Effects of fertilizer type and rate on partitioning of soil organic matter into pools of different stability

Type and rate of fertilizers influence the level of soil organic carbon (Corg) and total nitrogen (Nt) markedly, but the effect on C and N partitioning into different pools is open to question. The objectives of the present work were to: (i) quantify the impact of fertilizer type and rate on labile, intermediate and passive C and N pools by using a combination of biological, chemical and mathematical methods; (ii) explain previously reported differences in the soil organic matter (SOM) levels between soils receiving farmyard manure with or without biodynamic preparations by using Corg time series and information on SOM partitioning; and (iii) quantify the long-term and short-term dynamics of SOM in density fractions and microbial biomass as affected by fertilizer type and rate and determine the incorporation of crop residues into labile SOM fractions. Samples were taken from a sandy Cambisol from the long-term fertilization trial in Darmstadt, Germany, founded in 1980. The nine treatments (four field replicates) were: straw incorporation plus application of mineral fertilizer (MSI) and application of rotted farmyard manure with (DYN) or without (FYM) addition of biodynamic preparations, each at high (140 – 150 kg N ha-1 year-1; MSIH, DYNH, FYMH), medium (100 kg N ha-1 year-1; MSIM, DYNM, FYMM) and low (50 – 60 kg N ha-1 year-1; MSIL, DYNL, FYML) rates. The main findings were: (i) The stocks of Corg (t ha-1) were affected by fertilizer type and rate and increased in the order MSIL (23.6), MSIM (23.7), MSIH (24.2) < FYML (25.3) < FYMM (28.1), FYMH (28.1). Stocks of Nt were affected in the same way (C/N ratio: 11). Storage of C and N in the modelled labile pools (turnover times: 462 and 153 days for C and N, respectively) were not influenced by the type of fertilizer (FYM and MSI) but depended significantly (p ≤ 0.05) on the application rate and ranged from 1.8 to 3.2 t C ha 1 (7 – 13% of Corg) and from 90 to 140 kg N ha-1 (4-5% of Nt). In the calculated intermediate pool (C/N ratio 7), stocks of C were markedly higher in FYM treatments (15-18 t ha-1) compared to MSI treatments (12-14 t ha-1). This showed that differences in SOM stocks in the sandy Cambisol induced by fertilizer rate may be short-lived in case of changing management, but differences induced by fertilizer type may persist for decades. (ii) Crop yields, estimated C inputs (1.5 t ha-1 year-1) with crop residue, microbial bio¬mass C (Cmic, 118 – 150 mg kg-1), microbial biomass N (17 – 20 mg kg-1) and labile C and N pools did not differ significantly between FYM and DYN treatments. However, labile C increased linearly with application rate (R2 = 0.53) from 7 to 11% of Corg. This also applied for labile N (3.5 to 4.9% of Nt). The higher contents of Corg in DYN treatments existed since 1982, when the first sampling was conducted for all individual treatments. Contents of Corg between DYN and FYM treatments con-verged slightly since then. Furthermore, at least 30% of the difference in Corg was located in the passive pool where a treatment effect could be excluded. Therefore, the reported differences in Corg contents existed most likely since the beginning of the experiment and, as a single factor of biodynamic agriculture, application of bio-dynamic preparations had no effect on SOM stocks. (iii) Stocks of SOM, light fraction organic C (LFOC, ρ ≤ 2.0 g cm-3), light fraction organic N and Cmic decreased in the order FYMH > FYML > MSIH, MSIL for all sampling dates in 2008 (March, May, September, December). However, statistical significance of treatment effects differed between the dates, probably due to dif-ferences in the spatial variation throughout the year. The high proportion of LFOC on total Corg stocks (45 – 55%) highlighted the importance of selective preservation of OM as a stabilization mechanism in this sandy Cambisol. The apparent turnover time of LFOC was between 21 and 32 years, which agreed very well with studies with substantially longer vegetation change compared to our study. Overall, both approaches; (I) the combination of incubation, chemical fractionation and simple modelling and (II) the density fractionation; provided complementary information on the partitioning of SOM into pools of different stability. The density fractionation showed that differences in Corg stocks between FYM and MSI treatments were mainly located in the light fraction, i.e. induced by higher recalcitrance of the organic input in the FYM treatments. Moreover, the use of the combination of biological, chemical and mathematical methods indicated that effects of fertilizer rate on total Corg and Nt stocks may be short-lived, but that the effect of fertilizer type may persist for longer time spans in the sandy Cambisol.

Influence of education levels on dissemination of soil fertility management information in the central highlands of Kenya

Inadequate links between researchers and farmers has resulted in low uptake of research advances recommended to improve food security in the central highlands of Kenya. Access to timely and accurate information by extension agents and farmers is paramount in dissemination of soil fertility management practices. Hence, the study sought to investigate the effect of education levels on communication channels used to disseminate soil fertility technologies in the Central highlands of Kenya. Questionnaires were used to elicit information from 105 extension agents and 240 farmers. About 50.5% of the extension officers were certificate holders while 29.5% were diploma holders from agricultural institutes. Majority of the farmers had attained primary education (59.6%) while 25.8% and 9.2% had attained secondary and post secondary education, respectively. Research institutions were the most accessible sources of information on soil fertility management practices by extension agents while internet and scientific conferences were the least scored as accessible sources of soil fertility management information by extension agents. Education levels significantly influenced preference of individual approach methods by farmers. There was a significant positive relationship between education and accessibility of internet as a source of information on green manure. The implication of the study was that education levels influenced the mode of communication used in the transfer of soil fertility research outputs to the end users. Consequently, it is extremely important to consider education levels in selection of dissemination pathways used in agriculture.

Testing for Hidden Information and Action in Automobile Insurance Market

I test the presence of hidden information and action in the automobile insurance market using a data set from several Colombian insurers. To identify the presence of hidden information I find a common knowledge variable providing information on policyholder s risk type which is related to both experienced risk and insurance demand and that was excluded from the pricing mechanism. Such unused variable is the record of policyholder s traffic offenses. I find evidence of adverse selection in six of the nine insurance companies for which the test is performed. From the point of view of hidden action I develop a dynamic model of effort in accident prevention given an insurance contract with bonus experience rating scheme and I show that individual accident probability decreases with previous accidents. This result brings a testable implication for the empirical identification of hidden action and based on that result I estimate an econometric model of the time spans between the purchase of the insurance and the first claim, between the first claim and the second one, and so on. I find strong evidence on the existence of unobserved heterogeneity that deceives the testable implication. Once the unobserved heterogeneity is controlled, I find conclusive statistical grounds supporting the presence of moral hazard in the Colombian insurance market.

Changing Education Paradigms - Sir Ken Robinson

This animation was adapted from a talk given at the RSA by Sir Ken Robinson, world-renowned education and creativity expert and recipient of the RSA's Benjamin Franklin award. For more information on Sir Ken's work visit: http://www.sirkenrobinson.com

The Representative Soil Sampling Scheme of England and Wales: a statistical analysis of topsoil nutrient status and pH between 1971 and 2001

The Representative Soil Sampling Scheme of England and Wales has recorded information on the soil of agricultural land in England and Wales since 1969. It is a valuable source of information about the soil in the context of monitoring for sustainable agricultural development. Changes in soil nutrient status and pH were examined over the period 1971-2001. Several methods of statistical analysis were applied to data from the surveys during this period. The main focus here is on the data for 1971, 1981, 1991 and 2001. The results of examining change over time in general show that levels of potassium in the soil have increased, those of magnesium have remained fairly constant, those of phosphorus have declined and pH has changed little. Future sampling needs have been assessed in the context of monitoring, to determine the mean at a given level of confidence and tolerable error and to detect change in the mean over time at these same levels over periods of 5 and 10 years. The results of a non-hierarchical multivariate classification suggest that England and Wales could be stratified to optimize future sampling and analysis. To monitor soil quality and health more generally than for agriculture, more of the country should be sampled and a wider range of properties recorded.

Effect of Information about benefits of biotechnology on consumer acceptance of genetically modified food; evidence from experimental auctions in the United States, England, and France

This study investigates the effect of information about potential benefits of biotechnology on consumer acceptance of genetically modified (GM) foods. Consumer willingness to accept compensation to consume a GM food was elicited using an incentive compatible auction mechanism in three US states (California, Florida, and Texas) and in two European countries (England and France). Results indicate that information on environmental benefits, health benefits and benefits to the third world significantly decreased the amount of money consumers demanded to consume GM food; however, the effect of information varied by type of information and location. Consistent with prior research, we find that initial attitudes toward biotechnology have a significant effect on how individuals responded to new information.

Design and formative evaluation of an information kiosk on cattle health for landless cattle owners

This paper describes and analyses the experience of designing, installing and evaluating a farmer-usable touch screen information kiosk on cattle health in a veterinary institution in Pondicherry. The contents of the kiosk were prepared based on identified demands for information on cattle health, arrived at through various stakeholders meetings. Information on these cattle diseases and conditions affecting the livelihoods of the poor was provided through graphics, text and audio back-up, keeping in mind the needs of landless and illiterate poor cattle owners. A methodology for kiosk evaluation based on the feedback obtained from kiosk facilitator, critical group reflection and individual users was formulated. The formative evaluation reveals the potential strength this ICT has in transferring information to the cattle owners in a service delivery centre. Such information is vital in preventing diseases and helps cattle owners to present and treat their animals at an early stage of disease condition. This in turn helps prevent direct and indirect losses to the cattle owners. The study reveals how an information kiosk installed at a government institution as a freely accessible source of information to all farmers irrespective of their class and caste can help in transfer of information among poor cattle owners, provided periodic updating, interactivity and communication variability are taken care of. Being in the veterinary centre, the kiosk helps stimulate dialogue, and facilitates demand of services based on the information provided by the kiosk screens.

A statistical evaluation of the fixed dose procedure

The fixed-dose procedure (FDP) was introduced as OECD Test Guideline 420 in 1992, as an alternative to the conventional median lethal dose (LD50) test for the assessment of acute oral toxicity (OECD Test Guideline 401). The FDP uses fewer animals and causes less suffering than the conventional test, while providing information on the acute toxicity to allow substances to be ranked according to the EU hazard classification system. Recently the FDP has been revised, with the aim of providing further reductions and refinements, and classification according to the criteria of the Globally Harmonized Hazard Classification and Labelling scheme (GHS). This paper describes the revised FDP and analyses its properties, as determined by a statistical modelling approach. The analysis shows that the revised FDP classifies substances for acute oral toxicity generally in the same, or a more stringent, hazard class as that based on the LD50 value, according to either the GHS or the EU classification scheme. The likelihood of achieving the same classification is greatest for substances with a steep dose-response curve and median toxic dose (TD50) close to the LD50. The revised FDP usually requires five or six animals with two or fewer dying as a result of treatment in most cases.

Effects of active information processing on the understanding of risk information

Two experiments investigated effects of active processing of risk information on participants' understanding and judgments. It was hypothesized that more active processing would lead to better understanding and differences in affective judgments (e.g. increased satisfaction and reduced perceived risk to health). In both experiments participants were given a written scenario about their being prescribed a fictitious medication. This medication was said to cause side effects in 2% of people who took it. Before answering a series of written questions, participants in the active conditions of both experiments were asked to carry out a reflective task (portraying the size of risk on a bar chart in Experiment 1 and answering a reflective question in Experiment 2). The results showed that active participants rated the likelihood of experiencing possible side effects significantly lower than passive participants (Experiment 1), and that active participants were significantly more satisfied with the information and judged perceived risk to health from taking the medication significantly lower than passive participants (Experiment 2). In both experiments, active participants were significantly more correct in their probability and frequency estimates. The studies demonstrate that active processing of risk information leads to improved understanding of the information given. This has important implications for risk communication. In the context of health, better understanding should lead to improved decision-making and health outcomes. Copyright (C) 2004 John Wiley Sons, Ltd.

On the design of opportunistic cooperative transmission strategies with partial CSI information

The aim of this paper is to study the impact of channel state information on the design of cooperative transmission protocols. This is motivated by the fact that the performance gain achieved by cooperative diversity comes at the price of the extra bandwidth resource consumption. Several opportunistic relaying strategies are developed to fully utilize the different types of a priori channel information. The information-theoretic measures such as outage probability and diversity-multiplexing tradeoff are developed for the proposed protocols. The analytical and numerical results demonstrate that the use of such a priori information increases the spectral efficiency of cooperative diversity, especially at low signal-to-noise ratio.

The impacts of learning styles, learning patterns and demographic factors on learners’ performance in a blended learning environment

Many studies have widely accepted the assumption that learning processes can be promoted when teaching styles and learning styles are well matched. In this study, the synergy between learning styles, learning patterns, and gender as a selected demographic feature and learners’ performance were quantitatively investigated in a blended learning setting. This environment adopts a traditional teaching approach of ‘one-sizefits-all’ without considering individual user’s preferences and attitudes. Hence, evidence can be provided about the value of taking such factors into account in Adaptive Educational Hypermedia Systems (AEHSs). Felder and Soloman’s Index of Learning Styles (ILS) was used to identify the learning styles of 59 undergraduate students at the University of Babylon. Five hypotheses were investigated in the experiment. Our findings show that there is no statistical significance in some of the assessed factors. However, processing dimension, the total number of hits on course website and gender indicated a statistical significance on learners’ performance. This finding needs more investigation in order to identify the effective factors on students’ achievement to be considered in Adaptive Educational Hypermedia Systems (AEHSs).

Multivariate modelling of landuse on in-stream salinity over multiple spatial scales

An impediment to sustainable dryland salinity management is the lack of information on contributing factors. GIS and satellite imagery now offer a cost-effective means of generating relevant land and water resource information for integrated regional management of salinity. In this paper the relationships between patterns in land uselcover distribution and base flow salt concentration in streams (indicated by EC) are investigated and modelled. The Glenelg-Hopkins area is a large regional watershed in southwest Victoria, Australia, covering approximately 2.6 million ha. It is currently estimated that 27,400 ha of land is affected by dryland salinity and this is predicted to rapidly increase in the next decade' if current conditions prevail. Salt concentration data from five gauging stations were analysed with multi-temporal land use maps obtained from satellite imagery. Multiple regression analyses demonstrated that the variables Native Vegetation and Dry/and Grain Cropping were the most significant influences on in~stream salinity in the whole catchment (1=88.9%) and 500 m V=88.3%) and 100 m riparian buffers (1=86.9%) during times of base flow. The implications for future land use planning, effectiveness of riparian zones and revegetation programmes is discussed. This work also demonstrates the utility of applying nmltivariate statistical analyses, spatial statistics, and remote sensing with data integrated in a GIS framework for the purpose of predicting and managing the regional salinity threat.

The successful school: a genuine trend or a statistical artifice?

Schools are increasingly being expected to make improvements based on data about students' learning outcomes. Such an expectation implies that principals, teachers and key personnel within systems can read and act upon the data available. There is evidence, however, that many people have poor understanding of statistical information, and that many factors inside and outside the school have an effect on students' outcomes. This study considers one primary school's data from statewide testing programs. Trends across time are considered as a basis for making judgments about the school's performance in improving students' learning outcomes in literacy and numeracy.

Monitoring the marine environment adjacent to a petroleum refinery on Corio Bay, Victoria, Australia /Peter James Gilbert

The objective of the work reported in this thesis was to design and implement an ecological effects environmental monitoring program which would: 1) Collect baseline biological information on sessile epibiotic fouling communities from an area adjacent to a petroleum refinery located on Corio Bay, Victoria, to allow comparison with results of future monitoring for the assessment of long term temporal water quality trends. 2) Detect and — if possible - estimate the magnitude of any influence on epibiotic fouling communities within the Corio Bay marine ecosystem attributable to operations at the Shell Petroleum Refinery. 3) Investigate the extent of thermal stratification and rate of dispersal of the petroleum refinery main cooling-water outfall plume (discharging up to 350,000 tonnes of warmed seawater per day), and its effect on epibiotic communities within the EPA-defined mixing zone. A major component of the work undertaken was the design and development of artificial-substrate biological sampling stations suitable for use under the conditions prevailing in Corio Bay, and the development of appropriate quantitative underwater photographic sampling techniques to fulfil the experimental criteria outlined above. Experimental and other constraints imposed on the design of the stations precluded the simple suspension of frames from jetties or pylons, a technique widely used in previous work of this type. Artificial substrate panels were deployed along three radial transects centred within and extending beyond the petroleum refinery main cooling-water mixing zone. Identical substrate panels were deployed at a number of control sites located throughout Corio Bay, each chosen for differences in their degree of exposure to such factors as water movement, depth, shipping traffic and/or comparable industrial activity. The rate of colonisation (space utilisation) and the development of epibiotic fouling communities on artificial substrate panels was monitored over two twelve-month sampling periods using quantitative underwater photographic sampling techniques. Sampling was conducted at 4-8 week intervals with the rate of panel colonisation and community structure determined via coverage measurements. Various species of marine algae, polychaete tubeworms, hydroids, barnacles, simple and colonial ascidians, sponges, bivalve molluscs and encrusting bryozoans were all detected growing on panels. Communities which established on panels within the cooling-water mixing-zone and those at control sites were compared using statistical procedures including agglomerative hierarchical cluster analysis. A photographic sample archive has been established to allow comparison with similar future studies.

Evaluation of salmon farming effects on marine systems in the inner seas of southern Chile : a large-scale mensurative experiment

The impact of salmon farming on the environment has been widely studied; there is, however, no consensus on the magnitude and quality of these effects and little information on their extent over large salmon farming areas. Forty-three salmon farm sites of which 29 are in full operation and grouped in nine locations in southern Chile were evaluated. Using statistical methods (two-way anova), no effects were found on water column variables such as nitrate, ammonia, orthophosphate and chlorophyll, whereas they were significant on sediment variables such as nitrogen (N), phosphorus (P) and organic carbon (OC), among others. Natural variability evaluation of some parameters revealed that P in sediments had the lowest coefficient of variation (23.2%) when compared with N (65.2%), particulate organic matter (POM) (139%) and OC (39%), and showed more marked salmon farming effects with no locality effects. Four of the nine locations showed stronger effects on sediments, with average P values ranging from 150 to 230 mmol that were six to nine times higher than in control sites (25 mmol). Nitrogen and carbon in sediments, while showing significant effects on salmon farming, also showed locality effects that revealed other biogenic processes influencing sediment composition. Thus, P in sediments was proposed as a promising indicator of impact on salmon farming, although the relationship with fauna in sediments was not linear and somewhat variable; more research is therefore needed to understand such connections. Considering entire geographical locations, no relationship was found between sediment conditions under salmon cages and the condition of the water column at a farm. This may indicate the possibility of high dilution rates and recycling processes, which so far preclude the detection of more global impacts beyond the cages shadow.