bluuebunny/crossref_metadata_2025 huggingface dataset:
Economic Impact of Improved Service-Life Prediction for Seams in Low-Slope EPDM Roofing
Authors: Thomas Douglas S.
Published: July 2014

In the early part of the 1970s, built-up roofing dominated the U.S. membrane roofing industry. It was estimated that 10 % to 15 % of these roofs failed prematurely, but by the early 1980s new membranes were being rapidly adopted. Among them, ethylene-propylene-diene terpolymer (EPDM) rubber, manufactured as preformed single-ply sheets ready for field installation, experienced the most rapid growth. Although performance was generally satisfactory, far too often, disbonding of seams occurred. National Institute of Standards and Technology (NIST) researchers developed a creep-rupture methodology to study the factors affecting seam performance including mechanical loading of the seam, thickness of the adhesive used to form the seam, and rubber surface cleanness of the rubber before the adhesive was applied. This research had a noteworthy impact on the EPDM roofing industry in that it accelerated changes to seam technology and increased users’ confidence that EPDM would provide satisfactory long-term performance. This paper examines the economic impact of the research conducted by NIST’s Service Life Prediction (SLP) Program for EPDM roofing. Three ASTM standards are used to calculate the value of NIST’s research investment: (1) present value of net savings (PVNS) [ASTM E1074-09: Practice for Measuring Net Benefits and Net Savings for Investments in Buildings and Building Systems, Annual Book of ASTM Standards, ASTM International, West Conshohocken, PA, 2012], (2) savings-to-investment ratio (SIR) [ASTM E964-06: Practice for Measuring Benefit-to-Cost and Savings-to-Investment Ratios for Buildings and Building Systems, Annual Book of ASTM Standards, ASTM International, West Conshohocken, PA, 2012], and (3) adjusted internal rate of return (AIRR) [ASTM E1057-06: Standard Practice for Measuring Internal Rate of Return and Adjusted Internal Rate of Return for Investments in Buildings and Building Systems, Annual Book of ASTM Standards, ASTM International, West Conshohocken, PA, 2012]. The results show that the PVNS attributable to NIST is $26.7 × 106 with an SIR of 2.5 and an AIRR of 13.7 %. Stated in present-value terms, every public dollar invested in NIST’s SLP-related research, development, and deployment effort generated $2.5 in cost savings to the public.
Traffic control: adaptor proteins guide dynein–cargo takeoff
Authors: Cianfrocco Michael A , Leschziner Andres E
Published: July 2014

The precise movement of intracellular components requires active transport by molecular motors along the filamentous tracks of the cytoskeleton. While yeast cytoplasmic dynein can walk for some distance along microtubules, mammalian dynein is non‐processive. This has raised the question of how this motor can transport cargo. In two recent papers by the Carter, Bullock and Vale labs, mammalian dynein processivity has now been successfully reconstituted in vitro in the presence of adaptor proteins.
Assessing biophysical controls on Gulf of Mexico hypoxia through probabilistic modeling
Authors: Obenour Daniel R. , Michalak Anna M. , Scavia Donald
Published: July 2014

A mechanistic model was developed to predict midsummer bottom‐water dissolved oxygen (BWDO) concentration and hypoxic area on the Louisiana shelf of the northern Gulf of Mexico, USA (1985–2011). Because of its parsimonious formulation, the model possesses many of the benefits of simpler, more empirical models, in that it is computationally efficient and can rigorously account for uncertainty through Bayesian inference. At the same time, the model incorporates important biophysical processes such that its parameterization can be informed by field‐measured biological and physical rates. The model is used to explore how freshwater flow, nutrient load, benthic oxygen demand, and wind velocity affect hypoxia on the western and eastern sections of the shelf, delineated by the Atchafalaya River outfall. The model explains over 70% of the variability in BWDO on both shelf sections, and outperforms linear regression models developed from the same input variables. Model results suggest that physical factors (i.e., wind and flow) control a larger portion of the year‐to‐year variability in hypoxia than previously thought, especially on the western shelf, though seasonal nutrient loads remain an important driver of hypoxia, as well. Unlike several previous Gulf hypoxia modeling studies, results do not indicate a temporal shift in the system's propensity for hypoxia formation (i.e., no regime change). Results do indicate that benthic oxygen demand is a substantial BWDO sink, and a better understanding of the long‐term dynamics of this sink is required to better predict how the size of the hypoxic zone will respond to proposed reductions in nutrient loading.
A new twist on a very old binary similarity coefficient
Authors: Alroy John
Published: July 2014

Pairwise similarity coefficients are downward biased when samples only record presences and sampling is partial. A simple but forgotten index proposed by Stephen Forbes in 1907 can help solve this problem. His original equation requires knowing the number of species absent in both samples that could have been present. It is proposed that this count should simply be ignored and that the coefficient should be adjusted using a simple heuristic correction. Four analyses show that the corrected equation outperforms the Dice and Simpson indices, which are highly correlated with many others. In two‐sample simulations, similarity is almost always closer to the assumed value when the species pool size and sampling intensity are varied, regardless of whether the underlying abundance distribution is uniform, log‐normal, or geometric. The index is also much more robust when sampling is unequal. An analysis of bat samples from peninsular Malaysia buttresses these conclusions. The corrected coefficient also indicates that local assemblages of North American mammals are random subsamples of larger species pools by returning similarity of values of around 1, and it suggests a more consistent relationship between biome‐scale comparisons and local‐scale comparisons. Finally, it yields a better‐dispersed pattern when the biome‐scale inventories are ordinated. If these results are generalizable, then the new and old equation should see wide application, potentially taking the place of the two most commonly used alternatives (the interrelated Dice and Jaccard indices) whenever sampling is incomplete.
Orchardgrass and Tall Fescue Utilization of Nitrogen from Dairy Manure and Commercial Fertilizer
Authors: Cherney Debbie J. R. , Cherney Jerome H. , Mikhailova Elena A.
Published: July 2014

Our objective was to compare multiyear N utilization by orchardgrass (Dactylis glomerataL. ‘Okay’) and tall fescue (Festuca arundinaceaeSchreb. ‘Stargrazer’) from dairy manure or commercial fertilizer N. The study was conducted from 1994 through 2000 at the Cornell University Baker Farm, Willsboro, NY, on a poorly drained Kingsbury silty clay (very fine, illitic, mesic Aeric Epiaqualfs). The design was a split plot in a randomized complete block with two annual manure rates (33.6 and 67.2 Mg ha−1) and a recommended rate of inorganic fertilizer N as main‐plot treatments and grass species as subplot treatments, replicated six times. Dry matter (DM) yield of grass receiving the higher manure treatment was similar to that of N‐fertilized grass after 2 yr of manure applications, and residual effects of manure were large at least 3 yr following manure application. Orchardgrass had higher tissue N concentrations but lower total seasonal DM yields than tall fescue. Orchardgrass produced greater spring harvest yields but lower regrowth yields than tall fescue under two‐ or three‐harvest management regimes (1995–2000). No differences in N removal were observed between grass species under a three‐harvest management regime. Relative N recovery (including N supplied from the soil) was 59 to 86% from inorganic N fertilizer and 28 to 70% from manure (1995–1997). Manure at commonly used rates resulted in grass yield and N uptake comparable to commercial N fertilization at a recommended rate.
Corn Yield Response to Nitrogen Fertilizer Timing and Deficiency Level
Authors: Scharf Peter C. , Wiebold William J. , Lory John A.
Published: July 2014

Nitrogen fertilizer is typically applied to corn (Zea mays L.) shortly before planting, but there are several reasons why later N applications may be of interest: to spread work away from the busy planting season, to avoid the frequent wet field conditions in spring, to reduce or remedy in‐season N loss in wet years, or to allow use of in‐season diagnostic tools. One of the obstacles to the use of later N applications is the fear that irreversible yield loss will occur due to N stress. Our objective was to evaluate the yield impact of delaying N applications until the late vegetative growth stages and as far as silking. We conducted a total of 28 experiments with timing of a single N application as the experimental treatment. We found little or no evidence of irreversible yield loss when N applications were delayed as late as stage V11, even when N stress was highly visible. There was weak evidence of minor yield loss (about 3%) when N applications were delayed until stage V12 to V16. Only 3 of the 28 experiments had N applications later than V16—all were at silking and relative yields were 0.71, 0.89, and 0.95. Though full yield was not achieved when N applications were delayed until silking, yield was still highly responsive to N application at this stage—yield response exceeded 2.2 Mg ha−1 in all three experiments.
A Geometric Ultraviolet‐B Radiation Transfer Model Applied to Vegetation Canopies
Authors: Gao Wei , Grant Richard H. , Heisler Gordon M. , Slusser James R.
Published: July 2014

The decrease in stratospheric ozone (O3) has prompted continued efforts to assess the potential damage to plant and animal life due to enhanced levels of solar ultraviolet (UV)‐B (280–320 nm) radiation. The objective of this study was to develop and evaluate an analytical model to simulate the UV‐B irradiance loading on horizontal below‐canopy surfaces, as influenced by vegetation. The UV‐B irradiance above canopy and transmitted to below‐canopy points was measured in a widely spaced orchard and in a closely spaced maize (Zea mays L.) crop during cloud‐free days, with solar zenith angle ranging from 20° to 80°. The sky view fraction was typically 0.59 for the orchard and 0.28 for the maize canopy. Transmitted irradiance fractions were simulated and compared to measured fractions. Measured and simulated values of UV‐B canopy transmittance generally agreed well both for points in locations shaded by plant crowns and for points below the top of the canopy that were not shaded. The model had mean bias errors of 0.04 and 0.03 for the orchard and maize canopies respectively, and the root mean squared error of the model was 0.08 for orchard and 0.06 for maize. The model can serve as a much‐needed tool to examine UV‐B irradiance loading of organisms below tree canopies and of sensitive plant surfaces in and below tree and vegetation canopies.
Economics of Conservation Tillage in a Wheat–Fallow Rotation
Authors: Janosky Jeffrey S. , Young Douglas L. , Schillinger William F.
Published: July 2014

Wind erosion and blowing dust on conventionally tilled winter wheat (Triticum aestivum L.)–summer fallow cropland in eastern Washington, USA, reduces soil productivity and can contribute to poor air quality. Conservation tillage during fallow has long been known to curtail erosion and dust, but conventional tillage (CT) is still practiced on more than 80% of the cropland in the region. This paper reports the economic results of a 5‐yr (1995–1999 harvest years) tillage system study at Lind, WA. The site averages 244 mm of annual precipitation, and the soil is a Shano silt loam (coarse‐silty, mixed, superactive, mesic Xeric Haplocambids). Tillage systems were (i) CT, (ii) minimum tillage (MT; herbicides and tillage), and (iii) delayed MT (DMT; herbicides and delayed tillage). Wheat grain yield across years ranged from 1.79 to 5.20 Mg ha−1, but there were no differences in grain yield among tillage systems in any year or when analyzed across years. Tillage systems were economically equivalent based on market returns over total production costs, but DMT was slightly less profitable than CT based on market returns over variable costs. Economic analysis indicates that no subsidies should be required to entice producers to switch from CT to MT fallow because the systems are equally profitable. Because there is no short‐ or long‐term economic sacrifice for converting to the soil‐saving MT system, it represents a win‐win solution for farmers and the environment.
Establishment of Wheat Seedlings after Early Sowing and Germination in an Arid Mediterranean Environment
Authors: Klein Joshua D. , Mufradi Israel , Cohen Shlomo , Hebbe Yonit , Asido Silvia , Dolgin Bella , Bonfil David J.
Published: July 2014

Seedling establishment of dryland crops in semiarid and arid zones is limited by precipitation. Spring wheat (Triticum aestivum L. emend. Thell.) generally is sown in dry soil in the dryland regions of Israel before the rainy season starts. We compared the effects of no‐tillage, conventional tillage, and plant growth regulators on wheat seedling growth to identify the optimal crop management system for seedling establishment in dryland farming. Experiments were conducted during 1998 and 1999 at the Gilat Experimental Station located in southern Israel (annual precipitation of 222 and 72 mm for 1998 and 1999, respectively; soil type is sandy loam loess—Torrifluvents). Neither inhibitors of gibberellin synthesis (chlorocoline chloride, paclobutrazol, and trinexapac‐ethyl) nor monopotassium phosphate (KH2PO4) enhanced seedling survival under drought stress when sprayed on seedlings at the two‐leaf stage. No‐tillage led to increases in water content in the upper (0–30 cm) soil layer and in seedling water content and seedling biomass. No‐tillage management also maintained seedling viability compared with the control, with seedlings surviving as long as 35 d without precipitation. No‐tillage management allows successful seedling establishment and growth after a dry period that follows germination.
Sugarcane Cultivar Response to High Summer Water Tables in the Everglades
Authors: Glaz Barry , Edme Serge J. , Miller Jimmy D. , Milligan Scott B. , Holder David G.
Published: July 2014

Sugarcane (interspecific hybrids of Saccharum spp.) in the Everglades Agricultural Area (EAA) in Florida is frequently subjected to periods of higher‐than‐desired water levels. This study was conducted to evaluate yields of nine sugarcane cultivars subjected to two higher‐than‐conventional water tables in the EAA during the summer rainy season from the plant cane through the second‐ratoon annual crop cycles. Field experiments were planted in February 1997 and January 1998. During the summers from 1997 through 1999, we sought to maintain water <15 cm below the soil surface (BSS) in the wetter field and from 15 to 38 cm BSS in the drier field. Water tables for sugarcane in the EAA fluctuate from 40 to 95 cm BSS. Targeted water levels were achieved for 40 d in 1997, 104 d in 1998, and 96 d in 1999 in the wetter field and for 35 d in 1997, 96 d in 1998, and 82 d in 1999 in the drier field. The mean sugar per hectare in the wetter field was 91.7% that of the drier field. Yields of ‘Canal Point (CP) 72–2086’ and ‘CP 82–1172’ were not affected by water table. Cultivar CP 85–1308 had higher yields in the wetter field in two of five harvests. Sugar per hectare of ‘CP 80–1743’ was reduced by 25.1% in the wetter field. The variability among commercial cultivars to maintain yields at high water tables suggests that routine screening of promising sugarcane genotypes under high water tables would help identify more cultivars that maintain high yields in wetter conditions in the EAA.
Intercropping System Optimization for Yield, Quality, and Weed Suppression Combining Mechanistic and Descriptive Models
Authors: Baumann Daniel T. , Bastiaans Lammert , Kropff Martin J.
Published: July 2014

Intercropping leek (Allium porrum L.) with celery (Apium graveolens L.) is an option to reduce growth and reproductive potential of weeds while maintaining productivity. In this study, a combined modeling approach is used to optimize a leek—celery intercropping system with respect to crop yield, product quality, and weed suppression. An ecophysiological model for interplant competition was used to simulate yield and product quality of the crops as well as biomass and seed production of the weed Senecio vulgaris L. for a wide range of crop mixtures and weed infestations. The results of the simulations were summarized using a descriptive hyperbolic yield–density model, which then allowed evaluation of the intercropping system in terms of productivity, product quality, and ability to suppress weeds. In a weed‐free mixture, the competitive ability of celery was six times higher than that of leek. With respect to late‐emerging S. vulgaris, the relative competitive ability of leek was 5.4 times lower than that of celery. Replacing two leek plants of a leek monoculture by one celery plant resulted in almost 20% biomass reduction of late‐emerging S. vulgaris. Crop mixtures with a leek density of about 20 plants m−2 and a leek/celery ratio of 2 proved to be the optimum intercropping system, given the current price ratios. Compared with leek monoculture, profitability was maintained, and late‐season weed suppression was greatly increased, resulting in reduced weed seed production.
Improving Nitrogen Use Efficiency in Cereal Grain Production with Optical Sensing and Variable Rate Application
Authors: Raun William R. , Solie John B. , Johnson Gordon V. , Stone Marvin L. , Mullen Robert W. , Freeman Kyle W. , Thomason Wade E. , Lukina Erna V.
Published: July 2014

In 2001, N fertilizer prices nearly doubled as a result of increased natural gas prices. This was further troubling when considering that the world N use efficiency (NUE) in cereal grain production averages only 33%. Methods to improve NUE in winter wheat (Triticum aestivum L.) have not included high spatial‐resolution management based on sensed plant growth properties nor on midseason prediction of grain yield. Our objective was to determine the validity of using in‐season estimates of grain yield (INSEY) and a response index (RI) to modulate N at 1‐m2 spatial resolution. Four winter wheat field experiments were conducted that evaluated prescribed midseason N applications compared with uniform rates that simulated farmer practices. Our methods recognize that each 1‐m2 area in wheat fields needs to be sensed and managed independently and that the need for fertilizer N is temporally dependent. Averaged over locations, NUE was improved by >15% when N fertilization was based on optically sensed INSEY, determined for each 1‐m2 area, and a RI compared with traditional practices at uniform N rates.
Chlorophyll Meter– and Leaf Color Chart–Based Nitrogen Management for Rice and Wheat in Northwestern India
Authors: Singh Bijay , Singh Yadvinder , Ladha Jagdish K. , Bronson Kevin F. , Balasubramanian Vethaiya , Singh Jagdeep , Khind Charan S.
Published: July 2014

Overapplication of N in cereal crops leads to low N recovery efficiency and risk of NO3 pollution of ground water. The chlorophyll meter, also known as SPAD meter, is a simple, portable diagnostic tool for identifying crop N status. We used it to test need‐based N management approaches for rice (Oryza sativa L.) and wheat (Triticum aestivum L.) on a loamy sand in northwestern India. Applying 30 kg N ha−1 each time the SPAD value fell below the critical value of 37.5 resulted in application of 90 kg N ha−1, which produced rice yields equivalent to those with 120 kg N ha−1 applied in three splits. Using a SPAD value of 35 was inadequate for the two rice cultivars because it resulted in application of only 60 kg N ha−1 and, thus, low yields. With high inherent soil fertility resulting in rice yield of >3 Mg ha−1 in zero‐N plots, applying N basally or a week after rice transplanting did not further increase yield. Limited experimentation with leaf color chart (LCC) indicated that N management based on LCC shade 4 helped avoid overapplication of N to rice. Wheat responded to N application at maximum tillering (MT) when SPAD value fell below 44. Wheat yield increased by 20% when 30 kg N ha−1 was applied at SPAD value of 42 at MT. Results show that plant need–based N management through chlorophyll meter reduces N requirement of rice from 12.5 to 25%, with no loss in yield.
Limestone, Gypsum, and Magnesium Oxide Influence Restoration of an Abandoned Appalachian Pasture
Authors: Ritchey K. Dale , Snuffer J. Diane
Published: July 2014

When restoring abandoned pastures on acidic hill‐land soils to productivity, it is important to bring soil Ca and Mg to adequate levels. Gypsum is a readily available Ca amendment that is sufficiently soluble to move rapidly into the soil when surface‐applied. Gypsum has been shown to reduce detrimental effects of subsurface acidity in soils of the southeastern USA. A 4‐yr experiment was initiated to measure effects of surface gypsum application on forage production and to evaluate Mg‐containing amendments to avoid gypsum‐induced Mg deficiency. The study site was a southern West Virginia Gilpin silt loam (fine‐loamy, mixed, mesic, Typic Hapludult) where abandoned hill‐land pasture was being restored to productivity. Treatments included 0, 1000, 8000, 16 000, and 32 000 kg/ha flue gas desulfurization coal combustion by‐product gypsum (gypsum) together with dolomitic limestone and five additional treatments to evaluate sources of supplemental Mg. Application of 16000 kg/ha gypsum together with limestone increased forage yields of mixed orchardgrass (Dactylis glomerataL.) and tall fescue (Festuca arundinaceaSchreb) pasture during establishment by 42% and production by 11% compared with limestone alone. About 8% of the mean 790 kg/ha yield increase could be attributed to acidity‐neutralizing effects of alkaline constituents in the gypsum by‐product. Plants in higher gypsum treatments had higher concentrations of K and P, but gypsum application decreased soil and plant Mg concentrations. This indicated that gypsum should not be applied on typical acid soils without supplemental Mg.
Evaluation of Rhizobial Inoculation Methods for Chickpea
Authors: Kyei‐Boahen Stephen , Slinkard Alfred E. , Walley Fran L.
Published: July 2014

Rhizobia inoculated onto legume seeds are often exposed to adverse environmental conditions, which can affect survival and subsequent effectiveness. Hence, soil‐applied granular inoculants have received much attention recently. We examined the efficacy of various inoculation methods at four sites in Saskatchewan, Canada, in 1997 and 1998 using desi‐ and kabuli‐type chickpea (Cicer arietinum L.). Seed inoculation treatments (liquid or peat‐based powder) were compared with soil inoculation (granular inoculant) either placed in the seed furrow or side‐banded (i.e., 2.5 cm to the side) at depths of either 2.5 or 8 cm below the seed. Nodule formation in the seed inoculation treatments was restricted to the crown region of the root system, whereas soil inoculation enhanced nodulation on the lateral roots. In 1997, granular inoculant placed below the seed increased kabuli seed yield by 36 and 14% over the liquid and peat‐based inoculants, respectively, whereas desi seed yield increased 17 and 5%, respectively. Seed yield responses were inconsistent in 1998. Seed protein concentration, percentage N derived from the atmosphere (%Ndfa), and amount of N2 fixed were typically lower for the liquid inoculant than for the peat and granular inoculants, which did not differ. The dry weight of lateral‐root nodules was highly correlated with yield parameters, suggesting that the lateral‐root nodules contributed significantly to N2 fixation and yield. Although the peat and granular inoculants were equally effective in establishing successful symbiosis, placing granular inoculant 2.5 to 8.0 cm below the seed may improve yield and quality.
Correcting Measurements of Pasture Forage Mass by Vacuuming the Stubble
Authors: Unruh Lori J. , Fick Gary W.
Published: July 2014

Estimates of forage mass in pasture obtained by harvesting small plots may be too low because fragments of the harvested herbage are dropped into the stubble and not recovered. Our objective was to evaluate stubble vacuuming as a means of retrieving such material, thereby improving the accuracy of forage mass estimation. Our study was conducted on intensively managed dairy pastures dominated by orchardgrass (Dactylis glomerata L.) and white clover (Trifolium repens L.). The stubble was vacuumed following conventional harvesting of small quadrats to a stubble height of 2 cm. Harvested herbage and vacuumed stubble were oven‐dried separately and then ashed to correct for soil contamination. The slope of the regression of total organic matter (OM), which included vacuumed material, on the mass of harvested herbage without vacuuming showed that clippings lost into the stubble in this study amounted to 0.045 Mg/ha OM for each Mg/ha unvacuumed herbage dry weight or 0.286 Mg/ha OM for each Mg/ha unvacuumed herbage OM. Because of the extra cost of the procedure, it is not recommended, except for ecological studies where very accurate estimations of OM distribution are required.
Low Temperature–Tolerant Bradyrhizobium japonicum Strains Allowing Improved Soybean Yield in Short‐Season Areas
Authors: Zhang Hao , Charles Trevor C. , Driscoll Brian T. , Prithiviraj Balakrishnan , Smith Donald L.
Published: July 2014

In short‐season soybean [Glycine max (L.) Merr.] production areas, low soil temperature is potentially an important factor limiting soybean growth and yield. Some strains originating from cooler areas can cause more nodulation and nitrogenase activity under low‐temperature conditions. We have attempted to find Bradyrhizobium japonicum strains that can fix more N than strain 532 C under low‐temperature conditions. We selected 40 B. japonicum strains from the USDA collection based on their isolation from soils of northern locations. These 40 strains were tested for their ability to grow at a low (15°C) temperature, and the best two (USDA 30 and USDA 31) were selected for evaluation under field conditions. Inoculation with USDA 30 and USDA 31 resulted in greater soybean yields (an 8% increase, averaged over the 2 yr) than inoculation with 532 C. The increased yield was due to the formation of more pods per plant, and more seeds per plant, but not due to an increase in 100‐seed weight. This indicated that the benefit caused by the superior strains occurred early in plant development, probably due to increased N fixation early in the growing season. This possibility was supported by the observations that leaf areas, grain protein production, and total protein levels for plants inoculated with USDA 30 and USDA 31 were greater than those inoculated with 532 C. These findings clearly demonstrate that inoculant strains likely to perform best in a given geographical area are those selected for the conditions prevalent in the area.
Nutrient Uptake in Plant Parts of Sixteen Forages Fertilized with Poultry Litter
Authors: Pederson Gary A. , Brink Geoffrey E. , Fairbrother Timothy E.
Published: July 2014

Poultry litter used as fertilizer for forages often results in nutrient accumulation in soils over time. Maximizing nutrient uptake by forages would facilitate nutrient removal from litter‐treated soils when the plants are mechanically harvested. This study compared N, P, K, Cu, and Zn concentrations and distribution in plant parts of annual ryegrass (Lolium multiflorum Lam.) with 15 other cool‐season forages fertilized with poultry litter. Annual ryegrass, three cereals, and 12 legumes were seeded in a pasture at Collins, MS, on a Savannah fine sandy loam (fine‐loamy, siliceous, semiactive, thermic Typic Fragiudult) fertilized with poultry litter. Each species was harvested at full maturity and separated into root, stem, leaf, and flower components, and N, P, K, Cu, and Zn concentration and content of each component was determined. Most legumes had greater P, Cu, and Zn concentrations than annual ryegrass in many plant parts. Content of P, Cu, and Zn was similar between annual ryegrass and legumes due to greater dry matter yield of annual ryegrass compared with legumes. Stems, especially oat (Avena sativa L.) stems, had the lowest N/P ratio of all plant parts, which was more comparable to the N/P ratio of poultry litter. Nitrogen concentration was highly correlated with P, Cu, and Zn concentrations in aboveground plant parts, suggesting that improvements in N fertility would improve P, Cu, and Zn concentration in plants. To maximize P uptake in poultry litter–fertilized forages, management practices and breeding objectives should concentrate on optimizing stem production, while maintaining palatability, because almost 60% of total P in forages is located in stems.
The Impact of Intercropping Annual ‘Sava’ Snail Medic on Corn Production
Authors: Smeltekop Hugh , Clay David E. , Clay Sharon A.
Published: July 2014

Interseeding a leguminous cover crop into corn (Zea mays L.) may reduce corn yields. By understanding the mechanisms responsible for yield reductions, improved management strategies can be developed. The objective of this study was to determine the influence of an annual medic (Medicago scutellata Mill cv. Sava) interseeded into corn at planting on N and water stress in corn. Field research was conducted at three South Dakota sites. Treatments were two broadcast medic (0 and 33 kg ha−1) and two N (0 or recommended) rates. Water infiltration was measured at Aurora in 1997 and 1998. Carbon‐13 discrimination (Δ) in corn grain was measured at Aurora in 1998 and Beresford in 1998. Medic biomass at Aurora in 1997, Aurora in 1998, and Beresford in 1998 was 1290, 215, and 913 kg ha−1, respectively. At Aurora, on 11 July 1997, medic increased water infiltration from 0.0156 to 0.035 cm s−1. Similar results were measured at Aurora in 1998. Medic reduced corn growth as early as 17 July at Aurora in 1997 and 19 June at Beresford in 1998. Associated with reduced corn biomass production in the fertilized treatments were lower N concentration and fertilizer efficiency. Interseeding medic into corn did not increase Δ in corn at Beresford in 1998 or Aurora in 1998. These results suggest that the negative effects of medic on corn primarily resulted from N stress and not increased water stress. Given these results, management strategies that reduce the competition between medic and corn for N should be developed.
Historical Development of Soil and Weathering Profile Concepts from Europe to the United States of America
Authors: Tandarich John P. , Darmody Robert G. , Follmer Leon R. , Johnson Donald L.
Published: July 2014

In the 1870s, agricultural geologists (pioneer pedologists) in Germany, Denmark, and Russia conceived of the soil profile. In more than a century since, pedologists have generally agreed on the reasons and purpose for using symbols such as A‐B‐C for the designations, but not on the definitions themselves or the assigned significance of the designations. In this paper, we submit that two seemingly conflicting classes of profile concepts evolved in the USA from European roots. The conflict stems historically from arbitrarily definedthinandthickprofile concepts, often referred to as thesoilorgeologic weatheringprofiles, respectively. Thepedologicor thin profile concept is depth‐restricted when compared with the geologic thick weathering profile. The geologic profile concept was developed as a homologue of the pedologic profile and is considered to be the full or complete profile of weathering. Throughout the 20th century many variations of the concept of profile appeared, and all seem to havepedo–geoconflicts, exemplified by the myriad C horizon definitions by soil scientists. Recent concepts, such as the pedoweathering profile, have integrated the terminology used by pedologists and geologists into a functional and useful classification for all horizons of complete profiles. Full 21st century understanding of soils beyond the historic 20th century needs of agriculture, increasingly requires a knowledge of soil properties to greater depth than merely the historic solum and upper C horizon, and makes understanding subsolum properties more critical than ever before.
Determining Air Entry Value in Peat Substrates
Authors: Nemati M. R. , Caron J. , Banton O. , Tardif P.
Published: July 2014

Insufficient aeration in artificial mixes used for nursery and greenhouse production is commonly reported to be a problem. To diagnose aeration problems, gas relative diffusivity estimates can be used. These estimates can be obtained indirectly from measurements of air entry value, saturated hydraulic conductivity and the water desorption curve. In here, a rapid tension chamber method for measuring air entry is proposed. To verify applicability of the method, different potted substrates were inserted into a tension chamber apparatus and water was extracted from the saturated substrate by establishing a contact with an unsaturated body located outside the chamber. The potential within the chamber was monitored over a 5‐min period and the point of air entry was calculated thereafter. Statistically equal estimates of air entry were obtained with this technique compared with values derived from the tension table, for a wide range of air entry values in peat‐based substrates.
Using TDR to Estimate Hydraulic Conductivity and Air Entry in Growing Media and Sand
Authors: Caron Jean , Rivière Louis-Marie , Charpentier Sylvain , Renault Pierre , Michel Jean-Charles
Published: July 2014

Gas relative diffusivity measurements are key indicators of the quality of growing media. Previous studies have shown that this property can be estimated indirectly from measurements of the point of air entry (ψa), air‐filled porosity (θa), and saturated hydraulic conductivity (Ks). Different tools are required to measure these parameters and this paper investigates how a single tool, time domain reflectrometry (TDR), already used to determine θa from measurements of volumetric water content (θ), could be utilized to measure ψa and Ks in growing media. Cylinders were filled with 13 different substrates and coarse sand. A transient‐state technique (vertical infiltration at −1 hPa of water potential) was used to calculate Ks from θ measurements in time. In growing media, calculated Ks values from transient‐state experiment were statistically equal to estimates obtained from steady‐state measurements at a potential of −1hPa. However, both methods underestimated the Ks values obtained under steady‐state conditions after a pulse of water had been applied or after prolonged wetting. For sand, TDR‐based measurements and steady‐state infiltration at −1 hPa, provided estimates of Ks equal to those obtained after prolonged saturation. To estimate ψa, TDR probes in a horizontal and a vertical position were tested in addition to a pressure transducer technique. For growing media, the horizontal positioning of the probes provided more consistent estimates of ψa than the other two techniques. Estimates of ψa with TDR in sand, both in vertical and horizontal position, were similar.
A heavy‐duty time domain reflectometry soil moisture probe for use in intensive field sampling
Authors: Long Dan S. , Wraith Jon M. , Kegel Greg
Published: July 2014

Mapping soil water content for site‐specific management of farm fields is commonly achieved through grid soil sampling. This effort frequently requires intensive soil coring, which is destructive and time consuming. Precision farming and research can be facilitated if sampling techniques are improved and made cost effective. We designed and constructed a heavy‐duty time domain reflectometry (TDR) probe of simple design that fits a hydraulic soil sampling machine. The design is simple enough to be adapted to the TDR equipment and hydraulic sampler that a researcher or practitioner may already possess. The probe consists of a housing and adapter that can be fabricated in a local machine shop from materials that are easily obtainable. Probe schematics and summary soil water maps obtained using the new design are presented. As with conventional TDR probe designs, stony or indurate soils may present particular problems in effective insertion of the probe.
Competitive Adsorption of Arsenate and Arsenite on Oxides and Clay Minerals
Authors: Goldberg Sabine
Published: July 2014

Arsenic adsorption on amorphous Al and Fe oxides and the clay minerals, kaolinite, montmorillonite, and illite was investigated as a function of solution pH and As redox state, i.e., arsenite [As(III)] and arsenate [As(V)]. Arsenic adsorption experiments were carried out in batch systems to determine adsorption envelopes, amount of As(III), As(V), or both adsorbed as a function of solution pH per fixed total As concentration of 20 μM As. Arsenate adsorption on oxides and clays was maximal at low pH and decreased with increasing pH above pH 9 for Al oxide, pH 7 for Fe oxide and pH 5 for clays. Arsenite adsorption exhibited parabolic behavior with an adsorption maximum around pH 8.5 for all materials. There was no competitive effect of the presence of equimolar arsenite on arsenate adsorption. The competitive effect of equimolar arsenate on arsenite adsorption was small and apparent only on kaolinite and illite in the pH range 6.5 to 9. The constant capacitance model was able to fit the arsenate and arsenite adsorption envelopes to obtain values of the intrinsic As surface complexation constants. These intrinsic surface complexation constants were then used in the model to predict competitive arsenate and arsenite adsorption from solutions containing equimolar As(III) and As(V) concentrations. The constant capacitance model was able to predict As adsorption from mixed As(III)‐As(V) solutions in systems where there was no competitive effect.
Soil Organic Matter Characteristics as Affected by Tillage Management
Authors: Ding G. , Novak J. M. , Amarasiriwardena D. , Hunt P. G. , Xing B.
Published: July 2014

Soil organic matter (SOM) is of primary importance for maintaining soil productivity, and agricultural management practices may significantly influence SOM chemical properties. However, how SOM chemical characteristics change with agricultural practices is poorly understood. Therefore, in this study, we evaluated the impacts of tillage (conventional vs. conservation) management on the structural and compositional characteristics of SOM using cross‐polarization magic‐angle‐spinning (CPMAS) and total sideband suppression (TOSS) solid‐state 13C nuclear magnetic resonance (NMR) and diffuse reflectance Fourier transform infrared (DRIFT) spectroscopy. We characterized both physically and chemically isolated SOM fractions from a Norfolk soil (fine‐loamy, siliceous, thermic Typic Kandiudults) under long‐term tillage management (20 yr). The solid‐state 13C NMR results indicated that humic acid (HA) from conventional tillage (CT, 0–5 cm) was less aliphatic and more aromatic than HA from conservation tillage (CnT). The aliphatic C content decreased with increasing depth (0–15 cm) for both CT and CnT treatments. The reverse trend was true for aromatic C content. Based on reactive/recalcitrant (O/R) peak ratio comparisons, HA was more reactive in the top soil (0–5 cm) under CnT than CT. Both soil organic C (SOC) and light fraction (LF) material were higher in the 0‐ to 5‐cm soil of CnT than CT treatment. Our results show that long‐term tillage management can significantly change the characteristics of both physical and chemical fractions of SOM.
Ammonium–Potassium–Calcium Exchange on Vermiculite and Hydroxy‐aluminum Vermiculite
Authors: Evangelou V. P. , Lumbanraja J.
Published: July 2014

Binary and ternary cation‐exchange reactions involving NH+4, K+, and Ca2+ on vermiculite and hydroxy‐Al interlayered vermiculite (HIV) were investigated. In the case of vermiculite, NH4‐Ca exchange was nearly indistinguishable from the nonpreference isotherm while HIV exhibited preference for NH+4 The presence of K+ had significant suppressing impact on the apparent NH+4 selectivity in NH4‐Ca exchange in HIV most likely because of retardation of Ca2+ diffusion in the interlayer. For vermiculite, the presence of K+ in the NH4‐Ca system induced apparent high affinity sites for NH+4 most likely because of interlayer collapse. The overall study demonstrated that cation‐exchange selectivity coefficients in vermiculite and HIV are dependent on number and type of cations present.
Nitrogen Dynamics in Humic Fractions under Alternative Straw Management in Temperate Rice
Authors: Bird Jeffrey A. , van Kessel Chris , Horwath William R.
Published: July 2014

Crop residue management practices can affect N immobilization and stabilization processes important to efficient utilization of N from fertilizers, crop residues, and soil organic matter (SOM). A 2‐yr,15N‐labeling field study was conducted to examine the effects of winter‐fallow flooding (vs. unflooded) and straw residue incorporation (vs. burning) on the rates of sequestration and stability of specific SOM pools critical in sustaining N fertility in rice (Oryza sativaL.). Five SOM fractions were examined from soil samples obtained over Years 4 to 6 of a field trial: light fraction (LF), mobile humic acid (MHA), mobile fulvic acid (MFA), metal‐associated humic acid (MAHA), and alkali‐insoluble humics (HUM). After 4 yr of straw management treatments, soil incorporation of straw increased MHA and LF C and N compared with burned straw. Immobilization of N fertilizer peaked in all SOM fractions after one growing season (120 d) and was greatest in the MHA fraction over the 2‐yr15N study. Nitrogen fertilizer sequestration in MHA and LF was greater with straw incorporation compared with burned. Turnover of immobilized15N‐fertilizer in the stable organic components was fastest in the labile MHA and MFA fractions (7‐ to 9‐yr half‐life) compared with the half‐lives of the moderately resistant MAHA fraction (53 yr) and most stable HUM fraction (153 yr). While the MAHA and HUM fractions played a significant role in N fertilizer immobilization and turnover, the MHA and LF fractions represented the primary active sink and source of sequestered N affecting both short‐ and long‐term soil fertility.
Conservation Tillage Systems for Cotton in the Tennessee Valley
Authors: Schwab E. B. , Reeves D. W. , Burmester C. H. , Raper R. L.
Published: July 2014

Yield reductions from no‐tillage cotton (Gossypium hirsutum L.) jeopardized adoption of conservation systems in the Tennessee Valley region of north Alabama in the early 1990s. We conducted a study from 1995 to 1999 on a Decatur silt loam (fine, kaolinitic, thermic Rhodic Paleudults) to develop a practical conservation tillage system with competitive yields for the region. Treatments included a factorial combination of fall ridging (ridged and nonridged) and fall non‐inversion deep tillage (none, in‐row subsoiling, paratilling), along with spring strip tillage and conventional tillage (fall chisel‐spring disk). All treatments, except conventional tillage, were established with a rye (Secale cereale L.) cover crop. Tillage systems were evaluated for soil temperature, penetration resistance, a soil compaction index, soil water, plant population, and seed cotton yield. Paratilling reduced soil compaction index 29 and 31% compared with conventional tillage and no‐tillage, respectively. Subsoiling reduced the compaction index 12 and 15% compared with conventional tillage and no‐tillage, respectively. Soil water content was decreased with the fall paratilled and subsoiled conservation tillage systems, compared with conventional tillage and no‐tillage, suggesting increased rooting. Fall non‐inversion deep tillage, either paratilling or in‐row subsoiling with a narrow‐shanked subsoiler, resulted in the highest seed cotton yields; 16% greater than conventional tillage (2660 kg ha−1), and 10% greater than strict no‐tillage (2810 kg ha−1) across a 4‐yr duration. In this region, non‐inversion deep tillage under the row in fall, coupled with a rye cover crop to produce adequate residue for moisture conservation and erosion control, is a highly competitive and practical conservation tillage system.
Non‐labile Soil 15Nitrogen Retention beneath Three Tree Species in a Tropical Plantation
Authors: Kaye Jason P. , Binkley Dan , Zou Xiaoming , Parrotta John A.
Published: July 2014

Soil organic matter is the largest sink for N additions to forests. Species composition may affect soil N retention by altering the amount or proportion of added N stored in non‐labile organic pools. We measured 15N tracer retention in labile and non‐labile pools of surface (0–20 cm) mineral soils, 7 yr after the tracer was applied to a 9 yr‐old Puerto Rican tree plantation with replicated stands of three species (two N‐fixers, one Eucalyptus, Euc). Laboratory incubations (13 mo) with repeated leaching separated total soil N into labile (inorganic N leached) and non‐labile (total N minus leached N) pools, and a labile C treatment tested linkages between C availability and N retention. We hypothesized that species composition would alter the amount and proportion of recovered tracer N in non‐labile organic matter. Surface soils contained 45% of the tracer, but the amount retained in labile and non‐labile pools was similar among species. In contrast, the proportion of recovered tracer in non‐labile pools was greater in soils beneath N‐fixers (75%) than Euc (62%). Labile C additions increased the size of the non‐labile tracer N pool. We conclude that tree species composition may affect long‐term soil N retention by altering the proportion of N in slow‐turnover, non‐labile pools. Plants may also alter soil N retention by renewing labile C pools; a continuous supply of labile C increased the transfer of 15N into non‐labile organic matter.
Predicting Phosphorus Desorption from Mid‐Atlantic Coastal Plain Soils
Authors: Vadas Peter A. , Sims J. Thomas
Published: July 2014

Pollution of surface waters by P from agricultural areas is a water quality issue in Delaware. The FHANTM 2.0 computer model can help identify areas with a high potential for P loss, but the model's representation of P desorption from soils to runoff waters needs re‐evaluation. The equation,, has been proposed to predict such P desorption, but equations originally proposed to predict values for the constantsK, α, and β from the ratio of soil clay content/soil organic C content may not be accurate for Delaware soils. Therefore, we measured P desorption for 23 sandy Delaware soils for times of 5 to 180 min, water/soil ratios of 10 to 1000 L kg−1, and three initial levels of soil desorbable P. Values for the constantsK, α, and β were calculated and related to soil properties. We found thatK, α, and β values were not well related to clay/OC, but were better related to the ratio of oxalate‐extractable Fe/OC content (α) or the sum of oxalate extractable Fe and Al (β andK). These results can be used to help refine the FHANTM 2.0 model in predicting P loss from agricultural areas in Delaware and similar landscapes in the Mid‐Atlantic Coastal Plain.