Showing papers in "Transactions of the ASABE in 1982"

Estimation of Soil Water Properties

Abstract: RELATIONSHIPS of soil water tension and hydraulic conductivity with soil water content are needed to quantify plant available water and to model the move-ment of water and solutes in and through soils. Field and laboratory measurement of these hydraulic soil proper-ties is very difficult, laborous, and costly. To provide the best estimates possible from previous analyses, a com-prehensive search of the literature and data sources for hydraulic conductivity and related soil-water data was made in 1978. From this search, data for 1,323 soils with about 5,350 horizons from 32 states were assembled. From the data, the Brooks and Corey water retention parameters, soil water retention volumes at 0.33 bar and 15 bar, total porosity, and saturated conductivities for the major USDA soil textures classes were developed. Also, relationships for predicting water retention volumes for particular tensions and saturated hydraulic conductivities based on soil properties are presented.

Fuel properties of eleven vegetable oils

Abstract: ELEVEN vegetable oils that can be grown as domestic field crops were identified for inclusion in a com-parative study of chemical and fuel properties. Sample lots of each oil were subjected to ASTM tests appropriate for diesel fuels. The tests identified some problem areas with vegetable oil fuels. The oil samples were also characterized chemically and certain fuel properties were correlated to chemical compositions.

Field Evaluation of Furrow Infiltration and Advance Functions

Abstract: MORE than 100 comprehensive furrow evaluations were made at three Colorado locations. These data were used to study the adequacy of various infiltration and advance relations based on a kinematic, or volume balance, approach. The Kostiakov-Lewis function with an additional term for the asymptotic long-time infiltra-tion rate proved highly effective in simulating infiltrated volumes when reliable estimates of the steady infiltration rate could be obtained. The commonly employed power advance function was calibrated using regression and the **two-point method, with the latter demonstrating substantial advantages.

Moisture and Density Effect on Cone Index

Abstract: CONE index, a measure of the penetration resistance of a soil, is affected by many factors including soil density, moisture content, and soil type. The effect of each of these three variables on cone index was in-vestigated and discussed. Based on experimental data, an equation for cone index as a function of moisture con-tent and density was developed for each soil type considered.

A Comprehensive Dynamic Model for Animal Waste Methanogenesis

Abstract: DYNAMIC simulation of methane fermentation of animal waste has advanced with the development of a more accurate and comprehensive mathematical model that considers and describes two basic biological pathways of methane formation. Recent work in the field of microbology has shown that there are four major microbial cultures involved in methanogenesis, with the final pathways to methane formation involving acetic acid metabolism and the reduction of carbon dioxide with hydrogen. Digestion failure, often encountered using animal waste because of the high organic and nitrogen content, can only be predicted when the dynamic relationship of these four microbial groups are considered in a symbiotic manner. Work reported here describes a dynamic computer model that predicts digestor operating conditions for the four major animal types. Validation of the computer predicted operating conditions was performed using the steady-state data of 16 pilot and full-scale methane fermentation plants (four each of swine, dairy, beef and poultry). Upon validation of the model using these data, projected minimum deten-tion times at specific loading rates for temperatures of 35 °C and 60 °C were determined. Relationships developed in this model provide some insight into the basic response, under dynamic conditions, of biological processes.

Factors Affecting Ammonia Release in Broiler Houses

Abstract: A computer program for modeling ammonia (NH3) re-lease in broiler houses has been developed. The model estimated that during the first weeks for flocks grown on reused litter, NH3 concentrations can reach 200-300 ppm; safe levels ( moisture content.

Field Evaluation of a Water Management Simulation Model

Abstract: THE water management simulation model, DRAINMOD, was tested using field data for over 5 yr of record from three locations in the NC Coastal Plains. Each site had field scale drainage systems with provisions for subirrigation and controlled drainage. Three soil types and five different drainage system designs were included in the experiment from which 21 site-yr of data were obtained. Rainfall intensity and water table elevations were measured continuously at each site and the observed day end water table elevations were compared to predicted values. Effective lateral hydraulic conductivity values were measured in the field using both auger hole and water table drawdown methods. Numerous other field and laboratory mea-surements were made for each soil to determine input soil property and site parameter data. Comparison of predicted and measured water table elevations were in excellent agreement with the daily water table depths having standard errors of estimate ranging from 7.5 to 19.6 cm. The average absolute devia-tion between predicted and observed water table depths for 21 site-years of data (approximately 7400 pairs of daily predicted and measured values) was only 8.1 cm. Based on the results of the study, DRAINMOD can be reliably used to predict the effect of drainage system design on water table elevations.

Models for the Rheology and Statistical Strength of Uniformly Stressed Vegetative Tissue

Abstract: THE first part of this paper is a literature review of the important features of plant vegetative tissue that relate to its rheological and strength properties. Several internal mechanisms by which an applied load is resisted are described, and two internal mechanisms of failure initiation are discussed. Second, a simple elastic me-chanics model is developed for the cellular structure under a uniform load, and results are obtained which give a qualitative relation between applied external stresses and strains, cell wall stresses, and cell turgidity. Third, a description of the statistical failure process in uniformly stressed samples is postulated, and a probabil-ity model is developed for the initiation of this failure process. The theoretical development leads to the use of the Weibull distribution to describe the yield strength of tissues exhibiting a sharp reduction in stress at yielding. Experimental data for apple and potato samples show the Weibull model to be adequate statistically. The Weibull model is a useful tool for predicting the amount of damaged tissue under a known applied stress.

Soil Cover Prediction with Various Amounts and Types of Crop Residue

Abstract: AN equation has been derived to predict the fraction of soil covered by crop residue as a function of the mass of residue. The equation was checked with ex-perimental data reported in the literature. A method of physically measuring the calibration coefficient in the equation was also checked. Coefficients for several types of crop residue were measured. Finally, the equation was verified and found to work for actual field conditions. The derived equation is relatively simple yet provides a fundamental theoretical basis on which residue manage-ment systems can be analyzed.

Post-Drying Fissure Developments in Rough Rice

Abstract: SELECTED test grains from good long-grain rough rice at about 14 and 20 percent moisture dry basis, were dried with heated air at 39, 47 and 60 °C. The test kernels, placed into plastic envelopes at the top and bot-tom of a column of rough rice 15 cm deep, were dried for 2, 10 and 24 h. Air-flow rate during drying was main-tained constant at 0.147 mVmin for 0.015 m^ floor area of drying column. Inspection of grains for fissures im-mediately after drying and after 12-h intervals for 144 h during storage in airtight vials indicated that few kernels fissured while drying, but most of the Assuring occurred within 48 h thereafter.

Effects of corn residue and fertilizer management on soluble nutrient runoff losses.

Abstract: SIMULATED rainfall was used to determine the ef-fects of fertilizer rate and placement, and corn residue amount on the soil surface, on soluble nutrient runoff losses from a fallow soil. Four levels of residue (0, 375, 750, and 1500 kg/ha), two levels of fertilization (none versus 77, 66, and 27 kg/ha of NH4-N, NO3-N, and PO4-P, respectively), and two methods of fertilizer place-ment were evaluated. On plots with no residue, the chemicals were either surface-applied or point-injected to a depth of 5 cm; on plots with residue, chemicals were surface-applied either above or below the residue. Bromide, at the rate of 151 kg/ha, also was applied to the fertilized plots. Residue on the unfertilized plots increased nutrient concentrations in runoff little, if at all. Surface fertiliza-tion significantly increased nutrient concentrations in runoff, particularly for the ions interacting with soil (NH4 and POJ). Placement with respect to corn residue did not significantly affect concentrations in runoff. In-jected fertilizer did not increase concentrations in runoff relative to concentrations for unfertilized plots. Concen-trations of nonadsorbed NO3 and Br~ ions in runoff from plots receiving chemical application were closely cor-related. Increases in losses of NO3-N and Br over unfer-tilized plots were less than 1 percent of that applied. In-creases in NH4-N and PO4-P losses from fertilization were as high as 5 and 3 percent of that applied, respec-tively.

Tillage for Continuous Corn and Corn-Soybean Rotation

Abstract: CONSERVATION and conventional tillage systems were evaluated for continuous production of corn (Zea mays L.) and for production of corn and soybeans [Glycine max (L.) Merr.] in rotation. The fall moldboard plow system had the highest 5-yr average yield for con-tinuous corn production. Tillage systems did not signifi-cantly affect yields of either corn or soybeans in the corn-soybean rotation study. The percentage of the soil sur-face covered with plant residue following soybeans, in the corn-soybean rotation, was nearly as great as following corn. However, the soybean residue cover was much more easily destroyed by tillage than was the corn residue.

Residual Tillage Effects as Determined by Cone Index

Abstract: CONE index values indicated that the residual effec-tiveness of in-row subsoiling was evident for one additional year but was not detectable beyond 2 yr in a Coastal Plain soil. Recompaction of soil occurred using either no-till or moldboard tillage, with no-till resulting in a loss of 50 percent of the potential root zone compared to moldboard plow.

Verification Study of a Numerical Greenhouse Microclimate Model

Abstract: A numerical one-dimensional model was designed to simulate the diurnal changes of the greenhouse en-vironment The model consists of: a soil layer, a vegeta-tion layer, an air layer and a cover The thermal radiative, sensible, latent and conductive heat fluxes were modeled in each layer in terms of its unknown temperature and vapor pressure In order to obtain flexibility and accuracy of the model, sophisticated models were adopted to simulate each of the greenhouse sublayers and a theoretical method was proposed to describe the water diffusion through stomata as a function of the environmental parameters Numerical experiments were conducted to test the sen-sitivity of the model to some parameters The results in-dicate the necessity to properly initialize the model and to determine an accurate inside air transfer coefficient of sensible and latent heat An observational study was performed in order to test the ability of the model to properly describe the greenhouse microclimate Good agreement was obtained between predicted and observed temperatures and humidities

Soil crusts and cotton emergence relationships.

Abstract: RAIN-FORMED soil crusts annually necessitate the replanting of thousands of hectares of cotton. Therefore, we studied the relationships of cotton emergence characteristics and soil-crust strength (penetrometer resistance), and the relative crust-breaking efficiencies of two mechanical devices. As penetrometer resistance increased, mean emergence date was delayed, emergence percentage was decreased, emergence rate index was reduced, and seedling hypocotyl diameter was increased. The rotary hoe was superior to the small-disk device only when the crust-breaking operation was delayed until some seedlings had already emerged.

Evaluation of Rainfall-Runoff Erosivity Factors for Individual Storms

Abstract: THE Universal Soil-Loss Equation is widely used to satisfactorily estimate average annual soil loss from rainfall. Without modification, it is somewhat unsatis-factory for estimating soil loss from individual storms. Several erosivity factors that could be used to estimate soil loss from individual storms were investigated in this study. Rainfall erosivity factors like EI30 that include both rainfall rate and amount terms were found to be much better predictors of soil loss than a factor including rainfall amount alone. Lumped erosivity factors that in-clude rainfall amount, rainfall intensity, and runoff amount were even better predictors than EI30, whereas erosivity factors with separate terms for rainfall and runoff erosivity were best. However, these factors did not greatly improve soil loss predictions as compared with EI30.

Seasonal Variations of Manning's Roughness Coefficient in a Subtropical Marsh

Abstract: Manning's roughness coefficient, N, ranged from 0.16 to 0.55 in a subtropical marsh over the flow depth varying between 65 to 40 cm. The N value increas-ed with a decrease in flow depth. The roughness coeffi-cient tripled over a six month period from June to November. The N value in a nonsprayed area was twice of that determined in a chemically defoliated area. The N value and vegetation density were parabolically related. The increase in N value was directly proportional to the 1/2 power of vegetation density and 2A power of flow depth in all types of vegetation.

A Thermal Infrared Technique for Monitoring Cotton Water Stress and Scheduling Irrigations e

Abstract: STEPWISE, multiple linear regression analysis estab-lished that a crop water stress index (CWSI) derived from mid-day radiant leaf temperatures, air tempera-tures, and vapor pressure deficits was the most impor-tant independent variable in predicting the xylem pres-sure potential of cotton leaves. When the CWSI was combined with the age of the crop and the evaporative demand of the atmosphere, the water potential of cotton could be predicted throughout the entire growing season. This permits day by day monitoring of cotton plant water status which could facilitate the irrigation decision mak-ing progress without resorting to tedious physiological plant measurements.

Evaluation of Diesel Fuel — Ethanol Microemulsions

Abstract: ANHYDROUS ethanol can be blended with No. 2 diesel fuel to form a homogeneous blend, but low temperatures or water contamination cause a phase separation. Certain organic additives were used to form cosolvent and microemulsion blends of 190-proof ethanol in diesel fuel. Data on properties and engine evaluations of the blended fuels are reported.

Light Energy Utilization Efficiency for Photosynthesis

Abstract: THE radiation output of sources used in growth cham-bers and for supplemental lighting in horticulture was measured in terms of irradiance, photon flux densi-ty, and two photosynthetic responses based on the mean relative action spectrum and mean relative quantum yield of photosynthesis. The outputs of the sources were given in terms of a constant power input and showed the necessity of comparing electrical conversion efficiences on an installed rather than 'test' basis. A rating of the sources based on the calculated photosynthetic utiliza-tion efficiencies was given for the sources tested. A source with broad spectral outputs can be evaluated with either photon flux density or photosynthetic photon flux density. However, analysis of less homogenous sources with narrow spectral emissions showed that the photon flux density was not a valid index of photosynthetic utilization efficiency. Plants, lettuce and tomato, grown under daylight, blue and red spectral quality sources showed large differences in morphology between the plants. The best indicator of photosynthetic utilization efficiency of a source was found to be either the photosynthetic action photon flux density or the photosynthetic yield photon flux density as modified by an absorptance greater than that previously given in the literature. The net assimilation rates of lettuce and tomato plants grown under a blue source would predict that the mean relative action spectrum was low in the blue region.

Factors Affecting the Dielectric Properties of Grain

Abstract: THE influences of various factors that affect the di-electric properties of grain are discussed, based on information in the literature. Moisture content of the grain and frequency of the applied electric field are the two most important factors. Bulk density of the grain and temperature also affect the dielectric properties. The moisture sorption-desorption history of the grain and its chemical composition have lesser influences on the dielectric properties. Nonhomogeneity of the grain as a dielectric can affect the measured dielectric properties when kernel dimensions are an appreciable fraction of the distance between electrodes in the sample holder. The dielectric constant increases with increasing moisture content and decreasing frequency, whereas the loss tangent and loss factor may increase or decrease with changes in these two variables, depending upon the range of each. The dielectric constant has positive bulk-density and temperature coefficients, but the cor-responding coefficients for loss tangent and loss factor may have either sign, depending upon moisture content and frequency. Sources of information on the dielectric properties of grain are identified, and contour plots of the dielectric properties of wheat and corn are presented as functions of frequency and moisture content.

Hydraulics of Failure of Unanchored Cornstalk and Wheat Straw Mulches for Erosion Control

Abstract: BASIC hydraulic theory that divides a flow's total shear stress into that acting on soil and that acting on mulch was used to derive equations giving critical slope length for failure of unanchored mulch on untitled soils as a function of mulch type (cornstalk or wheat straw) and amount, slope, rainfall erosivity, runoff, and soil susceptibility to rill erosion. Parameter values for the equations were determined from experimental data. Values computed from the equations agreed well with recommended values for wheat straw mulch on construc-tion sites for slopes greater than 13 percent. Graphical solutions to the equations were prepared to facilitate ap-plication of the analysis.

Rough Rice Drying as a Two-Compartment Model

Abstract: A two-compartment drying model was developed to ex-plain the desorption phenomenon of rice since the grain consists of such distinct components as the hull, bran and starchy endosperm. Test grains of the Labelle variety were dried for 2, 10, 18 and 24 h with drying temperatures of 24, 43 and 56 °C. Air-flow rates were between 0.198 and 0.277 mVmin for 0.015 m2 floor area of a drying column. Drying rates are explained more logically with an equation representing a two-compart-ment model than by another equation that considers the rough rice kernel to be a homogeneous mass.

Mass Bank Failure Analysis of Selected Yazoo Basin Streams

Abstract: IN the streams studied, bank instabilities occurred as a result of channel entrenchment and local scouring of the outerbank in bendways. Banks retreated primarily by mass failures of overheightened and oversteepened banks. Failures usually followed periods of heavy precipitation that increased the bank material weight and decreased its strength. These failures were generally associated with banks with extensive tension cracks. Slope stability analyses were used to assess the stability of streambanks and to predict limiting values for the bank height and slope angle. In this study, the limit analysis for a logarithmic spiral toe failure was used. This analysis required data on the strength properties and distribution of the bank materials which were ob-tained from a borehole survey of bank materials and from in situ strength tests. The applicability of the stability analyses was evaluated using field observations of bank geometry. Observations of bank failures showed good agreement with the analyses suggesting that the logarithmic spiral method of analysis can be used with confidence as an aid in redesigning unstable banks in the Yazoo Basin in northern Mississippi.

RF Dielectric Heating for Pecan Weevil Control

Abstract: FRACTIONAL-MINUTE exposures of pecan weevil larvae, both in in-shell pecans and in broken pecan pieces, to 40-MHz dielectric heating treatments killed all of the insects Similar treatments of another lot of in-shell pecans substantially reduced the viability of the pecans tested for germination Exposures that raised pecan-kernel temperatures momentarily to about 80 °C were required for complete control of the larvae in in-shell pecans of 61-percent moisture content Similar treatments achieved complete mortality of the insects in pecan pieces of 26-percent moisture content when heated only to 53 °C by 15-s exposures

Dependence Structure of Daily Temperature and Solar Radiation

Abstract: DAILY weather variables tend to persist in time and are mutually interdependent. The dependence of daily maximum temperature, minimum temperature, and solar radiation is analyzed for 31 stations in the United States. Maximum temperature and minimum temperature have an average lag-one serial correlation coefficient of 0.671 and 0.621, respectively. Solar radia-tion has an average serial correlation coefficient of 0.251. The serial correlation of maximum temperature and solar radiation are related to location. The lag-zero cross correlation between maximum and minimum tempera-ture averaged 0.633. Maximum temperature and radia-tion have an average cross correlation of 0.186, and minimum temperature and radiation have an average cross correlation of -0.193. All of the cross correlation coefficients varied with season and location.

Quality Detection by Frequency Spectrum Analysis of the Fruit Impact Force

Abstract: THE application of fast Fourier transform algorithms to the impact force of a fruit falling on a rigid plate was discussed. Analysis of the force in the frequency do-main indicated that there exists a relationship between the magnitude of the force components and firmness parameters of the fruit as given by the elastic modulus or Magness-Taylor values. It was found that non-destructive sorting for firmness could be accomplished based on the electronic processing of the fruit impact force measurement.

Flow Retardance of Submerged Grass Channel Linings

Abstract: AN improved method for determining the flow re-sistance of a grass-lined open channel is introduced. This method relates the flow retardance potential of a grass lining directly to physical parameters normally familiar and available to the design engineer. Retar-dance potential is related to flow resistance through an infinite family of retardance curves, with the traditional *n-VR curves' approximating specific members of this curve family. Use of the relations presented reduces the subjectivity required for flow resistance determinations. The method is applicable for general usage and is especially useful in numerical procedures such as the allowable tractive force method for stability design.

Corn Stover Harvest for Energy Production

Abstract: CORN stover was recovered and stored by big roll baler and by large stackwagon systems. Time studies were made of the various operations to determine capaci-ties and losses. About 30 percent of the original dry matter was pack-aged and 25 percent remained after outdoor storage for six months. Cost per dry tonne equations were developed with har-vestable yield and transport distance as variables. Total estimated cost, field to plant, for a 16-km one-way haul varied from $20/t for 3.4 t/ha to $35/t for 1.1 t/ha yield. At an 80-km haul, costs were $28 to $42/t for bales and $39 to $55/t for stacks because of less than half the dry weight per load.