bluuebunny/crossref_metadata_2025_split huggingface dataset:
Field Testing a Rapid Method for Estimating Alfalfa Quality
Authors: Sulc R. Mark , Albrecht Kenneth A. , Cherney Jerome H. , Hall Marvin H. , Mueller Shannon C. , Orloff Steve B. 
Published: July 2010

AbstractPredictive equations for alfalfa quality (PEAQ) based on height of the tallest stem and maturity stage of the most mature stem in a sample were developed to estimate neutral‐detergent fiber (NDF) and acid‐detergent fiber (ADF) concentrations in alfalfa (Medicago sativa L.). Field testing of these equations is limited outside the state of Wisconsin where they were developed. Our objectives were to test these equations for estimating alfalfa NDF and ADF across a wide geographic area and to evaluate the performance of PEAQ on a whole‐field basis by using within‐field subsampling. Alfalfa samples varying in height and maturity were collected throughout the growing season from fields in New York (n = 28), Pennsylvania (n = 23), Ohio (n = 48), California (n = 45), and Wisconsin (n = 48) in 1994 to 1996. Additional samples were collected in Ohio and Wisconsin from producer‐managed fields in which 5 to 10 subsamples per field were taken on each sampling date (n = 296 subsamples from 51 fields). Observed NDF and ADF values were regressed on estimated values. The accuracy of PEAQ in other states was at least equal to that observed in Wisconsin. Across all states, regression equations for NDF and ADF were slightly biased (b ≠ 1.0 and/or y‐intercept ≠ 0 at P < 0.01); however, prediction errors were sufficiently low to allow use of PEAQ as a preharvest management tool. Root mean square error values ranged from 19.1 to 23.9 g kg−1 for NDF and 15.0 to 19.0 g kg−1 for ADF. Prediction errors were 16.2 g kg−1 for NDF and 13.2 g kg−1 for ADF across Ohio and Wisconsin when regressing observed means on estimated means of five subsamples per fieldsampling date combination. We conclude that predictive equations for alfalfa quality based on a combination of stem height and maturity were robust across a wide range of environments.
Upper Threshholds of Nitrogen Uptake Rates and Associated Nitrogen Fertilizer Efficiencies in Irrigated Rice
Authors: Peng Shaobing , Cassman Kenneth G. 
Published: July 2010

AbstractMeasurements of the N uptake rate of rice (Oryza sativa L.) have usually been conducted over a period of 7 to 14 d. Such a sampling interval may not accurately determine the maximum rate, since information concerning N uptake dynamics during the first week after N topdressing is limited. In this study, N uptake dynamics and fertilizer N recovery efficiency following N topdressing were determined with more frequent samplings. Field experiments were conducted at International Rice Research Institute (IRRI) and at the Philippine Rice Research Institute (PRRI) during the 1995 dry season. Treatments consisted of 0, 50, and 100 kg N ha−1 applied at midtillering (MT) or panicle initiation (PI). Tissue N concentration and N uptake were measured 0, 2, 4, 6, 9, and 14 d after N application. Fertilizer N recovery efficiency was estimated using the difference method. At PI, maximum N uptake rates of 9 to 12 kg ha−1 d−1 were measured over the 4‐d period following application of 100 kg N ha−1, which is up to double the previously reported maximum value of 6 kg ha−1 d−1. The much larger estimates of maximum N uptake rates in our study probably resulted from more frequent sampling than in previous studies. Nitrogen uptake rates at PI were similar, regardless of N rate at MT. Recovery efficiency of N applied at PI reached 74 to 78%, and was significantly higher than that at MT. Recovery efficiency was relatively insensitive to the amount of N applied at MT and PI, which suggests that high N fertilizer efficiency can be achieved with large rates of applied N when growth conditions are favorable.
Sand and Organic Amendment Influences on Soil Physical Properties Related to Turf Establishment
Authors: McCoy Edward L. 
Published: July 2010

AbstractTopsoil blending is a common practice in many metropolitan areas, yet few scientific guidelines are available for design of general‐use, lawn‐area soils. The objective of this study was to provide blending guidelines with focus on establishing a vigorous turfgrass ground cover. A Mahoning silt loam (fine, illitic, mesic Aerie Epiaqualf) and a Tioga loam (coarse‐loamy, mixed, mesic Dystric Fluventic Eutrochrept) were each blended with a spent foundry sand and a peat humus to form 28 individual soil mixes for each native soil. Soil properties and perennial ryegrass (Lolium perenne L.) growth were measured for each soil mix. Cation exchange capacity (CEC), bulk density, and plant available water exhibited changes due to soil mix that largely resulted from differences in mix organic matter (OM) content. Compression index, bubbling pressure (Hb), air‐filled porosity, and saturated hydraulic conductivity (Ksat) responded to both sand and OM contents of the soil mixes. The pore distribution parameter, λ, exhibited a response to sand and OM contents, but only at high levels of either component. Principal component analysis (PCA) of soil properties revealed that the first two principal components contained 85 to 88% of the total data variation with correlations between compression index, Hb, air‐filled porosity, Ksat, and λ contained in the first component and correlation between CEC, bulk density, and available water contained in the second component. Regression of turf clipping yield vs. PCA factor scores and regression of factor scores vs. total sand and OM contents suggested that a high‐quality, general‐use soil for lawn establishment would contain about 65% sand and have an OM content of 8% by weight. The multivariate process of relating turf yield to soil physical properties, as applied in this study, should provide more generalized mix formulation guidelines than do recommendations based on relating turf yield to mix composition.
SALTDATA: A Database of Plant Yield Response to Salinity
Authors: Ulery April L. , Teed Jennifer A. , van Genuchten Martinus Th. , Shannon Michael C. 
Published: July 2010

AbstractCrop salt‐tolerance data are crucial for the effective management of salt‐affected agronomic systems in arid and semiarid regions. Numerous field and laboratory experiments have been conducted over the years to obtain these data, leading to generalized salt‐tolerance lists used by growers and researchers. Plant response to salinity is affected by several factors, including crop variety, soil texture, climate, and irrigation or other cultural practices. Consideration of these factors in growth‐response models would permit a more realistic and site‐specific prediction of crop yield as a function of soil salinity. A computerized salt‐tolerance database management program, SALTDATA, was developed to store experimental data relating observed crop yields to average rootzone salinity and other parameters affecting plant growth. The information was selectively retrieved from a large collection of published references on salt tolerance. The data were stored in their original reported units, but conversion equations were included to allow comparison of salinity and yield data of different experiments reported in different units. Thus, a comprehensive data set can be built for retrieval, export, and subsequent analysis by various crop salt‐tolerance models.
Winter Wheat Seedling Emergence from Deep Sowing Depths
Authors: Schillinger William F. , Donaldson Edwin , Allan Robert E. , Jones Stephen S. 
Published: July 2010

AbstractGrowers in low‐precipitation (<300 mm annual) dryland wheat‐fallow areas of the inland Pacific Northwest need winter wheat (Triticum aestivum L.) cultivars that emerge from deep sowing depths in dry soils. Stand establishment is the most important factor affecting winter wheat grain yield in this region. Despite poor resistance to disease, modest grain yield potential, and other problems, the outdated soft white winter wheat (SWWW) cultivar Moro is widely sown in these dry areas, due to its excellent emergence ability. All other SWWW cultivars are semidwarfs that carry emergence‐impeding Rht1 or Rht2 reduced‐height genes. From 12 sowing trials at 2 locations over 4 yr, we compared the emergence capability of Moro to (i) 8 SWWW cultivars and (ii) 16 SWWW advanced experimental Mororeplacement lines. Under both wet and dry soil conditions (soil water content in the seed zone ranged from 11 to 19 mm3 mm−3), seeds were sown deep, with 110 to 160 mm of soil cover. Moro always emerged fastest and achieved the best final stand compared with the semidwarf cultivars. The advanced experimental lines, which contained either no reduced‐height gene or a Rht1, Rht2, or Rht8 reduced‐height gene, had superior straw strength, disease resistance, and grain quality compared with Moro. The best‐emerging advanced experimental lines had coleoptile lengths >100 mm. Coleoptile length was associated with emergence capability among both cultivars (r2 = 0.71, P < 0.004) and advanced lines (r2 = 0.62, P < 0.001). From deep sowing depths in this study: (i) cultivars and advanced lines with Rht1 and Rht2 reduced‐height genes always emerged poorly compared with Moro; (ii) the Rht8 reduced‐height gene did not hamper emergence to the extent that Rht1 and Rht2 did; and (iii) several advanced experimental lines with long coleoptiles equaled or exceeded Moro for emergence.
Harvest Management of Switchgrass for Biomass Feedstock and Forage Production
Authors: Sanderson Matt A. , Read James C. , Reed Roderick L. 
Published: July 2010

AbstractSwitchgrass (Panicum virgatum L.), a warm‐season perennial grass native to North America, has potential as a biomass energy crop. Our objective was to develop harvest management recommendations for biomass feedstock and forage production. ‘Alamo’ switchgrass was established in 1992 at Stephenville and Dallas, TX. Four harvest frequencies (one to four cuts per year) and three final autumn harvests (Sept., Oct., or Nov.) were imposed from 1993 to 1996. Tiller densities were counted each spring. Neutral detergent fiber (NDF) and crude protein (CP) concentrations were measured in 1993 and 1994. Concentrations of NDF were lowest (avg. = 640 g kg−1) and of CP (avg. = 110 g kg−1) were highest in May‐harvested biomass. Forage quality of regrowth decreased with age, reaching NDF concentrations of 790 g kg−1 and CP of <20 g kg−1. Total seasonal yields decreased as harvest frequency increased; however, a severe drought reversed this trend at Dallas in 1996. The highest yields (15–20 Mg ha−1) occurred with a single harvest in mid‐September. Delaying the final harvest until November reduced yields. Harvest date and frequency did not affect tiller density, although tiller density decreased from 900 to 650 and 630 to 310 m−2 at Dallas and Stephenville, respectively, during 1994 to 1997. Thus, a single mid‐September harvest should maximize biomass yields in the south‐central USA. A two‐cut (spring‐autumn) system may allow a farmer to use initial growth as forage and the regrowth for biomass, but total yields would be reduced. More frequent harvests would reduce yields further.
Models of Yield, Grain Protein, and Residual Mineral Nitrogen Responses to Applied Nitrogen for Winter Wheat
Authors: Makowski David , Wallach Daniel , Meynard Jean‐Marc 
Published: July 2010

AbstractThe proper use of N fertilizer is fundamental for farm profitability and environmental protection. In France, fertilizer recommendations are generally based on the balance‐sheet method, which is not sensitive to the economic or regulatory context. A way to generalize the balance‐sheet method is to use models that describe crop response to applied N. The goal of this paper is to propose, in the case of winter wheat (Triticum aestivum L.), functional forms for the response of yield, grain protein content, and residual mineral N left in the soil at harvest to applied N. The originality of our models is that all three responses (yield, protein, and residual mineral N) are modeled, using N uptake as an intermediate variable. Furthermore, these models have two clear links with the balance‐sheet method. First, the parameters of the balance‐sheet method appear explicitly in the models. Second, the N dose recommended by the balance‐sheet method appears in our models as the smallest N dose that maximizes yield. Within this general modeling framework, three variants of the yield model, three variants of the grain protein content model, and two variants of the residual mineral N model are considered. The different models are adjusted, site‐year by site‐year, to 28 site‐years of data. All models give satisfactory fits to the data. For example, the root mean square error varies between 0.21 and 0.23 Mg ha−1 for the yield models. Almost all the adjusted parameter values vary widely from site‐year to site‐year. This must be taken into account when calculating optimal N doses for new site‐years.
Decomposition of Surface Crop Residues in Long‐Term Studies of Dryland Agroecosystems
Authors: Ma Liwang , Ahuja Lajpat R. , Shaffer Marvin J. , Rojas Kenneth W. , Peterson Gary A. , Sherrod Lucretia 
Published: July 2010

AbstractDecomposition of surface crop residues is important for agricultural management, especially under conservation tillage. The objective of this study was to test several models for describing crop residue decomposition under three eastern Colorado dryland agroecosystems at Sterling, Stratton, and Walsh with a yearly mean air temperature of 9.7, 10.4, and 12.0°C, respectively. At each site, a soil toposequence common to its geographic region was chosen to include a summit, a sideslope, and a toeslope position, and several crop rotations were practiced under no‐till conditions. Grab samples were taken at planting and before harvesting for surface residue measurement since 1985. Simulation results showed that the Douglas‐Rickman model described surface crop residue decomposition better than the Gregory model during a 13‐year period, based on a normalized objective function (NOF). Our fitted decomposition rate coefficients using the Douglas‐Rickman model matched those originally published. The Douglas‐Rickman model, which uses a first‐order decay with respect to degree‐days, was further evaluated against two other first‐order decay models: one using a first‐order decay equation with respect to decomposition‐days and the other assuming a first‐order decay with respect to time (d). Although the three approaches performed equally well in terms of NOF values (P = 0.354), fitted decomposition rate coefficients were significantly different (P < 0.012) among the three experiment sites when models based on decomposition‐days or on time (in days) were used. Therefore, the Douglas‐Rickman model may be more applicable for describing long‐term crop residue decomposition because of its consistency in model parameters among experimental sites and simplicity in modeling approach.
Nitric Acid Oxidation of Danish Illuvial Organic Matter
Authors: Hansen E. H. , Schnitzer M. 
Published: July 2010

AbstractOrganic matter extracted from the Bh horizon of a Danish Podzol was oxidized with 2N and with 7.5N HNO3. Oxidation with 2N HNO3 produced 2.10% nitro phenols and nitro benzoic acids, 0.60% hydroxy benzoic and 3.23% benzene carboxylic acids. The products resulting from oxidation with 7.5N HNO3 contained 5.50% picric acid, 0.20% hydroxy benzoic and 3.78% benzene carboxylic acids. The yields are expressed on the basis of the original dry ash‐free organic matter.From the results of this and earlier investigations it appears that Danish illuvial organic matter consists primarily of isolated aromatic rings—heavily substituted with oxygen‐containing functional groups—that are linked to each other via aliphatic chains or saturated cyclic or hydroaromatic structures. The occurrence in this organic matter of substantial numbers of condensed aromatic ring systems is unlikely.
Soil Concretions: I. X‐Ray Spectrograph and Electron Microprobe Analyses
Authors: Gallaher R. N. , Perkins H. F. , Radcliffe D. 
Published: July 2010

AbstractX‐ray spectrographic analyses of soil concretions collected in Georgia and Tennessee from different soil parent material and moisture regimes indicated wide variation in chemical composition. Analyses showed higher concentrations of Mn and Ba in the inner core than in the outer layer of Fe‐Mn concretions from Henry and Iredell soils. A larger concentration of Fe and Ti was found in the outer layer as compared to the inner core. Distribution of Mn, Ba, Fe, and Ti indicated that they were accumulated by a similar mechanism in Henry and Iredell Fe‐Mn concretions. Concretions from the Tifton soil were composed of randomly distributed quartz grains cemented by Fe, Al, and Si oxides; whereas, those from the Decatur soil consisted of a homogenous mixture of Mn and Ba oxides. Electron probe micrographs supported the indication that elemental distribution within concretions differed as a result of weathering conditions at different geographic locations.
Organic Compound Effects on Swelling and Flocculation of Upton Montmorillonite
Authors: Chen Shizheng , Low Philip F. , Cushman John H. , Roth Charles B. 
Published: July 2010

AbstractThe swelling and shrinking and flocculation and deflocculation of clays is of fundamental importance in the transport of solutes through a porous medium because these processes affect the permeability of the medium. Since organic solutes frequently occur in toxic wastes, we conducted an investigation of the effect of eight soluble organic compounds, representing different kinds of structures and functional groups, on the swelling and flocculation of sodium saturated Upton montmorillonite. These compounds were ethanol, 1,4‐dioxane, phenol, urea, benzamide, ethylamine hydrochloride, acetic acid, and sodium acetate. In general, we found that increases in the concentration of the compounds that ionize in water decreased swelling and increased flocculation to a greater extent than those that remained un‐ionized, i.e., electrically neutral. However, 1,4‐dioxane was exceptional in that, despite its electrical neutrality, it reduced swelling and increased flocculation significantly. Possible reasons for the effects of the different compounds on swelling and flocculation were advanced.
Centrifugation: A Solution to the Problems Posed by Ammonium and Nitrate Contamination of Filters in Soil Extract Analysis
Authors: Scharf Peter , Alley M. M. 
Published: July 2010

AbstractThe objective of this study was to develop a rapid and effective method of removing particulate matter from 2 M KCl soil extracts without contaminating the extracts with NH+4 and/or NO−3. Seven types of filters were first tested by eluting them with 2 M KCl solution and analyzing the eluents. All filters tested eluted unacceptable levels of NH+4, NO−3, or both, and are thus unsuitable for filtration of 2 M KCl soil extracts which are to be analyzed for both NH+4 and NO−3. Subsequently, soil extracts were centrifuged at varying speeds and for varying times in an attempt to remove particulate matter from the extracts without filtration. Particulate matter content of the resulting supernatants was measured with a Coulter counter. Centrifuging the soil extracts at 1800 rpm for 10 min reduced particulate contamination to levels comparable to those in filtered extracts.
Ponded Infiltration From a Single Ring: I. Analysis of Steady Flow
Authors: Reynolds W. D. , Elrick D. E. 
Published: July 2010

AbstractA new analysis of steady, ponded infiltration from within a single ring takes soil hydraulic properties, ring radius, depth of ring insertion, and depth of ponding into account. It also provides a means for determining the field‐saturated hydraulic conductivity (Kfs) and the matric flux potential (φm). The analysis employs numerically determined shape factors (G) that are found to depend significantly on ring radius (a) and depth of ring insertion (d), but only slightly on depth of ponding (H) and soil hydraulic properties. As a consequence, averaged G values (Ge) can be developed for specified d and a that apply to a wide range of ponded heads and soil types. Procedures for calculating Kfs and φm are based on G or Ge, and on the ponding of one, two, or multiple H levels in the ring. Test calculations based on Ge suggest that Kfs can be obtained with an accuracy of about ±20% for H = 0.05 to 0.25 m and α = 1 to 36 m−1, where α is the soil parameter of the exponential hydraulic conductivity‐pressure head relationship. A similar level of accuracy (using Ge) is obtained for φm when α is small (α ≤ 4 m−1), and when both α and H are large (α > 4 m−1, H ≥ 0.20 m). Significant errors in φm can occur, however, when α is large but H is small. Potentially important features of this single ring method include low sensitivity of the Kfs calculation to errors in Ge, reduced measurement errors resulting from small‐scale soil variability, and the ability to pond large heads in order to increase flow rates in low‐permeability materials.
Fuzzy‐c‐Means and Kriging for Mapping Soil as a Continuous System
Authors: Odeh Inakwu O. A. , Chittleborough David J. , McBratney Alex B. 
Published: July 2010

AbstractEven though soil has long been recognized as a continous system in both the geographical and taxonomic context, there has been no practical approach to mapping soil as a continuum. Fuzzy set theory and the regionalized variable theory provide for such an approach. A predetermined optimal sampling scheme was used for sampling of pedons in an area of 627 by 375 m. The fuzzy‐c‐means (FCM) algorithm was first used to quantify the pedons into intragrade and extragrade classes by minimization of the fuzzy objective function. The resulting matrix of membership coefficients was used to determine membership semivariograms for the c + 1 continuous soil classes. The resulting semivariogram parameters were further used for kriging of the membership coefficients, yielding an isarithmic map for each of the c + 1 fuzzy soil classes. A composite map that presents the core areas of the continuous classification units was produced by overlaying of the isarithmic maps of the c + 1 classes. The significance of this approach to geographical (or soil) information systems is the associated minimum loss of information if fuzzy logic and operations are integrated into the systems.