Though some researchers have argued that the Big Barrens grasslands of Kentucky were the product of anthropogenic land clearing practices by Native Americans, heretofore, this hypothesis had not been tested archaeologically. More work was needed to refine chronologies of fire activity in the region, determine the extent to which humans played a role in the process, and integrate these findings with the paleoenvironmental and archaeological record. With these goals in mind, I conducted archaeological and geoarchaeological investigations at Crumps Sink in the Sinkhole Plain of Kentucky. The archaeological record and site formation history of Crumps Sink were compared with environmental and archaeological data from the Interior Low Plateaus and Southern Appalachian Mountains for an understanding of how the site fits into the larger story of human-environmental interactions in the Eastern Woodlands. Based on the data recovered, I argue that through land burning Archaic hunter-gatherers were active managers of ecosystems to a greater degree than previously acknowledged. Excavations at Crumps Sink revealed stratified archaeological deposits spanning the late Middle Archaic to Terminal Late Archaic periods. Radiocarbon dates and an analysis of projectile point typologies provided information on the chronological and cultural history of the site. Magnetic susceptibility, loss-on-ignition, plant available phosphorous, and soil micromorphological analyses were conducted to examine landform dynamics in response to environmental change and to trace the anthropogenic signature created by human activities at the site. Masses of lithic debitage, animal bone, and burned sediment nodules per ten-cm-level provide an indication of human occupation intensity and shifting activities over time. Radiocarbon dates were used to reconstruct rates of sediment accumulation in the sink. These varying datasets were considered together for a holistic understanding of localized environmental and anthropogenic impacts on the landform. Between 7200 and 5600 cal. BP, during the Middle Holocene Thermal Maximum and corresponding with the late Middle Archaic period, sediment accumulation was sustained with one identifiable episode of very weak soil development. Background magnetic and chemical signatures in the soils were greater than they were at pre-occupation levels, demonstrating that human activities left a lasting imprint in soils as early as the late Middle Archaic period. Between 5600 and 3900 cal. BP, periods of diminished sedimentation led to more pronounced episodes of soil formation. However, these soil horizons are interposed by pulses of enhanced sediment accumulation. These soil data may signal shifting environmental regimes during the Middle to Late Holocene transition. Between 5600 and 3900 cal. BP scattered plant ash, elevated masses of burned sediment nodules, and pestle fragments in Late Archaic deposits suggest that hunter-gatherers were intensively processing nut mast, potentially in association with early forest clearance and silviculture. Botanical assemblages from a coincident archaeological sequence at the Carlston Annis site in the nearby middle Green River region has demonstrated woodland disturbance and potential silviculture in central Kentucky during this time. During the Late Archaic and Terminal Late Archaic periods (3900-3000 cal. BP), substantial plant ash deposition occurred in a stratum that accumulated relatively quickly. Very low burned sediment nodule masses in this deposit indicate that combustion features were not common in the immediate vicinity and that elevated frequencies of plant ash were the result of burning on a broader expanse of the surrounding landform. Chronologically, the zone with enhanced plant ash deposition is coeval with previously demonstrated occurrences of increased forest fires, grassland expansion, and a shift to early horticultural economies throughout the region. Soil development occurred after 3000 cal. BP, and this episode of landform stability may have lasted for over two millennia until being capped by sediment accumulation from historic agriculture. The late Middle Archaic through Terminal Late Archaic data from Crumps Sink demonstrate that hunter-gatherer activities left lasting signatures in soils in Kentucky. The data from the Late Archaic to Terminal Late Archaic periods (ca. 5600-3000 cal. BP) may indicate intentional land burning by hunter-gatherers to create anthropogenic environments, first for silviculture and then for early plant domestication. This forces a rethinking of labor and subsistence systems within hunter-gatherer societies. Thus, if hunter-gatherers were utilizing long-term forest management methods, they were employing a delayed-return economic system relying on labor investment and negotiated understandings about land tenure. Further characterization of the origin of fire management activities will help us to elucidate the nature of incipient indigenous plant domestication in the Eastern Woodlands.

Physical and chemical properties of non-composted spent coffee (CF) and tea (T) suggest they may have applications as soil amendments for improving poor soils. Studies were conducted to determine 1) the effect of amendments on grass growth and soil properties, 2) the effect of incorporation versus surface application of amendments on soil properties, and 3) the effect of amendment application frequency on grass growth and soil properties. In the first study, amendments were mixed with sand and planted to bermudagrass. Treatments included CF, T, and peat moss (PM) mixed with sand, and 100% sand as a control. In the second study, amendments were topdressed onto a sand base with different timings. Pots were either aerified or not. Treatments included T, CF, PM, and a control. Nutrient contents and soil CEC and OM under CF and T treatments were equivalent to or greater than PM treatments. Tea showed comparable grass cover to the PM treatment, while CF showed an inhibitory effect to grass growth in the first year of the study. Aerification showed no benefit. Additionally, a field study was conducted to evaluate CF and T on surface hardness, VWC, and quality after trafficking. Differences were not observed among treatments.

The relationship between biodiversity and ecosystem functioning is important in maintaining agroecosystem sustainability. Plant-microbe symbioses, such as exists between the grass tall fescue (Schedonorus arundinaceum) and the asexual fungal endophyte Epichloë coenophiala, can be utilized to enhance agroecosystem functions, such as herbivore resistance. “Novel” E. coenophiala strains that vary in the production of mammal- and insect-toxic compounds have been identified, inserted into tall fescue cultivars, and are planted in pastures globally. Novel fungal endophyte-tall fescue associations may have divergent ecosystem function effects. This study assessed effects of different fescue-endophyte symbiotic combinations on pasture ecosystem function, including aboveground (fescue biomass, plant species richness, alkaloid synthesis, arthropod abundance) and belowground (soil microbial biomass, soil enzyme activity, trace gas fluxes) parameters. Results showed no significant effects of increasing symbiotic diversity within a fescue stand on aboveground measurements, bar arthropod abundance and alkaloid synthesis. Most soil parameters quantified had significant symbiotic diversity effects. For example, soil microbial biomass decreased whereas soil enzyme activity increased with increasing symbiotic diversity. Overall, our results suggested that increasing symbiotic diversity had weak to moderate effects on aboveground processes and stronger effects on certain belowground processes, indicating that symbiotic diversity can impact ecosystem functions and warrants further research.

This paper explores two potential land use planning strategies that can be used to preserve and enhance the economic viability of agricultural operations surrounded by suburban development in Santa Barbara County’s Eastern Goleta Valley: buffers between agriculture and other land uses, and agritourism. In the case of buffers, academic literature is examined to determine how effective buffers are at various tasks (filtering runoff, mitigating dust and wind, providing habitat, etc.) and how to construct buffers to maximize their effectiveness. Land use plans and codes from several California jurisdictions are studied to see how buffers are put to use. Academic literature is then reviewed to discover the benefits and potential drawbacks of agritourism to agricultural operations and the larger area. The zoning codes from the top five agritourism counties in California are evaluated to see how effective they are at facilitating five common agritourism uses; these best practices are then compared to the current zoning in Santa Barbara County. This paper concludes by summarizing the applicability of the literature and case studies to Eastern Goleta Valley, and proposes a new zoning designation and other policies to help maintain the urban agriculture operations. This new zoning designation includes a 30-foot minimum width for buffers and a three-tier categorization of land uses capable of promoting agritourism.

Environmental perturbations are ubiquitous features of ecosystems and shape ecological structure and function. Climate change will alter the intensity and frequency of disturbances and expose ecosystems to novel combinations of useful inputs (subsidies) and harmful inputs (stressors). Coastal wetlands are particularly vulnerable to changing environmental conditions and are increasingly exposed to effects of interacting subsidies and stressors. In particular, the Florida Coastal Everglades, which has experienced accelerated change due to a history of water management practices, is vulnerable to new disturbances associated with climate change. The low-lying Florida Everglades faces multiple disturbances from storm surge, nutrient enrichment, and sea-level rise which will influence its responses to future environmental perturbations. Microbial communities are often used to characterize environmental change because of their high surface area to volume ratio, permeable membrane, and quick turnover rates. Therefore, assessing how microbial function changes can provide insights into how subsidies and stressors interact to alter biogeochemical cycles. I tested how nutrient enrichment can alter ecosystem responses to stress and found that it did not promote recovery in mangrove plants. I examined how long-term exposure to salinity and phosphorus (the limiting nutrient in the Everglades) affected microbial enzyme activity and found that salinity alone acts as a suppressor of enzyme activity but phosphorus addition can mitigate salinity stress in sawgrass soil. I tested how pulses of salinity can affect the microbially-mediated breakdown of organic material and found that the microbial community was functionally redundant and unaffected by saltwater pulses; however, microbial activity was consistently lower in the brackish marsh compared to the freshwater marsh. I investigated how gradients of salinity and phosphorus affected freshwater and brackish soils and determined previous exposure to saltwater intrusion dominates affects microbial function and soil composition. Across these experiments, I found that environmental perturbations alter the microbial-mediated processing of nutrients and carbon, and legacies of previous disturbances influence the microbial response to new disturbance regimes.

Although silicon (Si) has not yet been recognized as an essential nutrient element, its application to sugarcane (Saccharum officinarum L.) has proved to be beneficial. Since optimum crop production depends on the maintenance of adequate plant nutrients in the soil, there is a need in the South African sugar industry for a reliable index for assessing the requirement for supplemental silicon (Si) in soils, particularly in reducing the risk of Eldana saccharina stalk borer infestation in cane. The objective of this study was to assess Si availability in soils, to select a suitable Si extraction method and a critical value for determining when a response is likely. For this purpose, five acid soils (representing. some of the most important agricultural soil groups used for sugarcane production in the sugar belt) were used in October 2004, in the lAKE WILSON glasshouse of the South African Sugarcane Research Institute (SASRI) based at Mount Edgecombe. Except for the Arcadia form soil with an initial Si content of 1.2 mmol kg- I as estimated using the O.OlM H2S04 + (NH4)zS04) extractant, soils representing the other five soil forms namely Cartref, Glenrosa, Longlands and Nomanci; exhibited a sub-optimal Si content of not more than 4.0 mmol kg-I. Sorghum was used as a plant crop and sugarcane as a ratoon crop because of their Si accumulator status. Three different Si sources: calmasil, slagment and wollastonite; with respectively 9.85, 15.20, and 5.25% Si content were applied at increasing rates of 0, 3 and 6 tons ha- 1 as Si fertilizers. Silicon (Si) was extracted from untreated and treated soils by utilizing six different extractants, (1) O.OlM H2S04 + (NH4)2S04; (2) Distilled water; (3) 0.025M H2S04; (4) 0.5M CH3COOH; (5) 0.5M CH3COONH4pH 4.8; and (6) O.OlM CaCh.2H20. The amount of soil Si extracted followed the order: 0.025M H2S04 > 0.5M CH3COOH > O.OlM H2S04 + (NH4)2S04 > O.OlM CaCh.2H20 > 0.5M CH3COON~ pH 4.8 > distilled water. Soil Si extracted by 0.025M H2S04 was significantly correlated with soil exchangeable cations,. CEC, clay content, cane biomass yield, cane Si uptake and increasing rates of applied Si. Averaged over all soil forms investigated, the increases in dry biomass yield and Si uptake ranged. from 18% to 154% for sorghum; and from 23% to 85% for cane respectively. Even though the highest increases (%) in cane biomass yield and Si uptake were obtained on a Nomanci form soil with initial poor fertility status, the highest means were obtained on an Arcadia form soil with the highest Si initial content. There was no difference between different Si sources in their ability to influence cane biomass yield and Si uptake, and therefore the supply to the soils. Even though the lower and higher Si source rates were not different from each other, they increased cane yield and Si uptake, indicating that Si was undoubtedly beneficial for sugarcane. The Si critical levels for different soils as estimated by 0.025M H2S04 were 6.0 mmol kg-1 (168 mg kg-I) for Arcadia; 2.6 mmol kg-I (64 mg kg-I) for Cartrel; 2.5 mmol kg-I (64 mg kg-I) for Glenrosa; 1.6 mmol kg-I (45 mg kg-I) for Longlands; and 2.4 mmol kg-I (67 mg kg-i) for Nomanci form soils. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2007.

Little is known regarding the effects of land use on soil organic matter and P status of South African soils. For that reason, the effects of the main agricultural land uses in the midlands region of KwaZulu-Natal [maize (Zea mays), sugarcane (Saccharum spp), annual ryegrass pasture (Lolium multiflorum), permanent kikuyu pasture (Pennisetum clandestnum), gum (Eucalyptus grandis) and pine (Pinus patula)] on soil organic matter content, microbial biomass C and P and inorganic and organic P pools derived from a modified Hedley P fractionation was investigated on two sites where the longterm history of land management was known. In comparison with undisturbed native grassland, permanent kikuyu pasture resulted in an increase in organic C, organic P and microbial biomass C and P. Maize and sugarcane production resulted in a decrease in organic C, organic P and microbial C and P. Under annual pasture, gum and pine forests, organic matter and microbial biomass concentrations remained similar to those under native grassland. Under native grassland, extractable organic P accounted for 50% or more of the total P content of soils but under agricultural management with regular applications of fertilizer P, there was an increase in the percentage of total P present as inorganic P. Agricultural management greatly affected the distribution of P among the various inorganic and organic P fractions. Resin-Pi and NaHC03-Pi (the potentially-available forms of Pi) showed similar trends with land use being greatly elevated under kikuyu pasture at both sites and sugarcane and maize at one site. This accumulated Pi was thought to have originated from recent fertilizer applications and possibly recently mineralized organic P. Trends for NaOH-Pi with land use differed greatly from those of the Resin- and NaHC03Pi fractions. Concentrations were notably high under maize and sugarcane production. Of the pools of soil organic P, the NaHC03-Po fraction was most greatly affected by land use, being elevated under kikuyu and decreased under maize and sugarcane. This supports the assertion that it is the NaHC03-Po fraction that is the most labile soil organic P pool. It was concluded that land use greatly affects soil organic C and P status, soil microbial biomass C and P contents, soil inorganic P concentrations and the distribution of P among the various P fractions. A short-term (8 weeks) laboratory incubation experiment was carried out to compare the effects of inorganic (KH2P04) and organic (cattle manure, poultry manure and maize crop residues) sources of P, applied at a rate equivalent to 30 kg P ha-1 , on soil inorganic and organic P fractions and the potential availability of soil P. Additional treatments consisted of lime [Ca(OHhl at 5 ton ha-1 and lime plus inorganic P. Applications of lime raised soil pH to a similar extent after 1, 4 and 8 weeks incubation. After 8 weeks, a small increase in soil pH was also noted for the cattle and poultry manure and maize residue treatments. For the inorganic P fractions, substantial treatment effects were observed only for the Resin-Pi fraction. The inorganic P source was more effective than the organic ones at increasing Resin-Pi after 1 and 4 weeks incubation and of the organic sources, cattle and poultry manure were more effective than maize residues. Resin-Pi concentrations generally increased between 1 and 4 weeks incubation but then declined rapidly between 4 and 8 weeks incubation. After 8 weeks incubation, treatment effects on Resin-Pi were small. Concentrations of NaHC03-Pi, dilute HCI-Pi and concentrated HCI-Pi all declined over the incubation period. There was no clear trend with incubation for NaOH-Pi although for the poultry manure and maize treatments, concentrations declined between 4 and 8 weeks incubation. In general, concentrations of NaHC03-Po were greater for organic than inorganic P sources after 8 weeks incubation suggesting microbial immobilization of P in these treatments. There were increases in NaHC03-Po and concentrated HCI-Po over the incubation period suggesting progressive immobilization of P from the Pi fractions that declined in concentration during the incubation. Concentrations of NaOH-Po were not greatly affected by incubation period. The lime treatments, however, had lower NaOH-Po concentrations than the others suggesting that liming may have stimulated microbial mineralization of Po. Residual-P concentrations increased over the incubation period. This was attributed to conversion of extractable Pi fractions into recalcitrant, non-extractable Pi forms and/or immobilization of Pinto intransigent organic forms. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2006.

In the past, the indigenous knowledge of soils of small-scale farmers in South Africa has been largely ignored in scientific research. Hence the use of scientific approaches to land evaluation has often failed to improve land use in rural areas where understanding of the prescriptive scientific logic is lacking. Despite this, it is clear that local people and smallscale farmers have knowledge of their lands based on soil and land characteristics that remain largely unknown to the scientific community. It is therefore important for researchers to understand farmers’ knowledge of soil classification and management. To address this issue, a study was conducted in the uMbumbulu area of KwaZulu-Natal to investigate the use of indigenous knowledge as well as farmers’ perceptions and assessments of soil fertility. A preliminary questionnaire was designed to explore indigenous knowledge in a group interview that was conducted prior to the study. Another questionnaire was used to elicit indigenous knowledge from 59 randomly chosen homesteads representative of the population of Ezigeni and Ogagwini villages. Six homesteads were chosen for further detailed information on the cropping history, knowledge specific to the cultivated lands, detailed soil description and fertility. Soil samples were taken from these homesteads under different land uses (taro, fallow, veld and vegetable) at 0-30 and 30-60 cm depth for laboratory analysis. This was done to determine the effect of land use on soil physical and chemical properties and soil microbial activity. For scientific evaluation a general purpose free soil survey was conducted to produce land capability and suitability maps. Farmers identified ten soil types using soil morphological characteristics, mainly soil colour and texture. These soil properties were also used in the farmers’ land suitability assessment. In addition, slope position, natural vegetation and village location were used to indicate land suitability. The amount of topsoil was also used in land evaluation. However, slope position was considered the most important factor as it affects the pattern of soils and hence their suitability. Soils on the footslope were considered more suitable for crops than those found on the midslope and upslope. The yield difference observed between villages, which were higher in Ogagwini than Ezigeni, was also used as a criterion for evaluation. Farmers attributed these yield differences for various crops to the effect of soil type on productivity. In support, scientific evaluation found that Ezigeni village had a number of soils with a heavy textured, pedocutanic B horizon and hence a relatively shallow effective rooting depth. Moreover, the Ezigeni village land suitability was limited in places by poor drainage and stoniness. These limitations were rarely found for the Ogagwini village soils. Farmers had a total of six comprehensive and well defined soil fertility indicators, namely crop yield, crop appearance, natural vegetation, soil texture, soil colour and presence of mesofauna. Results showed that farmers’ fertility perceptions are more holistic than those of researchers. However, despite this, their assessment correlated with soil analysis. There was a close relationship between scientific and indigenous suitability evaluation for three commonly cultivated crops (taro, maize and dry beans). This was further substantiated by yield measurements which were significantly higher for Ogagwini as rated by both farmers and scientific evaluation as the more suitable. The significant agreements between the scientific and indigenous approaches imply that there are fundamental similarities between them. Recognizing this and subsequently integrating the two approaches will produce land use plans relevant and profitable for both small-scale farmers and scientists. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.

Long-term environmental quality is closely linked to maintaining soil quality. Therefore, assessment of the effect of land use on soil chemical, physical and biological properties provides fundamental information about soil sustainability. The role of vegetation on soil structural and aggregate stability has received much attention over the last few decades. The loss of soil due to erosion and reduction in organic matter due to change in vegetation is usually caused by invasion of grassland by trees. The response of soils to land use depends on the inherent soil properties and environmental conditions thus the effect of land use on soil stability is site specific. The objectives of this study were to assess and compare soil aggregate stability under trees and in open grassland from open-savannah woodland and nearby deeply eroded dongas (gullies). Within the dongas, tree encroachment was expected to improve soil structural stability by increasing the organic matter content. Results that were obtained from this study are aimed at improving management of soil for smallholder and pastoral farming systems. The study site was located at Potshini, KwaZulu-Natal Province, South Africa, about 18 km south-east of Bergville. The vegetation of the area is classified as grassland biome. Acacia sieberiana var. Woodii has encroached into the valley especially onto the eroded areas. Within the study area itself the dominant parent materials are sandstone and dolerite, with colluvium covering the lower slopes. The dominant soil was classified as Hutton form. Effects of different vegetation types (grass and trees) on the soil structural stability was evaluated for their effects on soil organic carbon (SOC), mean weight diameter, bulk density, root density, clay mineralogy and some other chemical properties. For this study the site was divided into two areas i.e., the donga (D) and the grassland (G). These were then each subdivided into two parts namely, donga under a tree (DUT) with a corresponding open area (DOA), and grassland under a tree (GUT) with its corresponding open area (GOA). Three bulk samples were collected from each sampling area from 0 to 20 cm (topsoil only) using a spade. Samples for bulk density were collected from 0 - 10 cm. For soil aggregate stability determinations, samples were dried and sieved to collect soil aggregates between 2.8 and 5 mm. Some of the bulk sample was analysed for SOC, pH, exchangeable bases, nitrogen and clay mineralogy. For root biomass, soil samples were collected from 0 - 10 cm using a stainless steel cylinder of 1766 cm3 volume. The type of vegetation affected the soil physical and chemical properties of the soil in the investigated horizon (A horizon). Although the results were not significantly (p > 0.05) different, the open area showed a positive effect on soil structural stability where higher soil aggregate stability and root density were observed, as opposed to under trees in both donga and grassland. Due to the non-significant differences observed in both donga and grassland, the effect of trees and grass on the aggregate stability was considered as the positive effect. The bulk density showed an unusual trend. Bulk density was higher in the open areas where high aggregate stability was observed. From these results it was concluded that because trees have larger roots than grass these are more effective in loosening the soil particles but less effective in stabilizing the soil aggregates. In other words, the high amount of fine roots increased the soil stability while large roots improved the loosening of the soil particles. The amount of vegetation considerably affected all the physical and chemical soil properties investigated. The SOC and root density was considerably higher under grassland compared to the donga. The clay mineralogy differed between the donga and grassland. The donga soils had a higher kaolinite content and amount of interstratified smectite/mica compared to grassland. The presence of interstratified smectite/mica in the donga could cause lower aggregate stability due to shrinking-swelling cycles during wetting-drying conditions. The effects of mineralogy have been overridden by organic carbon in the grassland. From this study it was revealed that soil aggregate stability is the product of interactions between soil clay minerals, and organic fractions which are influenced by soil environment, land use and soil properties. This means that all the factors involved in aggregate formation and their stabilization are interdependent. It is suggested that factors that were driving the soil aggregate stability in the donga were different to the ones in grassland. It is suggested that the aggregate stability was driven by inorganic factors i.e., clay, clay mineralogy, bases and CEC in the donga while organic carbon and plants roots were dominating in the grassland / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.

An essential step in producing "drinking" water is to precipitate the suspended and dissolved colloids through the addition of flocculents such as lime, ferric chloride, aluminium sulphate and/or poly-electrolytes. The by-product of this process is termed water treatment sludge (WTS) and contains mainly silt, clay and some organic matter. Previously this material was disposed of in landfill but more recently, alternative methods for its disposal are being evaluated. A potential disposal option is land treatment. In this system of waste disposal the inherent properties of the soil are used to assimilate the waste. Although the effect of the land disposal of WTS on soil chemical quality is gaining increasing research attention, few studies have investigated the effects on soil physical quality. This study was originally commissioned by a local water utility to evaluate the effects of the land disposal of sludge produced at their works, on soil quality. At this plant organic polymers are used to both flocculate the material and to thicken the sludge in the water recovery process. Fresh sludge has a consistence approaching that of slurry but dries to angular shaped aggregates of extremely high strength. Nevertheless, sludge aggregates comprise a network of micro-pores and channels and are therefore porous. Because of these properties, the potential use of WTS as a soil conditioner was considered.. Since lime, gypsum and polyacrylamide are wellrecognised soil conditioners, these were included as reference treatments in the study. Two field trials (Brookdale and Ukulinga) and laboratory experiments were designed to investigate the influence of WTS on soil in terms of water retention, hydraulic conductivity, evaporation, aeration, aggregation and strength. Seven rates of WTS are represented at the . Brookdale trial but research efforts were concentrated on the 0, 80, 320 and 1280 Mg ha' treatments. WTS was also applied as a mulch (without incorporation into the soil) at the 320, 640 and 1280 Mg ha" level. Gypsum was applied at rates of 5 and 10 Mg ha", lime at 2 and 10 Mg ha' and anionic polyacrylamide at 15 and 30 kg ha'. At the Ukulinga trial, WTS was mixed with the upper 0.2 m of the soil at rates of 0, 80, 320 and 1280 Mgha'. Only the high rates of gypsum, lime and anionic polyacrylamide being tested at the Brookdale trial are represented at the Ukulinga trial. All treatments in this study were maintained fallow. The laboratory study features an additional two soils to those from the field experiments, chosen to produce a range in clay contents. WTS influenced several soil physical properties. Soil bulk density decreased following the addition of sludge to soil. This caused an increase in porosity (particularly macro-porosity) and therefore water retained at saturation, but only of statistical significance at the 1280 Mg ha" level. Equally an increase in water retention at the wilting point (-1500 kPa matric potential) also occurred, owing to the high microporosity of sludge aggregates. Despite these effects very little change in both the plant available and readily available water content occurred. Neither, gypsum nor lime caused any significant change in water retention. Aslight improvement was noted on the polyacrylamide treatment at the Brookdale site but this effect did not persist for very long after the trial was established. Although in situ field measurements were influenced strongly by natural spatial variability, WTScaused a marked increase in the saturated hydraulic conductivity (Ks). The reasons for this relate to the higher porosity and the inherently stable nature of the sludge aggregates, which imparts a more open structure to the soil and reduces the extent of pore blockage. This finding was corroborated in a laboratory study in which strong positive correlations between sludge content and Ks was found. The water retention curve and saturated hydraulic conductivity was used to predict the unsaturated hydraulic conductivity function (Kw)using the RETe computer model of van Genuchten et al., 1991. The results showed a decrease in Kw on the sludgeamended treatments the extent of which increased with sludge content. This finding was tested in an evaporation study conducted under controlled environmental conditions. More water was conserved on the sludge-amended treatments than the control, because of its lower Kw. The application of the sludge as a mulch was more effective in conserving water than incorporating the sludge with soil. The air-filled porosity at field capacity (-10 kPa matric potential) of the sludge-amended soil remained within a favourable aeration range of 10-15%, which suggests that aeration should not be a limiting factor for plant growth. Air-permeability nevertheless improved substantially. Attempts at using the size distribution of dry soil aggregates to evaluate the influence of the sludge on aggregation proved unsuccessful. Saturated soil paste extracts for selected soil depths beneath the mulch layers at the Brookdale trial, nevertheless, showed significant increases in Ca2+ and Mt+ concentrations, which is encouraging from a soil stability perspective. Due to the inherently strongly aggregated nature of this soil, no meaningful change in aggregate stability, however, was measured. Significant improvements in soil stability were, nevertheless, found when fresh sludge was mixed with soil. If the sludge is not allowed to dry fully beforehand the polymer that it contains remains active and available for bonding of the soil particles together. Upon drying, these polymers become irreversibly attached to the soil substrate and win not become reactivated even upon re-wetting of the soil. This also explains why sludge aggregates found below only a few centimetres of the soil surface maintained their strongly aggregated nature. This suggests that although WTS consists of mainly silt and clay, the risk of this constituent fraction becoming released and clogging water conductive soil pores are, at present, low. Despite the high strength of the sludge aggregates the penetrometer soil . strength (PSS)within the tilled layer was non-significantly different from the control treatment. Below the tilled layer, however, the PSS on the sludge-amended treatments were lower owing mainly to wetter soil conditions. The research completed to date suggests that land treatment as an environmentally acceptable disposal option for water treatment sludge shows promise since soil conditions tend to be improved. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 2001