This thesis presents the results of detailed field and laboratory investigations of the soils developed over Carboniferous rocks in some 35 square miles of North Staffordshire and Derbyshire uplands. Information about the geology, morphology, climate and vegetation was collected as a background to the soil studies. The significance of this environmental information is discussed in relation to soil development. About 170 soil profiles were described of which 50 selected to illustrate the range of profiles encountered these profiles, which fall into four main morphological groups, are used to define units for subsequent mapping by auger. The problems associated with auger mapping of soils are discussed. Laboratory studies were confined to the investigation of the particle size distribution, certain micromorphological features and the iron distribution of the soils. It is suggested that the joint use of these techniques has considerably elucidated the problems of soil origin and development in the study area. A new particle size analysis method, developed by the author for this study, is discussed and compared with the standard sedimentation technique. Although the soil units are not given Series names, they are compared with the units recognised in local and general British classifications. The soils are also classified according to the current American system and the additional laboratory information required for this purpose is included. The groups of soils thus obtained are compared with equivalent groups in the British system and the relative merits of each classification are discussed from the standpoint of the present study. The origin and development of the soils is discussed. It is argued that although there are indications of soil development during the Bast (Eemian) Interglacial most development dates from the Pausdorf (Weichselian) Interstadial, or is a Post-Glacial phenomenon. There seems to be little indication of polycyclic development, but widespread evidence of polygenetic soil formation.

An investigation was carried out into the effects of Bromoxynil, Chloroflurazole, Chlorothamid, Dichlobenil, Diquat, Endothal, Ioxynil, Paraquat, Picloram, Propanil and 2,3,6-TBA on soil nitrification. The perfusion technique was employed for studies on herbicide effects on the nitrification process in soil previously enriched with nitrifiers, and also on their effects on the enrichment growth of nitrifiers in a soil continuously treated with the herbicides. The results obtained with these methods were compared with those from nitrite production and utilization by pure cultures of Nitrosomonas sp and Nitrobacter sp respectively, and with measurement of oxygen uptake by these organisms and enriched soil, by conventional Warburg techniques for these herbicides. The results indicate that there were differential effects of the herbicides on the growth and metabolism of the nitrifying organisms; the nitrification process was affected at a lower herbicide concentration than the growth rate. The evidence suggests that there was an adaptation of the nitrifying organisms during growth, i.e. a selective proliferation of a tolerant strain. Ioxynil, propanil, chloroflurazole and bromoxynil were the most toxic while dichlobenil, paraquat and endothal were the least toxic of the herbicides. Endothal in thesoil perfusion experiments, and also in the pure cultures, stimulated nitrification, while paraquat was more inhibiting in the pure cultures than in the perfuser experiments.

The microbial degradation of paraquat dichloride by Lipomyces starkeyi was investigated by both spectrophotometric determination and c14-labelled carbon dioxide emission. 90% of the paraquat, when used in liquid culture as the sole nitrogen source, was decomposed in 72 hours. When incorporated as an unessential component of the medium, paraquat took longer to be broken down (7-11 days) depending on the time allowed for Lipomyces starkeyi establisment before addition of herbicide. The breakdown of paraquat, in liquid cultures containing a range of soils varying in organic/inorganic matter ratio, was investigated. Breakdown was seen to occur within the first 96 hours, after the commencement of incubation, in cultures containing high organic matter soils. Adsorption isotherms showed that the high organic matter soils had a greater total adsorption of paraquat in solution concentrations in excess of 250 ppm. A high organic matter soil was divided by ultra-sonic disintegration into it's organic and inorganic components. Paraquat breakdown was seen to occur in cultures containing the former but not the latter. The passage of c14-labelled paraquat from the organic components through a dialysis membrane was observed and demonstrated to be due largely to the presence of inorganic material outside the membrane. A system was proposed, whereby the decomposition of paraquat in the soil by Lipomyces starkeyi occured during the stage when the herbicide was weakly adsorbed onto the organic soil components. After a period of time (less then 96 hours in one instance) readsorption onto the inorganic soil component rendered the paraquat unavailable to microbial degradation.

Field studies throughout England showed that the pattern of bryophyte recolonisation on a burnt site depends largely on the type of fire from which the site results. Two types of fire were distinguished, rapid fires and bonfires, these differing mainly in the amount of ash deposited and the duration of high temperatures, both being greater during a bonfire. On bonfire sites, after an initial period of growth inhibition, Funaria hypgrometrica characteristically became abundant, whilst scattered shoots of Bryum argenteum, Ceratodon purpureus and tuberous species of Bryum were often found. Then, as the angiosperm cover increased these pioneer mosses were replaced by the pre-burn species. Rapid fire sites in contrast, were colonised largely by species characteristic of the pre-burn vegetation, these only becoming abundant when angiosperm recolonisation was slow. Culture on inorganic nutrient agar showed that in the presence of adequate amounts of potassium and particularly phosphorus, growth of Funaria was stimulated by raising the level of nitrate nitrogen and soil analyses indicated some correlation between these requirements and. conditions in bonfire soils. Addition of inorganic nutrients to unburnt soil however, did not stimulate growth. Thus under natural conditions soluble organic nutrients, present in high concentrations in bonfire soils, may be essential for growth, or alternatively a heat-labile inhibitor may prevent good growth of Funaria on unburnt soil, though this seems unlikely. The excessively high concentrations of soluble substances found immediately after burning, together with the inhibition of nitrification, would explain the initial growth inhibition on bonfire sites, whilst the later disappearance of Funaria from bonfire sites could be linked with the gradual return of nutrient conditions to the pre-burn state and increasing angiosperm competition.

This thesis examines various factors controlling algal nitrogen fixation and nitrogen release in temperate agricultural soils. New apparatus for investigating nitrogenase activity on uniform soil grown algal crusts and for the in situ estimation of nitrogen fixation in the field is described. The effects of oxygen concentration and temperature on acetylene reduction by soil grown cultures of Nostoc ellipsosporum in the light and in the dark suggest that ATP generated by oxidative phosphorylation contributes to fixation even in the light. The oxygen concentration giving optimum nitrogenase activity depends on the intensity of illumination, largely because of the continuing contribution from dark fixation. The oxygen dependant acetylene reduction continued throughout the night in the field at 20% of the midday rate. This proportion is dependant on daytime light intensity and day/night temperature drop. The release of nitrogenous compounds by soil and sand grown cultures of N. ellipsosporum was investigated in the laboratory. Algal cultures growing on sand released only 2% of the total nitrogen compared with 10% released by liquid cultures. Freezing to below -3°C, drying to less than 4% moisture or pathogenic infection all cause extensive cellular lysis with a concomitant loss of nitrogenase activity, followed, after several days, by a surge in ammonia concentration. The recovery of nitrogenase activity after re-wetting was investigated in the field after a period of dry weather. All samples achieved a steady rate of nitrogenase activity after 400 minutes irrespective of the magnitude of recovery. Nitrogenase activity in the field was monitored at weekly intervals using an in situ technique over a two year period on Broadbalk, one of the Rothamsted classic plots sown to winter wheat. The seasonal fixation rates varied from 1.4 to 28 Kg/ha depending on the fertilizer and herbicide treatment. The greatest seasonal fixation was given bynon-herbicide plots receiving 48 Kg N/ha of applied nitrogen. The effect of various species of algal inoculum was investigated on 60 plots sown to winter wheat with and without irrigation and added nitrogen. A significant increase in fixation was produced and the most effective treatment was a liquid application of N. ellipsosporum. Both the N. punctiforme and Anabaena cylindrica were more effective when applied as dried sand cultures. The most important single factor limiting algal development in field experiments was soil moisture.

<p> Few studies provide data that can document the long-term landscape evolution of the Piedmont of the southeastern United States. Here we present the results of field mapping and a soil chronosequence for fluvial terraces along a ~46 km reach of the Catawba River, NC and SC. Five terrace units (Qt1&ndash;5) have been mapped along the reach, and in certain regions a sixth surface (Qt0) was mapped. Observations of bedrock surfaces on Qt3&ndash;Qt0 confirmed that these units are strath terraces. Longitudinal profiles of terrace units constructed from mapping data revealed static channel convexities in Qt5&ndash;Qt1 in the lower reach of the study area at Landsford Canal State Park, and a lack of an obvious influence on terraces profiles within the Gold and Silver Hill shear zones in the middle reach. Age dating of terraces in this study included deriving ages based on surface height above the channel (Mills, 2000) and IRSL samples obtained from Qt3 exposures. Ages, reported in ka, are as follows: Qt0&mdash;4591 &plusmn; 404 ka, Qt1&mdash;1852 &plusmn; 365 ka, Qt2&mdash;1181 &plusmn; 194 ka, Qt3 (average of two IRSL ages)&mdash;142 &plusmn; 32 ka, Qt4&mdash;50 &plusmn; 8 ka, and Qt5&mdash;5 &plusmn; 2 ka. Up to 3 soil pits were dug on each terrace unit Qt5&mdash;Qt2, and soils described as per Birkeland (1999). Chronofunction trends of soil morphological properties include soil colors in the most developed B horizons reddening and clay films increasing in amount and prominence with surface age. Soil samples were analyzed for particle size, pedogenic iron (AAS), bulk density and major elements (XRF). Some of these analyses show expected trends with respect increasing surface age for terraces of the Catawba River, such as increases in clay content (%) and decreases in iron activity ratios in most weathered B horizons with increasing surface age. Overall the history Catawba River is one of five distinct periods of lateral planation of the valley, possibly driven by transitions to interglacial periods, punctuated by periods of incision, whose cause is currently unknown. The soil chronosequence, ages, and data derived from mapping, however, provide a strong foundation that can be used in further studies of the long-term landscape evolution of the SE Piedmont of the SE United States.</p><p>

<p> Methylmercury (MeHg) is a toxic and bioaccumulative form of mercury that can be produced by bacteria living in water saturated soils, including those found in flooded rice fields. In the Sacramento Valley, California, rice is grown on 240,000 hectares, and mercury is a concern due to a history of mining in the surrounding mountains. </p><p> Using unfiltered aqueous MeHg data from MeHg monitoring programs in the Sacramento River watershed from 1996 to 2007, the MeHg contribution from rice systems to the Sacramento River, was assessed. AgDrain MeHg concentrations were elevated compared to upstream river water during November through May, but were not significantly different during June through October. June through October AgDrain MeHg loads (concentration &times; flow) contributed 10.7&ndash;14.8% of the total Sacramento River MeHg load. Missing flow data prevented calculation of the percent contribution of AgDrains in November through May. </p><p> Field scale MeHg dynamics were studied in two commercial rice fields in the Sacramento Valley. The Studied fields had soil total mercury concentrations of 25 and 57 ng g^-1, which is near the global background level. Surface water and rice grain MeHg and THg concentrations were low compared to previously studied fields. An analysis of surface water drainage loads indicates that both fields were net MeHg importers during the growing season and net MeHg exporters during the fallow season. </p><p> Since the microbes that produce MeHg prefer flooded environments, management that dries the soil might reduce MeHg production. Conventional continuously flooded (CF) rice field water management was compared to alternate wetting and drying, where irrigation was stopped twice during the growing season, allowing soil to dry to 35% volumetric moisture content, at which point plots were re-flooded (AWD-35). Compared to CF, AWD-35 resulted in a significant reduction of MeHg concentration in soil, surface water and rice grain.</p><p>

<p> Concerns over delayed soil warming and drying have hindered adoption of conservation tillage practices in frigid environments. Our objectives were to evaluate the effects of chisel plow (CP), vertical tillage (VT), strip tillage with coulters (STC), and strip tillage with shanks (STS) on soil warming and drying and their potential consequences to crop yields. A two-year study was conduct at three full-scale, producer-managed, corn-soybean fields in the Red River Valley of eastern North Dakota and western Minnesota. Tillage treatments were assessed to measure crop residue cover, soil temperatures, soil volumetric water contents, crop yields, and other metrics. Our study indicated significant differences for many soil physical and chemical parameters, but little to none for soil warming and crop yields. Yield differences were attributed to varying fertilizer management practices, timing, and application method. These findings emphasize the importance of field management practices that compliment conservation tillage for obtaining competitive crop yields. </p><p>

<p> This thesis reconstructs the landscape evolution of the Billy Big Spring site (24GL304, Glacier County, north-central Montana) from the last glacial maximum to present through the analysis of sediment and soil samples collected from a transect of auger tests that bisected the site and surrounding landforms. Interpretations were drawn from stratigraphy, pedologic data, sedimentologic analysis and radiocarbon dating. The site landscape came into being in the late-Pleistocene, after Wisconsin-age glaciers retreated. Glacial retreat left a meltdown depression on the land that filled with water to form a pond, which persisted through the early-Holocene. The onset of the mid-Holocene (Altithermal) occurred before ~8,415 cal. yrs. BP, when increasingly arid conditions caused the water level to drop. The first radiocarbon dated human occupation of this site occurred during the Altithermal, ~7,030 cal. yrs. BP, after the eruption of Mount Mazama (~7,633 cal. yrs. BP). Arid conditions continued until ~7,000 cal. yrs. BP, when pond water re-expanded across the basin, marking the transition to the cooler late-Holocene. Sometime before 2,100 cal. yrs. BP, dry conditions returned, and the extent of the pond water decreased again. Since this time, overland alluvial processes have deposited sediments in the basin. Many hypotheses on how the Altithermal impacted the people of the Northwestern Plains have been proposed since the 1950s, but little agreement has been reached. This is due to the fact that there was great variation in how the Altithermal expressed itself throughout the Northwestern Plains. The human reactions to this phenomena cannot be explained simplistically for the region as a whole. This study shows that the Billy Big Spring site experienced drying during the Altithermal, but despite this, people continued to occupy this site. This evidence adds to the argument that the Altithermal climate of the Northwestern Plains did not have severe enough impacts to impose much hardship on its occupants.</p><p>

Bulk soil is a stressful environment low in readily available nutrients and characterized by a low oxygen tension. Additionally, many soils undergo conditions of drought. Strategies that common soil bacteria take to cope with adverse conditions may be crucial to the ability of soil microorganisms to persist in soil. Therefore, studying genetic loci inducible by stress conditions commonly applied to soil microorganisms may shed light on the strategies used, and a thorough understanding of molecular responses to these stresses is critical. This dissertation explores in detail the responses of S. meliloti 1021 to experimentally induced salinity and desiccation. We have identified a number of factors central to S. meliloti 1021's ability to survive desiccation, including temperature, stationary growth phase, chloride and sulfate availability. We were also successful in identifying two genetic loci that are important in the adaptation of S. meliloti 1021 to increased levels of NaCl. One such locus ( asnO) was shown to contain a hypothetical glutamine-dependent asparagin synthetase. We showed that asnO::tn5LuxAB (a transcriptional fusion with luciferase on a Tn5 derivative) was induced by chloride and osmotic stress, and during the stationary phase. The main function of AsnO is not asparagine synthesis since addition of aminoacids to cells at elevated NaCl concentrations did not complement growth. However, AsnO is not involved in NaCl mediated survival during desiccation. We also tested a second locus for its involvement in NaCl response and desiccation. Open reading frame smb20482, contains a putative dAla-dala ligase domain and is induced by osmotic stress. Disruption of this locus caused NaCl mediated desiccation sensitivity. Penicillin sensitivity indicates a function for this gene in crosslinking of peptidoglycan. Interestingly, homologs of this gene are only found among the proteobacteria. In conclusion, (1) chloride availability enhances survival during desiccation of S. meliloti 1021, (2) we identified two NaCl responsive loci also involved in adaptation to NaCl and, (3) one locus (smb20482) is also involved in survival during desiccation. Thus, our strategy to identify genetic loci involved in the survival during desiccation has been successful.