Corrosion, an important factor for the durability of a metal finish after exposure to water and chemicals, is a real concern for many wet-process industries. The effects of rouging, corrosion, and biofouling are costly problems on the surface of stainless steel, the most common material in processing plants. We have developed a corrosive treatment that is indicative of the wet-processing conditions commonly used in food processing, pharmaceutical, and bioprocess applications to test the effects of surface corrosion on bacterial attachment. Samples of surface finishes (electropolished, steel-ball burnished, glass-beaded, acid-dipped, steel-shot burnished, and sandblasted) were compared with mill finish controls to determine the variation in bacterial attachment on each finish. A duplicate set of samples was exposed to the corrosive treatment to simulate processing conditions. All samples were examined by visual inspection and electron probe microanalysis for surface characteristics and elemental composition of the stainless steel finishes. Samples were exposed to natural bacterial populations from chicken carcass rinses to allow growth of bacteria and development of biofilms on the surfaces. The kinetics of bacterial growth during surface exposure was followed by UV-visible spectrophotometry, and counts of bacteria and early biofilm formation were determined from micrographs following scanning electron microscopy. Bacterial attachment on each surface finish was measured and compared with controls and the five other finishes. Exposure to the corrosive treatment conditions resulted in changes in the numbers of bacteria that attached to each surface finish. After exposure to corrosive treatment, significantly greater numbers of bacteria attached to steel-ball burnished and glass-beaded finishes. However, the control mill finish and electropolished samples had fewer bacteria attached after exposure. Electropolished samples were significantly most resistant, before and after exposure to corrosive treatment, than the seven other finishes tested.

1D3D and 2D2D cyclones were tested at Amarillo, Texas, to evaluate the effect of air density on cyclone performance. Both airflow rate and cyclone inlet velocity change with the change in air density. Two sets of inlet design velocities determined by the different air densities were used for the tests: one set based on the actual airflow, and the other set based on standard airflow. Experimental results indicate that optimal cyclone design velocities, which are 16 m/s (3200 ft/min) of standard air for 1D3D cyclones and 15 m/s (3000 ft/min) of standard air for 2D2D cyclones, should be determined based on standard air density. It is important to consider the air density effect on cyclone performance in the design of cyclone abatement systems. The proposed design velocities should be the basis for sizing cyclones and determining the cyclone pressure drop. The recommended sizes for 1D3D, 2D2D, and 1D2D cyclones are reported in this article.

Physical and mechanical properties of 50 and 60 month old coffee trees of three varieties were experimentally determined at the Centro Nacional de Investigaciones de Café (CENICAFE). We measured the following mechanical properties, which are required for mathematical modeling of the tree and for the design of mechanical harvesters using vibrations applied to the trunk: mass of trunk, limbs and leaves; density, elasticity, stiffness, damping, and natural frequency of the trunk; diameter of trunk at different heights; and number of fruits per node. From a mechanical viewpoint, the red-fruit Caturra variety exhibited the best physical and mechanical properties for the use of harvesters applying vibrations to the trunk.

A corn silage harvester using a shredding/crushing mechanism was designed, fabricated, and tested during two harvesting seasons with the objective of improving the feed value of corn silage. Two pairs of toothed rolls turning at different speeds shredded whole-plant corn. Corn stalks were shredded, kernels were broken, and cobs were crushed. Average specific energy required to shred whole-plant corn ranged from 2.5 to 5.9 kWh/Mg DM. Average specific energy for an added flail cutter/blower ranged from 2.0 to 4.7 kWh/Mg DM for a total harvester specific energy requirement of 4.5 to 10.6 kWh/Mg DM. Average specific energy requirements for shredding varied significantly among different roll speed treatments at a unit roll force of 15 N/mm (front and rear), but no significant effect of roll speed configuration was found at other unit roll forces. Packed density was lower for shredded silage than for chopped silage, but shredded and chopped samples both ensiled well with pH values of 3.8 to 4.1 after fermentation. Particle size distributions of shredded and flail-cut samples were similar at moisture levels of 60% and 65% w.b.; however, the 70% moisture crop was coarser. Shredding produced fewer small particles (<9 mm) and more large particles (>9 mm) than chopping, while shredded and flail-cut samples had more small particles and more large particles than chopped samples.

Research has shown that application errors exist with variable-rate technology (VRT) systems. Consequently, using prescription maps for economic and agronomic analyses can generate misleading results. The intent of this article was to develop and validate a spatial data model for generating "as-applied" maps to support the advancement of precision agriculture practices. Previous research modified ASAE Standard S341.2 to include a 2-D matrix of collection pans to assess fixed-rate and variable-rate (VR) deposition of granular fertilizers and agricultural lime from a spinner disc spreader. The "as-applied" spatial data model uses GIS functionality to generate "as-applied" surfaces by merging distribution patterns and a spatial field application file (FAF) into an "as-applied" surface representing the actual distribution of granular fertilizer or agricultural lime across a field. To validate the "as-applied" spatial data model, field studies were conducted by randomly placing collection pans across two fields. Murate of potash was then applied using a VR spinner spreader. The "as-applied" spatial data model was used to predict the amount of material each pan should have received. Comparisons were made between the actual and predicted application rates for two fields, with R2 values of 0.45 (field A) and 0.58 (field B) computed. However, R2 values of 0.16 (field A) and 0.21 (field B) were observed when comparing the actual application rates and prescription maps. These low R2 values indicated poor application by the spinner spreader but demonstrated that the "as-applied" model did a better job of representing the distribution of murate of potash when contrasted with the prescription maps. "As-applied" surfaces provide a means for evaluating fixed-rate and VR application of granular products while enhancing researchers' ability to compare VR management approaches.

Excess rainfall and subsequent surface runoff is a challenge to farmers of the Lower Mississippi River Valley region. In 1993, we established an experimental field site in Baton Rouge, Louisiana, consisting of 16 hydraulically isolated plots (0.2 ha) on a Commerce soil (Aeric Fluvaquents). Our objective was to determine drainage system impacts on surface runoff, subsurface drainage effluent, nitrate loss, and corn (Zea mays L.) yield. We evaluated the following drainage systems (four replications) in 1995 and 1996: surface drainage only (SUR), controlled subsurface drainage at 1.1 m below the soil surface (DCD), and shallow water table control at a 0.8 m depth via controlled-drainage/subirrigation (CDSI). Planting date, fertility management, and minimum tillage were consistent across treatments. When compared to SUR, DCD and CDSI did not reduce surface runoff or nitrate loss in runoff. This is in contrast to previous research showing that subsurface drainage systems decreased runoff on this soil, the difference being that we did not use deep tillage. Our results suggest that subsurface drainage systems should be coupled with deep tillage to reduce nutrient loss in runoff from this alluvial soil. DCD and CDSI controlled the shallow water table, but the increased annual effluent from subsurface drainage increased nitrate loss compared to SUR. DCD and CDSI had no affect on corn yield under these rainfall conditions. With respect to nitrate loss and crop yield in this region, typical SUR drainage may be the best management practice (BMP) in the absence of effective runoff mitigation, such as deep tillage.

Growing concern about nitrate-N in effluent from subsurface drains requires technically and statistically valid water quality data. However, intensive monitoring with frequent (daily or more) sampling and analysis of nitrate-N concentrations is expensive and difficult. The objective of this study was to determine the accuracy and precision of nitrate-N loss estimates from subsurface drainage plots based on varying sampling frequencies. A case study was performed for the 5, 10, and 20 m drain spacings at the Southeast Purdue Agricultural Center for three years. Concentration values representing 7-, 30-, and 90-day sampling frequencies were combined with continuous flow data to obtain mass loss estimates, using all possible combinations or random (Monte Carlo) selections of samples, depending on the number of all combinations. Estimates were compared to the “true” mass loss (based on flow-proportional sampling using all available concentration measurements) to obtain probability distributions and 95% confidence intervals of mass loss estimates. On average over these three spacings for three years, the probability of estimating the annual mass loss within ± 15% of the “true” mass loss was 92% for the weekly sample frequency, 68% for the monthly (30-day) sampling frequency, and 51% for the 90-day frequency. Results of this study can help researchers select cost-effective sampling frequencies based on their specific accuracy requirement.

A radiometric normalization procedure utilizing the soil line concept is developed and tested. The routine, referred to as the soil line transformation (SLT) technique, is developed to provide a system for transforming multi-temporal images to a common reference scene. The routine involves developing soil lines not only for the bare soil images, but also for images with vegetative cover, assuming that some pixels within the entire image would represent bare soil conditions or pseudo-invariant features. The procedure uses the soil lines developed for the image-to-be-transformed and the reference image to form transforming equations using pixels within a specified interval of both soil lines. In this research, the SLT technique is evaluated using multi-temporal images of crop development. Digital aerial images of two corn (Zea mays L.) fields are used to test the SLT routine based on expected change in pixel intensity due to crop development. The SLT technique is also compared against an alternative histogram matching technique based on the percentage of pixels matching the expected growth pattern away from the soil line. For two fields over two growing seasons, the SLT technique outperformed histogram matching, resulting in at least 87% of pixels demonstrating the expected growth pattern between the images.

Recent advances in radar remote sensing techniques illustrate the potential for monitoring soil moisture conditions at spatial and temporal scales required for regional and local modeling efforts. This research examined the feasibility of producing accurate and spatially distributed estimates of soil moisture using a time series of ERS–2 radar images for a tallgrass prairie ecosystem in northeast Kansas. Methods used included field data collection of soil moisture, digital image interpretation of optical (NOAA AVHRR and LANDSAT TM) and radar (ERS–2) imagery, and environmental modeling in a raster geographic information system (GIS) and image processing environment. Critical to this study was determining the scattering behavior of overlying vegetation, or the contribution of vegetation backscatter (s° veg) to the total backscatter coefficient (s.o total), which was simulated using a modified water cloud model. By removing s° veg from s° total, the amount of backscatter contributed by the soil surface (s° soil) was isolated and the linear relationship between s° soil and volumetric soil moisture determined. Single–date correlations averaged r = 0.62 and r = 0.67 for a burned and unburned watershed, respectively, within the study area. While previous studies have questioned the sensitivity of C–band radars to near–surface soil moisture conditions, these results show that ERS–2 data may be capable of monitoring soil moisture conditions over even extremely dense natural grassland vegetation.

The high density of animal production in southeastern Coastal Plain watersheds has caused some soils to contain excess amounts of plant-available soil phosphorus (P). Runoff, erosion, and leaching can transport P to surface water systems and out of these watersheds. High P concentrations in downstream aquatic ecosystems can increase the risk of eutrophication. Our objectives were to determine stream dissolved phosphorus (DP) mass loads transported under storm and base flow conditions and to examine relationships between precipitation, stream flow, and DP concentrations and export loads from an agriculturally intensive Coastal Plain watershed. This watershed was separated into four subwatersheds, and stream flows at their outlets were separated into base and storm flow conditions. Over the 2-year study period, stream base flow accounted for the majority of total stream flow at all outlets (58% to 73%). Average stream total DP mass loads at the watershed outlet in 1994 and 1995 were 234 and 477 mg DP ha(-1) d(-1), and higher DP mass loads (57% to 71% of the cumulative total) were exported during base flow conditions. In 1995, a series of intense storm events over two months caused a large DP pulse (approximately 63% of the stream's yearly annual DP mass load) to exit the watershed. Regression analysis showed a linear relationship (P < 0.001) between log10 instantaneous stream flow and log10 DP export. Our results showed that more DP was exported during stream base flow conditions. However, intensive summer storms can greatly accelerate stream DP export from this agriculturally intensive Coastal Plain watershed.