIST OF TABLES—Continued

Table Page

13. Effect of treatment as shown by the multi­variate analysis of variance data at both locations 51

14. Variation of soil properties/ soil NO3-N and plant NO3-N due to sampling dates as shown by the Lease Significant Differences Test. . 53

LIST OF ILLUSTRATIONS

Figure Page

1. Salt movement under furrow irrigation .... 28

2. View of the wheat plots on April 27, 1976, about one month before harvest 32

3. Effect of ̂ SO^ on wheat and cotton yields. . 33

4. Effect of H2SO4 on soil nitrogen (NO,-N)

and its variation during the season, Buckelew Farm 35

5. Effect of H2SO4 on soil nitrogen (NH.-N + NO3-N) and its variation during the season (Buckelew Farm) 38

6. Variation of soil nitrogen (NO3-N) along the field beginning at the irrigation ditch, Buckelew Farm 39

7. Effect of H^SO^ on plant nitrogen (NO3-N) and its variation during the season 43

8. Effect of H^SO^ on water nitrogen (NO3-N) and its variation along the cotton field (Buckelew Farm, July 1976) 47

viii

ABSTRACT

The noticeably irritating odor of ammonia after

field applications indicates that there is a loss of N

by volatilization and necessary action should be taken to

assure efficient and economical use. In this study,

anhydrous ammonia was applied in the irrigation water

along with and without the additional sulfuric acid

(H2SO4). Ammonia losses by volatilization were measured

indirectly by measuring nitrogen in soils, plant tissue

and irrigation water at two field locations. This study

showed that adding H2SO4 (approximately 300 lbs/acre)

with irrigation water reduced the loss of nitrogen

through ammonia volatilization. The acid is effective

in reducing NH3 losses under alkaline soil conditions

of the arid and semi-arid climates, especially when the

irrigation water contains high levels of sodium relative

to calcium.

In such cases, H2SO4, which became abundant

through industrial by-product recovery, could be used

economically as an aid to reduce ammonia volatilization

losses under field conditions.

ix

CHAPTER 1

INTRODUCTION

Nitrogen (N) is the fertilizer element generally

most needed in irrigated soils of the world. In the

southwestern United States anhydrous ammonia (NH^) is

the most common source of fertilizer N because of its

high analysis (82% N), convenience of handling, and lower

cost than other commonly used materials. Ammonia may be

injected into the soil at any time prior to or during

the growing season. After the crop is established,

however, NE^ is often added to the irrigation water.

Ammonia applied to the water is a very simple and

inexpensive method of application and can be done without

driving equipment through the field. In addition the

desired amount of NHg can be metered into the water very

precisely.

Fertilizer nitrogen applied in the irrigation

water is subject to losses by volatilization, leaching

and denitrification. Furthermore, the distribution of N

depends on the uniformity of water application, which is

dependent on uniformity of the soil and slope of the land.

Soil texture and cation exchange capacity of each soil

could influence losses by leaching, volatilization

1

2

and denitrification and possibly influence the

distribution down the field.

Losses of N by volatilization and denitrification

in the field are difficult to measure. Laboratory

experiments and experiments with sprinkler irrigation

have shown that sulfuric acid (H2SC>4) , a relatively

cheap copper refining by-product in the west, can reduce

volatilization of NH^ from irrigation water.

Results of field experiments may be contradictory

or of different magnitude to results from laboratory

and greenhouse experiments, especially in soil fertility

research. Volatilization or leaching losses of N are not

as easily controlled in the field as in covered containers

in the laboratory or where water is precisely applied in

the greenhouse. Temperature differences may also exert

a major influence on rates of NHg volatilization.

Measurement of ammonia losses by volatilization and

reduction of losses by acidification of irrigation water

have not been made in Arizona in the field during the

summer growing season. Distribution of N resulting from

water-applied fertilizer has not been studied sufficiently.

These data are needed in order to make economically sound

recommendations for farmers as to the extent that they

can reduce ammonia losses by using I^SO^ and to improve N

distribution by modifying irrigation practices.

The objectives of this study were (1) to

indirectly measure N losses from ammoniated and acidified

water by soil, water and tissue analyses; (2) to compare

yields of wheat (Triticum aestivum L.) and cotton

(Gossypium hirsutum L.) when irrigated with the two

water treatments, and (3) to determine the distribution

and forms of N from the two treated waters in the irriga­

tion ditch and down the furrow.

CHAPTER 2

LITERATURE REVIEW

Potential Production and Availability of Sulfuric Acid

Production of sulfuric acid (I^SO^) in the future

in the southwestern United States may exceed demand and

thus require disposal in some mariner. In the southwestern

states, acid production from copper smelters alone has

increased from an annual rate of 100 thousand to about 1

million tons within the past few years and further

increases are projected in the future (McKee 1969; Jones

1972). In addition, large quantities are generated

through the biological oxidation of mined sulfide minerals

(Blovins, Bailey and Ballard 1970), and through the chem­

ical oxidation of sulfur dioxide discharged to the atmo­

sphere (Bohn 1972). Treatment of poor quality water and

large areas of sodic soils has proven to be a beneficial

use for surplus acid (Miyamoto, Prather and Stroehlein

1975; Yahia, Miyamoto and Stroehlein 1975).

Because of this surplus, large quantities of acid

are being utilized successfully by agriculture, mostly for

treating certain types of irrigation waters and soils.

Bohn and Westerman (1971) estimated that 1.6 million

5

tons/year could be beneficially added to irrigation water

in southern Arizona.

Chemical Functions of Sulfuric Acid When Applied to Calcareous Soils

A high content of exchangeable sodium (Na) has been

given as a reason for the unfavorable physical properties

of some soils. Certain non-productive soils of southern

Arizona which exhibit notably poor structure and permeabil­

ity to water have been found to contain excess amounts -of

adsorbed or exchangeable Na. In sodium-affected soils,

water movement (especially when low salt water is used for

irrigation) is very slow and makes irrigation management

difficult.

Sulfuric acid has been used for reclaiming alkali

soils for almost 80 years, although, of course, it was im­

practical because of application difficulties. Recently

the development of materials and application techniques

have made it easier and possible to widely use t^SO^

economically as a soil and water amendment.

In relation to the present topic, the most impor­

tant chemical function of H~SO. is the dissolution of earth 2 4

carbonates (mostly calcium carbonates) in calcareous soils.

This, of course, enhances the replacement of Na by calcium

(Ca) from exchange sites so that the Na can be readily

leached away as Na2SO^. It is commonly assumed that one

mole of ^SO^ replaces two moles of exchangeable Na (Over-

street, Martin and King 1951).

Sulfuric acid is in many cases added directly to

the soil surface to correct and improve some of the physi­

cal properties adversely influenced by excessive levels of

exchangeable Na. For example, permeability is restricted

in sodic soils, especially when the irrigation water con­

tains high levels of Na relative to Ca and magnesium (Mg)

(Yahia, Miyamoto and Stroehlein 1975).

Chemical Functions of Sulfuric Acid When Applied to Irrigation Water and Its

Effect on Soil Properties

Fertilizer material in irrigation water and its

soluble components are subject to numerous chemical reac­

tions before and after it percolates through the soil.

Many of these reactions are not well understood under field

conditions. Certain components may be lost by volatiliza­

tion even before reaching the soil, an example of one such

important component is ammonia N (NH^-N). When irrigation

water moves through a calcareous soil, many other reactions

take place including cation exchange. As a result of these

reactions, many soil properties will be affected. For

example, irrigation with water containing high amounts of

Na and soluble salts can create saline-sodic soil condi­

tions which can interfere with plant growth, especially if

there is not enough Ca in the soil and/or poor management

is practiced. Gumma, Prather and Miyamoto (1976) have

reported that when was applied in water in amounts

sufficient to prevent Ca precipitation, such rates of acid

7

reduced the Na hazard and increased the rate of water

movement.

Field studies at the Buckelew Farm in the late

1960s by The University of Arizona (J. Armstrong, personal

correspondence, August 2, 1974) revealed relatively high

exchangeable Na in the soil as a result of irrigating with

the wells which have a high sodium adsorption ratio (SAR).

No Na problem resulted on the fields which received the

well waters high in Ca. Gypsum application reduced the

ESP but was not regarded as a satisfactory treatment due

to costs and difficulties with water application. A pre­

liminary study in 1974 revealed less than two tons of

E^SO^ per acre would greatly increase the infiltration

rate when using the high sodium waters (S. Miyamoto,

personal correspondence, August 22, 1974).

In relation to the present topic, the most impor­

tant chemical function of E^SO^ is its acidifying effect

or lowering the pH of irrigation water and soil. Miyamoto,

Ryan and Stroehlein (1975) concluded that application of

aqua-ammonia to alkaline irrigation water increases CaCO^

formation and precipitation by converting HCO~ to CO"^.

Thus the more soluble cations such as Na remain in the

water increasing SAR. This results in increased exchange­

able Na and NH^, and causes water penetration problem.

As the application of NHg through irrigation water

is a common practice in the Western states, the possibility

8

became obvious. Sulfuric acid application was found to

reduce the concentration of NH^OH relative to the total N

applied as NH3 principally by lowering pH. Thus simul­

taneous application of acid and ammonia helps to control

ammonia loss (Miyamoto, Ryan and Stroehlein 1975).

involved in ammonia loss by volatilization. For example,

Fenn and Kissel (1973) proposed a mechanism for the ob­

served loss of NHg as follows: When an ammonium salt dis-

varying solubility form. Ammonium carbonate subsequently

decomposes, losing C02 at a faster rate than NH3- This

causes formation of NH^OH and an increase in pH and thus

greater NH^ losses as represented by the following general

reaction:

X(NH4)Z Y + N CaC03(s) N(NH4)2C03 + Can YX (1)

where Y represents the anion assoicated with ammonium and

N, X, and Z are dependent on the valances of the anion and

cation. The resulting reaction product (NH^^CO^ is

unstable and decomposes as follows:

Some efforts have been made to determine mechanisms

2+ solves in a calcareous soil, (NH4)2CC>3 and Ca salts of

(2)

9

where the amount of NH^OH formed in a given time would

depend on the solubility of CanYx and its rate of forma­

tion.

When (NH^^COg decomposes according to reaction

(2), CC>2 is lost from solution at a faster rate than NH^,

thereby producing additional 0H~ ions and an increase in

pH, consequently more solution NH* becomes electrically

balanced by 0H~ which would favor NH^ loss as represented

by the following reaction:

NH* + OH" NH4OH sj=5= NH3 + H20 (3)

If CanYx is soluble, then the NH^ loss which occurs

will be dependent on the resulting pH of the soil. The

NH^ —> NH^ equilibrium is pH dependent with lower pH

values favoring the NH^ form.

It has been proven that acid application decreases

bicarbonate concentration, thereby reducing Ca precipita­

tion and thus prevents an increase in SAR of the irrigation

water accompanied with lowering the pH of the water

(Miyamoto, Prather and Stroehlein 1975).

10

The Relation between pH and Ammonia Equilibria in Soil

Although it has been recognized that pH may

directly influence NH^ volatilization from soils, some

reports ascribe great prominence to the direct effect of

pH (Ernst and Massey 1960), while others, such as Jackson

and Chang (1947), do not see much importance in the role

of pH in volatilization losses of NH^. Yet, it is gener­

ally accepted that NH^ losses would decrease as the pH of

the system is decreased. The results of the study by

Martin and Chapman (1951) showed that at alkaline pH

values and with the presence of NH* in the soil, volatil­

ization loss of NH.j will take place; however, the loss

occurred only when there was a simultaneous loss of water.

They also concluded that the cation exchange capacity (CEC)

or buffer capacity of the soil is important in determining

the extent of nitrogen losses from applied NH^OH or from

materials quickly yielding NHg upon decomposition. Their

data showed that acidifying the soil surface is the best

way to minimize or prevent nitrogen volatilization losses

from fertilizer containing or forming NHj. Mills, Barker

and Maynard (1974) also concluded that NH^.losses with or

without plants in the system increased as the soil reaction

and amount of NH*-N application increased. Wahhab, Randhawa

and Alam (1957) made the interesting postulation that NH^

losses occurring when (NH^^SO^ had been added to a

11

slightly acid soil could be due to an equilibrium reaction

of the following form:

(NH4)2S04 ̂ 2 NH+ + SOJ" (4)

NH* + 0H~ -«=*- NH3 + H20 (5)

Thus, the effective hydroxyl ion concentration would be

dependent on the pH of the system.

Ammonia volatilization was directly related to the

initial pH of the soil and increased with an increase in

pH (DuPlessis and Kroontje 1964). As a result, the linear

relationship found between predicted and measured amounts

of NHj lost from acid as well as neutral soils was inter­

preted as evidence of the existence of the proposed

volatilization mechanism in soils. The NH^ losses were

found to be proportional to the original soil pH (Chao and

Kroontje 1964) .

Ammonia and Ammonium Reactions

While there is general agreement on several points,

interpretations often differ regarding reactions of NH^ and

NH^ with soils. Part of the difficulty is that the reser­

voir of basic data and observations from enough soils and

treatment conditions is not yet adequate to define the

general cases or the exceptions.

12

Retention of NH_ by ammoniated air-dry samples was approximately 0.7 meq N per meq of soil CEC. In the surface horizon retention of NH, was roughly 0.3 and 2.6 meq N per 100 g of soil for each percent clay and organic carbon, respectively. Ratios of "NH3 retained by air-dry ammoniated samples" to "H2O retained by the air-dry samples prior to ammo-niation" ranged from 0.03 to 0.19 but were generally < 0.1 (Young 1964, p. 339).

•j" Although mineral fixation of NH^ and/or NH^ from

anhydrous NH^ accounted for only a small part of retained

NH^f the quantities involved on a pounds per acre furrow-

slice basis could be significant in some soils. It was

found that air-drying increased fixation from about 2 to

3^ times (Young 1964). A number of observations concerning

NH^ reactions with soils were encountered in a study made

by Young and Cattani (1962) where they found that several

of the air-dry samples exhibited 5 to 10 times greater

fixation from the anhydrous than the aqueous NH^ source.

DuPlessis and Kroontje (1966) concluded that retention of

NHg by clay soil has been increased in the presence of

CC>2 • The increase in soil pH resulting from NH^ applica­

tion favored the volatilization of NHg. Volatilization

was a result of the dominance of molecular NH^ in the

reaction NH3+H20 . NH* + OH~.

Chemisorption of NH^ by a clay system may suppos­

edly occur through a number of different mechanisms.

These possible mechanisms include: (1) reaction of NH^

with exchangeable hydrogen; (2) reaction of NH^ with clay

exchangeable ions; and (3) reactions of NH^' with water and J.

subsequent exchange reaction between NH^ and the exchange­

able cations. Brown and Bartholomew (1962) were able to

explain the differential chemisorption capacities of dry

homoionic clays for NHg on the basis of differences in the

degree of hydration of ions using a manometric technique

employing equilibrium measurements in a special sorption

apparatus. They reported that "chemisorbed NH^ is believed

to be that which has gained a proton and undergone

exchange reactions with the exchangeable cations and that

which has reacted with the weakly dissociated hydroxy1

groups of the lattice edges" (p. 258).

Ammonia Volatilization from Soils

Transformations and volatilization of nitrogenous

compounds in soils have been the subject of many investi­

gations. Loss of NH^ by volatilization is of concern to

soil scientists and farmers. Jones (1932) found a corre­

lation between moisture content and the rate of transfor­

mation of urea to NH^ and subsequently to NOg. Mills,

Barker and Maynard (1974) concluded that NH^ losses by

volatilization increase as the pH increases as a result

of the increase of OH activity. Total N loss, however,

was reduced by the presence of plants as compared with

bare-soil treatments. Volatilization of NH^ presumably

occurred as a consequence of the hydrolysis of applied

urea to (NH^^CO^ which would raise the pH of the surface

layer of the soil. The rate of NH^ volatilization

increased with an increase in the rate of urea application

(Overrein 1968). Several previous studies (Volk 1959;

Watkins et al. 1972) have pointed out serious volatili­

zation losses of nitrogen from urea compounds that can

occur with surface application. Losses in most of these

situations were considered to be as gaseous NH^ and were

magnified by increasing pH, increasing temperature,

increasing moisture, evaporation rate and decreasing soil

CEC. Chin and Kroontje (1963) concluded that urea hydrol­

ysis and NH^ volatilization from (NH^^CO^ is a first

order reaction:

CO(NH2»2(s) + H2°(g) C02 (g) + 2HH3(g) <6>

Factors Affecting Ammonia Volatilization in Soil

Many studies have been made of NH^ volatilization

as affected by: (1) soil reaction, (2) method of applica­

tion, (3) depth of mixing into the soil, (4) temperature,

(5) rate of drying as determined by relative humidity, and

(6) initial soil moisture content. Volk (1961), for

example, reported that increasing soil pH decreased the

NHg adsorption potential of Florida soils, and resulted in

greater NH^ volatilization from applied urea. Increasing

soil pH has been found to cause marked increases in the

volatilization of NH^ from other NH^ yielding fertilizers

(Wahhab, Randhawa and Alam, 1957). Earlier investigators,

using CaC03 to increase soil pH, observed an increase in

NH^ volatilization under alkaline conditions. Ernst and

Massey (1960) gave two explanations for this increase

(1) a greater degree of Ca saturation of the soil exchange

complex with increasing pH; therefore less adsorption of

NH^ formed by the hydrolysis of urea; and/or (2) an

increased OH"" activity in the soil solution, thus favoring

the volatilization of gaseous NH^. They pointed out that

•J- — an NH^ + OH -v ^O + NH^ equilibrium also exists in

the soil solution. Thus increasing soil pH by liming, for

example, causes an increase in activity of both NH4 and

OH ions, driving the equilibrium to the right and increas

ing the volatilization loss of ammonia. Ernst and Massey

(1960) also reported that the incomplete hydrolysis of the

added urea could partially account for the decreased NH^

loss at the lower temperatures. In addition, temperature

affects the solubility of NH^ in water and possibly may

affect the NH^ (adsorbed) ^ "w NH^ (solution) equilib­

rium in soils. Martin and Chapman (1951) have reported

that the loss of NH^ from a soil to the atmosphere is

dependent on the loss of moisture from the soil.

Overrein and Moe (1967) concluded from their study

that NH^ volatilization rates increased at an exponential

16

rate as rates of urea application were increased. This

resulted in a large proportion of the added urea nitrogen

being lost from the soil through NH^ volatilization at the

higher rates of urea application. Ammonia volatilization

rates were inversely proportional to the depth of urea

application and decreased more rapidly with depth in wet

soil than in moist soil. But since NH^ volatilization is

dependent upon many factors other than the rate of NH^

production in the soil, the rate of NH^ volatilization

therefore may not always be directly correlated with the

rate of urea hydrolysis.

Jewitt (1942) reported that the basic factors

revealed by the experiments are the paramount influence

of the total quantity of NHg salt present, and the close

relationship between the loss of ammonia and the loss of

water. The moisture content does appear to have an impor­

tant effect as the loss of NH^ ceases when there is no loss

of moisture.

Considerable gaseous NH^ loss may take place when

nitrogen fertilizers such as anhydrous NH^ and ammonium

sulfate (NH^^SO^ are applied to alkaline-calcareous soils.

The loss might take place over long periods from the moist

soils, at a rate greatly influenced by the rate of fertil­

izer application and moisture content. A mechanism for

NH^ loss was suggested by Jewitt (1942) according to which

the base exchange equilibrium in the soil tends to maintain

17

the concentration of NH^ in the soil solution at a constant

level, whereas the normal buffered state of the soil

solution maintains constant the hydroxyl-ion concentration.

Under these circumstances the NH^ is lost as from a dilute

solution, at a constant rate proportional to the NH^ con­

centration in the soil solution. This loss will continue

(if the soil is kept moist) for a long or short period,

depending on the reserves of NH^ ions on the cation

exchange complex. If the exchange capacity is low, the

rate of loss of NHg is not maintained at a constant rate

and is comparable with that from a dilute solution, the

NH3 content of which declines progressively as evaporation

proceeds.

An economic analysis was conducted to determine

the response fifteen Arizona farmers had obtained to acid

application (Ayer, Menzie and Jacobs 1976). The results

of field application of acid on wheat indicated that

yield was increased (Table 1). Four farmers reported

using in irrigation water for cotton. The acid

application increased profits from $100 to nearly $200

per acre on three of the four farms (Table 2).

Sulfuric acid has been used widely the last few

years for reclamation of sodic and saline sodic soils as

well as for improving the irrigation water quality. The

effect of I^SO^ on the physical and chemical properties of

Table 1. Per acre yields, costs, and returns of sulfuric acid applied to Arizona cotton farms, 1974 crop year (Ayer, Menzie and Jacobs, 1976)

Returns Total returns Returns — from lint & seed cost of treatment

Lint Seed Location and Yield 6 0 Total 0 @ Application Treatment 8 0 6 0 70-74 avg. Current treatment 70-74 avg Current Type Tons/acre Lint Seed $.3536/lb $.415/lb $.0425/lb $.06/lb price price cost prices prices

Buckeye 0 1200 1980 $424 $498 $ 84 $119 $508 $617 $ 0 $508 $617 water run 0.38 11003 1815 389 457 77 109 466 566 30 436 536

Buckeye 0 1344 2218 475 558 94 133 569 691 0 569 691 water run 0.11 1728° 2851 611 717 121 171 732 888 9 723 879

Buckeye 0 780 1287 276 324 55 77 331 401 0 331 401 water run 0.30 1080 1782 382 448 76 107 458 555 24 434 531

Chandler 0 1116 1838 395 463 78 110 473 573 0 473 573 water run 0.11 14883 2450 526 618 102 147 628 765 9 619 756

aMeasured against test plot

Table 2. Per acre yields, costs, and returns of sulfuric acid applied to Arizona wheat farms, 1973-74 crop year (Ayer, Menzie and Jacobs, 1976)

Location, application type

Treatment ton/acre

Yield tons/acre

Total returns Total treatment cost

Returns— Cost of treatment Location,

application type

Treatment ton/acre

Yield tons/acre

<a $70/T

@ $102/T

Total treatment cost

@ $70/T

<3 $102/T

Willcox 0 1.85 130 189 $ 0 130 189 injected 0.15 2.60 182 265 20 162 245

Chandler 0 2.81 197 287 0 197 287 water run 0.09 3.75 263 383 7 256 376

Three Points 0 1.32 92 135 0 92 135 water run 0.75 1.98a 139 202 60 79 143

Glendale 0.075 3.3 231 336 6 225 330 water run 0.15 1.5^ 105 153 12 93 141

0.30 1.8a 126 184 24 102 160

aMeasured with control plot comparison

20

soils, and plant growth and yields has been reported. This

study reports the effects of f^SO^ on chemical properties

of soils, NH^ volatilization and yield of wheat and cotton

grown under field conditions.

CHAPTER 3

MATERIALS AND METHODS

Three field experiments were conducted at two loca­

tions: The University of Arizona Marana Experiment Farm,

and the R.G. Buckelew Farm, which are located in the Avra

Valley. The Marana farm is about 25 miles northwest of

Tucson; the Buckelew farm is about 25 miles west. The

Avra Valley area has an arid climate characterized by

long periods of no precipitation, low annual rainfall, a

dry atmosphere, great variation of temperature, and a

large number of sunny days each year. The average annual

rainfall is about 10 inches. The mean annual temperature

ranges from 56 to 70°F and the frost free season is from

160 to 300 days (Sellers and Hill 1974).

The experiment at Marana was conducted with cotton

in Field B-2 which is classified as Pima clay loam, fine-

loamy, mixed, thermic family of typic torrifluvents.

Soils of the farm are in Land Capability Class I

(Pereira 1971).

The R.G. Buckelew Farm is located about one mile

west of Three Points on the north side of Ajo Road. The

cotton experiment was conducted in Field 3 which contains

two soil types. The south side of the field was mapped

21

Gila loam soil of Land Capability Class I and the north

part of the field as Class HIS, Vinton fine sandy loam.

The wheat experiment was located in Field 7. The soil was

mapped as Adelanto fine sandy loam, Class IIS, (U.S.D.A.

Soil Conservation Service 1957). The properties of the

soils and waters at the two locations are shown in Tables

3 and 4, respectively.

Anhydrous ammonia (NHg) versus NH^ plus H2SO^

applied in the irrigation water was added to wheat and

cotton. Anhydrous ammonia at a rate of 106 lbs./acre

and f^SO^ at 1500 lbs./acre were applied during the grow­

ing season for wheat. Dates of irrigation, H2SO^ and NHg

application, and soil, water and plant sample collection

for the cotton experiment at both locations are shown in

Tables 5 and 6, respectively. The treated water was

analyzed for ammonium nitrogen (NH^-N), nitrate nitrogen

(NO^-N), other important ions and pH. Since soil and

petiole analysis have become a common tool in determining

N requirements for cotton, both methods were used to de­

termine soil nitrogen availability during the growing

season. Soil samples consisting of about 10 cores per

plot 6 inches (15 cm) deep from the side of the beds were

collected periodically. Sampling the soil in this manner

has been found to give the best estimate of available

nitrogen in irrigated soils (Ray, Tucker and Amburgey

1964), because it takes into account the salt movement

Table 3. Properties of experimental soils collected from the two study areas

pH

Saturation Extract

ECexl03 TSSa

mmhos/cm ppm

Na K

meq/1

ESP NO3-N P

ppm

CEC

meq/1OOg

Marana Farm

Pima clay loam 8 . 0 0.4 273 2.7 0.3 5.0 12.7 2.3 31.5

Buckelew Farm

Gila loam 7.8 0.7 490 Vinton fine sandy loam 7.8 0.6 420 Adelanto fine sandy loam 7.8 1.07 749

4.2 3.7

0.3 0 . 2

9.0 7.0

11.5 2.4 11.5 2.6 42.0 7.0

32.5 2 0 . 6

Total soluble salts

10

Table 4. Chemical properties of well waters used for the studies

mg/l or ppm Water sample EC xlO3 pH TSS Ca Mg Na CI S04 HCO3 CO3 F NO3-N

mmhos/cm

Marana 0.35 7.5 383 100 4.0 36 26 48 166 0 0.2 2.7

Buckelew Farm

Cotton 0.41 7.9 388 17 1.0 71 51 72 166 0 1.6 8.9

Wheat 0.29 9.2 221 2 trace 69 20 16 98 14 0.5

Table 5. Dates of irrigation, H2SO4 and NH3 application, and soil, water and plant sample collection, Marana Farm

Irrigation H2SO4 and NH3 Treatment

Samples Collected Soil Water Plant

3/09/76 3/09/76a 4/06/76

5/21/76 5/29/76 5/28/76

6/21/76 6/21/76 7/17/76 6/21/76 7/17/76

7/26/76 7/26/76 8/09/76 7/26/76 8/09/76

8/17/76 8/20/76 8/20/76

9/13/76 8/30/76 8/30/76

9/15/76 9/05/76

10/18/76 9/15/76

cL N was applied directly to the soil as urea and no H2SO4 was added at this time

26

Table 6. Dates of irrigation, H2SO4 and NH3 application and soil, water and plant sample collection, Buckelew Farm

Irrigation H2S04 and NH3 Treatment

Samples Soil

: Collected Water Plant

3/31/76 3/31/76 4/16/76

5/21/76 5/21/76 5/28/76 5/21/76 5/28/76

6/22/76 6/21/76 6/28/76 6/22/76

7/07/76 7/07/76 7/17/76 7/07/76 7/17/76

8/05/76 8/02/76 8/02/76

8/31/76 8/20/76 8/20/76

8/30/76 8/30/76

9/15/76 9/15/76

— — 10/07/76

27

from furrow to hill under furrow irrigation (see Fig. 1).

The collected "soil samples before and after treatment were

air dried and sieved through a 6.23 mm (1/4 inch) screen.

The cation exchange capacity (CEC) was determined from

saturation extract analysis by ammonium acetate extraction

method (U.S.D.A. Salinity Laboratory Staff 1954). The

exchangeable sodium percentage (ESP), pH, total soluble

salts (TSS), NH^-N and NO^-N were determined using methods

discussed by Black (1965). Petioles from the youngest

mature leaf were taken several times during the season

from 25 to 30 plants per plot according to Ray, Tucker and

Amburgey (1964). These sampling periods correspond roughly

to the time of the early stage of growth, first flower,

first boll, first open boll and just prior to harvesting.

•The NOg-N content of the petiole samples was determined

by the phenoldisulfonic acid method (Johnson and Ulrich

1959). Water samples were also taken at 200 m. intervals

starting from the well going along the ditch and then

through the field and analyzed for NH^-N, NOg-N and pH.

The wheat and cotton cultivars used in these exper­

iments, the planting dates, harvesting dates, fertilizer

application rates and H2S04 rates are shown in the general

information table, Appendix C.

Since the NHg and I^SO^ treatments were applied in

the irrigation water the experimental design had to conform

to the irrigation scheme at each location. In the wheat

Seed location Sampling site Salt accumulation

Fig. 1. Salt movement under furrow irrigation — The arrows show direction of water movement and the dark zones indicate areas of high salt con­centration.

N> 00

29

experiment strips across the entire field were considered

a plot, each being 1200 ft. long. Two plots received

H2SO4 and NH3 while the rest of the field received only

NH3. The width of each plot varied according to a stan­

dard irrigation set. For the cotton experiment, paired

sample locations were selected through the field for soil

and tissue analyses.

Standard cultural practices for the area including

cultivating, irrigating and pest control were used at both

locations for wheat and cotton. Wheat was harvested by

combining strips throughout the length of the filed. Two

strips treated with NH3 + H2SO4 and three control strips

were harvested. Cotton was harvested by a mechanical

picker. Two rounds were made in each treatment area at

Buckelew's and weighed separately. One round was harvested

at the Marana Farm for each treatment. Yields are pre­

sented in terms of seed cotton in pounds per acre and only

one picking was made.

A multivariate analysis of variance was run for

all the cotton data collected at different dates. Three

main variable factors were considered (Treatment, Blocks

and Pairs,;see Appendix D. A separate multivariate anal­

ysis then was run for the combined dates that showed sig­

nificant differences. Furthermore, the Least Significant

Differences Test (LSD) was used to detect where the

differences are. A Linear Contrast Test was also run to

show whether or not the soil and plant nitrate-nitrogen

varied linearly down the field.

CHAPTER 4

RESULTS

Wheat

The wheat experiment was carried out as a prelimi­

nary study and only observations and yield data were taken.

According to Mr. Buckelew a fine seed bed was not prepared

resulting in a stand somewhat less than desired. The acid

treated plots appeared to have had a better stand or at

least had more tillers. In addition, head size and weight

were improved by the acid application. As the plants

approached maturity, the acid treated plants remained

darker green in color throughout the length of the plot

(Fig. 2). A 50% increase in wheat yield (Fig. 3) bears

out the observation that H2SO4 improved the condition of

the plants and increased nitrogen availability.

Soil Analysis

The results of analysis of soils frdm Buckelew

Farm, presented in Table 7 and shown in Fig. 4, show that

soil nitrate-nitrogen content increased for a time follow­

ing N application (mid-June), gradually declined, then

started increasing again toward the end of the season.

The increase could have been a result of a decreased rate

of cotton growth following the last irrigation on August 31

31

o 32

Fig. 2. View of the wheat plots on April 27, 1976, about one month before harvest.

A plot which received NH3 is on the left and the plot which re­ceived NH3 plus H2SO4 is on the right of the stake. The second NHg plot can be seen in the back­ground just to the right of the utility pole.

O O O CN

•p

0 r-H a. •v

0) XJ H

rd rH 0) •H

O O O iH

S3

'.V

£

T5E

Acid Control Acid Control

• WHEAT COTTON

Buckelew Farm

JXT I

Avg.

Fig. 3.

R e p l i c a t e s

Effect of I^SO^ on wheat and cotton yields, Buckelew Farm u> fca

34

Table 7. Nitrate-N (NO3-N) in the soils during the season (Buckelew Farm, 1976) in ppm

May June July Aug. Sept. Oct.

Control 13.7 8.0 12.7 6.0 6.5 11.0

Treatment 13.0 7.8 13.2 7.5 9.7 16.2

20 O O Treatment

• • Control

15

10

April May June July

Time

Aug Sept Oct

Fig. 4. Effect of ^SO^ on soil nitrogen (NO^-N) and its variation during the season, Buckelew Farm

to oi

r

36

and defoliation prior to harvest. Nitrification could have

continued since the soil was warm and not completely dry.

The increase in NO^-N of the acid treated plots could be

evidence of reduced NH^ volatilization. With the exception

of the first two months (May and June) in all cases, the

nitrate-nitrogen content of soil samples was higher in the

acid treated plots compared with the control, the differ­

ence between the treatment and the control was statisti­

cally significant at the 5% level. The increase in NH^-N

plus NOj-N in August (which is presented in Table 8 and

shown in Fig. 5) was probably due to the normal decrease

in plant growth during that season of the year.

Data from Buckelew's Farm presented in Fig. 6 show

a linear decrease of N03~N of the soils down the field.

This leads to the conclusion that the length of irrigation

runs should be shortened if anhydrous ammonia is to be

applied in the irrigation water. This would be of partic­

ular concern on light-textured soils, as sandy soils lack

the capacity for adsorption of large quantities of ammonia

and excessive losses will take .place (McDowell and Smith

1958).

As a side observation, the results presented in

Table 9 indicate that preirrigation plays an important role

in releasing some nitrogen due to acceleration of mineral­

ization of immobilized nitrogen (Chapman, Liebig and

Rayner 1949) which would be very beneficial nutritionally

37

Table 8. Total-N season

(NH4-N + (Buckelew

NO3-N) Farm,

in the soils 1976) in ppm

during the

May June July Aug. Sept. Oct.

Control 20.5 16.5 12.7 9.7 11.8 15.1

Treatment 19.5 15.8 12.4 11.5 16.6 19.9

E 04 &

25 _ O O Treatment

• • Control

s i ro O S

3 1 K 2

S3 I rH •H O CO

IW o •p c 3 o

20

15

10

April May June July Aug Sept Oct

Time

Pig. 5. Effect of H2SO4 on soil nitrogen (NH4-N + NO3-N) and its variation during the season (Buckelew Farm). U)

00

1400 —

1200 —

1000

800 —

600

400

2 0 0 —

10 15

Soil. NO^-N (ppm)

Fig. 6,

4-> IH

T3 rH 0) •H m a) si +j Cn C O

<D U C 03 •P CO •H Q

Variation of soil nitrogen (NO-^-N) along the field beginning at the irrigation ditch (Buckelew Farm)

39

4Q

Table 9. The importance of preirrigation in increasing the N availability and redistributing soluble salts at the Marana Farm

Sample ECexl03 Number pH ECexl03 TSS Na K ESP N P mmhos/cm ppm meq/1 % ppm

a. Before : pre-irrigation

1 8.1 0.61 427 2.7 0.33 2.0 10.0 2.3 2 8.0 0.42 294 2.0 0.26 2.0 10.1 2.0 3 8.0 0.39 272 2.7 0.26 5.0 12.7 2.3 4 8.0 0.69 483 2.6 0.26 1.5 11.7 1.7

b. After pre-irrigation

1 8.1 0.75 526 3.5 0.3 6.0 19.0 5.0 2 8.1 0.64 448 3.3 0.3 5.0 18.8 3.5 3 8.1 0.60 420 3.2 0.3 6.0 19.0 3.8 4 8.1 0.81 567 3.7 0.3 5.0 18.8 3.8

a

The numbers are as shown in the sketch map of the field, Pig. B.l, Appendix B

as well as financially. Acid application reduced the ESP

at both locations but only to a small extent (statistically

non significant) due to the low rates of the acid used in

this study (see Appendix B, Table B.l).

Plant Analysis

The nitrate-nitrogen contents of the cotton peti­

oles at the various sampling dates are presented in Table

10 and shown in Fig. 7a and b. The concentration of

nitrate-nitrogen was greatest at the earliest sampling

dates (May) and decreased as the season progressed. This

pattern was to be expected; however, the levels at Marana

were slightly in excess while those at Buckelew's could

be considered to be minimal for good yields (Ray, Tucker

and Amburgey 1964). The high nitrate-nitrogen rate re­

sulted in levels up to 22,600 ppm for the control plots

(Fig. 7a) for petioles sampled May 28. By early September

the nitrate-nitrogen level dropped in the same plots to

about 4200 ppm. Acid treatment apparently reduced the NH^

loss as indicated by the higher level of nitrate-nitrogen

in plants which received acid-treated water. The differ­

ence between acid treatment and control was highest in

late June and early July (4000 ppm) during the hottest

part of the season. The low petiole nitrate levels in

late July and August are normal and are due to the high

N consumption by the plant during this period of heavy

Table 10. Nitrate-N in the cotton petioles during the season in ppm

June July Aug. Sept.

a. Buckelew Farm

Control 6489 5153 1048 559

Treatment 6554 5842 1464 814

b. Marana Farm

Control 22600

Treatment 23400

13100

17000

5832

6022

4256

5645

24,000

O Acid

2 0 , 0 0 0 • Control

i 16,000 m

12,000

8 , 0 0 0

May June July Aug Sep 4,000 2 8 28 15 15

Time

Fig. 7. Effect of H2S0^ on plant nitrogen (M03~N) and its variation during the season.

a. Marana Farm

7,000

6 , 0 0 0

E a O. 5,000

4,000

3,000

2,000

1,000

May June J July 28 28 15

Time

Pig. 7, continued, b. Buckelew Farm

—O \cid

-ont. rol

4^

45

fruiting. The treatment effect on plant nitrate-nitrogen

is statistically significant at the 1% level for

Buckelew's Farm but not for Marana.

Water Analysis

Anhydrous ammonia dissolves in irrigation water

and becomes NH4OH. An alkaline condition is produced and

the pH may reach as high as 11 (Jenny, Avers and Hosking

1945). Data presented in Table 11 reveal a high pH but

the maximum was 9.6, because under field conditions as a

result of C02 pressure the reaction is less alkaline. The

acid reduced the carbonate and bicarbonate concentration

and lowered the pH values of the irrigation water. The

data also showed that acid treatment increased the NO3-N

content of the irrigation water as compared by the control

along the field but decreased the NH^-N, however, the to­

tal N(NH4-N + NO3-N) appeared to increase. Data shown in

Fig. 8 show no difference in the NO3-N content of irriga­

tion water down the field, neither in the control nor in

the treated plots, which indicates the uniformity of dis­

tribution of NH3 in the irrigation water.

Yield

The data presented in Table 12 and shown in Fig. 3

indicate that acid treatment can have a significant effect

on yield of cotton and wheat. The effect on wheat is

highly significant compared with the cotton yield. The

Table 11. Representative water analysis from Buckelew Farm (samples collected July 3-7, 1976)

mg/1 or ppm Sample Number pH EC xl()3 TSS^ ca Mg Na CI S04 HCO3 CO3 F NO3-N NH4-N

iranhos/cm ppm ppm

1D 7.9 0.5 369 9 0.4 78 18 126 107 0 1.2 1.6 7.9 2 9.6 0.3 282 21 0.1 79 17 9 117 41 1.4 0.3 10.3 3 7.7 0.5 345 10 0.9 75 16 126 103 0 1.6 1.8 7.0 4 9.6 0.3 289 21 0.3 75 17 9 127 38 1.2 0.4 8.3 5 7.6 0.5 346 6 0.4 76 16 132 103 1.2 1.6 1.8 7.6 6 9.5 0.3 322 39 0.2 77 17 9 142 36 1.2 0.4 8.3 7 7.6 0.5 349 8 0.6 77 16 132 105 0 1.4 1.8 6.8 8 9.4 0.3 276 20 0.1 77 17 9 137 36 1.3 0.5 7.5 9 7.5 0.5 356 7 0.5 78 16 132 112 0 1.6 1.8 6.8 10 9.5 0.3 306 21 0.1 78 18 9 142 36 1.2 0.4 7.7 11 7.3 0.5 348 9 0.5 74 16 132 107 0 1.6 1.8 6.3 12 9.4 0.3 292 21 0.1 75 17 9 127 41 1.5 0.4 7.5

aTotal soluble salts

Numbers refer to sample sites in Fig. B.l, Appendix B

Treatment O——O

Control • •

3 —

2 —

s

1 —

_____ —• • • •

200 400 600 800 1000 1200

Distance Across the Field (ft.)

Fig. 8. Effect of H2SO4 on water nitrogen (NCU-N) and its variation along the cotton field (Buckelew Farm, July 1976)

-j

48

Table 12. Effect of I^SO^ on wheat and cotton yields

Marana Farm (cotton field)

Plot # 1° 1160 1130

3 1040

4 990

5 1060

Treatment No treatment

Buckelew Farm (cotton field)

Rep 1 Rep 2 Rep 3 Total

1215 1130

1250 1110

1350 1135

3815 3375

Avg.

1257 1125

Treatment No treatment

Buckelew Farm (wheat field)

Rep 1

1775 1150

Rep 2

1825 1250

Rep 3 Avg.

1200 1800 1200

lbs/A

3960 2640

a

Acid treated plots as shown in Fig. B.l, Appendix B

49

reason may be that the rate of the acid used was not high

enough to reduce the amount of ammonia loss during the hot

season for cotton but was adequate for wheat during the

cool conditions of the winter.

CHAPTER 5

DISCUSSION AND CONCLUSIONS

The cotton experiments were carried out at two

locations for the purpose of comparing two different soil

and water conditions. The Buckelew Farm has experienced

poor infiltration rates for a number of years because of

the water quality (J. F. Armstrong, personal correspondence,

August 2, 1974). The Marana Farm has no known soil phys­

ical problem resulting from excess salts and sodium, either

in the soil or irrigation water (Margolis 1974). Thus, the

Buckelew study was confounded as I^SO^ not only was

expected to reduce NH^ volatilization, but also improve

infiltration rates, while the Marana study was to deal

only with soil and plant nitrogen.

The results of the multivariate analysis of vari­

ance presented in Table 13 showed a significant effect

of acid treatment on the soil pH, Na, TSS, soil NO^-N and

plant NO^-N at the Buckelew Farm. No significant effect

was found at the Marana Farm, which was expected because

there is no soil or water problem and the available soil

N level was adequate. The analysis also indicated some

statistically significant differences at the various

sampling dates. In the case of the Buckelew Farm, the

SO

Table 13. Effect of treatment as shovm by the multi-variate analysis of variance data at both locations

Soil Plant Treatment ESP pH Na K TSS NO3-N NO3N

% meq/1 ppm

a. Buckelew Farm

Control 7.952** 5.603* 0.3031 600.4** 7.898* 3725*

Treatment 7.870** 6.034* 0.3266 679.2** 9.262* 4015*

b. Marana Farm

Control 2.063 640.9 18.93 5114

Treatment 1.667 711.9 19.71 5364

* Significant (5% level)

** Highly significant (1% level)

52

significant differences were-at the 1% level for TSS, Na,

soil NOg-N and plant NOg-N, while at Marana the significant

difference was only for TSS and ESP, also significant at

the 1% level.

A Least Significant Differences Test was run to

detect where the differences exist; the data presented in

Table 14 showed variation between sampling dates for almost

all the tested values which are indicated by different

letters. The same letters, however, indicate that the

values are statistically equal (see Appendix D for sample

calculations). This leads to the conclusion that sampling

date is very important to consider, especially when dealing

with soil properties such as TSS and soil N.

Lowering the pH of irrigation water as well as

soil by acid application was found to decrease the volatil­

ization loss of ammonia. This loss could be at least

partially due to a decrease in OH" activity and/or reduc­

tion in the degree of Ca saturation of the exchange complex

of the soil as Wahhab et al. (1957) reported. It is

interesting to note that when the acid was applied the pH

of the water tended to reach a maximum of 8.6 which is

close to the pH of a saturated solution of ammonium bicar­

bonate. At this pH about 25% of the total N in an ammonium

bicarbonate solution is in the form of dissolved ammonia

molecules. This suggests that the behavior of water and

53

Table 14. Variation of soil properties, soil NO3-N and plant NO3-N due to sampling dates as shown by the Least Significant Differences Test

Dates ESP %

TSS Soil NO3-N

Plant NO3-N Dates ESP

% ppm

a. Buckelew Farm**

2 615.2a 7.650a,C 6046a

3 953.lb 12.980b 5498b

4 501.6C 7.400a 5721C

5 603.9a 6.715d 1256d

7 519.1C 8.116C 702.9e

LSD .05 22.41 0.49 84.73

b. Marana Farm

3 1.563a 865.4a 19.76a 5891a

4 1.550a 714.7b 23.69b 5573b

5 2.500b 472.8C 14.45C 4334C

LSD .05 0.14 38.75 2.01 86.38

**ppm concentrations are significant at the 5% level

54

soil with respect to loss of ammonia depends primarily on

their pH and on their base exchange relationship with the

ammonium ion.

On the other hand, the data indicated that vola­

tile loss of ammonia, following anhydrous ammonia appli­

cation in irrigation water may take place even when acid

was applied. That is probably because the rate of acid

that was used was not high enough. To eliminate NH^

losses would require a low pH which is not possible due

to corrosion of the concrete ditches.

The data shown in Figs. 4, 5, 6 and 7 which were

reflected on yield data presented in Table 12 indicate

that temperature does influence the rate of NHg volatili­

zation losses. This could be due to the effect of temper­

ature on the solubility of NHg in water and/or its effect

on the amount of NH^ adsorbed on the soil. Fenn and

Kissel (1976) found that the increasing temperature

increased losses of NH^-N from NH^NOg. NH^NOg lost 16,

18, and 26% of the applied NH^-N at 12, 22, and 32°C,

respectively. Martin and Chapman (1951) found that a

moisture level of 25% of field capacity and temperatures

of 21, 38, and 65°C produced NH^-N losses of 27, 55, and

53% of the applied NH^-N, respectively.

The results of this study showed the volatile

loss NHg from irrigation water as well as from surface

of alkaline soils as found under laboratory conditions

55

can be detected under field conditions and that this loss

can be reduced using H2SO4. According to this study

H2SO4 application is recommended as the best and most

economical way to minimize or prevent NH3 volatilization

losses under alkaline soil conditions, especially for those

waters high in Na. In particular, if summer application

is necessary,'the acid rates should be sufficient to

reduce the water pH to near neutral. The data indicated

that loss took place mostly from the soil and increased

with distance along irrigation furrows.

This study considered only the benefits of adding

H2SO4 in terms of saving NH3. As pointed out in the lit­

erature review, acid has a great effect on water infiltra­

tion in calcareous-sodic soils. The Buckelew farm had a

known water penetration problem on many of the fields due

to sodium in the soil and the use of high sodium water for

irrigation. As a result of the wheat experiment, Mr.

Buckelew has routinely begun to add acid to his sodic

waters. He has noted a decided decrease in runoff waters

into his sump. As a result he is not using his pump-back

system as much and is saving energy and water.

CHAPTER 6

SUMMARY

Sulfuric acid and other sulfur compounds have been

used for reducing Na accumulation and associated deteriora­

tion of soil physical conditions which may directly or

indirectly cause low crop yields. Recently the use of

sulfuric acid has rapidly increased in Arizona as the

price and supply are becoming favorable, thus treatment of

ammoniated water with few gallons of acid should be

considered.

Although loss of nitrogen as ammonia from the

applied anhydrous ammonia fertilizer was not measured

directly, the data satisfactorily proved that acid appli­

cation under field conditions is worthwhile, as fertilizer

costs are increasing rapidly due to the present oil crisis.

In order to achieve our objectives of reducing the

volatile loss of N, more attention should be directed to

irrigation practices. Under the condition of our experi­

ments at the Buckelew Farm we recommend that the furrows

should not exceed 1000 feet in length. The acid rate

should be increased and ammonia application should be

avoided, if possible, when the temperature is high.

56

APPENDIX A

PROPERTIES AND HANDLING OF SULFURIC ACID AND ITS USE FOR AGRICULTURAL PURPOSES

Formula - H2S04

Molecular Weight = 98.076

Density at 20°C = 1.83 g/cm3 for 100% acid

Sulfuric acid of any strength under 100% is a non-

fuming acid (for further details, see Fasullo 1965), while

in any strength over 100% contains free sulfur trioxide

which causes the acid to vaporize and classifies it as a

fuming acid. Sulfuric acid of 100% concentration contains

81.63% SO3 and 18.37% water. This 18.37% water includes

free and combined water, the fuming acid (concentration

above 100%) has no free water. For the determination of

weight of sulfuric acid, the volume, specific gravity, and

strength should be known.

"Durion" is a popular commerical material obtain­

able at reasonable cost which is resistant to 100% sulfu­

ric acid at all temperatures, including boiling. Materials

more resistant than steel or cast iron may be justified in

cases where unusual aeration is involved.

Sulfuric acid has been used recently and exten­

sively in agricultural development in many ways.

57

58

Treatment of irrigation water for the purposes of

a. control of calcite precipitation which involves

the use of small amounts of the acid ranging

between (13-65 lbs of acid per acre-foot

water) for preventing plugging of the trickle

irrigation systems (Miyamoto, Prather, and

Stroehlein 1975).

b. • reducing the sodium hazards which might cause

water penetration problems and deterioration

of soil structure. High acid rates were used

in this case depending on the Na level (Gumma,

Prather, and Miyamoto 1976).

c. to reduce ammonia volatilization losses which

have been covered in this study the acid

requirement ranges from 350-550 lbs/acre and

it also depends on the sodium level of both

soils and water.

Soil treatments for the purpose of

a. sodic soil reclamation for improving water

penetration (Yahia, Miyamoto, and Stroehlein

1975).

b. nutrients release from the soil, such nutrients

as phosphorus, zinc, iron. Low acid rates are

required.

c. specific ion problem such as boron.

A

APPENDIX B

REPRESENTATIVE SAMPLES OF SOIL, WATER, AND PLANTS

Table B.l. Representative soil sampling analysis from Buckelew Farm (soils collected June 28, 1976)

Saturation extract

Location pH ECexl03 TSSa Na K ESP N.b P pH mmhos/cm ppm meq/1 % ppm

lc 7.7 0.8 660 4.9 0.3 5.0 10.8 7.5 2 7.7 1.0 665 6.8 0.3 5.0 10.8 9.5 3 7.8 0.7 578 5.2 0.3 5.0 10.8 9.5 4 7.8 0.7 455 4.6 0.3 5.0 10.3 10.0 5 7.9 0.8 667 6.4 0.3 6.0 9.3 4.3 6 8.0 0.9 609 6.3 0.3 8.0 9.0 5.3 7 8.0 0.9 723 7.0 0.3 9.0 9.0 4.5 8 8.1 1.0 707 11.0 0.3 9.0 8.5 3.8 9 8.0 0.9 623 6.4 0.3 7.0 8.0 2.3 10 8.1 0.9 616 5.9 0.3 7.0 6.0 4.3 11 7.9 1.1 784 8.2 0.4 6.0 7.3 8.5 12 8.1 0.9 644 6.3 0.4 8.0 7.3 7.0

aTSS stands for total soluble salts

N stands for nitrate-N

cSample location numbers are as shown in Fig. 2.

59

Table B.2. Representative water sampling analysis from Marana Farm main irrigation ditch (samples collected July 23, 1976) in ppm

Sample pH NO-j-N NH4~N Total N

Control la 9.9 2.0 56.0 58.0 2 9.7 1.9 54.8 56.7 3 9.7 1.9 52.0 53.9 4 9.6 1.8 49.6 51.5 5 9.7 1.7 44.8 46.5

Treatment 1 8.3 2.7 60.4 63.1 2 8.2 2.7 60.8 63.5 3 8.2 2.7 64.0 66.7 4 8.0 2.6 65.0 67.6 5 8.2 2.6 67.2 69.8

aThe numbers 1 to 5 are sampling sites at 200 meter ' intervals from the well to the field.

61

Table B.3. Representative plant sampling analysis from Marana Farm (samples collected August 11, 1976) in ppm

Sample Number NO^-N Ave/plot

1 5156 2 5697 5494 Control 3 5598 4 5517

5 6058 6 5608 5865 Treatment 7 5743 8 6050

9 5858 10 5608 5832 Control 11 6048 12 5811

13 6019 14 6009 6022 Treatment 15 6024 16 6032

17 6068 18 5548 5845 Control 19 5868 20 5897

N** T N* IJAMC;

to H M 00 O <7\ to

. — 2 M -J 2 3 OJ (—1 w 1—' — K W — 3 vo 3 (JI oj OJ U> ffi — W •—• w to u> + OJ + +

H re o o NO o to to 0

0 01 o 03 03 3 ti — O — 3 o o rt ^ rt M J* H rt .c* >£> — i-i M 4 O H <Ti to 0 00 O -— — O — — H — |_i 1—'

M vo U1 H OJ

45 ROWS 40 ROWS 40 ROWS 40 ROWS 11 14 ROWS ROWS

DITCH

Pig. B.l. A sketch of the field showing the locations of sampling sites at the Marana Farm

N* = no nitrogen fertilizer was applied at preplanting time. N** = nitrogen fertilizer was applied at preplanting time.

63

(25) ( 2 6 )

(24) (23) (11) (12)

( 2 2 ) (10) (21)

(N

(19) ( 2 0 ) (7) CO

(18) (17) m

(16) (4) (15)

(.1) (14)

•DITCH-

Fig. B.2. A sketch of the field showing the locations of sampling sites at the Buckelew Farm.

APPENDIX C

GENEPvAL INFORMATION TABLE

Buckelew Farm Marana Farm

Cotton Wheat Cotton

Variety Deltapine 16 Produra wheat

Planting date Apr. 10, 1976 Dec. 20, 1974

Stoneville 213

Apr. 9, 1976

Harvesting date Oct. 7, 1976 Jun. 10, 1975 Nov. 2, 1976

Fertilizer application rates

Lbs.

Pre-irrigation 1st irrigation 2nd irrigation 3rd irrigation 4th irrigation

of NH^/Acre

33.6 28.4 32.4 14.6 0

106

30 lbs. N/Acre 0

54 lbs. NH,/Acre 54 lbs. NH^/Acre

H^SO^ Rates

Pre-irrigation 63 1st irrigation 63 2nd irrigation 63 3rd irrigation 63 4th irrigation o

Lbs. H^SO^/Acre

1500

0 0 79 79 0

64

APPENDIX D

SAMPLE CALCULATIONS

X. The Least Significant Differences Test (LSD)

LSD = t a/2,n2 2 MSE n

where n2 is df of error

n is number of observations

MSE is mean square error

Example: for TSS in Table 14 a at the various dates,

= t a/2,n2

' 2 (11622.975764} 130

~ t.95,47 x 13-37 = 1.6759 x 13.37 = 22.41

If Xi - xj ̂ LSD we reject the HQ

a. 953.1 - 501.6

b. 953.1 - 615.2

c. 615.2 - 603.9

d. 603.9 - 501.6

e. 603.9 - 519.1

f. 519.1-501.6

451.5^22.41, significantly different

337.9^22.41, significantly different

11.3^22.41, no significant difference

102.3^22.41, significantly different

84.8^22.41, significantly different

17.5^22.41, no significant difference

65

66

The results are:

615.2a 953.lb 501.6C 603.9a 519.lc

which means that date 3 is significantly different at the

5 % level from all the others; dates 2 and 5 are the same

(no significant difference), and date 4 and 7 are the same.

2. Effect of blocks and pairs on various soil properties

(Buckelew Farm).

Block I

pH** TSS** Na** K** Soil-N** ppm meq/1 ppm

Pair

Block II Pair

1 7. 720 722. 4 5. 930 0. 4000 14. 18 2 7. 730 682. 5 5. 730 0. 3500 12. 35 3 7. 950 653. 1 5. 980 0. 3100 7. 990 4 7. 950 599. 2 6. 490 0. 3500 5. 990 5 8. 010 614. 6 5. 970 0. 3400 5. 780 6 7. 970 626. 5 5. 550 0. 3600 6. 640

1 7. 760 577. 5 4. 850 0. 2700 11. 53 2 7. 640 636. 4 5. 340 0. 3300 10. 29 3 7. 910 662. 3 5. 770 0. 2900 10. 54 4 8. 050 684. 6 6. 670 0. 3200 8. 100 5 8. 010 548. 8 4. 960 0. 2600 5. 510 6 8. 150 680. 4 6. 760 0. 3200 7. 150 7 8. 067 623. 8 5. 600 0. 2889 5. 078

'9cfc Significant at the 5% level.

67

3. Linear contrast for soil (NO^-N),

Cj = - 2 . 5 , -1.5, -0.5, .5, 1.5, 2.5, -3, -2, -1, 0,

1, 2, 3

Xj Cj = -35.45, (-18.53), (-4), (3), (8.67), (16.6),

(-34.59), (-20.58), (-10.54), (0), (5.510),

(14.3), (15.23)

(10 £x_. c.)2 = [10 (-60.38) ]2

364574.44 SSCLin = 10 (6.25 + 2.25 + 0.25 + 0.25 + 2.25

+ 6 . 2 6 + 9 + 4 + 1 + 0 + 1 + 4 + 9 )

SSCLin = 5°6Qi281 = 143.05 (it is highly significant)

The linear contrast is significant and it fits

the data well.

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