The South Burnett region of Queensland is Australia's most important rainfed peanut (Arachis hypogea L.) production area. It also produces a considerable amount of cereal and grain legume crops. The cropping soils of the region are red, acid to neutral, clay loams that are classified as Ferrosols (Australian Soil Classification). Over 50 years of cropping on these soils has resulted in severe depletion of nutrient reserves, particularly potassium (K). In addition, the remaining K is predominantly confined to the surface 10 or 15cm of the soil profile, a feature commonly refered to as nutrient stratification. Dry periods during the summer cropping season are common due to the highly variable, summer-dominant rainfall pattern of the South Burnett. As topsoil dries out, crops forage for moisture and nutrients from lower in the soil profile where K reserves are smaller. It is therefore suspected that the combination of dry periods and stratified K reserves have resulted in an increasing incidence of K deficiency symptoms in summer crops. To investigate these issues, K relations of Ferrosols of the South Burnett were studied using soils from two representative sites. The pools of soil K that are important to crop growth in Ferrosols, and their interaction was examined through fractionation of soil K pools, and determination of quantity/intensity relationships, charge characteristics and clay mineralogy, and a leaching column study. A rapid K uptake period was identified for peanut and the effect of profile distribution and soil moisture during this period on K accessibility was studied in a divided column experiment. Finally, on-farm trials were used to evaluate commercial-scale options for improving K distribution in field profiles. It was found that the immediately available exchangeable K pool in these soils was the most important source of soil K, and was poorly buffered by slowly available non-exchangeable K. However the leaching column study revealed that K was preferentially adsorbed onto soil cation exchange sites, displacing calcium (Ca) and magnesium (Mg) ions, and therefore was not susceptible to vertical movement within the soil profile. These observations helped to explain the development of stratified K profiles in these soil types. Peanut (cv. Streeton) was found to take up most of its K requirement between 25-70 days after planting. The divided column study showed that profile distribution, and topsoil iv moisture content during this rapid K uptake period, were able to affect the ability of peanut plants to access K. Plants that grew in low K soil, or where soil was dry at the site of K supply, had reduced access to K. However, improving access to K did not result in improved growth, but rather in a significant reduction in dry matter (DM) production, apparently due to interference in the availability of other nutrients, possibly phosphorus (P), magnesium (Mg) or boron (B). Field studies showed that application of K and profile inversion improved K uptake and DM production of various crop species. However, in most instances improved K uptake and DM production was not reflected in increased yield. It was suggested that a combination of agronomic factors, seasonal conditions and crop type prevented the expression of yield responses to improved K nutrition and these influences need to be understood. The findings of this project have important consequences for nutrition of crops grown on Ferrosols in the South Burnett region. Surface applied K cannot be expected to increase exchangeable K in the subsoil unless it is incorporated to depth. Similarly, band applied K will remain close to the site of application as a result of only limited vertical or lateral movement. This may affect the ability of roots to access band applied K. The ability of surface applied K to displace Ca and Mg from soil exchange sites may have negative implications for the Ca nutrition of developing peanut pods. On the other hand, it could present an opportunity for the movement of Ca into deeper soil layers to address the amelioration of acid subsoils. The unexplained negative responses to potassium chloride application and apparent effect on P, Mg or B nutrition need to be investigated.

Call number: LD2668 .T4 1979 B57 / Master of Science

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

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<p>Nitrogen deposition leads to environmental damage in areas where the nitrogen deposition is high. Southwest Sweden receives an annual nitrogen deposition of up to 20 kg N/ha. Nitrogen that is not assimilated by the vegetation is accumulated in the soil, which may lead to nitrogen saturation and an elevated risk of nitrogen leaching. Nitrogen leaching from forest areas in southern Sweden has proven to be higher than from agricultural areas, which have been thought to be the main contributors to elevated nitrogen levels in rivers and lakes. The amount of nitrogen that leaches depends on the fraction of the total nitrogen in the soil that consists of nitrate, since nitrate is easily transported through the soil. Nitrogen leaching increases after clear-cutting since the uptake by vegetation is greatly reduced.</p><p>In this study the soil chemistry of two clear-cut spruce stands in Halland, in southwest Sweden, has been analyzed. A previous study in these areas has indicated higher nitrate concentrations in the groundwater in one of the areas and thus a greater nitrogen leaching. Nitrogen deposition in the two areas is estimated to be the same and therefore the soil chemistry has been analyzed to evaluate if differences in the soil can have resulted in differences in the nitrate concentration in the groundwater. The hypothesis is that the area with higher nitrate concentrations in the groundwater has properties more favorable for nitrification, which would be especially apparent in a lower carbon to nitrogen ratio. The pH and storage of nitrate, ammonium, total carbon, total nitrogen and exchangeable cations was analyzed in soil samples from both areas. In addition, a study of stand properties and previous use of the areas was made.</p><p>The analyses performed in this study indicate that the soil properties could not explain the differences in nitrate concentration in the groundwater. The differences found between the areas were that the area with lower nitrate concentrations in the groundwater had higher nitrate and ammonium concentrations and higher pH in the soil. The reason for this might be that the soil in this area has larger capacity to bind elements. The fact that the soil samples were sampled during different seasons probably had a major effect on these results. The history and stand properties of the two areas were similar. According to site index one area was more fertile, which benefits nitrification. This fact was not confirmed by the analyses, but it probably caused the nitrification rate to be higher in this area.</p> / <p>Det stora nedfallet av föroreningar i form av kväve i framförallt sydvästra Sverige leder till försurning och övergödning av både skogsmarker och vattendrag. Kvävedepositionen i södra Sverige kan uppgå till 20 kg N/ha och år. Det kväve som inte tas upp av vegetationen ackumuleras i marken som efterhand riskerar att bli kvävemättad vilket ökar risken för kväveutlakning. Kväveutlakningen från svenska skogsmarker har visat sig kunna vara i samma storleksordning som från jordbruksmarker som anses vara en av de största orsakerna till ökande kvävehalter i sjöar och vattendrag. Kväveutlakningens storlek beror till stor del på hur stor del av markens kväveförråd som finns i den oorganiska formen nitrat eftersom den är en lättrörlig jon. Efter skogsavverkning ökar nitratutlakningen betydligt på grund av att det finns väldigt lite vegetation kvar som tar upp kväveföreningarna.</p><p>I den här studien har markkemin i två avverkade granskogsområden i Halland undersökts. Tidigare studier i dessa två områden har visat att halterna av nitrat var högre i grundvattnet i det ena området än i det andra, och således var även nitratutlakningen större i detta område. Eftersom kvävedepositionen anses vara densamma i de två områdena har markemin undersökts för att finna skillnader där som kan förklara de olika nitratnivåerna i grundvattnet. Hypotesen var att det ena området skulle ha mer gynnsamma förhållanden för nitrifikation, framförallt en lägre C/N-kvot. Markens förråd av nitrat- och ammoniumkväve, totalkol, totalkväve, utbytbara katjoner samt pH undersöktes i båda områdena. En studie av områdenas historia gjordes även för att kunna utesluta skillnader där som kunde ge upphov till skillnaden i nitrat i grundvattnet.</p><p>Slutsatsen som kan dras från studien är att de analyserade egenskaperna inte visade på mer gynnsamma förhållanden för nitrifikation i det ena området än i det andra. Ingen skillnad i C/N-kvot uppmättes. Skillnaderna som hittades var att området med lägst halter av nitrat i grundvattnet hade högst halter av oorganiskt kväve i marken och högre pH. Att nitrathalterna var högre i grundvattnet men inte i marken kan ha sin förklaring i att marken i det ena området har större förmåga att binda till sig kväve vilket gör att det inte lika lätt kommer ut i grundvattnet. Antagligen spelade det stor roll för dessa resultat att jordproven tagits vid olika årstider. Undersökningen av tidigare användningsområde i skogarna visade att de hade en tämligen liknade historia. Det ena området har enligt ståndortsindex högre bördighet vilket gynnar nitrifikation. Detta framgick dock inte av analyserna men är antagligen orsaken till de högre nitrathalterna i grundvattnet i detta område.</p>

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, in ful llment of the requirements for the degree of Master of Science. March 27, 2013 / The transport of chemicals through soils to the groundwater or precipitation at the soils surfaces leads to degradation of the resources such as soil fertility, drinking water and so on. Serious consequences may be su ered in the long run. In this dissertation, we consider macroscopic deterministic models de- scribing contaminant transport in saturated soils under uniform radial water ow backgrounds. The arising convection-dispersion equation given in terms of the stream functions is analyzed using classical Lie point symmetries. A number of exotic Lie point symmetries are admitted. Group invariant solu- tions are classi ed according to the elements of the one-dimensional optimal systems. We analyze the group invariant solutions which satisfy some physical boundary conditions. The governing equation describing movements of contaminants under ra- dial water ow background may be given in conserved form. As such, the conserved form of the governing equation may be written as a system of rst order partial di erential equation referred to as an auxiliary system, by an in- troduction of the nonlocal variable. The resulting system of equations admits a number of (local) point symmetries which induce the nonlocal symmetries for the original governing equation. We construct classes of solutions using the admitted genuine nonlocal symmetries, which include the invariant solutions obtained via corresponding point symmetries of the governing equation.

Typescript (photocopy). / Digitized by Kansas Correctional Industries

In this research project, systematic studies of polymer-assisted flocculation and dewatering behaviour of colloidal gibbsite (y-Al(OH)3) dispersions, together with polymeric flocculant structure-mediated interfacial chemistry and particle interactions, have been performed. Clear links between flocculation performance, interfacial chemistry, particle interactions, dispersion settling rate and sediment consolidation were established for improved dewaterability.