Leaching and surface runoff losses of sulphur and potassium from a Tokomaru soil : a thesis presented in partial fulfilment of the requirements for the degree of Master of Philosophy in Soil Science at Massey University

Sulphur and potassium surface and subsurface drainage water losses from grazed pastures on a yellow-grey earth soil, the Tokomaru silt loam, were investigated in field experiments. Runoff losses from undrained and drained pastures fertilised in spring or autumn were measured over a six week winter interval in 1976. Losses from undrained pastures were measured throughout the runoff season in 1977. In 1977, S and K leaching losses from pastures fertilised in spring or autumn, were determined by measuring tile drainage water losses and monitoring changes in soil S and K levels. An attempt was also made to relate soil S and K levels to tile drainage water losses. This field study illustrates that SO4 -S is readily leached in the Tokomaru silt loam. Losses in tile drainage waters occurred from all depths above the mole drains (i.e. 45 cm depth) during individual flow events. On average 7.5 kg dissolved S04 -S ha-1 was lost from the two non-irrigated pastures fertilised in spring. An additional 6.7 kg SO4 -S ha-1 was discharged in tile drainage waters from two irrigated pastures fertilised in spring (i.e. total 14.2 kg SO4 -S ha-1 ). Evidence indicated that SO4 -S may have bypassed the drains in water seeping beyond the fragipan. An autumn application of fertiliser S (45 kg S ha-1 ) significantly enhanced the extent of leaching. The equivalent of 10% of the applied S (4.47 ± 1.5 kg SO4 -S ha-1 ) was leached over a period of 17 weeks from July 1 to September 21. Losses occurred throughout this period. On average, 15.2 kg SO4 -S ha>-1 was discharged from the two non-irrigated pastures fertilised in autumn. An additional 3.4 kg SO4 S ha-1 was lost from the two irrigated pastures. An appreciable quantity (13.8 kg SO4 -S ha-1 ) of the fertiliser S applied in autumn but not leached in tile drainage waters, was recovered as water soluble SO4 -S, leached below the 20 cm depth (i.e. below the zone from which pasture species are likely to obtain most of their S. Over a period of six weeks in 1976, 0.9 kg SO4 -S ha-1 was lost in surface runoff from an undrained pasture fertilised (19 kg S ha-1 in superphosphate) in spring. Less SO4 -S was lost from the associated drained plot (0.2 kg SO4 -S ha-1 ). Undrained and drained plots fertilised in autumn (57 kg S ha-1 in superphosphate) lost 8% and 1.8% of the S applied (i.e. 5.5 and 0.9 kg SO4 -S ha-1 ) respectively. In 1977, on average only 0.8 kg SO4 -S ha-1 was transported in surface runoff off two undrained plots fertilised (36 kg S ha-1 in superphosphate) in spring. An average of 8.0 kg SO4 -S ha-1 was lost from two plots fertilised (55 kg solution S ha-1 ) in autumn. Hence surface runoff is an important S loss mechanism if undrained plots are fertilised in autum. Sulphur received in the rainfall over a five month interval in 1977 amounted to 3.1 kg ha-1 . From these results it was concluded that total drainage water losses from non-irrigated, drained pastures were likely to be largely offset by S received in the rain in 1977. A significant net S loss (in relation to annual pasture S requirements) will have occurred from pastures irrigated the preceding summer and/or fertilised in autumn. Sulphur fertilisation in autumn and winter is not recommended. Under the conditions likely to prevail at this time an appreciable fraction of the applied S may be lost in drainage waters. Results of this study indicate that leaching is not an important K loss process in the Tokomaru silt loam. Dissolved K leaching losses from pastures fertilised in spring or autumn averaged 4.66 and 4.05 kg K ha-1 respectively. Potassium surface runoff losses are generally of no consequence. In 1976 only 1.1 kg K ha-1 was lost from an undrained pasture fertilised (50 kg K ha-1 ) in spring, whilst 0.3 kg K ha-1 was discharged from the associated drained plot. A minimal fraction (3%) of the K applied in autumn (50 kg K ha-1 ) to an undrained plot was lost in surface runoff. Less than 1% of that applied was discharged from the associated drained plot. Throughout 1977, on average, 1.35 kg K ha-1 was discharged from undrained plots fertilised (57 kg K ha-1 ) in spring. An additional 3.75 kg K ha-1 was lost from pastures fertilised (55 kg K ha-1 ) in autumn. Rainfall K additions measured ever a five month interval in 1977 were low (total 1.4 kg K ha-1 ). However, because of the trend for K concentrations to vary on a seasonal basis it was concluded that K received in rainfall throughout 1977 was likely to largely offset total drainage water losses from undrained and drained pastures. The results indicate that K deficiencies in pasture on K retentive yellow-grey earth soils are not attributable to drainage water losses. Regression analyses showed that SO4 -S concentrations in leachate, but not SO4 -S loadings, were significantly related to water soluble soil SO4 -S levels (0-40 cm), determined at frequent intervals during the drainage season, if the quantity of water percolating through the soil is measured. No relationship was found between measured water soluble or ammonium acetate extractable soil K levels and leachate K concentrations or loadings

Individual and Group Performance on Insight Problems: The Effects of Experimentally Induced Fixation

Recent research has shown that the benefits associated with incubation periods during individual problem solving can be explained in terms of forgetting the material or of any strategy that serves to block progress toward success (e.g., Smith & Blankenship, 1991). While interacting groups reliably outperform individuals on both problem-solving and recall tasks, groups’ superior memory capacity may serve to hinder problem solving, especially when fixation has occurred. In the present study, individuals and three-person groups attempted to solve a set of 20 rebus puzzles on two different occasions. In the first session rebuses were accompanied by “clues,” that were designed to either help or hinder problem solving. Following a 15-minute filled incubation period, the rebuses were again presented without the clues. As expected, groups recalled more of the clues than did individual problem solvers. Additionally, individual problem-solvers’ performance was improved following the incubation period on the misleading clue items but not the good clue items. Following incubation, groups improved on both the helpful and misleading clue items. The possibility that incubation effects may vary with task type in group problem-solving contexts is discussed

Investment Decisions by Individuals and Groups in \u27Sunk Cost\u27 Situations: The Potential Impact of Shared Representations

Past research has shown that individuals prefer to continue investing resources into a failing endeavor once a considerable investment has been made, even when abandoning the project would be more rational economically. This phenomenon has been labeled the sunk cost effect (Arkes & Blumer, 1985). Since investment decisions are often made by groups, we compared individual and group propensities for falling prey to the sunk cost effect. we also varied whether or not individuals and groups needed to justify their investment decision to a superior. Both individuals and groups showed the sunk cost effect. Group process analyses showed that error-prone majorities were more powerful than more rational minorities. In addition, group decisions seemed to be a function of two competing task representations--one favoring the sunk cost interpretation and the other favoring economic rationality

The role of cosmic ray pressure in accelerating galactic outflows

We study the formation of galactic outflows from supernova explosions (SNe) with the moving-mesh code AREPO in a stratified column of gas with a surface density similar to the Milky Way disk at the solar circle. We compare different simulation models for SNe placement and energy feedback, including cosmic rays (CR), and find that models that place SNe in dense gas and account for CR diffusion are able to drive outflows with similar mass loading as obtained from a random placement of SNe with no CRs. Despite this similarity, CR-driven outflows differ in several other key properties including their overall clumpiness and velocity. Moreover, the forces driving these outflows originate in different sources of pressure, with the CR diffusion model relying on non-thermal pressure gradients to create an outflow driven by internal pressure and the random-placement model depending on kinetic pressure gradients to propel a ballistic outflow. CRs therefore appear to be non-negligible physics in the formation of outflows from the interstellar medium.Comment: 8 pages, 4 figures, accepted for publication in ApJL; movie of simulated gas densities can be found here: http://www.h-its.org/tap-images/galactic-outflows

Elementary school grade retention : a qualitative study of high school seniors' perceptions of being held back

Studies dating back to the 1920s have argued the effects of retention on the academic achievement, social adjustment, and emotional states of students. Researchers have shown the detrimental outcomes as well as the benefits of holding students back in elementary school. Studies regarding the phenomenon are substantially quantitative, and comparatively, qualitative studies are few in number. This study fills a void in the qualitative research by examining the experiences of 22 high school seniors, all of whom planned to participate in post high school education, who have been held back a grade in elementary school. Most of the participants did not want to be held back at the time they were retained, fearing they would lose their friends. However, they all exhibited resiliency as they overcame their challenges and found success in school. Examples of resiliency were viewed through the lens of the transactional model of development. The cascade of events in their lives illustrated their pathways that lead them to graduating high school with a college preparatory diploma. Many of the participants saw the benefits of retention on their academic achievement. Several viewed retention merely as prolonging their schooling. Protective factors included mother‘s support, family support, early academic interventions, extra-curricular activities in high school, and early grade retention. Participants advised educators to consider all of a student‘s personal stories, and envision his or her future when deciding upon retention

Pharmacist-led management of chronic pain in primary care:results from a randomised controlled exploratory trial

To compare the effectiveness of pharmacist medication review, with or without pharmacist prescribing, with standard care, for patients with chronic pain

Corporate governance, market valuation and dividend policy in Brazil

This study investigates the effects of the corporate governance structure on market valuation and dividend payout of Brazilian companies. The empirical results indicate a high degree of ownership and control concentration. We can also note a significant difference between the voting and total capital owned by the largest shareholders, mainly through the existence of non-voting shares, pyramidal structures, and shareholding agreements. These mechanisms seem to be used by controlling shareholders to keep the firm’s control without having to own 50% of the total capital. The evidence also reveals that there is a relationship between governance structure, market valuation, and dividend policy in Brazil.Indisponível