Physical Sciences and Mathematics Commons^™

Runoff From Fescue Plots Treated With Trimec, Cristopher G. Moss, Dwayne R. Edwards, Stephen R. Workman, R. Michael Williams

Biosystems and Agricultural Engineering Faculty Publications

Runoff of herbicides can promote adverse impacts in receiving waters. The objective of this study was to assess the effects of rainfall delay, herbicide application rate, rainfall intensity, and pre-application rainfall on runoff of TRIMEC (a combination of 2,4-D, dicamba, and mecoprop), a herbicide that is commonly used in central Kentucky. The levels of rainfall delay were 0, 2, and 4 d following application; and the levels of herbicide application rate were 0, 0.5, 1 and 2 times the recommended rate. Simulated rainfall was applied at intensities of 64, 102, and 140 mm h^-1; and the depths of …

Observations Of Shallow Groundwater Contamination Due To Leakage Of Dairy Effluent Ponds On The Swan Coastal Plain, Wa, Richard J. George Dr, D L. Bennett, J R M Bell, Roger Wrigley

Resource management technical reports

In response to the risk of pollution of surface water from farm runoff, dairy farmers have been encouraged to install effluent storage ponds. Previous research has indicated that leachate from these storages can contribute to groundwater contamination. This project assessed the performance of storages at eight sites on the Swan Coastal Plain (SCP), WA. Groundwater conditions were monitored for over three years to study the influence of soil type, water table depth and waste water characteristics.

Results Of The Improved Soil Management & Cropping Systems For Waterlog-Prone Soils Project, Derk Bakker, G J. Hamilton, Peter I. Tipping, Cliff Spann, Doug Rowe

Resource management technical reports

No abstract provided.

The Salinity And Hydrology Of The Upper Slab Hut Catchment, R Ferdowsian, A T. Ryder

Resource management technical reports

No abstract provided.

Investigation Of The Determinants Of African Savanna Vegetation Distribution: A Case Study From The Lower Omo Basin, Ethiopia, Catherine A. Schloeder

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Ethiopian Wildlife Conservation Organization has little information on the extent and ecological determinants of plant species composition and distribution in Omo National Park. Elsewhere, the determinants of African savanna vegetation dynamics have been the focus of numerous investigations, yet our understanding of the hierarchical nature and relative importance of any relationships remains very general. As well, our ability to derive predictions about vegetation responses is limited to extreme generalizations. African savanna landscape ecotones have received even less attention than most landscapes. In this dissertation, I test hypotheses about plant species distribution-determinant relationships in Omo National Park, a park that …

The Power Of Structured Designs And Mixed Models In A Real World Experiment, J. C. Galland, G. A. Milliken, D. R. Hyatt, M. Hornback, K. Cudjoe

Conference on Applied Statistics in Agriculture

Justifications usually given for adopting an automated system pertain to a reduction in labor and an improvement in quality control. A manufacturer of a prototype instrument that automated some of the steps for culturing bacteria wanted to compare the automated system to the manual system. The manufacturer wanted to compare the two systems in 1) Total time needed to isolate the target bacteria, 2) Ability to isolate the target bacteria, 3) Amount of interference from background (non-target) bacterial growth, and 1) Extent of cross (sample to sample) contamination.

This paper presents the experimental design used to make these comparisons and …

Investigating Power Of Analysis Of Covariance Methods, James R. Schwenke, J. Mark Donovan

Conference on Applied Statistics in Agriculture

Analysis of covariance is a well-utilized statistical methodology. The procedure involves a series of statistical tests to first construct a most significant analysis model to characterize the effect of the covariate on response. Pairwise comparisons among treatments are then based on the finalized model.

For traditional Normal error assumptions, each step of the process is based on exact statistical tests. However, the series of statistical tests defines a conditional probability scheme with possible multiplicity issues. The question then becomes if the analysis of covariance methodology considered in entirety is able to maintain a nominal level of significance with good power. …

Starting Values For Proc Mixed With Repeated Measures Data, J. C. Recknor, W. W. Stroup

Conference on Applied Statistics in Agriculture

A major advantage of PROC MIXED for repeated measures data is that one could choose from many different correlated error models. However, MIXED uses default starting values that may cause difficulty obtaining REML estimates of the covariance parameters for several of the models available. This can take the form of excessively long run times or even failure to converge. We have written a program to obtain initial covariance parameter estimates that result in greatly improved performance of the REML algorithm. We will use two covariance models frequently of interest in animal health experiments, the first-order ante-dependence model [ANTE(l)] and the …

Analysis Of Genotype-By-Environment Interaction With Ammi Models Using Sas Proc Mixed, Raul E. Macchiavelli, James S. Beaver

Conference on Applied Statistics in Agriculture

Genotype-by-environment (GE) interaction can be analyzed using different approaches. Among these, the additive main effects and multiplicative interaction model yields useful interpretations and can be applied successfully to plant breeding programs. In this paper we review fitting strategies for this model and show how to combine the capabilities of the Mixed and IML procedures in SAS to fit this model. This permits straightforward use of likelihood-based inference in standard and non standard situations like complex experimental designs. The proposed procedures were applied to data from red mottled bean variety trials conducted in the Dominican Republic and Puerto Rico in 9 …

The Analysis Of Count Data In A One-Way Layout, Yuhua Wang, Dallas E. Johnson, Linda J . Young

Conference on Applied Statistics in Agriculture

An efficient score statistic for testing the equality of the means of several groups of count data in the presence of a common dispersion parameter is introduced and a new approximation to its distribution is given. The performance of the efficient score statistic using this approximation, the original efficient score statistic approximated by X ² (t -1), the likelihood ratio statistic and four more ANOVA methods based on raw data or transformed data are compared in terms of size and power by using Monte Carlo simulations. The efficient score statistic with its new approximation is recommended. An application is given.

Hydrological Normalization Of Nutrient Deliveries From Agricultural Catchments, Per Stalnacke, Anders Grimvall

Conference on Applied Statistics in Agriculture

Nutrient deliveries from agricultural catchments are strongly influenced by natural fluctuations in water discharge. Hydrological normalization of such data may therefore facilitate estimation of human impact on the environment. In the present study, we compared conventional statistical normalization techniques with a recently proposed, semi-parametric regression technique, which can accommodate time-dependent relationships between nutrient deliveries and water discharge. Case studies of agricultural catchments in Sweden and Norway demonstrated that all of the tested normalization techniques were able to remove a substantial fraction of the interannual variation in nitrogen deliveries, whereas normalization of phosphorus loads was problematic. Semi-parametric regression models were found …

A Computationally Efficient Method For Determining Significance In Interval Mapping Of Quantitative Trait Loci, Dan Nettleton

Conference on Applied Statistics in Agriculture

This paper provides a brief introduction to the mapping of quantitative trait loci (QTL). An example on mapping QTL for root thickness in rice is presented to illustrate popular statistical methods used in QTL mapping. Interval mapping is used in conjunction with permutation testing techniques to detect significant associations between genetic positions and quantitative traits while controlling overall type I error rate. A review of a recent technique that can greatly reduce the computational expense of permutation testing in QTL mapping is discussed. Theory is provided for an extension of recent results that may lead to more powerful methods of …

An Improved Estimator For Assessing The Measure Of Agreement With A Gold Standard, Brent D. Burch, Ian R. Harris, Roy T. St. Laurent

Conference on Applied Statistics in Agriculture

St. Laurent (1998, Biometrics 54, 537-545) developed a measure of agreement for method comparison studies in which an approximate method of measurement is compared to a gold standard method of measurement. The measure of agreement proposed was shown to be related to a population intraclass correlation coefficient. This paper develops a family of estimators for the measure of agreement based on pivotal quantities. A blend of two particular members of the family is suggested as an estimator itself. In general, this estimator outperforms the maximum likelihood estimator in terms of bias and mean-squared error.

Nonlinear Models For Multi-Factor Plant Nutrition Experiments, R. D. Landes, W. W. Stroup, E. T. Paparozzi, M. E. Conley

Conference on Applied Statistics in Agriculture

Plant scientists are interested in measuring plant response to quantitative treatment factors, e.g. amount of nutrient applied. Response surface methods are often used for experiments with multiple quantitative factors. However, in many plant nutrition studies, second-order response surface models result in unacceptable lack of fit. This paper explores multi-factor nonlinear models as an alternative. We have developed multi-factor extensions of Mitscherlich and Gompertz models, and fit them to data from experiments conducted at the University of Nebraska-Lincoln Horticulture department. These data are typical of experiments for which conventional response surface models perform poorly. We propose design selection strategies to facilitate …

Using Isotonic Regression To Improve Estimation In Factorial Experiments With Ordered Factor Levels, Matt Strand, Jim Higgins

Conference on Applied Statistics in Agriculture

In many designed experiments in agriculture and the life sciences, a researcher can anticipate the direction that responses will take when treatments are varied. For example, in a 2-way factorial, a researcher may know that increasing the levels of nitrogen and phosphorus will increase yields of a crop. Classical analysis of variance does not take into account a known ordering among population means. However, it can be shown that by restricting the estimates of means to have the same ordering as the anticipated ordering of population means, a reduction in mean-squared errors of estimators will likely occur, often by more …

Characterizing The Statistical Distribution Of Organic Carbon And Extractable Phosphorus At A Regional Scale, John J. Brejda, David W. Meek, Douglas L. Karlen

Conference on Applied Statistics in Agriculture

Greater awareness of potential environmental problems has created the need to monitor total organic carbon (TOC) and extractable phosphorus (P) concentrations at a regional scale. The probability distribution of these soil properties can have a significant effect on the power of statistical tests and the quality of inferences applied to these properties. The objectives of this study were to: (1) evaluate the probability distribution of TOC and extractable P at the regional scale in three Major Land Resource Areas (MLRA), and (2) identify appropriate transformations that will result in a normal distribution. Both TOC and extractable P were non-normally distributed …

Analysis Of Nuclei Fluorescence Histograms Using Non-Linear Functions Or Wavelets, Susanne Aref, Maria Kocherginsky, Carrie A. Northcott, Lane A. Rayburn

Conference on Applied Statistics in Agriculture

Histograms based on 5,000 nuclei from cells (Chinese hamster ovary cells, bone marrow cells) are used to determine the coefficient of variation (CV) of observations surrounding the highest peak. The cells are subjected to various treatments, for example exposure to herbicides. By eyeballing the histogram, an interval under the highest peak is determined. The CV calculated from the histogram on the eyeballed interval is the response variable in an ANOVA. To avoid the subjectivity of eyeballing the histogram, non-linear functions such as the Gaussian density function can be used to model the histogram. The CV may then be determined from …

On Using Proc Mixed For Longitudinal Data, Walter W. Stroup

Conference on Applied Statistics in Agriculture

PROC MIXED has become a standard tool for analyzing repeated measures data. Its popularity results from a wide choice of correlated error models compared to other software, e.g. PROC GLM. However, PROC MIXED's versatility comes at a price. Users must take care. Problems may result from MIXED defaults. These include: questionable criteria for selecting correlated error models; starting values that may impede REML estimation of covariance components; and biased standard errors and test statistics. Problems may be induced by inadequate design. This paper is a survey of current knowledge about mixed model methods for repeated measures. Examples are presented using …

Modeling The Fate Of Toxic Chemicals In Soils, Anabayan Kessavalou, Anne M. Parkhurst

Conference on Applied Statistics in Agriculture

Studies on the fate of toxic chemicals in soils are often reported with a minimum of descriptive statistics. Use of modeling techniques to describe the kinetics of chemical degradation provides a better understanding of the fate of chemicals in soil systems. When modeling nonlinear systems, assumptions made about the error term greatly influence the parameter estimation. Inappropriate use of linearization and failure to account for autocorrelated errors may result in inaccurate models. Information is also needed about the effects of the magnitude of autocorrelation on parameter estimation. The exponential decay function was chosen to fit the data obtained from a …

Estimating The Likelihood Of Yellow Starthistle Occurrence Using An Empirically Derived Nonlinear Regression Model, Bahman Shafii, William J. Price, Lawrence W. Lass, Donn C. Thill

Conference on Applied Statistics in Agriculture

Yellow starthistle is a noxious weed common in the semiarid climate of Central Idaho and other western states. Early detection of yellow starthistle and predicting its infestation potential have important scientific and managerial implications. Weed detection and delineation are often carried out by visual observation or survey techniques. However, such methods may be ineffective in detecting sparse infestations. The distribution of yellow starthistle over a large region may be affected by various exogenous variables such as elevation, slope and aspect. These landscape variables can be used to develop prediction models to estimate the potential invasion of yellow starthistle into new …

Statistics In The New Millennium: Some Personal Views, Bryan F.J. Manly

Conference on Applied Statistics in Agriculture

In this paper I discuss three topics that I believe are relevant to the subject of statistics in the new millennium: (a) the impact of computers, and the state of computer-intensive methods as far as practical applications of statistics are concerned; (b) methods for the analysis of the extremely large data sets that are now becoming available; and (c) the use of statistics by scientists in general. For the first topic I suggest that the main advantage of computer-intensive methods is that they can under certain circumstances give simple and believable answers to questions when other methods fail. However, I …

Editor's Preface And Table Of Contents, George A. Milliken

Conference on Applied Statistics in Agriculture

These proceedings contain papers presented in the eleventh annual Kansas State University Conference on Applied Statistics in Agriculture, held in Manhattan, Kansas, April 25-27, 1999.

Land Evaluation Standards For Land Resource Mapping : Guidelines For Assessing Land Qualities And Determining Land Capability In South-West Western Australia, Dennis Van Gool, Geoff Allan Moore

Resource management technical reports

Updated by report 298, van Gool, D, Tille, P J, and Moore, G A. (2005)
This report provides a standard method for attributing and evaluating digital land resource maps in Western Australia so that strategic decisions about the management, development and consevation of land resources can be based on the best information available. The standards update the generic methodology described by Wells and King (1989) which have been used routinely for the assessment of land resources in catchment and land use planning in Western Australia.

Salinity And Hydrology Of The Fence Road Catchment : A Focus Catchment Of The Blackwood Basin, Ben Whitfield

Resource management technical reports

It is the clearing of native vegetation and replacement with lower water-use annual crops and pastures that is responsible for the developing salinity problem. Traditional farming practices have led to increased recharge to the groundwater systems resulting in increased storage and/or greater areas or rates of discharge. Groundwater monitoring has revealed variable rates of rise throughout the Fence Road catchment, from static to 0.6 metres per year, in a period of average to below average rainfall.

Social And Economic Data For Regional And Natural Resource Management In Western Australia's South West Catchment : Results Of The 2006 Landholder Survey, Department Of Agriculture And Food, Western Australia, South West Catchments Council (W.A.), Michael Hanslip, Australia. Bureau Of Rural Sciences.

All other publications

This report presents a summary of the key findings from a mailed survey to 2,000 landholders in the South West Region of Western Australia in 2006. The survey gathered information on the key social and economic factors affecting landholder decision-making about the adoption of practices expected to improve the management of natural resources in the region. The response rate for the survey was 69.4%.

The South West Catchment Council, Western Australian Department of Agriculture and Food and the Bureau of Rural Sciences were key project partners. Funding was from a mix of national, state and regional programmes, including the Natural …

Coastal Land And Groundwater For Horticulture From Gingin To Augusta, Dennis Van Gool, Werner Runge

Resource management technical reports

Due to a variety of factors, including infrastructure needs, labour requirements and transport costs, horticulture is normally located near major urban centres. This study focuses on the coastal plain region from Gingin to Augusta. This region accomodates over 80% of Western Australia's population and includes the States major urban centres. This region also accounts for over half the State's horticultural production with a gross value of production of $244 million.

Using Spatial Systems To Establish Priorities For Catchment Management, David Deeley, David Weaver, J Hick

Conference papers and presentations

Priorities for catchment management can be established based on either, an objective assessment of relative priorities throughout the catchment, or by simply responding to crises associated with particular land uses and their sectional interests. While the latter method can have advantages in terms of establishing community good will, team cohesion, and a sense of achievement for particular sectional interests, it may have shortcomings in terms of a more objective and rational assessment of the relative magnitude and hence priority of land management problems. Spatial modelling using GIS can form the basis for developing a catchment-wide understanding of the relative importance …