Sludge Application Rates Research Articles

Elemental composition of globoid crystals in protein bodies of wheat grain grown on soil treated with sewage sludge

Wheat grain grown on soil treated with a heavy application rate of sewage sludge exhibited higher iron, zinc, copper, and cadmium contents than did wheat grain grown on an unfertilized control treatment. The sludge supplied more than the maximum amounts of zinc, copper, cadmium, and lead recommended for addition to Ontario agricultural lands.Globoid crystals, which are inclusions in protein bodies, are the major mineral storage component of wheat grain. The elemental composition of globoid crystals in wheat grain grown with and without sludge treatment was determined using energy dispersive X-ray (EDX) analysis. Globoid crystals from sludge-treated and control grains exhibited similar elemental compositions with the following exceptions. When comparing sludge-treated grains versus the controls: more globoid crystals in the aleurone layer farthest from the peduncle contained calcium; more coleoptile mesophyll globoid crystals contained calcium, manganese, and (or) iron; some globoid crystals in the young foliage leaves contained manganese; and some globoid crystals in the stele of the radicle contained calcium. The globoid crystals exhibited no tendency to accumulate toxic metals supplied by the sludge indicating that the mineral storage system in wheat is remarkably specific despite varying soil conditions.

Modeling Sewage Sludge Decomposition in Soil: I. Organic Carbon Transformation

AbstractMineralization of an activated and a digested sewage sludge in soil was studied in laboratory incubations. The activated sludge had a much higher mineralization rate than the digested sludge, mainly due to a larger portion of active organic carbon and less stability of the organic matter. After around 2 months of incubation, the mineralization rates of both sludges approached a square foot function of time. The amount of active organic carbon is a characteristic of sewage sludge and is important in determining the aerobic‐anaerobic status of the system. The mineralization of sewage sludges was proportional to the rate of sludge application at least up to 8% in the digested sludge and up to 4% in the activated sludge systems at 22°C. Between 8 and 22°C, the mineralization rate of sludges in soil increased about 1.9 times for every 10°C increase in temperature. Moisture levels between 0.06 and 0.33 bars had no significant effect on mineralization of the sludges. A regression model was developed in the form of an exponential function among the cumulative organic carbon mineralized and factors of time, sludge rate, and temperature. The model requires a minimal number of parameters to define the system and was least biased in regression analysis over a wide range of conditions.

Residual Nitrogen Availability from Soils Treated with Sewage Sludge in a Field Experiment

AbstractIn this experiment we determined the residual nitrogen availability from sewage sludges applied to a Hubbard sandy loam soil. In Study I, three sludge types—anaerobically digested (119, 237, and 466 metric tons/ha), aerobically digested (244 metric tons/ha), and mixed primary‐settled and waste‐activated (493 metric tons/ha)—were applied over a 3‐year period. Soil samples were collected from the field experiment 2 years after the final sludge application. Study II samples were obtained from plots of a field experiment in which an anaerobically digested sludge had been applied (63, 125, and 200 metric tons/ha) 4 years earlier.Several biological and chemical characteristics were examined as indexes of N availability. Cumulative N mineralization during aerobic incubation was approximately linearly related to time1/2 for all treatments. Index values for Study I samples varied widely, hut in general, reflected the quantity of sludge added: total soil C (1.05 to 4.66%), total soil N (0.092 to 0.608%), indigenous inorganic N (12 to 266 µg/g), N mineralized during 52 weeks of aerobic incubation (87 to 884 µg/g) and during 16 weeks of anaerobic incubation (14 to 525 µg/g), nitrogen mineralization potential, No (126 to 1,010 µg/g), and autoclave‐extractable N (76 to 441 µg/g). The sludge application rate was more important than the sludge type in affecting N mineralization. The sludge‐treated soils from Study II had lower and less varied index values than those from Study I.The evaluation of N‐availability indexes was based on the degree of correlation between the index values and N uptake by irrigated, field grown maize (Zea mays L.) (Study I) or sorghum‐sudangrass (Sorghum vulgare sudanese L., var. ‘Trudan V’) grown in the greenhouse (Study II). Each index was useful in determining relative differences of N availability for this soil having received greatly differing organic N treatments from sewage sludge. Nitrogen mineralized during short and long periods of incubation correlated with plant N uptake equally well. The chemical indexes of N availability were as reliable as more time‐consuming incubation procedures for determining the N‐supplying capacity of soils.

Effect of fertilizer, N rate and nitrapyrin on Ca and Mg nutrition of corn (zea hays, L.)

Abstract Corn was grown with three rates (200, 400, 800 rng N/pot) of sewage sludge (Milorganite), KNO3, or (NH4)2SO. application in the presence (10 ppm) or absence of nitrapyrin, a nitrification inhibitor. Bleached areas appeared on the lower leaves of plants at the lowest application of sludge when nitrapyrin was added. No other visible symptoms were noted. Five‐week‐old seedlings were harvested, weighed and analyzed for Ca and Mg. Nitrapyrin restricted dry weight production of plants receiving sludge and increased growth in those receiving KNO3. Concentrations of Ca and Mg were reduced in all plants receiving nitrapyrin except in those grown at the lowest rates of sludge application.

Root zone nitrogen simulation model for land application of sewage sludges

A root zone nitrogen simulation model was developed for the evaluation of the long term effects upon soil root zone nitrogen of various sewage sludge application rates, methods of sludge application, ammonia nitrogen fertilizer application and no fertilization. Effects examined include crop yield, root zone nitrogen build up, nitrate nitrogen leaching and crop nitrogen uptake as a percentage of nitrogen applied. Simulation results indicated that nitrate nitrogen leaching had a direct linear relationship to sludge application at the simulated application rates. The leaching rate increased 21 kg per ha per year for each metric ton (t) of sludge incorporated into farm soils and 22 kg per ha per year for each metric ton incorporated into stripmine soils. Surface application of sludge resulted in leaching rates 50% lower than incorporation. Crop uptake of nitrogen was simulated using Michaelis—Menten/Monod kinetics. The maximum uptake of nitrogen was 135 kg per ha per year for an incorporated loading rate of 25 t per ha per year. Depending upon the site, 25 t per ha per year of sludge built up organic nitrogen in the root zone by 8400 to 10,000 kg/ha over a 50-year period. Rigorous validation was not attempted but most model outputs compared favorably to literature values. Simulated application of 300 kg per ha per year of ammonia nitrogen yielded a 98-kg per ha per year crop nitrogen yield which is approximately average for the U.S. corn belt.

Elemental Composition of Barley and Ryegrass Grown on Acid Soils Amended with Scrubber Sludge

AbstractA greenhouse study assessed barley (Hordeum vulgare L.) and ryegrass (Secale cereale L.) growth on two acid soils amended with scrubber sludge from a coal‐fired, power‐generating plant. The scrubber sludge was the residue from flue gas desulfurization, which included unburned airborne particulates (fly ash). The feasibility of using this material as a soil amendment was investigated since both the source, low‐sulfur western coal, and the process by which this material was generated differ markedly from fly ashes used in many reported studies. Of particular interest were the effects of scrubber sludge applications on boron and selenium concentrations of barley and ryegrass.Soils used were a coarse sand, Typic Hapludalf (pH = 4.8), and a silt loam, Udorthentic Haploboroll (pH = 5.7). Scrubber sludge application rates ranged from 0 to 100 g sludge/kg soil. Dry matter production for 6 weeks of growth was depressed for barley and ryegrass when applications exceeded 12.5 g sludge/kg soil. Soil pH increased from 4.8 to 7.2 in the coarse sand and from 5.7 to 7.6 in the silt loam by applications of 100 g sludge/kg soil.Yield reductions for barley and ryegrass were attributed to high concentrations of tissue B, which ranged from 12 µg/g on control treatments to 150 and 2,000 µg/g on soils receiving 6.25 and 100 g sludge/kg soil, respectively. Tissue Se increased with added sludge, while Mn and Zn contents decreased, without reaching toxic or deficiency levels, respectively. Tissue Cd, Cu, P, and Pb levels fluctuated from soil to soil and crop to crop without approaching deficiency or toxicity levels.

EFFECTS OF SEWAGE SLUDGE APPLICATION ON THE HEAVY METAL CONTENT OF WHEAT AND FORAGE CROPS

A growth chamber experiment was employed to investigate the effect of digested sewage sludge application on the heavy metal content of wheat and brome-alfalfa forage crops. Samples of wheat were also obtained from farm fields which had received heavy applications of sludge. No adverse effects on yields or appearance of crops were noted. The tissue levels of Hg, Cr and Pb were unaffected by sludge treatment. Cu levels in wheat kernels and straw were only slightly increased, but Cu levels in the forage crop were elevated by the sludge treatment. There was a considerable increase in the Zn content of all crops, but levels were not excessive. Sludge treatment produced up to a sixfold increase in the Cd content of wheat kernels and a considerable increase in the Cd content of the forage crop. The increased cadium levels are undesirable, but can be controlled by restricting the sludge application rate. There was little or no effect of sludge treatment on Cd levels in wheat straw.

Effects of Soil‐applied Sewage Sludge on Concentrations of Elements in Earthworms

AbstractSamples of earthworms (Aporrectodea tuberculata [Annelida: Lumbricidae]) and their casts collected from field plots were analyzed by neutron activation analysis to evaluate the suitability of using earthworms to monitor the bioavailability of elements in soils, and to determine the effects of land application of sewage sludge on the concentrations of trace elements in earthworms. Culture of earthworms on soils treated with radioactive tracers shows that earthworms accumulate Cd, Co, Hg, and Zn, but not Hf, Sc, and Tb. The results for the earthworms from the field plots are corrected for the effects of contamination by uneliminated casts with the use of interelement ratios. The concentrations of Hg and Cr in the casts increase with increasing rates of sludge application, but the constant concentrations of these elements in the earthworms show that these elements are not bioavailable. The concentrations of Cd, Cu, and Zn in the earthworms increase, while those of Se decrease with increasing rates of sludge application. The very high concentrations of Cd in the earthworms, ranging from about 10 ppm in the control samples to over 100 ppm in the affected samples, show that earthworms efficiently accumulate Cd.

Cadmium from soil amended with sewage sludge: effects and residues in swine.

Liquid digested sewage sludge from a Chicago waste treatment plant was applied to experimental corn plots starting in 1968. The treatment plant received a high proportion of industrial effluent and the sludge averaged about 200 ppm Cd (dry weight). Corn grain harvested from the plots in 1974 was fed to growing swine for 56 days, and other swine were permitted to forage on the plots during the winters of 1975-76 and 1976-77. The sludge-fertilized corn contained higher concentrations of nutrient and toxic elements, but did not interfere with swine performance. Minor changes in hepatic microsomal oxidases and red blood cells accompanied significant increases in renal Cd and decreases in hepatic Fe. Swine foraging on these plots ingested considerable amounts of sludge soil and accumulated significantly higher concentrations of renal Cd. At lower rates of sludge application the swine outperformed those foraging both on control plots and those receiving heavy sludge applications in terms of weight gain, in-utero piglet survival, blood hemoglobin, and tissue Fe concentrations.

Cadmium from Soil Amended with Sewage Sludge: Effects and Residues in Swine

Liquid digested sewage sludge from a Chicago waste treatment plant was applied to experimental corn plots starting in 1968. The treatment plant received a high proportion of industrial effluent and the sludge averaged about 200 ppm Cd (dry weight). Corn grain harvested from the plots in 1974 was fed to growing swine for 56 days, and other swine were permitted to forage on the plots during the winters of 1975-76 and 1976-77. The sludge-fertilized corn contained higher concentrations of nutrient and toxic elements, but did not interfere with swine performance. Minor changes in hepatic microsomal oxidases and red blood cells accompanied significant increases in renal Cd and decreases in hepatic Fe. Swine foraging on these plots ingested considerable amounts of sludge soil and accumulated significantly higher concentrations of renal Cd. At lower rates of sludge application the swine outperformed those foraging both on control plots and those receiving heavy sludge applications in terms of weight gain, in-utero piglet survival, blood hemoglobin, and tissue Fe concentrations.

The Behavior of Nutrient Elements Added to a Forest Soil with Sewage Sludge

AbstractSludge applications were made at a rate of 247 metric tons/ha dry weight to a cleared gravelly Douglas fir forest soil to test limits of nutrient conservation mechanisms. First year losses due to treatments were 8% of added N, 15% of Ca, 1% of K, and none of P. Predictably, NO3‐N was the dominant mobile anion significantly increasing the calcium nitrate level in the ground water. Differences between sludge treatments, including plowing, reflected the degree of aeration and decomposition of NO3‐N production and P‐fixation. These differences were more pronounced deeper in the soil, except for K which was more controlled by the stage of weathering. A very heavy sludge application rate (618 metric tons/ha) had less impact on soil nutrient behavior due to a high water absorption capability. Alternate ways of reducing NO3‐N leakage from the forest soil are being investigated.

Growth and Metal Uptake of Snap Beans Grown on Sewage Sludge‐Amended Soil: A Four‐Year Field Study

AbstractTo establish the consequence of land application of sewage sludge on the extent of sludge‐borne metal accumulation in the food chain, long‐term trace metal accumulations in edible snap bean (Phaseolus vulgaris L. var. Tendergreen) tissue were measured, over a 4‐year period, for beans grown on a sludge‐amended sandy Udorthentic Haploboroll soil. The objectives of this study were to i) establish the effect of annual sludge applications on trace metal uptake, and ii) study the residual effect of adding a single, large sludge application on metal uptake on subsequent crops. For the first phase of this study, we applied a total of 0, 350, 700, and 1,400 metric tons/ha of anaerobically digested sludge in three equal applications. The second phase of the study consisted of a single sludge application of 0, 112, 225, and 450 metric tons/ha. Crop yields increased as rates of sludge application increased under both cultural systems and often exceeded those of a well‐managed, fertilized control. The Zn and Cu contents of edible tissue increased as rates of sludge application increased, and reached an apparent maximum value from which they did not decrease once sludge applications ceased. Cadmium levels in edible tissue did not respond directly to sludge applications and never exceeded 0.1 µg Cd/g tissue.

The effect of sludges from two Adelaide sewage treatment plants on the growth of and heavy metal concentrations in lettuce

In a glasshouse experiment, lettuce was grown on a market garden soil near Adelaide, South Australia, to investigate how yields and foliar concentrations of Cd, Cu, Ni, Mn, Pb, and Zn are affected by applications of sewage sludges of different origin. One sludge came from a modern treatment plant and the other from an abandoned treatment farm now within the Adelaide suburban area. Heat sterilization of one of the sludges decreased the uptake of Cd, Cu, and Zn, and especially of Ni and Mn. Fertilizing with sludges alone gave poor yields thus indicating the need for supplementary nutrients. High rates of sludge application gave marked increases in some metal concentrations in the lettuce. The ease with which metals in the sludges could be absorbed by lettuce decreased in the following order: Cd > Zn > Ni > Cu >> Pb. The effect of pot size is discussed. Monitoring of produce may be required if sludge is used at high rates in intensive crop production on a similar soil.

The uptake of heavy metals from sewage sludge applied to land by corn and soybeans

Abstract Sludge was applied to a Matapeake silt loam soil at loading rates of 0, 22, 45 and 90 mt/ha where corn and soybeans were planted. Corn seedling, ear leaf, grain and stover, and soybean seedling and grain samples were analyzed for their Al, B, Ba, Cu, Fe, Mn, Na, Sr and Zn. Corn grain and stover and soybean grain samples were analyzed for As, Cd, Cr, Hg and Pb. Normal concentrations of As, Cd, Cr, and Hg were found in the corn grain and stover and soybean grain. The Pb concentration in the corn stover increased with increased sludge application rates. The Al, Ba and Fe concentrations decreased in the corn seedling samples at the 45 and 90 mt/ha loading rates but all trace element concentrations in the corn ear leaf tissue were within the normal range for corn.

Effects of Incubation and Liming on Yield and Heavy Metal Uptake by Rye from Sewage‐Sludged Soil

AbstractRye (Secale cereale L., var. Balboa) was grown under controlled conditions on Evesboro sandy loam amended with digested secondary sewage sludge. Our purpose was to measure plant yield and uptake of Cd, Cu, Pb, and Zn as functions of sludge application rate (0 to 10%, dry weight basis), sludge origin (Baltimore, Md., and Washington, D. C.), pH of soil‐sludge mixture (two levels), incubation time between mixing and planting (0 to 7 weeks), and plant age (three clippings). Plant yields from successive clippings decreased as sludge application rates increased. Uptake of the four metals increased with sludge additions and with plant age, in the order Zn > Cd > Pb ≃ Cu. Metal uptake decreased in the order Zn > Cd > Pb > Cu with addition of lime. Incubation considerably diminished Cu and Pb uptake. All observations point to organic matter complex formation in the order Cu > Pb > Zn > Cd. The relative uptake of HCl‐extractable Cd from soil was greater than that of Zn, especially upon liming, while the total uptake of these metals then decreased.

Hydraulic and Thermal Properties of a Sandy Soil as Influenced by Incorporation of Sewage Sludge

AbstractSoil‐water retention was increased by incorporation of sewage sludge into a sandy soil. Most of this increase resulted from water adsorbed by organic matter (15‐bar water). At any given water content, unsaturated hydraulic conductivity and soil‐water diffusivity decreased as rates of sludge addition increased. However, saturated hydraulic conductivity increased as rates of sludge addition increased.Thermal conductivity decreased with increasing rates of sludge application. However, the heat capacity of all oven‐dried sludge‐soil mixtures was the same as that of the control treatment. The combination of a lower thermal conductivity and a higher specific heat (due to higher water content) buffered sludge‐amended soil against sudden temperature changes. Thus, maximum and minimum daily temperatures on plots receiving sludge were a few degrees lower and higher, respectively, than those on the control treatment.

Elemental Composition of Sludge-fertilized Chrysanthemums1

Abstract Chrysanthemum plants (Chrysanthemum morifolium Ramat. cv. Bright Golden Anne) were grown for 84 days in plastic pots containing media treated with inorganic fertilizers or liquid sewage sludge, added at a rate of 50, 100, or 200 ml/week, to determine if sludge could be used as a fertilizer. Plants grown with sludge at all application rates had higher N and lower K concentrations compared to plants grown with inorganic fertilizers. Leaf concentration of P, Ca, Mg, Fe, Zn, Cu, Cd, Ni, and Pb of plants grown with 50 ml sludge/week were similar to plants receiving inorganic fertilizers. As sludge application rate increased, leaf concentrations of Fe and Cu increased of plants grown in media consisting of all sand or all peat and Zn increased in leaves of plants grown in the standard greenhouse media (1 soil: 1 sand:l peat, by volume). Sludge-treated media had a higher pH and extractable Cu concentration, and a lower extractable K concentration, than media without sludge. Plants receiving 50 ml sludge/week grew as well as plants grown with inorganic fertilizers.

Effects of Sewage Sludge Composition, Application Rate, and Lime Regime on Plant Availability of Heavy Metals

AbstractPrimary digested sludge from the metropolitan Vancouver sewage treatment plant and commercially available Milorganite were applied to unlimed (pH 5.6) and limed (pH 6.4) silt loam at 0, 5, 10, 25, and 100 g/kg in a growth chamber study involving romaine lettuce (Lactuca sativa L. var. longifolia) and beets (Beta vulgaris L.). Concentrations of Cd, Zn, Pb, Cu, Ni, Mn, and Fe in lettuce, beet tops, and beet tubers were not simply or solely dependent upon the resultant sludge‐borne heavy metal contamination of the soil but a complexity of factors. Plant availability of the metals was influenced by the nature as well as the rate of sludge applied, lime regime, their interaction, the increase in soil acidity associated with Milorganite application and metal adsorption, and release from organic matter supplied.

Growth of Chrysanthemums Fertilized with Liquid Sewage Sludge1

Abstract Chrysanthemum plants (Chrysanthemum morifolium Ramat. cv. Bright Golden Anne) were grown for 84 days in plastic pots containing 6 different media treated with inorganic fertilizers or liquid digested sewage sludge at 50, 100, and 200 ml/week. Plants grown in 1 soil: 1 sand: 1 peat, 1 soil: 1 sand, and 1 soil: 1 peat were similar to each other in size, and larger than plants grown in 1 sand:1 peat, all sand, or all peat. Peat-grown plants were smallest. Plant size and flower diameter decreased with increasing rates of sludge application. Plants fertilized with inorganic sources of fertilizer looked the same as those grown with 50 ml/week sludge (6 mm), except the sludge-treated plants were shorter and had a smaller dry weight. Plants treated with 50 ml/week sludge had flowers with a diameter and dry weight equal to those of flowers grown with liquid or pelletized inorganic fertilizer.

NITRATE NITROGEN DISTRIBUTION IN CORN LAND FOLLOWING APPLICATIONS OF DIGESTED SEWAGE SLUDGE

Anaerobically digested sewage sludge was applied to a loam soil at rates of 1.25, 2.5 and 5.0 cm ha−1. Treatments were replicated four times, and all plots were cropped to corn. The soil in the 0- to 90-cm profile under each plot was sampled every month from May to October in 1972 and analyzed for NO3−-N and NH4+. The two highest sludge application rates resulted in significant increases in soil NO3−-N in the 0- to 90-cm soil profile, which persisted until October following crop harvest. Of the N supplied by the sludge, only about 3–12% was recovered by the corn crop. At the conclusion of the experiment, in October, 6–10% of the N supplied by the sludge remained in the soil and on the soil surface in the residual solids. Sludge applications in excess of 1.25 cm ha−1 did not produce significant increases in the yields of grain or stover.