Thesis (Ph. D.)--University of Wisconsin--Madison, 1954. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 101-107).

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Soil moisture distribution resulting from a line source subsurface trickle irrigation system was studied on bare and cropped layered soils. The soil type was an Uchee loamy sand. The Continuous System Modeling Program (CSMP) Model was used to simulate the soil moisture distribution resulting from the linesource. The model was modified and developed in FORTRAN programming language. The modification included the effects of layered soil, source position, number of sources, soil evaporation and plant transpiration. The model was also used to simulate daily and one-in-several-days irrigations. Field and laboratory experiments were conducted to determine the soil moisture retention curve, the hydraulic conductivity, and soil moisture distribution from the line source. This data was used for model verification with the lateral lines buried 13 inches below the soil surface and spaced 36 and 72 inches apart. Simulated and measured soil moisture distributions were in good agreement. Simulated moisture distribution indicated that the wetting front expansion is more a function of irrigation volume than irrigation rate. However, the irrigation rate does affect the soil moisture distribution. A higher rate will result in a larger quantity of horizontal water movement. The simulation also indicated that a one-in-ten days irrigation causes more horizontal movement than a daily irrigation. / Master of Science

Master of Science

Please read the abstract in the section 00front of this document / Dissertation (MSc (Soil Science))--University of Pretoria, 2007. / Plant Production and Soil Science / unrestricted

Content: To reduce the environmental impact of tanneries at source for all types of leather, a series of investigations started at laboratory, then large pilot scale, to rationalise liming and tanning processes. This included the elimination of washes at the end of these processes, with retention of residual processing floats at maximum concentration as a chemical resource for reuse in subsequent processing. Adopted by four tanneries manufacturing more than 70,000 hides per week to the chromium tanned state, analysis detailing the equalisation of ions and solubles within these closed-loops was possible, and the subsequent release mechanisms. Large scale wet blue units specifically built to match the technology are now in the final stages of construction. From foundation level these differ from normal design, also uses of equipment, management of discharges, and plant operation. Low-impact chemical processing is locked into the fabric of these new tanneries. The technology has also spread to large scale nappa sheepskin production. And at cottage scale, thirty small tanneries in a tanning cluster processing sheep, goat, and bovine leathers to the wet blue are already changed their processing to meet a policy of no chromium discharges from their tanning areas by June 2019. The aims of low-impact manufacture, where the use of active chemicals is complete, quality fully maintained, and waste minimised are being met. This new approach to leather making offers considerable benefits at both large and small scale for wet blue manufacture. Take-Away: Closed loop systems for liming and tanning are highly effective in leather manufacture. Hight quality leathers can result fron this technology. There are considerable savings in chemical use and minimisation of waste water treatment.

Call number: LD2668 .T4 1956 L33 / Master of Science

One of today's major environmental issues is algal blooms linked to eutrophication of lakes and oceans. That is a result of anthropogenic influence with nutrient loads (including phosphorus) from agriculture and industry, which benefits primary production (phytoplankton). Studies have shown that phosphorus availability in the water column can be limited by liming, therefore could be a way to counteract eutrophication. This was tested in the agriculturally surrounded lake Tåkern in southern Sweden, which in its present state is an internationally important bird lake and therefore in several respects would be affected by eutrophication. The purpose of this study was to investigate whether liming would be a good solution to solve any future eutrophication problems in Lake Tåkern. Liming experiments were performed in mesocosms during April 2015 with a mixture of limestone and slaked lime. Quantity and diversity of plankton and water chemical variables were measured before and after liming. Moreover, samples of phytoplankton from a similar experiment conducted in July 2014 were analyzed. Liming did not show any effect on neither phyto- nor zooplankton when performed in spring of 2015. During summer of 2014, there was an increase in number of phytoplankton (ml-1 ) and chlorophyll in controls while the study showed constant levels in treated mesocosms. For zooplankton there was no significant effects of liming on neither quantity nor diversity. Results of this study suggest that liming is not the most appropriate method to resolve eutrophication in Lake Tåkern.

Magistro darbe tiriamas skirtingų kalkinių medžiagų poveikis dirvožemio potencialiajam rūgštingumui ir judriajam aliuminiui. Darbo objektas – keturios kalkinės medžiagos: malta kreida, „Agrokalkės” (klinčių ir nedegtų kalkių miltelių mišinys), dolomitmičiai (dolomito atsijos), ir granuliuota kalkinė medžiaga „Kalktrąšė”. Darbo metodai – kalkinėmis medžiagomis buvo pakalkintos dvi, pasotinto balkšvažemio Dystric Albeluvisol ir nepasotinto balkšvažemio Eutric Albeluvisol, lauko bandymų aikštelės; dirvožemio potencialusis rūgštingumas nustatytas laboratorijoje elektroniniu pH-metru, judriojo aliuminio kiekis Sokolovo metodu; gauti duomenys palyginti tarpusavyje matematiniais-statistiniais metodais. Darbo rezultatai. Atlikus tyrimus nustatyta, kad efektyviausiai, bei statistiškai patikimai (p<0,05) dirvožemio rūgštingumą sumažino dulkios kalkinės medžiagos – kreida ir „Agrokalkės”. Stambesnės frakcijos, trupintos kalkinės medžiagos – dolomitmičių statistiškai patikimas poveikis nustatytas tik antrojoje bandymų aikštelėje nepasotintame balkšvažemyje Eutric Albeluvisol praėjus aštuoniolikai mėnesių po kalkinimo. Granuliuota kalkinė medžiaga „Kalktrąšė“ statistiškai nepatikimai veikė dirvožemio rūgštingumą. Efektyviausiai (99%) statistiškai patikimai (p<0,05), judriojo Al kiekį sumažino „Agrokalkės“. Taip pat efektyviai, kreida 97% ir dolomitmilčiai 79%, statistiškai patikimai (p<0,05) sumažino judriojo Al kiekį dirvožemyje. „Kalktrąšė“ iš visų tirtų kalkinių medžiagų prasčiausiai... [toliau žr. visą tekstą] / The Master Thesis analyses the impact of different liming materials on potential soil acidity and mobile aluminium. Object – four liming materials: powder chalk, agrolime (mixture of limestone and uncalcined lime powder), dolomite powder (dolomite siftings), and pelletized lime fertilizer “Kalktrąšė”. Methods – two experimental field plots, Dystric Albeluvisol and Eutric Albeluvisol, had been limed using four different liming materials; potential soil acidity had been determined in the laboratory by the electronic pH-metre, the amount of mobile aluminium was estimated by Sokolov method; the obtained data were inter-compared by the mathematical-statistical methods. Results. The research demonstrated that the use of powdered lime materials, i.e. chalk and agrolime, resulted in the most effective and statistically reliable (p<0.05) reduction of soil acidity. A statistically reliable impact of dolomite powder, a crushed lime material of larger fractions, was recorded only in the second testing ground, Eutric Albeluvisol, eighteen months after liming. Moreover, the effect of pelletized lime fertilizer “Kalktrąšė” on soil acidity was not statistically reliable. In contrast, agrolime was the most effective (99%) and statistically reliable (p<0.05) in reducing the amount of mobile aluminium. A similar, statistically reliable (p<0.05) impact was caused by chalk 97% and dolomite 79% powder (p<0.05), what reduce mobile Al in soil. Among all liming materials “Kalktrąšė” resulted in the... [to full text]