Agricultural research in Canada is largely centralized on Experimental Farms and Stations and at Agricultural Schools and Colleges where the property is owned, considerable equipment is available and a highly technical staff is employed. It is not possible for government services or educational institutions to establish such units in each of the numerous localities where study is required. Various methods of solving this problem have been developed, Many methods are dependent on farmer interest for their success, in others a small allowance is made for crop loss and inconvenience caused by the presence of tests on the farm. Some local problems are studied by technical men, other studies are dependent on the accuracy of the farmer co-operator. The Experimental Farms Service of the Federal Department of Agriculture has conducted experiments dealing with local problems through Illustration Stations; the Agricultural Colleges through local tests, and the farmers themselves have organized into Crop Improvement and other Associations in attempts to solve some of their own problems. All of these methods serve a useful purpose, particularly where they are close to a centralized station with its available technical staff and certain crop and other tests of short duration may be laid down and managed by trained personnel. Such experiments are usually of a demonstrational nature laid down to illustrate the results of well designed experiments conducted [...]

Dislodgeable foliar residues (DFR) can be a primary route for human exposure following pesticide application to turfgrass areas. Consequently, a significant portion of applied pesticide may be available for human exposure via dislodgeable residues. In this study, DFR were determined over a 15-day-period following application of the broadleaf weed herbicide carfentrazone (Ethyl alpha, 2-Dichloro-3-{2-chloro-4-fluoro-5-{4-(difluoromethyl)-4, 5-dihydro-3-methyl-5-oxo-1H-1, 2, 4-triazol-1-yl}-4-fluorobenzenepropanoate ), the pre-emergent herbicide prodiamine (5-dipropylamino-α,α,α-trifluoro-4,6-dinitro-o-toluidine or 2,6-dinitro-N1,N1-dipropyl-4-trifluoromethyl-m-phenylenediamine ) and the insecticide bifenthrin (2-methylbiphenyl-3-ylmethyl (1RS,3RS)-3-[(Z)-2-chloro-3,3,3-trifluoroprop-1-enyl]-2,2-di-methylcyclopropanecarboxylate) to a mature stand of ?Confederate? Tall Fescue (Festuca arundinacea Schreb). Dislodgeable foliar residues were determined by wiping treated turfgrass with a distilled-water-dampened cheesecloth and analyzing samples using gas chromatography/ mass spectrometry (GC/MS). Less than 20% of the total applied carfentrazone was dislodged with 14% of DFR occurring immediately after application and a total of 6% for the remainder of the 15-day study. Prodiamine DFR averaged 80% over the 11-day study with dislodgeable residue levels ranging from a maximum of 17% of the total applied chemical 8 hours after treatment to a low of 4% 11 days after treatment. Approximately 35% of the total applied bifenthrin was available to be dislodged over 15-day study with 34% DFR loss occurring immediately after application and a total of 1% for the remainder of the sampling periods. If pesticides are allowed to dry on the leaf surface, shortly after application carfentrazone, prodiamine and bifenthrin pose minimal risk to human health via dermal exposure when applied at the labeled rate.

Better understanding of transport of dissolved chemicals in soils and aquifers is important to evaluate and remediate contaminated soils and aquifers. Because of the nature of heterogeneity of field porous media, studies on transport processes in non-homogeneous media are necessary. In this study, transport of solutes in layered and heterogeneous media was investigated using numerical approximations. For layered soils, transport properties were assumed homogeneous within individual layers but different between layers. For heterogeneous systems, either a time-dependent or distance-dependent dispersivity was considered to represent the effects of heterogeneity. In a series of simulations of transport in two-layered soils, we found that breakthrough curves (BTCs) were similar regardless of the layering sequence for all reversible and irreversible solute retention mechanisms. Such findings were in agreement with results from laboratory experiments using tritium as a tracer and Ca and Mg as reactive solutes. Field measured apparent dispersivity is often found to increase with time because of the heterogeneity of soils and aquifers. We proposed a fractal model to explain the time dependency of dispersivity. Our model indicates a nonlinear increase of variance of travel distance with time or mean travel distance, which implies a time-dependent dispersivity. Application of our model to three field experiments (the Cape Cod, the Borden, and the Columbus sites) indicates fractal behavior for all three cases. The term "scale effects" is often used in the literature to refer to the dependency of dispersivity on either mean travel distance or distance from source. We presented a critical review on the ambiguity in definition of this term. We presented comparisons between transport processes in systems with time-dependent and distance-dependent dispersivities. Our results showed that enhanced spreading in BTCs consistently occurred in systems with time-dependent dispersivities. Recently, a new governing equation, factional-order advection-dispersion equation (FADE) was proposed to describe transport processes in heterogeneous systems. We proposed a statistical method to justify the use of a FADE. A fractional order of 1.82 was confirmed to be necessary to describe the bromide plumes at the Cape Cod site.

Genetic transformation using the rice shoot apical meristem, derived from germinating seedlings, was established in this study for commercial varieties of Oryza sativa. To optimize apex-mediated DNA transformation in rice several parameters were tested to improve the efficiency and reliability of isolation of the shoot apices and regeneration of vegetative shoot apices. Results from these experiments indicated that certain factors were important in increasing the frequency of survival rate of the apex, co-cultivation and co-transformation. These factors included: the starting size of the apex had to range between 1.0 mm and 1.2 mm for maximum survival of the apex, concentration of the infecting bacteria (pCL3 and pCL4) at an OD of 0.6-0.8 at 600nm and pTOK233 at an OD of 1.5-1.8 at 600nm, the minimum lethal concentration of hygromycin B was 5 mg/L, and use of Rice Shoot Apex (RSA) medium. Furthermore, the presence of acetosyringone before and during co-cultivation at levels between 400 ppm and 1000 ppm increased the number of transformed apices by 40%. Vacuum infiltration at 20-21 Hg for 5 minutes did not have an effect on apex survival, however apex transformation rate was increased by 30¨C35%. Adhering to the development of the new protocol resulted in a 90% shoot apex culturing success rate and a 95% transformation rate of the apices. Vectors containing the GUS gene with either the maize ubiquitin promoter or rice ubiquitin promoter resulted in > 85% transformation efficiency of the apices based on GUS assays. The vectors LBA4404 (pCL3) and LBA4404 (pCL4) proved to be more apex-specific than root-specific, an advantage over the super-binary vector LBA4404 (pTOK233). Preliminary vectors such as pRQGus, pRQHg and pSB41 were constructed for future use in experiments involving LBA4404 (pTOK233) and the results of the tissue culture experiments. Conducting experiments with both the results from tissue culture and vector construction could provide alternative routes to further enhance the efficiency of apex-mediated transformation.

Soil degradation due to improper use of off road vehicle (ORV) is among the major problems in the Kisatchie National Forest (KNF), especially in Catahoula (CRD), Evangeline Unit, Calcasieu (ERD), and Kisatchie Ranger (KRD) districts. The USDA-Forest Service (USFS) maintains designated trails within the forest, but many ORV users create their own trails. To address this issue, a research project was initiated in 2001 to assess the suitability of KNF soils for ORV traffic using Geographical Information System (GIS) software. The objectives were achieved by utilizing soil properties, rainfall events, soil trafficability ratings, Keetch-Byram Drought Index (KBDI), and infiltration parameters. Various GIS techniques, spatial statistics program, and mathematical models were employed. The spatial variability of KNF soils was determined using the choropleth and summarize zones techniques through ArcViewâ3.2. Surface runoff from soils with varying surface textures was estimated using the Green and Ampt Approach program through Lahey FORTRAN 90 version 4.0. Hotspots, or areas that have potential for soil degradation, and coldspots, or areas that are suitable for ORV use, were identified using the kernel density estimation technique through CrimeStatâ2.0. These areas were also reflected in the trafficability maps. The use of a KBDI critical value of 399 was found to be a rapid method of managing the forest with respect to opening or closing existing trails. The research results can be used by the USFS to effectively manage the forest. Most of the soils that occur within the CRD are suitable for ORV use. A portion of ERD should be restricted from ORV use. KRD should be permanently closed for all ORV traffic. Though the suitability analysis was successful, further research is necessary to test the validity of the methods used in the analyses. The recommended critical KBDI value should also be tested especially for the rainy season. Moreover, to validate the model used to estimate runoff, actual infiltration parameters should be used. Inclusion of other parameters in the model, such as saturation time and thickness will help determine the duration to restrict the ORV use of the forest based upon the soil moisture condition.

Soil phosphorus (P) build-up from long-term application of poultry litter may increase P loss in surface and subsurface water and lead to eutrophication. Anoxic conditions during water saturation may aggravate the problem by increasing P solubility and mobility. However, the same level of soil P at different locations may not yield equal runoff P if the capacity of the soil to retain P varies across the landscape. This study examined: 1) effects of soil water oxygenation and concentration of soil organic matter (SOM) on development of anoxic conditions leading to decreased P sorption and increased mobility in a Ruston (fine-loamy, siliceous, thermic Typic Paleudult) soil; and 2) the spatial variability of P sorption parameters (Langmuir sorption maximum, initial isotherm slope and sorption at solution concentration = 1 mg/L) in Ruston and Darley (fine, kaolinitic, thermic Typic Hapludult) soils. Batch Langmuir isotherms were developed for Ruston pasture (high SOM) and forest (low SOM) soils. Phosphorus movement through duplicate 5 cm long x 4.6 cm diameter columns of water-saturated soils with oxic or anoxic input solution was compared to P mobility predicted using the batch isotherms. The Eh of effluent (flow velocity ~ 2.5 cm/hr) indicated rapid development of reducing conditions regardless of input oxgenation. However, lower Eh values occurred in the pasture soil. Similar Ehs developed in the batch systems so that redox effect on P sorption was implictly included in transport predictions. Accordingly, predicted and measured elution of a 200 mg/L P pulse were generally consistent, particularly for the higher SOM pasture soil. Whether discrepancies between predicted and measured P elution were due to precipitation reactions was examined using MINTEQ, but results were inconclusive. Surface 0 to 5 cm samples of Ruston and Darley soils were taken on square grids (60 x 60 m and 30 x 30 m, respectively) and Langmuir isotherms developed for every location. Soil pH and SOM were also determined. Isotherm parameters were spatially correlated and well-described by exponential or Gaussian semivariograms. Correlations of P sorption parameters with pH or SOM were inconsistent between sites except for the relationship of P sorption maximum with SOM.

Identification of criteria for predicting soybean [Glycine max (L.) Merril] yield would provide farmers with useful management tools. Such criteria not only help in predicting the yield potential but also aid the farmer in determination of environmental factors limiting crop yield. Since a certain total dry matter (TDM) level is expected to optimize yield and R5 marks the end of the period for vegetative TDM accumulation, TDM(R5) is a good putative criterion for optimal yield. Determination of yield components important in yield formation helps to substantiate TDM(R5) as a criterion for optimum yield, since they are formed during discrete periods and therefore would indicate when TDM accumulation is important. Because TDM(R5) could be an efficient and accurate yield criterion and because little research has been done on this subject, our objectives were to use analyses of relationships between yield components, TDM, and yield to determine if: 1. TDM(R5) can be used as criterion for optimum yield; and 2. What level of TDM(R5) is required to optimize yield. The data for this study were collected from previous studies, that contained a variety of cultural treatments like planting dates, row spacings, plant populations, partial defoliation, and waterlogging stress, conducted near Baton Rouge, LA (300 N Lat) between 1987 to 1996 and combined to make a single data set. The data thus pooled was subjected to correlation, regression and path coefficient analyses to achieve our objectives. The study clearly indicated that use of TDM(R5) as a yield criterion is valid and the critical level of TDM(R5) was found to be 600 g m-2 to achieve optimum yield. The TDM(R5) criterion can be used as a very good management tool by the farmers. Yield components like seed number per area, pod number per area, reproductive node number per area and node number per area, which responded strongly to TDM accumulation, are likely to be affected by the cultural practices of the farmer. The farmer should adjust cultural practices to ensure that length of emergence to R5 period is long enough to achieve the required TDM(R5).

"Phosphorus is so basic to the whole problem of crop production that probably no other subject in the field of soil fertility has received more attention than the phosphorus problem in its various soil-plant and soil-animal relationships and it probably will continue to challenge the best efforts of investigators for many years”. (27). "Phosphorus is the only element which must be purchased and returned to the most common soils of the United States, it is the key to permanent agriculture on these soils". (20).

A number of sources of variation which may influence the evaluation of comparative yield trials of silage corn were investigated in 1951, namely, the effect of maturity, diurnal changes in percentage dry matter, and the variability of duplicate samples. In 1952 several proposed methods of evaluating comparative yield trials were compared with the "Standard Method" presently in use at Macdonald College. Inconsistent exceptions precluded the possibility of separating varieties into three distinct classes according to their green yield ranks, with the object of eliminating the class with the lowest yield. A "Whole Ear Method" in which unchopped ears were sampled was of comparable accuracy to the "Standard Method" of harvesting. "Methods of Combining Green Plant Materials" and the "Standard Method" produced comparable data; complications of field operation inherent in the former methods preclude their extended use. It may not be necessary to samp1e every replication for percentage dry matter estimations.

Red claver (Trifolium pratense) and birdsfoot trefoil (Lotus corniculatus) are leguminous forage species of demonstrated economic value. They are cross-pollinated, largely self-incompatible or self-sterile and highly heterozygous. Attempts at the improvement of red clover through plant breeding have occurred since the beginning of the century in a number of countries chief amongst which are Scandinavia, Great Britain, the United States and Canada. Interest in the employment and improvement of birdsfoot trefoil is fairly recent.