YIELDS AND LEAF ELEMENTAL COMPOSITION OF COTTON G R O W ON SLUDGE-AMENDED SOIL by John Earl Watson A Thesis Submitted to the Faculty of the DEPARTMENT OF SOILS, WATER, AND ENGINEERING In Partial Fulfillment of the Requirements For the Degree of MASTER OF SCIENCE WITH A MAJOR IN SOIL AND WATER SCIENCE In the Graduate College THE UNIVERSITY OF ARIZONA 19 7 9 STATEMENT BY AUTHOR This thesis has been submitted in partial fulfillment of re quirements 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 thesis 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 judg ment the proposed use of the material is in the interests of scholar ship. In all other instances, however, permission must be obtained from the author. SIGNED: APPROVAL BY THESIS DIRECTOR This thesis has been approved on the date shown below: i&Kl ( Ian L. Pepper Assistant Professor of Soils, Water and Engineering 7)/ ? ? ? Date To my wife, my parents, and Our Lord Jesus for their love, support and encouragement iii ACKNOWLEDGMENTS The author is extremely grateful to Dr. Ian L. Pepper for his guidance, suggestions, assistance, and encouragement throughout the course of this study. The kindness and understanding he extended to the author were a source of great motivation. Special thanks are extended to Drs, Thomas C. Tucker and Wallace , H . Fuller for their constructive advice and comments. A sincere thanks is extended to Mr. W. D. Ackley, who was an indispensible help and a constant source of encouragement. iv TABLE OF CONTENTS V. Page . LIST OF TABLES ............ ABSTRACT . . . . . . . . . . .. . . . . . INTRODUCTION . . . . . . . . .. . . . . . . LITERATURE REVIEW .. . . . ... vi . . . . . . vii . . .- . . . . 1 . . . . . . . . . . . . . . . . . . . . . . . 3 Nutrients Requirements of Cotton in Arizona .. . . . . . . Fertilizer Value of Sewage Sludge in Arizona .. . . . . . . Trace Metal Toxicity . . . . . . . . . . . . . . . . . . . . MATERIALS AND METHODS .. . . Field Study . . . . Laboratory Analyses RESULTS AND DISCUSSION Sludge Variability Nutrient Value . , Cotton Yields .. Metal Uptake . . . . . . . LITERATURE CITED . . . . . .. . . . . . . . . . 20 ..... . . . . . . . . . . . . . . . . .. .. . . . . . . . . . . ... . . . . .. SUMMARY AND CONCLUSIONS . . ... 3 7 9 . .. . . . . . .. . . . . . . . . . . . . » ... .. . . . . . . . ... . . ............ . . . . . . . . .. . . . ... . . . . .. . ... . . . . . . . . . . .. . . . ... . . . ... .. . . . . . v . . . . . . . . . . . . 24 . . . . . . . . . . . . . ... .. . . . . . 20 21 . 24 27 29 29 34 36 LIST OF TABLES Table Page 1. Typical analysis of Tucson sludge . . . . . . . . . . . . . 2. Analysis of Tucson sewage sludge used in the field study 3. Concentrations of N, P and DTPAextractable metals of the soil used in this study . . . . . . . . . . . . .„ . „. 1 2 4. Comparison of range, mean and medium of trace element con centrations of sewage sludges from Michigan . . .. . .. 14 Total concentrations of trace elements typically found in soils and plants . . . .. . . . . . . .. .. . . . . 15 Variations in total N, P and inorganic N concentration of Tucson sewage sludge over a six month period . .. . .. 25 Variations in total and extractable (5 g sludge; 50 mis extractant) metal concentrations of Tucson sludge over a six month period . . . . . . . * . . . .. . . . ... . 26 Soil and cotton leaf N and P concentrations 48 days after planting ♦ . . ... . . . . . . . . . . . . . . . . .. 28 Lint to seed ratio, turnout, and seed cotton and lint yields . . . . . . . . . . . . . . . * .. .. . . .. .. . 30 Concentrations of Cd, Zn, Cu, and Ni in cotton leaves 48 days after planting . . . . . . . . . . . . . . . . . . . 31 Concentrations of Cd, Zn, Cu, and Hi in cotton seeds at harvest , . . . . . . . . . . . . . . . . .. . . . . . . 33 5. 6. 7. 8. 9. 10. 11. vi 10 . 11 ABSTRACT A field experiment on The University of Arizona agricultural experiment station farm at Marana, Arizona was conducted to determine the yield and elemental composition of upland cotton (Gossypium hirgutum pli. 1 cultivar DPL55) grown on Pima clay loam soil with four rates (0, 16, 32, and 89 mt/ha) of anaerobically digested, air dried, Tucson sewage sludge. Analysis of leaf samples collected 48 days after planting in dicated that C d , Z n , C u , and Ni concentrations were below toxic levels. The highest Cd and Zn concentrations of 1,5 and 44.9 pg/g, respectively, occurred at the. highest sludge rate. Cd ratio. Sludge addition decreased the Zn: Leaf Cu and Ni varied little. Seed cotton yields significantly increased to a maximum of 3626 kg/ha at the 32 mt/ha sludge rate. sludge addition. Lint:seed ratio decreased with Yields from sludge addition were comparable to those obtained from a fertilizer control treatment. Seed Cd and Ni concentra tions were below 0.15 and 1.5 yg/g, respectively. Seed Zn and Cu con centrations did not vary significantly and averaged 23.8 and 8.1 pg/g, respectively. . vii INTRODUCTION" Tucson, Arizona, a metropolitan area of approximately 450,000 people has been using anerobically digested, air dried sewage sludge as a fertilizer amendment in its parks and on its golf courses for six years (Tucson Parks and Recreation Department, Park Superintendent Gale Bandrick, personal communication, 1979). This utilization has been shown to be very successful and a practical solution for the disposal of wastes for the present time. Since Tucson’s population is increasing rapidly, large volumes of sewage sludge and effluents will accumulate and alternate disposal methods will become necessary. An attractive means of sludge disposal for some municipalities ‘ has been the utilization of sewage sludge on agricultural lands Modest amounts of sewage sludge have been shown to improve the physical y condition of mineral soils (Epstein, 1975), as well as supply signif icant amounts of nitrogen (N) and phosphorus (?) as well as some potassium (K) and various micronutrients. However, large amounts of sewage sludge added to agricultural soils can damage crops, reducing . yields as well as lowering quality (Epstein, 1973). The possibilities of overloading the soil system with excess N and P (Lindsay, 1973) and of adding toxic heavy metals are relatively low in Tucson sludge, so the limiting factor for the maximum loading rates would probably be excess N. 2 In 1978, Arizona ranked sixth among the fourteen major cotton producing states in cotton acreage planted (Cox, 1979), planting 570,000 acres of cotton (Arizona Agricultural Experiment Station, 1979). Based on past trends this would represent from 20% to 30% of the value of all agricultural commodities produced or marketed in Arizona during the year (Mayes, Britton and Biggs, 1978). Usually 85% to 95% of the cotton acreage harvested has been planted to Upland cotton (Gossypium hirsutum: [L.]) (Mayes et al., 1978). This is the major crop in Pima County, Arizona and in 1977 brought to the area an estimated $9,4 million from the sale of cotton lint (Mayes et al., 1978). The clay loam soils in the Tucson area have sufficient K for cotton production, but need fertilizer N additions for maximum yields. Thes addition of P fertilizers have varying effects depending upon the local fertility and conditions and the crop to be grown. These soils are difficult to work when dry and have a moderate to moderately slow infiltration rate (Gelderman, 1972). The addition of moderate amounts of organic matter, such as sewage sludge, could therefore positively complement local farmer’s present fertility programs and improve their soil’s physical condition. Using anaerobically digested, air dried, Tucson municipal sewage sludge, this field study was conducted to: (a) evaluate the variability of Tucson sewage sludges, (b) determine its potential fertilizer value for cotton compared . with conventional grower fertilizer practices, (c) determine the sludge loading rate for best yields, and ■'(d)-. evaluate its potential phytotoxicity. LITERATURE" REVIEW Three of the considerations which must be evaluated when util izing sewage sludge agronomically are the nutritional needs of the crop grown, the nutrient supply of the sludge, and possible toxicity effects on the crop and on humans or other animals consuming the crop. Nutrients Requirements of Cotton in Arizona The largest cotton yield increases from fertilizer additions have been directly related to N applications (Tucker and Tucker, 1968). Amburgey and Ray (1959) summarized the fertilizer trials from 1949 through 1953 for soils in Arizona on which cotton is grown. They re ported that without prior growth of alfalfa, cotton consistently responded to N applications. They suggested approximately 84 to 121 kg N/ha (75 to 100 lbs/acre) in the warmer valleys and 34 to 56 kg N/ha (30 to 50 lbs/acre) at the higher elevations, for optimum cotton yields on most soils. Hamilton, Stanberry and Wootton (1956) found that N fertilizer additions to N deficient soils on the Yuma Mesa in Arizona increased the total number of flowers and bolls and yields. Gardner and Tucker (1962) also found that increasing N applications to a soil initially low in N increased flower and boll production, which were sig nificantly correlated with each other. number of flowers and number with yield. of bolls produced were highly correlated Black (1968) summarized the-relationship between the fruiting period and N supply. v They further stated that the . - He stated that the length of time cotton 3 ■ . - ■ - produces new flowers is partly determined by the availability of N to the plant. If the N supply is relatively high, flowers will be produced later in the season than would occur with N deficient plants. Tucker and Tucker (1968) pointed out that the prolonged fruiting period usually results in greater yields, but at a later harvest date than N deficient plants. The addition of N fertilizers cannot be expected to always give increased cotton yields. In fact, a reduction in yields can occur from large applications of N early in the season, especially when the soil contains excessive amounts of moisture (Tucker and Tucker, 1968). Stroehlein, Fenn and Fuller (1964), in Arizona, found that the applica tion of 280 kg N/ha (250 lbs/acre) significantly depressed cotton yields below yields from plots receiving.140 kg N/ha (125 lbs/acre). Kreizinger and Tucker (1962) showed that when the native soil fertility was sufficient, the addition of N did not significantly increase yields. Even when there is a yield increase due to N fertilization, it is not possible to state that a given amount of N addition will increase the yield every year. Work by Tucker, Carpenter and Abbott (1966) showed significant increases in cotton yields with N additions. How ever, in some years 56 kg N/ha (50 lbs/acre) resulted in significant differences, and in other years 121 kg N/ha (100 lbs/acre) or 168 kg N/ha (150 lbs/acre) were required before a significant increase in yield was observed, when cotton was grown continuously for four years. Abbott and Briggs (1961) found that cotton planted in early to mid-April responded to 84 kg N/ha (75 lbs/acre), but cotton planted later than ' mid-April did not. A 1972. survey of selected Arizona growers producing high yields of cotton found that all of the Central Arizona growers surveyed applied N. On the average, the total amount applied was 155 kg/ha (138 lbs/acre) ( H a t h o m and Taylor , 1972)« The relationship between cotton yields and P fertilization is not clear for Arizona soils. Where P is needed in Arizona, the re commended rates range from 0 to 39 kg P/ha (0 to 35 lbs/acre) (Jones and Bardsley, 1968), with most top producers in Central Arizona using 33 kg P/ha (29 lbs/acre) on the average ( H a t h o m and Taylor, 1972). However, ohe-third of the top cotton producers in Central Arizona do not add any P fertilizer (Hathorn and Taylor, 1972). Tucker, Abbott, Carpenter and Rauschkolb (1965) found a very positive response, to P fertilization at the Mesa experiment farm.on plots that had not received P fertilizers for seven years. The optimum fertil izer treatment was 56 kg N/ha (50 lbs/acre) plus 49 kg P/ha (44 lbs/ acre). This treatment gave cotton yields as high as or higher than 112 or 224 kg N/ha (100 lbs or 200 lbs/acre) alone. In 1959 in Northern Yuma County, Kreizinger and Tucker (1962) found that 67 kg N/ha (60 lbs/acre) plus 37 kg P/ha (33 lbs/acre) resulted in a statistically significant in crease in cotton yields above those obtained from the no fertilizer treatment. Other fertilizer treatments of N alone or N plus P did not .significantly increase yields above those from the control plots. .The following year, I960, however, they found that there appeared to be no beneficial effect on the yield of cotton when various levels of N , . ■ and/or P were applied, to P fertilization. 6 . ■ ; This is the normal response of Arizona cotton Fuller and Tucker (1964) found no significant dif ferences in cotton lint yields related to P fertilization when 0, 22 and 67 kg P/ha (0, 20, and 60 lbs/acre) were added to the soil. Other Arizona studies have also shown a lack of response by cotton to P fertilization (Kreizinger and Jackson, 1962; Tucker, Abbott and Carpenter, 1965; Abbott, 1965). Amburgey and Ray (1959) point out that in cotton fertilizer trials and demonstrations in Arizona from 1949 through 1953 there was a poor response to P fertilization, As of 1953 there had not been found any significant response to K fertilization of cotton in Arizona tests (Amburgey and R a y , 1959). This is expected since the soils of the cotton growing areas of Arizona usually confeain a large supply of available K (Kamprath and Welch, 1968). Fuller'(1962) referred to Arizona experiments in concluding that K appeared to be sufficiently abundant in the irrigated soils of the arid and semi-arid Southwest so as not to be a factor limiting crop production at that time. The secondary nutrients and micronutrients have not generally been of major importance in the Cotton Belt of the United States . (Hinkle and Brown, 1968). A boron deficiency has been reported for cotton in North and South Carolina, Georgia, Alabama, Mississippi, Tennessee and Arkansas. A manganese deficiency has been reported for cotton in South Carolina and a zinc deficiency occurs in California. No cotton producing state has reported a deficiency of copper, iron, chlorine or molybdenum in cotton.(Hinkle and Brown, 1968). Rarely do micronutrient toxiclties occur in cotton production. However, concentra tions of manganese above 2000 ppm in leaf tissues (Hinkle and Brown9 1968) have been found to produce manganese toxicity. This toxicity, called crinkle leaf, is usually only a problem on acid soils (Adams and Wear, 1957) and is corrected by liming. Fertilizer Value of Sewage Sludge in Arizona For many years some U.S. cities have been distributing sewage sludge as a soil conditioner (Olds, 1960), In areas where it has been utilized for agricultural purposes, the typical complaint has been that farmers could not get as much as they wanted (Evans, 1968). This re sponse indicated the fertilizer value of sewage sludge. Utilizing wastes for crop production is hot a new idea in Arizona. Fuller, Johnson and Sposito (1960) found that municipal re fuse compost fortified with N and P stimulated growth of greenhouse tomatoes more than N and P alone, and the residual influence of the compost was to stimulate cotton growth as much as 45 kg N/ha (40 lbs/ acre), or more. Tucker, Abbott and Carpenter (1966) reported that the annual application of 11 kg manure/ha (10 tons/acre) consistently re sulted in cotton yields comparable to or greater than those obtained from 56 kg N/ha (50 lbs/acre). After the first two years of the experi ment, and continuing through the sixth year, the manure applications gave comparable or greater yields than the highest yields due to N additions. The sixth year, N had little effect on seed cotton yields but manure additions resulted in yields approximately 50% greater than the Control yields. . Other Arizona studies have shown the value of using municipal effluent for the irrigation of various crops. D a y , Tucker and Vavich (1962) compared irrigation of barley, oats, and wheat with sewage effluent to irrigation with well water with N, P, and K additions equivalent to amoupts applied in the sewage effluent during the growing season. They found more grain was produced on the effluent irrigated plots, but the plants on these plots tended to lodge at maturity. A later study (Day and Kirkpatrick, 1973) was conducted to evaluate the grain and forage yields of oats and assess differences in forage and grain protein contents from irrigating with treated municipal waste water. It was found that oat grain yields, and oat forage and grain protein contents were comparable whether effluent or well water with recommended rates of N, P and K was used> Green forage production was the same for both the wastewater treatment and the well water plus N, P, K treatment. Since the green forage from the wastewater treatment had a higher moisture content, the dry matter produced by the well water with N, P, and K was significantly greater. Tucker and Cluff (1979) More recently, Day, conducted a field experiment near Buckeye, Arizona using a 50;50 mixture of municipal wastewater and pump water. Since the pump water was high in total soluble salts, the wastewater actually improved the quality of the irrigation water. The yields of seed cotton and lint cotton from the wastewater -- pump water mixture were equal to or greater than the yields from cotton fertilized with 56 kg N/ha (50 lbs/acre) and irrigated with pump water only. Cotton fiber quality characteristics were analyzed and it was found that wastewater had no significant detrimental effects on quality. 8 A recent greenhouse study (Day,";M£tchedl et al«3 19791. involved the addition df noaanercial fertilizer and/or dried sewage sludge to coal mine soil to. investigate the effects on estergenee ahd""growt%i of various plant species. The fertilizer additions and/or the dried sludge ad ditions resulted in taller plants of alfalfa and wheat, an increase in the number of stems per pot from alfalfa and barley, and a tendency to ward an increase in the production of forage from alfalfa, barley, and wheat. Assuming the 20% sludge N mineralization rate used by Galloway and Jacobs (1977) and using present Tucson sludge and soil data (Tables 1 , 2 and 3) approximately 20 mt of sludge/ha should meet the N nutrient requirements of cotton, and provide more than sufficient, amounts of P and K (Pdu* I960); Trace Metal Toxicity A major concern with the agronomic utilization of sewage sludge is metal enrichment of plant tissue. The metals of greatest concern, due to their harmful effects on plants or humans when in high concen trations , are cadmium (Cd,), copper, (Gu), molybdenum (Ho), nickel (Ni), zinc (Zn), and lead (Fb) '(Galloway and Jacobs, 1977) . four currently receiving Of these, the the most attention as regards their toxicity 1 ' are Cd, Cu, Ni, and Zn (Fuller, personal communication, 1979). Cadmium, Cu and Zn can be a significant potential hazard in the food _ _ _ _ _ - ■ ■>' 1. Optimum utilization of sewage sludge on agricultural land. Dept» of Soils, Water.and Engineering, Univ. of Arizona, Arizona State Report, Western Region Research Project W-124, 1977. Table 1. Typical analysis of Tucson sludge. pH (saturation extract) 6.2 EC (saturation extract) 15,000 mg salt/1 TOC 8.2% TIOC 0.9% Na 2,100 Pg/g K 3,600 pg/g Ca 18,000 pg/g Mg 4,800 pg/g Table 2. Analysis of Tucson sewage sludge used in the field study. Total N NH*-N 4 NO -N+ NO“-N v 3 . : ■ " »o / T .. Cd > .---- - Zn Cu Zn:Cd bg/g 24.2 97.5 2169 771 89.6 DTPA Extractable 7.4 16.0 437 123 59.1 HOAc Extractable 6.0 11.5 679 15.8 Total 1.8 0.27 0.01 p 1.23 113.2 12 Table 3. Concentrations of N, P and DTPA extractable metals of the soil used In this study. i Concentration Ug/g Element NO.-N 3 - 14.4 COg extractable P Cd . <0.1 Hi Zn ' CU 0.4 : < 0 ” 1 ■ 3.6 ' - 8.2 13 chain through plant accumulation, and Zn, Cu, and Ni are directly toxic to plants (Chaney, 1973). Page (1974) lists the ranges, means, and medians of Gd, Zn, Cu and Ni in some Michigan sewage sludges (Table 4), and. typical concen trations found in soils and plants (Table 5). The wide variation of sludge metal contents as indicated by Page suggest that the application of different Sludges will result in variable crop uptake of trace metals. Other factors also affect metal uptake and toxicity. The toxicity of a given nutrient is related to soil pH. According to Chaney (1973), Cd and Zn are easily translocated to plant tops in acid soils, but Cu and Hi are translocated in appreciable quantities only when severe injury to the plant has occurred. Page (1974) presented data indicating that Ni uptake by plants is much greater in acid soils than in calcareous soils, whereas Cu uptake seemed unaffected by soil pH. Other data presented by Page (1974) in dicated that concentrations of Zn and Cu in plant tops can be reduced by increasing soil pH. Work by Bezdicek et al. (1979), showed that increasing soil pH via'liming decreased Zn uptake by rye and corn silage, but Cd uptake was not greatly affected. Cadmium can accumulate in the edible portions of crops to con centrations which are toxic to humans and other animals without causing crop yield reduction (Galloway and Jacobs, 1977). . Lagerwerff (1972) reported that the U.S. Food and Drug Administration in 1971 was con sidering setting the maximum allowable Cd concentration in food and 14 Table 4. Element Comparison of range, mean and medium of trace element con centrations of sewage sludges from Michigan. Range Mean Median Mg/g Cd 2-1100 74 12 Zn 72-16,400 3315 2200 Cu 84-10,400 1024 700 Ni 12-2800 ' 371 52 - 15 Table 5. Element Total concentrations of trace elements typically found in soils and plants. Cone, in Soils (pg/g) Common Range 0.01-7 Cd 0.06 Ni 40 10-1000 Zn 50 10-300 Cu 20 2-100 Cone. in Plants (pg/g) Normal Toxic 0.2—0.8 — 1 >50 15-200 4-15 >200 >20 16 milk at 0.135 ug Cd/g fresh weight. Page (1974) listed the normal range of plant Cd content from 0.2 to 0.8 ug Cd/g. Chaney (1973) cited data showing the Cd content of c o m and soybeans grown on normal soil varying from 0.6 to 3.3 Ug/g in the leaves and from 0.07 to 0.37 ug/g in the grain. Melsted (1973) suggested the tolerance level for Cd in agronomic crops to be 3 ug/g in certain plant parts to be used for monitoring purposes, such as specific c o m and soybean leaves. From these values it c m be seen that what may be considered normal plant composition in one situation can be thought of as possibly toxic in the food chain in another situation, since at the present time standards have not been satisfactorily established. Cadmium uptake by a given crop is not only related to the amount applied to the soil via a given sludge, but is also influenced by the presence of other metals as well as plant nutrients. There is evidence that Zn can exclude Cd in plant uptake and in the food chain (Chaney, 1973). As a result, one guideline suggested to prevent the crop Cd content from becoming a hazard in the food chain was to limit sludge application according to its Cd:Zn ratio, Galloway and Jacobs (1977) stated that a sludge Cd:Zn ratio of 0.01 or less was suggested as a guideline for safe use on agricultural land. Chaney (1973) sug gested that Cd:Zn ratio should be less than 0.005 and as close as possible to 0.001 so that Zn would injure the crop before the crop Cd content would become a hazard in the food chain. It has been shown, however, that many plants growing on nearly neutral to calcareous soils can tolerate high Zn levels and still show an increase in their Cd . concentration. ■ . 17 Ham and Dowdy (1978) found that 200 mt/ha. of sludge, with a GdsZn ratio of slightly less than 0.005, significantly increased the Cd concentration of soybean leaves at maturity from 0.35 yg/g on the control plots to 1.08 ug/g on the sludge amended plots. Bezdicek et al. (1979) found that a sludge application of 89.7 mg/ha increased the Cd content of c o m leaves from 1.0 to 8,6 yg/g. The seriousness of the problem of Cd is decreased by the fact that Cd increases in the grain have generally been much lower than those in the vegetative tissues of crops receiving high sludge Cd ap plications . Kelling et al. (1977) found that a sludge application of 60 mt/ha significantly increased the Cd content of c o m stover from 0.08 to 0,27 yg/g but the grain Cd content did not change significantly. Bezdicek et al. (1979) found that a 44.8 mt/ha sludge application rate resulted in a c o m k e m e l Cd content of 0.5 yg/g, while the leaf Cd content was 6.2 yg/g. Application of 89.7 mt/ha of sludge increased the leaf Cd content to 8.6 yg/g, but the kernel Cd concentration remmained at 0.5 yg/g. The leaf and kernel Cd contents of the c o m grown on the control plots was 1.1 and 0.2 yg/g, respectively. Ham and Dowdy (1978) reported that 200 mt/ha of sludge increased the Cd con tent of soybean leaves from 0.35 to 1,08 yg/g, but the seed Cd concentration only increased from 0.11 to 0.15 yg/g. Thus, it seems that Cd concentration is not only a matter of plant uptake, but is also dependent upon translocation of Cd within the plant (Mitchell, Bingham and Page, 1978). Although Zn and Cu can be potential hazards in the food chain through plant accumulation, crop yield is usually reduced at lower , 18 .plant Zn levels than those that Injure tHe animal consuming the plant (Chaney, 1973). Animals sensitive to Zn suffer from Zn toxicity if their diet contains between 500 to 1000 pg/Zn/g (Chaney, 19-73). Jones (1972) states that Zn toxicities occur in several crops when Zn leaf levels ex ceed 400 pg/g; and plant Cu toxicities may occur when leaf concentra tions exceed. 20 Pg/g. Melsted (1973) suggested the tolerance level of Cu and Zn in crops to be 150 pg/g and 300 Pg/g, respectively. Page (1974) presented the toxic concentrations of Cu and Zn in plants as greater than 20 and 200 pg/g, respectively. Mitchell et al. (1978) found that a 25% yield decrease was associated with leaf Cu and Zn contents of 15.4 and 189 pg/g respectively, for wheat grown on cal careous soil. The sufficiency range for Zn in cotton leaves has been reported, as 20 to 100 pg/g, and the normal range for Cu concentration in cotton leaves is 8 to 20 pg/g (Sabbe and MacKenzie, 1973). Ham and Dowdy (1978) found that the Cu concentration of soybean seeds decreased from 11 to 8 pg/g and the Zn concentration increased from 45 to 69. pg/g, when sludge was added at the rate of 200 mt/ha. The corresponding soybean Cu and Zn mature leaf concentrations in creased significantly from 5 to 15 pg/g and from 205 to 331 pg/g, respectively. The green leaf samples taken at flowering showed a de crease in Cu concentration from 5 to 2"pg/g with sludge addition, and an increase in Zn concentration from 31 to 90 pg/g. Nickel is considered toxic to plants at relatively low concentrations (Fuller, personal communication, 1979). Page (1974) 2. Optimum utilization of sewage sludge on agricultural land. Arizona state report, Western region researclLproject, W-124, 1977. : 19 reported that concentrations of Ni in plants greater than 50 yg/g would be considered toxic. level as 3 yg/g. Melsted (1973) however, suggested the tolerance Mitchell et al. (1978) found that Ni was as toxic to wheat grown oil calcareous soil as were Gu and Zn. Kelling et al. (1977) found that a 60 mt/ha sludge addition significantly increased the uptake of Ni by rye and sorghum-sudan forage tissue, and by corn grain and stover. Ham and Dowdy (1978) found that the addition of 50 mt/ha of air dried sewage sludge increased the Ni concentration of soy bean seeds from 10 yg/g to 13 yg/g, and the green leaf Ni concentration increased from 5.2 yg/g to 7.3 yg/g. They also found that adding Ni salts changed the concentrations of other elements in the leaf samples, but did not increase the leaf Ni concentration. depress yieldsj Addition of Ni did not MATERIALS AND METHODS Field Study This field study was conducted at The Uaiverslty of Arizona agricultural experiment farm in Marana, Arizona, approximately 20 miles northwest of Tucson. The soil type used was Pima clay loam. The Pima series is a member of the fine-silty, mixed, thermic family of Typic TorrifInvents (Post, Hendricks and Pereira, 1978)* Anaerobically digested, air dried sewage sludge was obtained from Tucson, Arizona and applied to plots in early May, 1978, at rates of 0, 16, 32, and 89 mt/ha on a dry weight basis. A check plot fertilized with 53.8 kg N/ha as Urea (45% N), and 26.2 kg P/ha as Treble superphosphate (45% PgOg), was also included. Each plot was replicated four times in a.randomized complete block design. The sludge and fertilizer plot size was 3.0 m by 13.3 m within an 8.1 m by 21.3 m plot to negate border effects. Following treatment, all plots were disked, pre-irrigated, and rotary mulched prior to planting on 26 May with DPL 55, an upland cotton (Gossypium hirsutum [L.]) variety grown in the Tucson area with favor able yields in Arizona variety trials (Stedman, 1979). Rows were spaced 1 m apart and the cultural practices were those normally employed by the experiment station. On 7 November, two 9.1 m rows of cotton per plot were spindle picker harvested and field weights determined. Samples from each plot were cleaned and analyzed for lint to seed ratios. A, second pick was not made due to the small amount of remaining . material per plot, 20 . 21 Laboratory Analyses Anaerobically digested, air dried sewage sludge samples from Tucson were collected each month for six, months. These samples were further air dried of freeze-dried and analyzed for total N. and P» and inorganic N . Total, diethylenetriaminepentaacetic acid-triethanolamine (DTPA-TEA) extractable, and 0.5 N acetic acid (HOAe) extractable Cd, Zn, Cu and Ni were also determined. Similar analyses were completed for the actual sludge *applied to the field plots in May. The N analyses were completed using micro-Kj eldahl techniques (Bremner, 1965). A 0.1 g sample of dried sludge was extracted with 125 ml of 1 N_ potassium chloride. The extracts were vacuum filtered through Whatman #42 filter paper and raised to a volume of 250 ml. 25 ml aliquot w a s used in steam distillation for Magnesium oxide was added first for the distillation of A and NO^ -N. -N, fol lowed by Devarda? s Alloy addition to the same aliquot for the distilla tion of NOg . Pistillate was collected in a boric-acid indicator solution and titrated with 0.005 N potassium biiodate ( K H C l O g ^ ) . A 0.1 g sample of dried sludge was used in a micro-Kjeldahl digestion to determine total N. A potassium sulfate, copper sulfate, selemium-catalyst mixture was added to the sample w i t h 3 ml of con centrated sulfufuric acid. digest the organic N. The samples were heated for 3 hours to These were subsequently steam distilled after the addition of 10 ml of 50% NaOH. A boric-acid indicator solution was again used to collect the distillate, and the titrant was 0.02 N KH <I03>2- v 22 Total P was determined using the Murphy and Riley method (Watanabe and Olsen, 1965). A 0.1 g sample of ground, dried sludge was pre-digested overnight in 20 ml of concentrated nitric acid (HN0o) . Ten millileters of deionized water and 10 ml of reagent grade perchloric acid (HCIO^) were added to the pre-digest and the mixture was heated at approximately 140 C until approximately 5 ml of solution remained. The solution was cooled and filtered through 'Whatman #42 filter paper, then brought to volume in a 100 ml volumetric. was used for the P analysis. A Technicon AutoAnalyzer II The nitric-perchloric digestion mixture was also used for the determination of total Cd, Zn, Cu, and Ni, using a Jarrell Ash model 810 absorption spectrophotometer. A DTPA-TEA extraction (Lindsay and Norvell, 1969) of sludge, shaking 5 g of sludge in 25, 50 and 125 ml of DTPA-TEA for 2 hours, was analyzed for extractable Cd, Zn, Cu and Ni. A corresponding sludge extraction using 0.5.N HQAc was also analyzed for Cd, Zn, Cu and Ni. Before sludge addition in May, both surface and depth soil samples were taken from representative areas of the field, analyzed for NOg -N using a modified phenoldisulfonic acid method (Bremner, 1965), and analyzed for CO^ extractable P (University of Arizona, Soils, Water and Plant Tissue Testing Lab., T. McCreary, personal communication, 1979). The modified phenoldisulfonic acid method used an extracting solution of silver sulfate and calcium sulfate. After extraction and filtration the NO^ -N content was analyzed using an Orion nitrate electrode. Forty-eight days after planting, representative samples of the most recently matured leaves were taken from each of the plots. 23 oven-dried at 65 C, ground in a Wiley mill and analyzed for total N, P, Cd, Zn, Cu, and Ni. Total N was determined using a 0.05 g sample in a micro-Kjeldahl digestion (Bremner, 1965). Total P was determined using the Murphy and Riley method (Watanabe and Olsen, 1965) with a 50 'ml nitric-perchloric digestion solution of 0.5 g of plant tissue sample. A Bausch and Lomb spectrophotometer 20 was used for analysis of the solution. The nitric-perchloric digest was also analyzed for Cd, Zn, Cu and Ni using the Jarrell Ash model 810 absorption spectrophotometer, for determination of plant tissue totals. Surface soil samples were taken from each plot at the same time as the tissue samples. These soil samples were freeze-dried and analyzed for NOg -N and CO^ extractable P as previously outlined. RESULTS AND DISCUSSION Sludge Variability Variability between sewage sludges has been clearly documented (Page, 1974) . sludge. Variability also occurs over time for any particular As shown in Tables 6 and 7, over a 6 month period Tucson sewage sludge varied appreciably in its metal and nutrient content. Time variation could be the result of several factors: the original input constituent variation, the time allowed for air drying in the waste treatment plant drying beds, the mean air temperature and pre cipitation during this time, and the final moisture content would af fect the biological and chemical reactions taking place. The amount of a constituent which may be leached during a heavy rain or volatilized during drying is also variable. The extractability of constituents also changed with time as indicated by the variation in the DTPA and HOAc extractable metals (Table 7). Changes in the number and type of users of the waste treat ment system was also reflected in the amount and extractability of con stituents. Any attempt to make a general summary of plant nutrient value and/or potential metal phytotoxicity of Tucson sewage sludge must con sider this variability in total and readily available, or extractable, nutrients and metals. - i ' - 25 Table 6 . Variations in total N, P and inorganic N concentration of Tucson sewage sludge over a six month period. Total N Month Total P NB*-N 4 NO”-N+NO“-N Sept. ’77 2.9 1.1 2 0.31 0.03 Oct. ’77 2.3 1.27 0.37 0.02 Nov. ’77 2 .1 0.88 0.39 0.08 Dec. '77 • 2.3 1.25 0.40 0.03 Jan. 00 % 1. 6 0.79 0. 2 1 0.04 Feb. 00 1^. 1.1 0.73 0.11 0.02 Average 2 .0 1.01 0.30 0.04 C.V. (%) 31 21 39 61 Table 7. Month Variations in total and extractable (5 g sludge; 50 mis extractant) metal concentrations of Tucson sludge over a six month period. Cd Total Metal Zn Ni Cd Cu DTPA Extractable : : '. 'Metal • Ni Zn Cu HOAc Extractable Metal , Cd Ni Zn Cu Vg/g Sept. '77 35.6 105.4 3247 1028 12.1 38.4 990 114 7.6 27.2 963 19.2 Oct. '77 21.5 74.0 2623 685 10.2 23.4 670 128 6 .8 16.0 798 27.5 Nov. •77 24.5 69.5 2186 752 7.8 13.0 494 192 5.9 14.5 697 22.3 Dec. '77 26.2 83.5 2254 824 9.5 17.5 663 249 6 .1 14.6 672 26.3 Jan. '78 22.7 76.8 2098 780 6 .8 16.0 449 174 8.2 20.5 1182 22.9 Feb. *78 19.2 49.0 1315 562 V'e.rv 14,5 432 130 6.5 20.5 724 19.4 Average 25.0 76.4 2287 772 8 .8 20.5 615 164 6 .8 18.9 839 22.9 C.V. (%) 21.0 22.0 25,4 18.4 23.3 42.3 31.5 28.4 11.9 23.7 21.5 13.7 . o> 21 Nutrient Value Conventionally, N is added to cotton cropland at rates from 50 to 150 kg N/ha (Amburgey and R a y , 1959; Hathorn and Taylor, 1972), and P is usually added at rates from 0 to 39 kg/ha (Jones and Bardsley, 1968). The 16 mt/ha sludge rate used in this study, added approximately 45 kg available inorganic N per ha and 197 kg total P per ha (Table 2). The highest sludge rate (89 mt/ha) added approximately 250 kg of in organic N per ha, and approximately 1100 kg total P per ha (Table 2). The plant N and P concentrations were not significantly differ ent between treatments (Table 8 ), but the total plant uptake of N and P was greater at the higher sludge rates. Increased uptake was evi denced by increased vegetative growth, which was expected due to the increased soil NO^-N (Table 8 ) (Gardner and Tucker, 1962). Uptake of P should vary almost directly with the growth of the above ground plant (Jones and Bardsley, 1968). The soil NO^-N increased significantly from a low of 15.9 pg/g for the control plots to a high of 53.5 pg/g for the 89 mt/ha treatment (Table 8 ). The lowest sludge application rate resulted in a soil NO^-N content comparable to that of the control and fertilizer treatment. The variability of the sludge N was reflected in the variation of the soil N0--N. The soil content of CO^ extractable P increased significantly with each sludge addition (Table 8 ). The lowest sludge application rate resulted in about the same amount of extractable soil P as did the fertilizer treatment. 28 Table 8 . Soil and cotton leaf N and P concentrations 48 days after planting.* Treatment n o 3-n Soil CO^ Extractable P Plant Total N v mt/ha 0 Total P et ’ hg/g 15.9 b 0.5d 4.51a 0.30 a 16 2 0 .Sab 0.9c 4.78a 0.28 a 32 30.Sab 1 .8b 4.74a 0.29a 89 53.3a 2.7a 4.66a 0.31a 16.9b 1 .2 c 4.67a 0.29a Fertilizer guide N and P *Treatment means followed by the same letter within each column are not significantly different by the Duncan Multiple Range Test at the 5% level.: 29 Cotton Yields Yields shown (Table 9) are from the first pick only„ Second pick yields were not obtained due to insufficient sample size. The av erage upland cotton lint yield for Pima County from 1971 through 1976 was highest in 1976 at 1076 kg/ha (Firch, 1978). The yields obtained in this study are comparable to that average or slightly higher (Table ^ ' ■ . Seed cotton yields increased with increased sludge rate to the maximum of 3626 kg/ha at the 32 mt/ha sludge rate. It appeared that the yield decreased slightly at the high sludge rate, but it was not possible to validate this observation statistically. It was noted from field observations that vegetative growth increased at the 32 mt/ha rate mad was excessive at the 89 mt/ha rate. It is possible that ex cessive vegetative growth resulted: in decreased yields at the highest sludge rate (Gardner and Tucker, 1962). The maximum lint:seed ratio was associated with the fertilizer treatment ° A significant decrease in the lint:seed ratio occurred at the 32 mt/ha and 89 mt/ha sludge rates. A similar vegetative increase and lint:seed ratio decrease was found by Day, Tucker and Cluff (1979) when municipal wastewater was used as a source of irrigation, water for cotton. Metal Uptake The apparent increases in leaf concentrations of Cu and Zn (Table 10) from 0.59 and 23.6 Ug/g, respectively, for the control treatment to 1.50 and 44.9 ug/g, respectively, for the highest sludge rate, were not found to be statistically significant. Copper and Ni 30 Table 9. Lint to seed ratio, turnout, and seed cotton and lint yields. * „ Sludge Treatment Lint:Seed mt/ha Turnout Seed Cotton Yield Lint Yield % kg/ha kg/ha 997 o .7 lab 36.05 2765b 16 .71ab 35.98 3241ab 1166 32 .68bc 34.98 3626a 1268 89 .64c 33.92 : 3320ab 1126 3443a 1274 Fertilizer guide N and P .74a ....37.00 ^Treatment means followed by the same letter within each column are not significantly different by the Duncan Multiple Range Test at the 5% level. 31 Table 10. Concentrations of Cd» Zn» C u $ and Ni in cotton leaves 48 days after planting. Sludge Treatment Metal Cd Zn Cu Mi Zn: Cd hg/g mt/ha 0 0.59a 23.6a 9.8a 8.5a 40 16 0.75a 21.7a 1 0 .2 a 7.8a 29 32 0.93a 26.2a 8 .8a 5.7a 28 89 1.50a 44.9a 9.5 a 6.4a 30 Fertilizer guide N and P 0.96a 33.7a 9.0a 9.9a 35 Mean 0.94 v ' 29.2 9.5 ' 7.6 ^Treatment means followed, by the same letter within each column are not significantly different by the Duncan Multiple' Range Test at the 5% level. 32 leaf concentrations did not vary significantly with treatment (Table 10)j averaging 9.5 and 7.6 wg/g, respectively. The ZnrCd ratio de creased from 40 and 35 with the control and fertilizer treatments, respectivelyj to 29» 28 and 30 with the low medium and high sludge rates. This decrease indicates a greater increase in Cd uptake com pared with increased Zn uptake from the sludge amended plots. It is possible that the large quantities of P added in the sludge inhibited Zn uptake (Wallace, Mueller and Alexander, 1977). Overall, seed metal concentrations were equal to or lower than leaf metal concentrations. Seed Cu and Zn concentrations did not in dicate increases due to treatment (Table 11), with average concentra tions of 8.1 and 23.8 ug/g, respectively. These concentrations are comparable to the average leaf Cu and Zn concentrations. Seed Ni and Cd concentrations were less than 1.5 and 0.15 Ug/g, respectively, for all treatments (Table 11). This indicates that Ni and Cd were not translocated into the seeds to the extent Cu and Zn were. According to data presented by Page (1974) (Table 5) leaf Ni exceeded the normal the toxic range. concentrations found in plants, but was not within The leaf Cd concentrations from the control and 32 mt/ha treatments were within the normal range for plants. The 1.5 Ug/g Cd content of the cotton leaves at the 89 mt/ha sludge rate was not excessive compared with values obtained with or suggested for other agronomic crops. (Melsted, 1973; Chaney, 1973; Bezdicek et a l .» 1979). 33 Table 11. Concentrations of Cd, Zn, Cu, and Ni in cotton seeds at harvest.* Sludge Treatment Metal Cd Zn mt/ha Cu : ni ' Pg/g 0 < .15a 24.9a 8 .2 a < 1.5a 16 < .15a 27.9a 8.3a < 1.5a 32 < .15 a 19.4a 8 .1 a < 1.5a 89 < .15a 24.9 a 8.7a < 1.5a Fertilizer guide N and P < .15 a 19.6a 7.0a < 1.5a Mean < .15 23.8 8.1 <1.5 *Treatmeht means followed by the same letter within each column are not significantly different by the Duncan multiple Range Test at the 5% level. SUMMARY AND CONCLUSIONS Tucson sewage sludge composition varies over time in its nutrient and metal composition, with the greatest variation occurring with the inorganic N and DTPA extractable Ni and Zn. Such variations must be taken into account when using sludge agriculturally. Following soil amendment with sewage sludge, leaf and seed Cd, Zn, Cu and Ni contents were within non-toxic concentration ranges, but leaf Cd and Zn concentrations appeared to increase at the highest sludge rate. However, plant tissue concentrations remained low enough that the hazard of metal phytotoxicity was low during this first year. Tucson sewage sludge was as effective as fertilizer N and P in meeting the nutritional requirements of upland cotton. High rates of sewage sludge significantly increased soil NO^-N and .CQj extractable P contents over those of the control and fertilizer treatments, with a corresponding increase in vegetative growth and decrease in lint:seed ratio. Seed cotton yields from the sludge amended plots were comparable to those from the fertilizer treatment, with the 32 mt/ha sludge treat ment resulting in the best yield of any treatment. The results from this study indicated Tucson sewage sludge is ' .suitable for use as a fertilizer for cotton. Application rates must be based upon the inorganic N content to prevent excessive vegetative growth due to excess N addition. " Possible plant and animal toxicities 34 from sludge addition are minimal at application rates based upon op timal N additions. LITERATURE CITED Adams„ F. and J. I. Wear. 1957. Manganese toxicity and soil acidity in relation to crinkle leaf of cotton. SSSA. Proc. 21: 305-308. Abbott, J. L. 1965. Effects of planting date, variety, and fertility level on upland cotton, p. 12-14. In, Eighth annual report on soil fertility and fertilizer research. Univ. Arizona, College of Agric., Agric. Exp. Stn. and Agric. Extension Service Rep. N o . 7. ' Abbott, J. L. and R. E. Briggs. 1961, Effects of date of planting, variety and fertilizer level on cotton, p. 27-29. In, Fourth annual report on soil fertility and fertilizer research. Univ. Arizona, College of Agric., Agric. Exp. Stn. and Agric. Extension Service Rep. No. 3. Amburgey, L. R. and E. E. Ray. 1959. A summarization of cotton fertilizer tests, 1949-1953. p. 35— 37. In, Annual Arizona fertilization conference report. Univ. Arizona, College of Agric., Agiric. Exp. Sth. and Agric. Extension Service. Arizona Agricultural Experiment Station. 1979. Cotton: a college of agriculture report. Univ. Arizona, College of Agric., Agric. Exp. Stn. and Cooperative Extension Service. Series P-46. Bandrick, G. 1979. (pi), Personal Communication. Park Superintendent, Parks and Recreation Department, Tucson, Arizona. Bezdicek, D. F . , I. L. Pepper, A. S. Baker, D. 0. Turner, J. M. Sims and J. J..Madras. 1979. Application of dewatered sewage sludge on agriculture land. Western Washington Agric. Research and Extension Center, Puyallup and the Dept, of Agron. and Soils, Washington State Univ., Pullman, Wash. Black, C. A. (ed.). 1968. Soil-plant relationships. John Wiley and. Sons, Inc. New York, Second edition. Bremner, J. M. 1965. Total.nitrogen; inorganic forms of nitrogen; - Organic forms of nitrogen, p. 1149-1254. In, C. A. Black et al. (eds.). Methods of soil analysis (part 2), Agronomy 9, Amer, Soc. Agron., Madison, Wis. 36 37 Chaney, R.- L. 1973. Crop and food chain effects of toxic elements in .sludges and effluents. p. 129-142. In, Proc. Joint Conf. on Recycling Municipal Sludges and Effluents on Land. 9-13 July, Champaign, 111. Natl. Ass, of State Univ. and Land Grant Colleges, Washington, D.C. Cox, Do W. 1979. Growers plan acreage hike. p. 19-43. In, American, cotton grower magazine. No. 1, Vol. 15, Heister Pub. Co., Willoughby, Ohio. 1973. Effects of treated municipal Day, Ao D. and R. M. Kirkpatrick. wastewater on oat forage and grain. J. Environ. Qual. 2: 282- 284 • 1979ti Day, A. D . , G. F. Mitchell, T. C. Tucker and J. L, Thames. Emergence and growth of plant species in coal mine soil. J. Environ. Qual. 8 ; 110-114. Day, A. D . , T . C. Tucker and C. B. 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Test of an ascorbic acid method for determining phosphorus in water and NaHCOg extracts from soil. SSSA Proc. 29: 677-678.
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