A PRICE-SUPPORT PROGRAM FOR FARM COMMODITIES

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Springs of Florida

bulletin which documented the major and important springs in the state (Ferguson et al., 1947). This publication was revised in 1977, with many previously undocumented springs and many new water-quality analyses being added (Rosenau et al., 1977). The Florida Geological Survey's report on first magnitude springs (Scott et al., 2002) was the initial step in once again updating and revising the Springs of Florida bulletin. The new bulletin includes the spring descriptions and water-quality analyses from Scott et al. (2002). Nearly 300 springs were described in 1977. As of 2004, more than 700 springs have been recognized in the state and more are reported each year. To date, 33 first magnitude springs (with a flow greater than 100 cubic feet per second or approximately 64.6 million gallons of water per day) have been recognized in Florida, more than any other state or country (Rosenau et al., 1977). Our springs are a unique and invaluable natural resource. A comprehensive understanding of the spring systems will provide the basis for their protection and wise use. (Document pdf contains 677 pages

Development and evaluation of an intervention to improve further education students' understanding of higher education assessment criteria: three studies

Three studies about helping Further Education students prepare for study at universityThis paper reports three studies about preparing Further Education (FE) students for the transition to Higher Education (HE) by improving their understanding of HE assessment criteria. In study 1, students and tutors in both FE and HE were interviewed for a qualitative analysis of their understandings and expectations about assessment criteria. In study 2, students in FE and HE completed questionnaires measuring self-rated understanding and ability about assessment criteria, and beliefs about essay writing. Studies 1 and 2 both showed that FE students were more confident than HE students about their understanding and ability in relation to assessment criteria, but FE students’ understandings suggested more surface approaches to learning and more naïve epistemological beliefs. In study 3, a workshop intervention to improve FE students’ understandings of HE assessment criteria was evaluated in a comparative longitudinal trial. The intervention reduced FE students’ self-rated understanding and ability, and promoted more sophisticated beliefs about essay writing, by comparison with students who received standard tuition. We concluded that interventions to develop more realistic understandings of what is required in academic writing could be used to prepare FE students more effectively for the transition to HE

On the eigenvalues of Cayley graphs on the symmetric group generated by a complete multipartite set of transpositions

Given a finite simple graph \cG with $n$ vertices, we can construct the Cayley graph on the symmetric group $S_n$ generated by the edges of \cG, interpreted as transpositions. We show that, if \cG is complete multipartite, the eigenvalues of the Laplacian of \Cay(\cG) have a simple expression in terms of the irreducible characters of transpositions, and of the Littlewood-Richardson coefficients. As a consequence we can prove that the Laplacians of \cG and of \Cay(\cG) have the same first nontrivial eigenvalue. This is equivalent to saying that Aldous's conjecture, asserting that the random walk and the interchange process have the same spectral gap, holds for complete multipartite graphs.Comment: 29 pages. Includes modification which appear on the published version in J. Algebraic Combi

Polyacrylamide application to soil reduces the movement of microorganisms in water

Early reports of polymer treatment of furrow irrigation inflows resulting in clarification of outflow water were made by Paganyas (1975 ) and Mitchell (1986). Paganyas did not specify the chemical polymer used, although its description suggests some type of polyacrylamide (PAM) formulation. Mitchell specified use of anionic PAM and noted stream advance time and infiltration increases. Both added PAM to furrow inflows during the advance (only) (before runoff, while water first traverses the dry furrow). Neither Paganyas nor Mitchell quantified sediment effects. Lentz et al. (1992) reported PAM-use in furrow irrigation for erosion control and increased infiltration, quantifying changes in sediment concentration and accumulation over time, sediment loss, infiltration and runoff. Lentz and Sojka(1994) reported that PAM-treatment reduced runoff water concentration of ortho-P, total-P, and nitrate, and lowered biological oxygen demand. Runoff sediment loss was reduced 94% and infiltration increased 15% in a 3 yr series of studies. Subsequently others further documented that PAM-treatment of furrow irrigation water improved runoff water quality parameters, including pesticide loads (Agassi et al., 1995; Bahr and Steiber, 1996; Singh et al., 1996). The most frequent approach in these studies involved PAM-treatment of the furrow advance stream (only). Good results were achieved with PAM application at about 1 kg/ha (1 lb/acre) applied at 10 ppm only in the advancing furrow. McCutchan et al. (1994) also reported runoff sediment load reductions, however, they applied PAM at 2.5 ppm continuously throughout the irrigation. On-farm PAM cost is about $3 to$5 per pound. Typical farmer seasonal PAM-use is 3 to 5 lbs per acre. The technology was adopted on about 1,000,000 acres in the United States as of 1998 and continues to grow rapidly in the US and overseas. The practice has received much attention in Western US states now seeking ways to meet mandated total maximum daily loads (TMDL) for various contaminants, including sediment, nitrogen, and phosphorus, in irrigation runoff and return flows

The efficacy of polyacrylamide and related compounds to remove microorganisms and nutrients from animal wastewater

Polyacrylamide (PAM) is an effective flocculent and we hypothesized that it would reduce transport of microorganisms and nutrients in water flowing over and through soil. We measured nutrients, total coliform bacteria, fecal conform bacteria, fecal streptococci, active and total fungi, and active and total bacteria in water leached through cattle, fish, and swine manure, PAM, PAM + AI(SO4)3, or PAM + CaO mixtures, and 25-cm sand columns. In the laboratory study, PAM, PAM + AI(SO4)3, and PAM + CaO treatments reduced total coliform bacteria, fecal conform bacteria, and fecal streptococci by 10- to 1000-fold in water leached through sand columns. Polyacrylamide + Al(SO4)3 and PAM + GRO treatments reduced the concentration of NH., total P, and PO, by 20 to 60% in leachate when cattle and swine manure were applied. In a field study, after water flowed over all three manure sources and then PAM, PAM + Al(SO4)3, or PAM + CaO in furrows, total conform bacteria, fecal coliform bacteria, and fecal streptococci were reduced by 10- to 1000-fold in water flowing 1 and 27 m downstream of the treatments compared with the control treatment. When water flowed over cattle manure and then PAM + Al(SO4)3 or PAM + CaO, PO, concentration was reduced by 50 to 70% and total P concentration was reduced by 0 to 75% in water 27 m downstream of the treatments compared with the PAM alone treatment. Polyacrylamide + M(504)3 and PAM + CaO should be able to reduce the numbers of enteric microorganisms and nutrient concentration in animal wastewater running off animal confinement areas, reducing the amount of these pollutants entering surface and ground waters

Predicting university performance in psychology: the role of previous performance and discipline-specific knowledge

Recent initiatives to enhance retention and widen participation ensure it is crucial to understand the factors that predict students' performance during their undergraduate degree. The present research used Structural Equation Modeling (SEM) to test three separate models that examined the extent to which British Psychology students' A-level entry qualifications predicted: (1) their performance in years 1-3 of their Psychology degree, and (2) their overall degree performance. Students' overall A-level entry qualifications positively predicted performance during their first year and overall degree performance, but negatively predicted their performance during their third year. Additionally, and more specifically, students' A-level entry qualifications in Psychology positively predicted performance in the first year only. Such findings have implications for admissions tutors, as well as for students who have not studied Psychology before but who are considering applying to do so at university

Irrigation increases inorganic carbon in agricultural soils

Inorganic C reactions are among the most important chemical reactions that occur in irrigated soils and may contribute to the total amount of C sequestered in those soils. Because CO2 can escape from soils to the atmosphere or return to precipitate carbonate minerals, soils are open systems with regard to inorganic C. We measured inorganic and organic C stored in southern Idaho soils having long-term land-use histories that supported native sagebrush vegetation (NSB), irrigated moldboard plowed crops (IMP), irrigated conservation (chisel) tilled crops (ICT), and irrigated pasture systems (IP). Inorganic C and total C (inorganic + organic C) in soil decreased in the order IMP>ICT>IP>NSB. We use our findings to estimate that amount of possible inorganic and total C sequestration if irrigated agriculture were expanded by 10%. If irrigated agricultural land were expanded by 10% worldwide and NSB were converted to IMP, a possible 1.60 x 108 Mg inorganic C (2.78% of the total C emitted in the next 30 years) could be sequestered in soil. If irrigated agricultural land were expanded by 10% worldwide and NSB were converted to ICT, a possible 1.10 x 109 Mg inorganic C (1.87% of the total C emitted in the next 30 years) could be sequestered in soil. If irrigated agricultural land were expanded worldwide and NSB were converted to IP, a possible gain of 2.6 x 108 Mg inorganic C (0.04% of the total C emitted in the next 30 years) could be sequestered in soils. Inorganic C sequestered from land-use changes have little potential to make a significant impact on the concentration of atmospheric CO2. However, when coupled with organic C and altering land use to produce crops on high-output irrigated agriculture while selected less productive rain-fed agricultural land was returned to temperate forest or native grassland, there could be reductions in atmospheric CO2

Irrigation increases carbon in agricultural soils

Irrigated agriculture sequesters significant amounts of organic C. Irrigation may also sequester significant amounts of inorganic C. Inorganic C reactions are important chemical reactions in irrigated soils and may contribute to the total amount of C sequestered. Calcium content of arid and semi-arid soils tends to be higher than rainfed temperate soils due to calcium rich parent material and low rainfall. Carbonate formation is usually controlled by carbonate equilibrium reactions in the solid and g as phase CO2 . Respiration in plant roots and soil microorganisms continually produce CO, increasing its concentration in the soil atmosphere, modifying carbonate solubility. Since irrigation water flows through a series of canals, where smaller amounts of water are directly exposed to incoming radiation, irrigation water usually has higher temperatures than stream or ground water. Carbon dioxide dissolves in water to form both CO2 as a gas and H2CO3 in solution. Warmer water increases reaction time and, in favourable conditions, precipitates CaCO3 .We measured organic and inorganic C stored in southern Idaho soils having long term land use histories that supported native sagebrush vegetation (NSB), irrigated mouldboard ploughed crops (IMP), irrigated conservation - chisel- tilled crops (ICT) and irrigated pasture systems (IP). Inorganic C and total C (inorganic + organic C) in soil decreased in the order IMP>ICT>IP>NSB. We use our findings to estimate the amount of possible organic, inorganic and total C sequestration if irrigated agriculture were expanded by 10%. If irrigated agricultural land were expanded by 10% worldwide and NSB were converted to IMP, a possible 1.90 x 10' Mg total (organic +inorganic) C (2.72 % of the total C emitted in the next 30 yr) could be sequestered in soil. If irrigated agricultural lands were expanded by 10% worldwide and NSB were converted to ICT, a possible 1.30 x 10' Mg total C (2.24 % of the total C emitted in the next 30 yr) could be sequestered in soil. If irrigated agricultural land were expanded worldwide and NSB were converted to IP a possible gain of 1.7 x 10 8 Mg total C (1.174 % of the total C emitted in the next 30 yr) could be sequestered in soils. Altering land use to produce crops on high output irrigated agriculture, while selected less-productive rainfed agricultural land were returned to temperate forest or native grassland. there could be meaningful reductions in atmospheric CO 2