Laboratory studies and field trials were carried out to investigate the effect of addition of some organic residues to acid soils on soil pH, exchangeable and soluble AI, nutrient status, microbiological and biochemical indices and maize response. The organic wastes used in the first laboratory study included plant materials (maize. sorghum, kikuyu grass, soybean, red clover residues and acacia prunings), animal manures (kraal, pasture-fed and feedlot cattle manure, layer and broiler poultry manure and pig manure), household compost, sewage sludge, and filter cake. The poultry manure, pig manure and leguminous plant residues had the highest content of basic cations while sewage sludge had the highest N content. Poultry manure had very high values for proton consumption capacity, CaC03 content and ash alkalinity. Proton consumption capacity, ash alkalinity, total basic cation content and CaC03 content were closely correlated with one· another. Soil pH was increased and exchangeable AI and total (AIT) and monomeric (AIMono) AI in solution were decreased by addition of all the organic wastes: the effect was greater at the higher rate of application. Strong correlations were recorded between the rise in soil pH and proton consumption capacity, ash alkalinity, CaC03content and basic cation content of the residues. The major mechanisms responsible for the elevations in pH were suggested to be the substantial CaC03content of poultry and pig manures, and filter cake, the proton consumption capacity of humic material present in household compost and manures and decarboxylation of organic acid anions during the decomposition of plant residues and manures. It was proposed that ash alkalinity is a suitable laboratory test for predicting the potential Iiming effect of organic residues since it is strongly correlated with the rise in pH that occurs, it is relatively simple to measure and the values reflect the initial content of organic acid anions, humic materials and CaC03in the residues. A preliminary field experiment was set up to investigate the effectiveness of kraal manure as a Iiming material in an acid soil (pHwater =4.1) at a site close to a Zulu village. The experiment consisted of two rates of lime (L1 = 2.5 and L2 = 5.0 t ha1) and two rates of kraal manure (K1 = 10 and K2 = 20 t ha-1 ) which were banded and incorporated in a 30 cm wide strip down the plant rows. Treatments were arranged in a randomized block design with three replicates. A commercial maize cultivar PAN 6710 and a traditional variety EMBO, used by the farmers in the locality, were grown. Soils in the plant row were sampled at tasselling and at harvest. The addition of kraal manure significantly raised soil pH and reduced concentrations of exchangeable AI and those of both total and monomeric AI in soil solution. Lime raised pH and the pH continued to increase between tasselling and harvest. Maize yields for control, kraal manure (K1 and K2) and lime (L1 and L2) for PAN 6710 were 2.5, 3.7, 5.1, 5.3 and 6.3 t ha-1 ; respectively and for EMBO they were 3.0, 5.4, 5.8, 5.9and 8.2 t ha-1 , respectively. These results demonstrate the high yield potential of the traditional maize variety under small scale farming conditions, and show that large yield increases can be obtained by applying kraal manure. The long-term effects (24 weeks) of incubation of organic wastes (soybean residues, poultry, pig and kraal manures and sewage sludge) with an acid soil were investigated in a laboratory study. After incubation for six weeks incubation, soil pH was raised and exchangeable AI and Air and AIMono in soil solution were decreased . by addition of the wastes. Soil pH generally declined and exchangeable and soluble AI increased over the remainder of the incubation period. The decline in pH was attributed mainly to nitrification of NH4+ originating from mineralization of wastes-derived organic N. Addition of organic materials generally resulted in a decrease in the proportion of solution Air present as AIMono. That is, the effects of addition of organic materials was two-fold; an increase in pH in the short term and complexation of AI by organic matter. Since these effects occur simultaneously, it would be desirable to separate them. For this reason, short-term equilibration experiments (3 days) were conducted to study the solubility of AI in aqueous solution or in an Oxisol when in equilibrium , with 3 manures (kraal, pig and poultry) at pH values of 4.0, 4.5, 5.0, 5.5, 6.0 and 6.5. Addition of manures tended to reduce the concentrations of total AI in solution (AIT) in the lower pH range (Le. pH 4.0 and 4.5) but increased AIT concentrations compared to the control, at higher pH values (Le. at pH 5.5 and above). This was explained in terms of the complexing ability of both the solid and solution phases. At lower pH, where AI is highly soluble, complexation by added solid phase manure-organic matter results in a reduction of AI solubility. However, at high pH, where AI solubility is limited, the most important mechanism is complexation of AI by soluble organic matter and this increased AI solubility. Additions of manure reduced the proportion of Air present in monomeric form (AIMono). This effect was more pronounced in aqueous solution but was also clearly evident above pH 5.0 in the Oxisol. This reflects the fact that a large concentration of soluble C in solution can maintain relatively high concentrations of complexed AI in solution but at the same time maintain low concentrations of AIMono. It was concluded that formation of AI-organic matter complexes caused by additions of organic manures can alter the solubility of AI and reduce the amount of phytotoxic AIMono present in soil solution. A second field trial was conducted to compare the effects of additions of kraal manure, grass residues, lime and fertilizer (N-P-K) under field conditions, on soil pH, AI solubility and maize response and, at the same time follow concomitant changes in the size and activity of the soil microbial biomass and enzyme activity. The greatest effects of kraal manure in increasing soil pH and decreasing AI toxicity were recorded six weeks after planting whereas those of lime and grass residues were recorded at harvest. Kraal manure and fertilizer increased significantly AMBIC extractable P and exchangeable K and Zn. In addition, Kraal manure, and to a lesser extent lime significantly increased exchangeable Ca and Mg.. Soils in the plant row in the grass residue treatments had the highest microbial biomass C and microbial quotient,followed by kraal manure, lime and controls. Basal respiration rates and arginine ammonification, protease, aryl sulphatase, and acid phosphatase activity rates were significantly increased by addition of all treatments and these increases tended to be accentuated by fertilizer. Low values for metabolic quotient in the grass residue treatments were associated with high values for microbial biomass C in these treatments. The addition of all treatments tended to increase maize yields and, in general, these yields were greater for the high rate of application of each amendment. Yields for unfertilized kraal manure were markedly greater than those for the unfertilized grass residue and lime treatments. This was attributed to the ability of kraal manure to both increase pH and add nutrients to the soil. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2004.

Most natural products and xenobiotic molecules, irrespective of their molecular or structural complexity, are degradable by some microbial species/associations within particular environments. Atrazine- and selected petroleum hydrocarbon (benzene, toluen~ and 0-, m- and p-xylene (BTX))-degrading associations were enriched and isolated"trom atrazine- and petroleum hydrocarbon (PHC)-contaminated KwaZuluNatal loamy and sandy soils, respectively. In total, eight pesticide- and forty BTXcatabolizing associations were isolated. Electron microscopy revealed that, numerically, rods constituted the majority of the populations responsible for both atrazine and PHC catabolism. Cocci and, possibly, spores or fungal reproductive bodies were observed also. For the BTX-catabolizing associations, the population profiles appeared to be dependent on the enrichment pH and the molecule concentration. After combining selected associations, to ensure that all the isolated species were present, batch cultures were made to determine the optimum pH and temperature for growth; With an atrazine concentration of 30 mgr1, the highest specific growth rates, as determined by biomass (OD) changes, were recorded at 30DC and pH 4 although the rate§ at 25DC and pH 5 were comparable. For the BTX (50 mgr1)-catabolizing associations, the highest growth rates were recorded at pH 4 for the four temperatures (15, 20, 25 and 30DC) examined. The sole exception was p-xylene with the highest specific growth rate recorded at pH 5 and 30De. Batch and continuous (retentostat) cultivations in the presence/absence of methanol and under C- and N-limited conditions were used to investigate the impacts of the solvent and the catabolic potentials of a combined atrazine-catabolizing culture (KRA30). In general, different degradation rates were recorded for the culture in response to element limitation. Addition of citrate as the primary carbon source / effected atrazine (100 mg!"l) degradation rates comparable to that of Pseudomonas sp. strain ADP while succinate addition effected herbicide co-metabolism. Carbon supplementation may, therefore, be considered for site amelioration practices. To complement conventional culture-based microbiological procedures, molecular techniques were employed to explore the diversities and analyze the structures of the microbial communities. In parallel, anaerobic microbial associations which targeted atrazine were also characterized. The soil DNA isolation/characterization protocol adopted consisted of a clean-up step followed by the polymerase chain reaction (peR) and 16S rDNA fingerprinting by denaturing-gradient gel electrophoresis (DGGE). The preliminary results suggested that despite different, but chemically similar, petroleum hydrocarbon molecules, the common selection pressures of the primary enrichments effected the isolation of similar and complex aerobic microbial associations. Some similar numerically-dominant bands characterized the aerobic and anaerobic atrazine-catabolizing associations although distinct differences were also recorded on the basis of the enrichment/isolation pH value and the concentration of the herbicide. Cloning and sequencing were then used to identify some of the numerically-dominant and non-dominant association members. Community-level physiological profiling (CLPP) for physiological fingerprinting was made with Biolog EcoPlates and highlighted the differences in the isolated aerobic atrazine-catabolizing associations depending on the enrichment pH and molecule concentration. Logarithmic-phase cultures of the combined atrazine- and BTX-catabolizing associations were used to explore the association profiles following pH and temperaiure optImIzation. Although some common numerically-dominant components were maintained, differences in numerical and, possibly, activity dominance were observed in the 16S rDNA profiles in response to changes in pH and temperature. This indicated that environmental parameter optimization and characterization of catabolic association structure must precede bioaugmentation so that control of key variables will facilitate maintenance of the dominant site-specific species. Following KRA30 cultivation in the presence/absence of methanol and under carbon and nitrogen-limited conditions, the population fingerprints showed that the presence of methanol effected shifts in species numerical dominance and, possibly, changes in atrazine catabolic capacity. Also, Coulter counter results, optical density readings and 16S rDNA characterization by DGGE indicated that degradation rate changes were accompanied by shifts in species numerical/activity dominance within the association. Although N-limitation effected the highest rates of herbicide catabolism, a potential versatility of the combined association for bioaugmented and/or biosupplemented remediation with acceptable rates regardless of any elemental limitation was recorded. To determine if the contaminated and pristine source soils contained comparable catabolic populations and, thus, offered potential for intrinsic bioremediation, PCRDGGE was used to characterize the populations in comparison with the enriched/isolated associations. Some similar dominant bands characterized the contaminated soils and the enriched/isolated associations. The significance of this, in relation to a possible correlation between numerical and activity dominance in the component species, is discussed with respect to the use of PCR-DGGE to identify natural attenuation potential and monitor sustained intrinsic and enhanced (bioaugmented and biosupplemented) bioremediation. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 2001.

In many acid, highly leached South African soils, Na levels are very low. Applications of Na to highly leached soils may be advantageous in some situations as Na has been shown to interact with soil acidity, P availability, and K nutrition of plants. It was found that an increased level of Na at constant anion concentration in the soil solution resulted in lower soil solution pH and Al3 + activity, and improved maize root penetration into an acid subsoil (pot trial). In another pot trial, Na did not improve lucerne root growth into the same subsoil. In a field trial on a limed, low-Na soil with severe subsoil acidity, the effects off our rates of Na, three Na carriers, and three rates of gypsum on maize growth were compared. In three out of four seasons grain yield responses to the Na applications were positive, and of a similar magnitude to the response to gypsum (455-925 kg ha). In another field trial with maize, responses to Na (of up to 1027 kg grain ha) were recorded in two out of three years on plots with topsoil acid saturations of greater than 45%. The reason for the responses to Na was probably improved subsoil rooting as a result of modified soil solution composition in the presence of Na. In a field trial with Italian rye grass on an acid, highly weathered soil, the effect of sodium applications were investigated at different levels of lime and K. In the first season, 200 kg ha Na as NaCl increased dry matter yield from 11289 kg ha to 12815 kg ha , Sodium responses were possibly due to enhanced P uptake, or Na substitution for K, or a combination of the two mechanisms. No consistent lime x Na interaction was observed. Potassium and Na applications affected the mineral balance of the herbage produced. Potassium depressed herbage Ca, Mg and Na concentrations, and Na depressed herbage Ca and Mg where herbage K was low, but had no effect on herbage K. Where soil P and K reserves are marginal, rye grass pastures may benefit from Na applications. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 2000.

The environmental impact of anthropogenic disturbances such as agriculture, on the soil ecosystem, and particularly on soil microbial structural and functional diversity, is of great importance to soil health, conservation and remediation. Therefore, this study assessed the effects of various land use and management practices on both the structural (genetic) and functional (catabolic) diversity of the soil bacterial and fungal communities, at two long-term sites in KwaZulu-Natal. The first site is situated at Baynesfield Estate, and the second at Mount Edgecombe Sugarcane Research Institute. At site 1, the land uses investigated included soils under pre-harvest burnt sugarcane (Saccharum officinarum, Linn.) (SC); maize (Zea mays, Linn.) under conventional tillage (M); permanent kikuyu (Pennisetum clandestinum, Chiov) pasture (KIK); pine (Pinus patula, Schiede) plantation (PF); and wattle (Acacia mearnsii, De Wild) plantation (W), all fertilized; and undisturbed native grassland (NAT) that had never been cultivated or fertilized. At site 2, a sugarcane (Saccharum officinarum × S. spontaneum var. N27) pre-harvest burning and crop residue retention trial was investigated. The treatments studied included conventional pre-harvest burning of sugarcane with the tops removed (Bto), and green cane harvesting with retention of crop residues on the soil surface as a trash blanket (T). Each of these treatments was either fertilized (F) or unfertilized (Fo). The polymerase chain reaction (PCR), followed by denaturing gradient gel electrophoresis (DGGE) were used to determine the structural diversity, and community level physiological profiling (CLPP) using BIOLOG plates, the catabolic diversity. In addition, the soils were analysed with respect to selected physicochemical variables, and the effects of these on the soil microbial communities were determined. Replicate soil samples (0–5 cm) were randomly collected from three independent locations within each land use and management, at both sites. Soil suspensions for the CLPP analyses were prepared from fresh soil subsamples (within 24 h of collection) for the bacterial community analyses, and from 8-day-old soil subsamples (incubated at 4°C to allow for spore germination) for the fungal community analyses. BIOLOG EcoPlates™ were used for the bacterial CLPP study and SF-N2 MicroPlates™ for the fungal analysis, the protocols being adapted and optimized for local conditions. This data was log [X+1]-transformed and analysed by principal component analysis (PCA) and redundancy analysis (RDA). For PCRDGGE, total genomic DNA was isolated directly from each soil subsample, and purified using the MO BIO UltraClean™ soil DNA Isolation kit. Protocols were developed and optimized, and fragments of 16S rDNA from soil bacterial communities were PCR-amplified, using the universal bacterial primer pair 341fGC/534r. Different size 18S rDNA sequences were amplified from soil fungal communities, using the universal fungus-specific primer pairs NS1/FR1GC and FF390/FR1GC. Amplicons from both the bacterial and fungal communities were fingerprinted by DGGE, and bands in the fungal DGGE gels were excised and sequenced. The DGGE profiles were analysed by Bio-Rad Quantity One™ Image analysis software, with respect to band number, position, and relative intensity. Statistical analyses of this data then followed. Soil properties [organic C; pH (KCl); exchangeable acidity; total cations (ECEC); exchangeable K, Ca and Mg; and extractable P] were determined by PCA and were shown to have affected the structural and catabolic diversity of the resident microbial communities. At Baynesfield, canonical correspondence analysis (CCA) relating the selected soil variables to bacterial community structural diversity, indicated that ECEC, K, P and acidity were correlated with CCA1, accounting for 33.3% of the variance, whereas Mg and organic C were correlated with CCA2 and accounted for 22.9% of the variance. In the fungal structural diversity study, pH was correlated with CCA1, accounting for 43.8% of the variance, whereas P, ECEC and organic C were correlated with CCA2, and accounted for 30.4% of the variance. The RDA of the catabolic diversity data showed that the same soil variables affecting fungal structural diversity (organic C, P, ECEC and pH) had influenced both the bacterial and fungal catabolic diversity. In both the bacterial and fungal RDAs, organic C, P and ECEC were aligned with RDA1, and pH with RDA2. However in the bacterial analysis, RDA1 accounted for 46.0%, and RDA2 for 27.5% of the variance, whereas in the fungal RDA, RDA1 accounted for only 21.7%, and RDA2 for only 15.0% of the variance. The higher extractable P and exchangeable K concentrations under SC and M, were important in differentiating the structural diversity of these soil bacterial and fungal communities from those under the other land uses. High P concentrations under M were also associated with bacterial catabolic diversity and to a lesser extent with that of the soil fungal communities under M. Similarly, the higher organic C and exchangeable Mg concentrations under KIK and NAT, possibly contributed to the differentiation of these soil bacterial and fungal communities from those under the other land uses, whereas under PF, the high exchangeable acidity and low pH were possibly influencing factors. Under W, low concentrations of P and K were noted. Other factors, such as the presence/absence and frequency of tillage and irrigation, and the diversity of organic inputs due to the diversity of the above-ground plant community, (in NAT, for example) were considered potentially important influences on the nature and diversity of the various land use bacterial and fungal communities. At Mount Edgecombe, CCA showed that organic C and Mg had a significant effect on soil bacterial structural diversity. Organic C was closely correlated with CCA1, accounting for 58.7% of the variance, whereas Mg was associated with CCA2, and accounted for 41.3% of the variance. In the fungal structural diversity study, ECEC and pH were strongly correlated with CCA1 and accounted for 49.1% of the variance, while organic C was associated with CCA2, accounting for 29.6% of the variance. In the functional diversity studies, RDA showed that both bacterial and fungal community catabolic diversity was influenced by soil organic C, pH, and ECEC. In the bacterial analysis, RDA1 was associated with organic C and pH, and accounted for 43.1% of the variance, whereas ECEC was correlated with RDA2, accounting for 36.9% of the variance. In the fungal analysis, RDA1 was correlated with ECEC and accounted for 47.1% of the variance, while RDA2 was associated with pH and organic C, accounting for 35.8% of the variance. The retention of sugarcane harvest residues on the soil surface in the trashed treatments caused an accumulation of organic matter in the surface soil, which did not occur in the pre-harvest burnt sugarcane. This difference in organic C content was a factor in differentiating both bacterial and fungal communities between the trashed and the burnt treatments. Soil acidification under long-term N fertilizer applications caused an increase in exchangeable acidity and a loss of exchangeable Mg and Ca. Thus, as shown by CCA, a considerably lower exchangeable Mg concentration under F compared to Fo plots resulted, which was influential in differentiating the bacterial and fungal communities under these two treatments. In the structural diversity study at Baynesfield, differences were found in bacterial community species richness and diversity but not in evenness, whereas in the fungal analysis, differences in community species richness, evenness and diversity were shown. The soil bacterial and fungal communities associated with each land use were clearly differentiated. Trends for bacterial and fungal diversity followed the same order, namely: M < SC < KIK < NAT < PF < W. At Mount Edgecombe, no significant difference (p > 0.05) in bacterial structural diversity was found with oneway analysis of variance (ANOVA), but two-way ANOVA showed a slight significant difference in bacterial community species richness (p = 0.05), as an effect of fertilizer applications. A significant difference in fungal species richness (p = 0.02) as a result of management effects was detected, with the highest values recorded for the burnt/fertilized plots and the lowest for the burnt/unfertilized treatments. No significant difference was shown in species evenness, or diversity (p > 0.05), in either the bacterial or the fungal communities. In the catabolic diversity study at site 1, the non-parametric Kruskal-Wallis ANOVA showed that land use had not affected bacterial catabolic richness, evenness, or diversity. In contrast, while fungal catabolic richness had not been affected by land use, the soil fungal community catabolic evenness and diversity had. At site 2, the land treatments had a significant effect on soil bacterial community catabolic richness (p = 0.046), but not on evenness (p = 0.74) or diversity (p = 0.135). In the fungal study, land management had no significant effect on the catabolic richness (p = 0.706), evenness (p = 0.536) or diversity (p = 0.826). It was concluded, that the microbial communities under the different land use and trash management regimes had been successfully differentiated, using the optimized protocols for the PCR-DGGE of 16S rDNA (bacteria) and 18S rDNA (fungi). Sequencing bands produced in the 18S rDNA DGGE, enabled some of the soil fungal communities to be identified. CLPP of the soil microbial communities using BIOLOG plates showed that, on the basis of C substrate utilization, the soil bacterial and fungal communities’ catabolic profiles differed markedly. Thus, it was shown that the different land use and management practices had indeed influenced the structural and catabolic diversity of both the bacterial and fungal populations in the soil. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.

Abstract available on PDF file. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1978.

Phosphorus uptake cassava (Manihot esculanta Crantz) were tested using on thirty-six plants per plot under dryland conditions at four different sites selected Bioresource group 1 (BRG 1) of northern KwaZulu-Natal of South Africa, which is described as Moist, Coastal Forest, Thorn and Palm veld, exhibiting sub-tropical characteristics. Soils in this region are very low in Phosphorus (P) due to high fixation by iron and aluminium oxides. With its high root yields coupled with efficient nutrients miner, cassava removes large quantities of N, P, K and Mg. With the ever-increasing prices of P fertilizer, which impact on the socio-economic livelihood of smallscale farmers, there is the need to look into improving the P uptake by the crop by alternative means apart from using mineral fertilizers. The objective of this study was to investigate the use of Arbuscular Mycorrhizal Fungi (AMF) to improve P uptake by cassava in agricultural soils. Laboratory studies were conducted at Soil Fertility and Analytical Services in Cedara (Pietermaritzburg). A Latin Square design (LSD) was used. Four treatments used were Untreated (Control), P-fertilizer, AMF, and P + AMF. Correlation and path-coefficient (probabilities) were computed. The P + AMF were significantly (p<0.05) taller than those in P-fertilizer treatment plots but were significantly (p<0.05) similar to those in Control and AMF-treated plots. Percent leaf P was statistically similar at the four sites with grand mean of 0.4%. Adding AMF and P+AMF to the soil substantially increased leaf P concentration to 0.5%. Tubers collected from P+AMF-treated plots were significantly (p<0.05) the longest, while those from Control plots were the shortest. P, and AMF-treated plots increased tuber length relative to the Control. All soil treatments significantly (p<0.05) increased tuber yields over the Control-treatment plots. However, AMF and P+AMF treated plots were significantly higher than P and control plots. This study suggests that using AMF or P+AMF can improve cassava yield as compared P alone or control – untreated cassava plants. Cassava producers in northern KwaZulu- Natal should consider using AMF or P+AMF to optimize tuber yield. A further study into the economic implications of the use of AMF is recommended. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2014.

Thesis (PhD (Soil Science))--University of Stellenbosch, 2005. / Approximately 45% of apricot tree plantings in South Africa are centered on Montagu, Koo and Barrydale in the Little Karoo. Below average production in this area could be ascribed to the deteriorating water quality of the Breede River and highly saline groundwater from boreholes which provide this area with irrigation water. Profit margins for farmers are such that decreased yields cannot be tolerated. Correct management of low quality water could improve production and net farm income and could decrease irrigation return flow into the river system. The objective of this work was to establish whether international water quality guidelines for apricot are applicable under a different set of climatic conditions for a locally important cultivar and to revise guidelines if necessary for the management of irrigation with saline water. A drainage lysimeter was used to evaluate the effect of saline irrigation on apricot (Prunus armeniaca cultivar Palsteyn) trees over a period of four years at Stellenbosch (S33° 55’; E18° 53’) in the Western Cape.

Thesis (PhD)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: The use of cowdung as an organic fertilizer in Asian and African agriculture is an ancient practice. This explains its renewed interest, partly due to the financial inability of most farmers to purchase agrochemicals but also the ever increasing need to adopt greener technologies that do not adversely affect soil health, water quality, biodiversity and promote sustained or even increased food production. In this context, many innovative farmers have developed their own novel technologies based on the use of local resources. One such innovation is Sanjeevak (a mix of cow dung, cow urine, water and a handful of sugar); which showed very promising boosting effect on crop productivity. However, very little scientific work has so far been conducted to evaluate its effect as an organic product for soil amendments. The present study was subdivided into three main objectives. (i) To assess the fertilizing value, human health and ecological risk profiles of Sanjeevak; (ii) To screen Sanjeevak for phytohormones content using Salkowski colorimetric method and liquid chromatography – mass spectrometry (LC-MS) (iii) To evaluate Sanjeevak application at various rates on growth parameters and yield of various crops cultivated in glasshouse and field conditions. Sanjeevak was assessed for its micro and macro nutrients contents. The analysis showed the presence of micronutrients such as Mg, Na, Ca and Zn at variable concentrations and phosphorus (P) (0.007%) and potassium (K) (0.063%). However, Sanjeevak content in total nitrogen (TN) (0.11%), and total organic carbon (TOC) (0.71%) was very low; suggesting that it may be a viable source of nutrients only if applied at higher and consistent rates or alternatively by improving its formulation. Also, Sanjeevak was analysed for its microbiological characteristics and level of heavy metals content in comparison to the strictest legislations that regulate the use and application of wastewater sludge to agricultural land in South Africa. The findings showed that heavy metals, which averaged from 0.03±0.01 for Arsenic (As) to 4.74±0.92 mg/kg for Zinc (Zn) and feacal coliform was estimated at 1.2×102 CFU/g dry matter measured were considerably below the threshold (for Arsenic between 40 to 75 mg/kg dry weight; for Zinc between 2800 to 7500 mg/kg dry weight) and faecal coliform bacteria between 1000 to 1×107 CFU/g dry weight for application as a source of soil amendments. Studies investigating the detection and concentration of phytohormones in Sanjeevak were carried out. In using the Salkowski colorimetric method to detect and quantify auxins from Sanjeevak and its composites (cow urine and dung), the results showed the presence of indole-3-acetic acid (IAA) at variable concentrations ranging from 20.38±2.1 ppm in cow urine, 20.1±6.6 ppm in cow dung, Sanjeevak 17.90±1.1 ppm to up to 138.31±12.6 ppm when LTRP was added to Sanjeevak bacterial cultures and by varying parameters such as incubaton time and temperature. Screening of the above mentioned samples for IAA using LC-MS analysis validated earlier findings. Further analysis of these results strongly emphasized the influence of bacteria in Sanjeevak in producing IAA. Trials were carried out both in the glasshouse and the field. In the greenhouse, different Sanjeevak application rates consistently confirmed its root promoting effect on crops such as tomato, cucumber and grapevine and increased wheat yield independent of the nutrients it contains. Marginal increases were recorded between treatments under field conditions; for example compost and compost + Sanjeevak 20.35 and 20.61 t/ha; and 2.46 and 2.60 t/ha compared to the control 11.67 t/ha and 1.29 t/ha respectively for tomato and maize. However, statistical analysis of the results obtained, revealed that there was no difference between treatments (control, compost, Sanjeevak and compost + Sanjeevak) for the same crop tested due to the high coefficient of variation of the data. Therefore, the use of Sanjeevak as an organic source of soil amendments may be considered as a cheaper alternative to effective microorganisms (EM) technology made up of local and natural resources. As observed in the study, it may be best used in combination with a reliable source of plant nutrients. / RESUMEE: L'utilisation des excréments de vaches comme engrais organique dans l'agriculture asiatique et africaine est une pratique très ancienne. Ceci explique son intérêt renouvelé, en partie due à aux restrictions monétaires de la plupart des agriculteurs d'acheter des produits agrochimiques, mais aussi la nécessité croissante d'adopter des technologies vertes qui ne nuissent pas à la qualité des sols, des eaux, la biodiversité et qui permettent d’améliorer la production agricole. C’est dans ce contexte que de nombreux paysans ont développé des techniques nouvelles dépendant des ressources naturelles et locales. L’utilisation de Sanjeevak (un mélange d’excréments de vaches, d’urine de vaches, l'eau et du sucre), a démontré sa capacité à accroître la productivité des plantes vivrières. Cependant, très peu de travaux scientifiques ont jusqu'à présent été menée pour étudier ce produit organique. La présente étude a été subdivisée en trois objectifs principaux. (i) Evaluation de la valeur fertilisante, et les profils de risques écologiques et sanitaires de Sanjeevak, (ii) Etudes de détection des phytohormones et leurs concentrations en utilisant une méthode colorimétrique adaptée de celle de Salkowski et la chromatographie liquide - spectrométrie de masse (LC-MS) (iii) Etude des effets de l’utilisation de Sanjeevak a différents taux d’applications sur la croissance et le développement des plants. Sanjeevak a été évaluée pour son contenu en micro et macro nutriments. L'analyse a montré la présence d'oligo-éléments tels que Mg, Na, Ca et Zn à des concentrations variables. De plus, son contenu en éléments majors tels que le phosphore (P) (0.007%), le potassium (K) (0.063%), l’azote (N) (0.11%), et carbone (C) (0.71%) est très faible; suggérant qu'il pourrait être une source viable de nutriments que si elle est appliquée à des taux plus élevés et répétés ou alternativement en améliorant sa formulation. En outre, Sanjeevak a été analysé pour ses caractéristiques microbiologiques et sa concentration en métaux lourds en comparaison a la législation qui réglemente l'utilisation et l'application de déchets liquide d’origines domestiques sur les terres agricoles en Afrique du Sud. Les résultats ont révélé que des métaux lourds et le niveau de coliformes fécaux mesuré était inférieur aux seuils d'application en tant que source d'amendements de sols agricoles. Les études portant sur la détection et la concentration d’hormones végétales ont été effectuées. En utilisant la méthode colorimétrique de Salkowski pour détecter et quantifier les auxines de Sanjeevak, les urines et les excréments de vaches; les résultats ont révélé la présence d'acide indole-3-acétique (AIA) à des concentrations variables dans les urines, les excréments et Sanjeevak. Une autre analyse des échantillons mentionnés ci-dessus pour les AIA en utilisant LC-MS a validé les résultats obtenus au préalable. L’étude détaillée de ces résultats confirme l'influence des micro-organismes dans la production des hormones végétales. Concernant les expériences sous serre, les différents taux d'application de Sanjeevak ont confirmé son effet stimulant à la croissance accélérée des racines des plantes telles que la tomate et les raisins et augmenté le rendement du blé indépendamment des nutriments qu'il contient. L'analyse statistique des résultats obtenus dans des conditions de terrain, a révélé qu'il n'y avait pas de différence entre les traitements (contrôle, compost, compost + Sanjeevak et Sanjeevak) pour la même plantes testées. Par conséquent, l'utilisation de Sanjeevak comme un produit organique qui améliore la qualité des sols et le rendement des cultures vivrières; peu être considéré comme un inoculum contenant des microorganismes constitué de ressources locales et naturelles. Comme l'a observé dans l'étude, il pourrait être mieux utilisé en combinaison avec une source fiable de nutriments végétaux. / AFRIKAANSE OPSOMMING: Die gebruik van beesmis as 'n organiese kunsmis in Asië en Afrika is' n eeu-oue landbou praktyk. Dit verklaar die hernude belangstelling, deels vanweë die finansiële onvermoë van meeste boere om landbouchemikalieë aan te koop, maar ook as gevolg van die toenemende behoefte vir groener tegnologie wat nie nadelig is vir grond gesondheid, waterkwaliteit, biodiversiteit en wat volhoubaarheid of selfs verhoogde voedselproduksie bevorder. In hierdie konteks het baie vindingryke boere hul eie nuwe tegnologie, gebaseer op die gebruik van plaaslik verkrygde hulpbronne, ontwikkel. `n Voorbeeld hiervan is Sanjeevak ('n mengsel van beesmis, beesurine, water en die handvol melasse), wat belowende bevorderende effekte op gewas produktiwiteit en grond mikroflora getoon het. Tot dusver was daar egter baie min wetenskaplike werk gedoen om die effek daarvan as 'n organiese produkte vir grond wysigings te evalueer. Hierdie studie was verdeel in vier belangrike doelwitte. (i) Om die bemestingswaarde, menslike gesondheid en ekologiese risiko-profiele van Sanjeevak te evalueer; (ii) Om Sanjeevak vir fitohormone inhoud en vlakke met behulp van 'n kolorimetriese metode afgelei van dié van Salkowski en vloeistofchromatografie – massaspektrometrie (LC-MS) te besigtig; (iii) Glashuis en veld waarneming reaksies met betrekking tot groei parameters en opbrengs van verskeie gewasse na die toediening van Sanjeevak by verskillende tempos; (iv) Laastens, om die effek van die Sanjeevak voorbehandeling op saad ontkieming en voortplanting te toets in vergelyking met die metodes en tegnieke wat gereeld gebruik word. Sanjeevak is geassesseer vir die mikro-en makro voedingstowwe inhoud. Die analise het die teenwoordigheid van mikrovoedingstowwe soos Mg, Na, Ca en Zn by wisselende konsentrasies, asook fosfor (P) (0.007%) en kalium (K) (0.063%), getoon. Sanjeevak inhoud van totale stikstof (TN) (0.11%), en die totale organiese koolstof (TOC) (0.71%) was egter baie laag, wat daarop dui dat dit slegs 'n lewensvatbare bron van voedingstowwe is indien dit by hoër en konsekwente tempos toegedien word of alternatiewelik wanneer formulering daarvan verbeter word. Sanjeevak was ook ontleed vir die mikrobiologiese eienskappe en die vlakke van swaar metale in vergelyking met die streng wetgewing wat die gebruik en toediening van afvalwater slyk op landbougrond in Suid-Afrika reguleer. Die bevindinge het getoon dat swaar metale en fekalieë kolivorm vlakke hier gemeet, aan die drumpel vereistes voldoen vir die toediening as ‘n grondverbeteringsmiddel. Studies wat die opsporing en die konsentrasie van fitohormone in Sanjeevak ondersoek is uitgevoer. In die gebruik van die Salkowski kolorimetrise metode om die ouksiene op te spoor en te kwantifiseer uit Sanjeevak en sy mengsel (beesurine en mis), het die resultate die teenwoordigheid van indol-3-asynsuur (IAA) by wisselende konsentrasies wat wissel van 20 tot 140 ppm in beesurine, beesmis en Sanjeevak getoon. Evaluering van die bogenoemde monsters vir IAA met behulp van LC-MSanalise bevestig vroeër bevindings. Verdere ontleding van hierdie resultate beklemtoon sterk die invloed van Sanjeevak mikrobiota in fitohormone produksie. Proewe is uitgevoer in die glashuis en die veld. In die glashuis eksperimente, is het die verskeie toedieningstempo van Sanjeevak herhalend die wortelbevorderende effekte bevestig op gewasse soos tamaties, komkommer en wingerdstok en dit het opbrengs van koring verhoog, onafhanklik van die voedingstowwe wat dit bevat. Statistiese analise van die resultate verkry onder veldtoestande, het getoon dat daar geen verskil tussen die behandelings (kontrole, kompos, Sanjeevak en kompos + Sanjeevak) was nie, gegee dat dieselfde gewas getoets was. Ten slotte, laboratorium-eksperimente op Sanjeevak as voor-behandeling om die beworteling te verbeter van die wingerdstok (Ramsey) onderstok steggies, het baie belowende resultate getoon in vergelyking met naftaleen asynsuur (NAA) voorbehandeling en die kontrole. Dit beklemtoon die feit dat Sanjeevak 'n alternatief kan wees en wat verdere studie verdien, hoofsaaklik as gevolg van sy lae-koste en omgewingsvriendelike prosedures. Die gebruik van Sanjeevak as 'n organiese grondverbeteringsmiddel vir gewasproduksie en voortplanting kan beskou word as' n goedkoper alternatief tot effektiewe mikro-organisme (EM) tegnologie wat uit plaaslike en natuurlike hulpbronne saamgestel is. Soos waargeneem in die studie, kan dit die beste gebruik word in kombinasie met 'n betroubare bron van plantvoedingstowwe. Dus, moet die gebruik daarvan vir die produksie van gewasse en voortplanting aangemoedig word.

Thesis (MScAgric)--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: Coal mining in South Africa is estimated to produce 200 Ml of acid mine drainage (AMD) per day in the Pretoria-Witwatersrand-Vereeniging (PWV) area alone, while electricity production resulted in approximately 27 Mt of ash in 2001. A large number of collieries in South Africa are tied to power stations where these two waste streams, acid mine drainage and fly ash, have the capacity to neutralize each other and provide an opportunity for co-disposal. The aim of this study was to investigate the reactions that occur during the co-disposal of fly ash leachate (FAL) and AMD and to examine the precipitates that result from the neutralisation reactions. Potentiometric titration was employed to investigate the neutralisation of Al-Fe salt solutions, simulating acid mine drainage (AMD), with alkaline solutions of Ca or Na hydroxide as well as fresh alkaline leachate from fly ash (FAL). The effectiveness of fly ash in removing metals and other salts from acid mine water was examined by analysing the neutralised water and modelling the results thermodynamically. Precipitates, prepared from large scale synthetic AMD and FAL co-disposal at various pH levels and Fe:Al ratios, were characterised according to composition, mineralogy and surface properties. The experimental neutralisation of synthetic acid mine drainage was achieved through titrating the components of SAMD (Fe and Al salt solutions) and solutions of various Fe:Al mole ratios with different bases in air and N2, and comparing the SAMD-FAL system with these simple acids and bases. The FAL used in all experiments was produced from fresh fly ash collected at Arnot power station. The SAMD was prepared as a solution with a pH of 2.5 and containing 12.7 mmol/L Al, 10.9 mmol/L Fe and 40.8 mmol/L SO4. The characterisation of reaction solids was achieved by collecting the precipitates formed from the co-disposal of FAL and SAMD with Fe:Al ratios of 7.3, 0.8 and 2.5. From the titration experiments it was found that upscale potentiometric titrations of SAMD show buffer zones at pH values of 3.5, 4, 6 and 10 corresponding to Fe(III)precipitation, Al precipitation, Fe(II) hydrolysis and oxidation, and Al redissolution, respectively, while downscale potentiometric titrations with SAMD show buffer zones at pH values 12 – 11, 9 and 4.5, which correspond to Fe oxidation and precipitation, Al precipitation and Al re-dissolution, respectively. A high concentration of Al in the simulated AMD inhibited the crystallinity of the precipitates and resulted in a large quantity of SO4 being removed from solution, which suggests that an aluminium sulphate phase is precipitating, but it is not crystalline and cannot be identified by XRD. Titrations performed up-scale by adding FAL to AMD showed near-complete metal and substantial SO4 removal from solution. The characterisation of reaction solids by x-ray diffraction, infrared spectroscopy, thermal gravimetric and differential thermal analysis revealed that the precipitates consist of poorly crystalline, highly Al-substituted goethite and ferrihydrite with large amounts of SO4 included in the structure. Poorly crystalline bayerite appears at a high pH and high Al concentration, and calcite is present in precipitates made by adding SAMD to FAL. High surface charges of between 330 cmolc/kg positive and 550 cmolc/kg negative charge and potentially large specific surface areas between 7 and 236 m2/g suggest a strong potential for the precipitates to function as low-grade adsorbents in wastewater treatment. The similarity of these ochre precipitates to soil minerals implies that land disposal of the neutralised solids is also viable. / AFRIKAANSE OPSOMMING: Steenkool mynbou in SA produseer na benaming 200 ML suur mynwater per dag in die PWV area alleenlik, terwyl opwekking van elektrisiteit naastenby 27 Mt vliegas geproduseer het in 2001. ’n Groot aantal steenkoolmyne in SA word verbind met kragsentrales, waar hierdie twee strome afval, suur mynwater en vliegas, die kapasiteit het om mekaar te neutraliseer en die weg te baan vir gesamentlike wegdoening. Die doel van hierdie studie was om die reaksies wat plaasvind gedurende gesamentlike wegdoening van vliegas loog (VAL) en suur mynwater (SMW) te ondersoek, asook die neerslae wat mag vorm as gevolg van neutralisasie reaksies. Potensiometriese titrasies was gebruik om die neutralisering tussen Al:Fe-sout oplossings te ondersoek as nabootsing van SMW met gebruikmaking van alkaliese oplossings van Ca of Na hidroksied asook vars loog van VA. Die effektiwiteit van VA om metale en soute uit SMW te verwyder was getoets deur outleding van die geneutraliseerde water en modellering van die termodinamika. Neerslae berei uit groot-skaal sintetiese SMW en VAL en met gelyktydige storting by verskeie pH vlakke en Fe:Al verhoudings, was gekarakteriseer volgens samestelling, mineralogie en oppervlak eienskappe. Die eksperimentele neutralisering van sintetiese suur mynwater (SSMW) was gedoen deur titrering van die SSMW komponente en oplossings van verskeie Fe:Al molêre verhoudings met verskillende basisse in lug en N2, en vergelyking van SSMW-VAL sisteem met hierdie eenvoudige sure en basisse. Die VAL gebruik in alle eksperimente was geproduseer van vliegas verkry van die Arnot kragsentrale. Die SSMW was berei as ’n oplossing met ’n pH van 2.5 en bevat 12.7 mmol/L Al, 10.9 mmol/L Fe en 40.8 mmol/L SO4. Die karakterisering van vastestowwe uit die reaksie was gedoen deur die bemonstering van neerslae gevorm as gevolg van die gelyktydige wegdoening van VAL en SSMW met Al:Fe verhoudings van 7.3, 0.8 en 2.5.Die was waargeneem in die titrasie eksperimente dat hoër-skaal potensiometriese titrasie van SSMW buffersones, by pH waardes 3.5, 4, 6 en 10, ooreenstem met Fe(III) presipitasie, Al presipitasie, Fe(II) hidrolise en oksidasie, en Al her oplossing, terwyl laer skaal potensiometriese titrasie met SSMW buffer sones by pH waardes 12 - 11, 9 en 4.5 ooreenstem met Fe(III) presipitasie en oksidasie, Al presipitasie en heroplossing respektiewelik. ’n Hoë konsentrasie Al in die sintetiese SMW het kristalliniteit van die neerslae geïnhibeer en veroorsaak dat ’n hoeveelheid SO4 uit oplossing verwyder is, wat suggereer dat die AlSO4 fase neerslaan maar nie kristallyn is en gevolglik nie opgetel word met x-straal diffraksie nie. Titrasies gedoen by hoërskaal deur byvoeging van VAL tot SSMW, het feitlik volledige metaal en SO4 verwydering uit oplossing getoon. Die karakterisering deur x-straal diffraksie, infrarooispektroskopie, termies gravimetries en differentiële termiese analise, het getoon dat die presipitate bestaan uit swak kristallyne, hoë Al-gesubstitueerde goethiet en ferrihidriet met groot hoeveelhede SO4 vasgevang in die struktuur. Swak kristallyne bayeriet verskyn by hoë pH en hoë Al-konsentrasies en kalsiet is teenwoordig in neerslae gevorm deur byvoeging van SSMW tot VAL. Hoë oppervlakladings van tussen 330 cmolc/kg positief en 550 cmolc/kg negatiewe lading en ook potensieel groot spesifieke oppervlak van tussen 7 en 236 m2/g, dui op ’n sterk potensiaal vir neerslae om as laegraadse adsorbeermiddels in afvalwaterbehandeling gebruik te word. Die ooreenstemming in hierdie geelbruin neerslae met grond minerale, impliseer dat die land storting van geneutraliseerde vastestowwe ook lewensvatbaar is.

Thesis (MScAgric)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: In the humid Graskop region of Mpumalanga Province, South Africa, there is an anomalous body of highly weathered black, manganiferous oxisols derived from dolomite. With Mn contents as high as 17%, potential large-scale Mn release is an environmental concern under current, acid generating, forestry practices. This study aims at establishing the factors which may affect the stability of the manganiferous oxisols of Graskop and in the process, investigating some of the morphological, mineralogical and chemical properties of these unique soils. Typically, the soils show a reddish, nodule-rich horizon, containing 3-4% Mn, grading through a red and black mottled zone into a black (5YR 2.5/1) apedal subsoil with >7% Mn. The Mn gradient down the profile as well as the abundant nodule content of the upper subsoil horizons implies that Mn mobilization and redistribution are active pedogenic processes. The exceptional Mn content of these soils is complemented with Fe and Al concentrations of up to 10 and 8%, respectively, and anomalously high trace element levels in particular Ni and Zn (as high as 541 and 237 mg kg-1, respectively) which are at the upper limit of cited world natural maxima for soils. The Mn mineral lithiophorite [(Al,Li)MnO2(OH)2], dominates the mineralogy of the soils with accessory amounts of birnessite, gibbsite, goethite, hematite, maghemite, kaolinite, aluminous chlorite and mica - a mineral suite reflecting that of well weathered soils. With the pH of the soil being at or close to the point of zero charge (4.5-5.5) the soils show isoelectric equilibrium. The very low buffer capacity results in metal dissolution commencing with the first increment of titrated acidity. Manganese dissolution is relatively minor considering the large potential for release and is highly overshadowed by Al release. The apparent resilience of the Mn phase to added acidity may relate to the overwhelming poise of the soils which maintains robust, oxic conditions despite the usual instability of Mn oxides at low pH. Manganese release and soil redox properties are substantially affected by drying especially in the organic rich topsoils. Using various redox analyses, evidence is shown for involvement of Mn(III)-organic complexes in the drying reactions. Using this and information gained in a real time, attenuated total reflectance Fourier transform infrared(ATR-FTIR) spectroscopic study, a mechanism is suggested which may account for the observed Mn release and the loss of Cr oxidising capacity commonly observed in dried soils. The information provided by the ATR-FTIR study showed the decrease in surface pH of a clay film, from 5 to below 2, as well as the shift in coordination nature of sorbed oxalate from a more outer-sphere association to a more inner-sphere association concomitant with the removal of free water from the clay surface. This spectroscopic evidence for these chemical changes which accompany surface drying not only provides further insight into the reactions involving Mn oxides in soils but also highlights the suitability of ATR-FTIR for real time, in situ investigation into the chemistry of the drying water interface. From these results it is concluded that Mn release from the manganiferous oxisols, under acid generation of the kind known to occur in pine plantations, is less that anticipated. On the other hand, desiccation of the topsoil results in substantial Mn release with a suggested mechanism which involves a Mn(III) intermediate. / AFRIKAANSE OPSOMMING: ‘n Onreelmatige grondliggaam van hoogs verweerde, swart, mangaanhoudende oxisols wat uit dolomiet ontwikkel het, word in die humiede Graskop streek van die Mpumalanga Provinsie van Suid-Afrika aangetref. Die hoë Mn-inhoud (tot 17%) van hierdie oxisols is van groot omgewings-belang weens die potensiële grootskaalse Mn-vrystelling onder huidige, suur-genererende bosbou praktyke. Hierdie studie beoog om die faktore wat die stabiliteit van die mangaanhoudende oxisols van Graskop affekteer, vas te stel. Tesame hiermee word die morfologiese, mineralogiese en chemiese eienskappe van hierdie unieke gronde ondersoek. Kenmerkend van hierdie gronde is ‘n rooi, nodule-ryke horison met 3-4% Mn aan die oppervlakte. Bogenoemde horison verander met toename in diepte in ‘n rooi en swart gevlekte sone wat weer in ‘n swart (5YR 2.5/1) apedale ondergrond met >7% Mn oorgaan. Die Mn gradiënt in die profiel sowel as die hoë nodule-inhoud van die boonste grondhorison dui daarop dat Mn-mobilisasie en -herverspreiding huidige aktiewe pedogenetiese prosesse in die profiele is. Fe en Al, met konsentrasies van 10% en 8% onderskeidelik, word saam met die onreelmatig hoë Mn inhoud aangetref. Baie hoë vlakke van Ni en Zn (so hoog as 541 en 237 mg.kg-1 onderskeidelik) wat hoër is as aangehaalde wêreld natuurlike maksimum waardes, word ook aangetref. Die mineralogie van die gronde word deur die Mn mineraal litioforiet [(Al,Li)MnO2(OH)2] gedomineer. Bykomstige hoeveelhede van birnessiet, gibbsiet, goethiet, hematiet, maghemiet, kaoliniet, aluminiumryke chloried en mika word ook aangetref. Hierdie minerale samestelling is kenmerkend van hoogs verweerde gronde. Met die pH van die grond in die omgewing van die punt van geen lading (4.5 – 5.5), word ‘n iso-elektriese ekwilibrium by die gronde aangetref. Die baie lae bufferkapasiteit het metaal-oplossing aangehelp wat met die eerste inkrement van titreerbare suurheid ‘n aanvang geneem het. Mangaan-oplossing is baie klein indien die groot potensiaal vir vrystelling asook die groot mate van Al-vrystelling in ag geneem word. Die skynbare teenwerking van die Mn fase tot toegevoegde suurheid, mag toegeskryf word aan diesterk ewewig van die gronde om sterk, oksiese kondisies, ten spyte van die normale onstabiliteit van Mn oksiedes by lae pH, te onderhou. Mangaan vrystelling en grond redoks eienskappe word beduidend deur uitdroging beïnvloed en veral in die organies-ryke bogronde. Deur van verskeie redoks analises gebruik te maak is daar bewyse van die betrokkenheid van Mn(III)-organiese komplekse in die uitdroging-reaksies gevind. Dit. en data ingesamel in ‘n “real time, attenuated total reflectance Fourier transform infrared (ATR-FTIR)” spektroskopiese studie, is gebruik om ‘n meganisme voor te stel wat die waargenome Mn vrystelling en die verlies aan Cr oksidasie kapasiteit (algemeen waargeneem in droë gronde) te kan verklaar. Die data verkry met die ATR-FTIR studie het ‘n afname in oppervlak pH van 5 na 2 van ‘n klei film asook die verskuiwing in koördinasie toestand van die gesorbeerde oksalaat van ‘n meer buite-sfeer assosiasie tot ‘n meer binne-sfeer assosiasie, gepaardgaande met die verwydering van vry water van die klei oppervlaktes, uitgewys. Die spektroskopiese bewyse vir die chemiese veranderinge wat die oppervlak uitdroging vergesel, gee nie net meer insig in die reaksies rakende Mn oksiedes in gronde nie maar onderstreep ook die toepasbaarheid van die ATR-FTIR vir intydse (“real time”), in situ ondersoeke na die chemie van die uitdrogende water kontakvlak. Vanuit hierdie resultate kan afgelei word dat Mn vrystelling vanuit mangaanhoudende oxisols onder suur genererende denne plantasies laer is as wat verwag is. Aan die ander kant sal uitdroging van die bogrond tot aansienlike Mn vrystelling, met ‘n verwagte meganisme wat Mn (III) as intermediêre toestand insluit, lei.