bluuebunny/crossref_metadata_2025 huggingface dataset:
Desiccation and Germination of Grain Sorghum As Affected by Glufosinate
Authors: Bovey Rodney W. , Dahlberg Jeffery A. , Madera‐Torres Pablo , Senseman Scott A. , Miller Frederick R.
Published: July 2010

Preharvest desiccants are needed to reduce moisture content of grain sorghum [Sorghum bicolor (L.) Moench] for earlier harvest to preserve seed quality and quantity. Objectives of this study were (i) to examine the desiccant activity of glufosinate [2‐amino‐4‐(hydroxy‐methylphosphinyl)butanoic acid] applied at several rates to grain sorghum at different seed moisture levels in contrasting environments and (ii) to determine the effect of glufosinate on germination and seedling growth of the treated crop. The soil at College Station (east‐central Texas), was a Ships clay (very‐fine, mixed, active, thermic, Chromic Hapludert); at Mayagüez, PR, a Coto clay (very‐fine, kaolinitic, isohyperthermic Typic Hapludox). Glufosinate was evaluated because of its contact herbicidal properties and limited systemic activity. In both Texas and Puerto Rico, glufosinate was applied at 0, 0.56, 1.1, or 2.2 kg ha−1 to grain sorghum. Leaves and seed were sampled at 0, 1, 2, and 3 wk after treatment (WAT) for grain and leaf moisture. Seed was collected at 2 and 3 WAT for germination and growth studies. Glufosinate at all three treatment rates dried seed of the grain sorghum hybrid ATx638/Tx2783 in Texas from >350 g kg−1 grain moisture at application to a storable moisture of <120 g kg−1 at 2 WAT, at which time untreated grain moisture was 150 g kg−1. Glufosinate rate did not affect grain moisture except at the high glufosinate rate at 1 WAT. Leaf moisture reduction was glufosinate rate‐dependent, but all treatments significantly reduced leaf moisture content at 1 WAT. Germination and seedling growth were not affected by glufosinate treatment. Grain desiccation rate under a tropical environment (Puerto Rico) was slightly slower than in Texas, but leaf moisture reduction was rapid and reached <300 g kg−1 by 1 WAT from initial leaf moisture contents of 500 or 770 g kg−1. Germination was not adversely affected by glufosinate.
Physiological Changes from 58 Years of Genetic Improvement of Short‐Season Soybean Cultivars in Canada
Authors: Morrison Malcolm J. , Voldeng Harvey D. , Cober Elroy R.
Published: July 2010

In Canada, yield of short‐season soybean [Glycine max (L.) Merr.] cultivars has increased by approximately 0.5% per year since they were first cultivated in the early 1930s. Future yield gains may be dependent on an understanding of the changes made to soybean cultivars by breeding and selection. Our objective was to examine physiological differences associated with seed yield increase within a group of historical cultivars. At Ottawa, Ontario, we grew 14 cultivars representing seven decades of breeding and selection (1934–1992) in a randomized complete block design with four replications, across 4 years. Growth analysis provided data on leaf area and dry weight. Photosynthetic rate per leaf area was measured at several stages of development each year. Yield and harvest index were determined at maturity. The number of days to maturity and the total plant dry weight were not affected by the year of cultivar release. Seed yield, harvest index, and photosynthetic rate were found to have increased by 0.5% per year, while leaf area index decreased by 0.4% per year. The increase in seed yield with year of release was significantly correlated with an increase in harvest index, photosynthesis, and stomatal conductance and a decrease in leaf area index. Today's cultivars are more efficient at producing and allocating carbon resources to seeds than were their predecessors.
Irrigation and Nitrogen Management Effects on Potato Yield, Tuber Quality, and Nitrogen Uptake
Authors: Waddell J.T. , Gupta Satish C. , Moncrief John F. , Rosen Carl J. , Steele D.D.
Published: July 2010

Irrigation and N management are perhaps the most important aspects of successful potato (Solanum tuberosum L.) production in central Minnesota. With rising concern about current irrigation and N management practices and ground water quality, a two‐year study was undertaken to evaluate the impact of alternative irrigation and N management practices on potato yield, tuber quality, and N uptake. The treatments were different irrigation schemes (sprinkler and drip), irrigation triggers (70 and 40% of available water [AW] remaining), drip tape placements (surface or buried at 25 cm), N sources (urea, turkey manure, sulfur‐coated urea [SCU]), and timings of inorganic N fertilizer application. Rainfall in the area was less in 1994 (260 mm) than in 1995 (380 mm). As a result, irrigation applications in 1994 were greater than in 1995. Drip irrigation amounts were less than half of that applied by sprinkler irrigation treatments in both years. Except for the buried drip with fertigation (43.0 and 27.8 Mg ha−1 in 1994 and 1995) and the control (36.5 and 13.3 Mg ha−1 in 1994 and 1995), total tuber yields were similar regardless of irrigation and N source treatment. The turkey manure treatments in 1994 had significantly higher marketable tuber yields than the control, averaging 48.3 Mg ha−1 for both years. Total N uptake in 1994 was nearly 100% of that applied, while in 1995 it accounted for only 60% of the application. Lower N uptake was observed for the control (85.3 and 30.2 kg N ha−1 in 1994 and 1995, respectively), SCU (165.2 and 111.3 kg N ha−1 in 1994 and 1995), and BDF (157.2 and 80.1 kg N ha−1 in 1994 and 1995) treatments. The results showed that the use of unconventional N sources such as turkey manure and SCU are viable alternatives for potato production, provided they are managed properly.
Interference between Spring Cereals and Kochia scoparia Related to Environment and Photosynthetic Pathways
Authors: Fischer Albert J. , Messersmith Calvin G. , Nalewaja John D. , Duysen Murray E.
Published: July 2010

Kochia [Kochia scoparia (L.) Schrad.; syn. Bassia scoparia (L.) A.J. Scott] is a weed that infests cereal crops in the Great Plains of the USA, often severely reducing yields. Herbicides have controlled kochia, but recently kochia has developed resistance to many herbicides. Nonherbicide alternatives are therefore needed for the integrated management of kochia. Greenhouse and growth chamber competition studies were conducted between kochia, a C4 weed, and barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.) to determine the environmental conditions that would render kochia most vulnerable to competition by a small‐grain crop. Replacement‐series experiments between kochia and wheat or barley were conducted under various temperature, soil moisture, and light conditions. Unlike wheat, kochia growth and photosynthesis were suppressed under cool temperatures. Barley suppressed kochia more than wheat did because of its larger canopy, despite its lower photosynthetic rates. Under high radiation conditions and warm temperatures, growth and photosynthesis were greater for kochia than wheat. Warm temperatures also increased dark respiration and reduced water use efficiency under low radiation conditions, however, thus limiting kochia's competitiveness under a closed canopy. Water stress did not affect competition, although net photosynthetic rates of kochia were greater at photosynthetically active radiation (PAR) values > 400 μmol m−2 s−1. Growth and CO2 exchange rates varied among four different kochia accessions, but growth of all accessions was reduced by shade. Results suggest that a leafy, cold‐tolerant crop or cultivar, grown early in the season to produce necessary ground cover, should provide opportunity to suppress kochia.
Durum Grain Quality as Affected by Nitrogen Fertilization near Anthesis and Irrigation During Grain Fill
Authors: Ottman Michael J. , Doerge Thomas A. , Martin Edward C.
Published: July 2010

Nitrogen fertilization and irrigation practices can affect durum [Triticum turgidum subsp. durum (Desf.) Husn.] grain quality, especially protein content. The purpose of this study was to determine if irrigation frequency during grain fill influences the effectiveness of N applied near anthesis in increasing durum grain quality. A field study was conducted at Maricopa, AZ on a Casa Grande sandy loam soil (fine‐loamy, mixed, superactive, hyperthermic, Typic Natrargid). Durum was grown with recommended amounts of N fertilizer until anthesis when 0, 3.4, and 6.7 g N m−2 were applied and irrigation based on 30, 50, and 70% depletion of plant‐available soil water was initiated. Irrigation during grain fill had no effect on grain yield or grain quality except in 1996, when irrigating at 30, 50, and 70% depletion resulted in hard vitreous amber counts (HVAC) of 813, 870, and 934 g kg−1, respectively. Nitrogen application near anthesis of 0, 3.4, and 6.7 g N m−2 resulted in grain protein contents of 115, 127, and 140 g kg−1 in 1995 and 132, 141, and 151 g kg−1 in 1996, respectively. Nitrogen application near anthesis increased grain protein yield and HVAC in both years of the study and increased grain yield, grain volume weight, and kernel size in 1995. The results of this study suggest that N fertilizer application near anthesis has a primary influence on durum quality and that effects of irrigation frequency during grain fill are inconsistent or relatively minor.
Economic and Environmental Implications of Soybean Production and Use on Pennsylvania Dairy Farms
Authors: Rotz C. Alan , Roth Gregory W. , Soder Kathy J. , Schnabel Ronald R.
Published: July 2010

Soybean (Glycine max L.) production is rapidly increasing on Pennsylvania dairy farms. A whole‐farm analysis was conducted to determine the potential long‐term economic benefit to producers and the environmental impact of growing and feeding soybean as a protein feed supplement. Representative dairy farms were simulated with various production strategies for 25 yr of Pennsylvania weather using the Dairy Forage System Model (DAFOSYM). Production of soybean as a cash crop increased annual farm net return by up to $55 cow−1 when ample cropland was available to produce most of the feed requirement of the herd. With a more restricted land base, there was less economic benefit to shifting land from corn (Zea mays L.) or alfalfa (Medicago sativa L.) production to soybean. When the soybean was fed in a raw or roasted form, most of this economic benefit was offset, giving an increase in annual net return of <$15 cow−1. There was also little environmental benefit (reduced N loss or soil P accumulation) in growing soybean as a cash crop or feed on dairy farms. In general, the current trend toward producing and feeding soybean on Pennsylvania dairy farms does not appear to provide substantial long‐term economic benefit to the producer, nor does it appear to reduce the potential impact of the farm on its environment. However, under specific farming practices such as inefficient feeding of protein supplements or the production and feeding of high corn silage rations, an economic benefit of up to $100 cow−1 can be obtained through soybean production and feeding.
Residue Decomposition and Prediction of Carbon and Nitrogen Release Rates Based on Biochemical Fractions Using Principal‐Component Regression
Authors: Ruffo Matías L. , Bollero Germán A.
Published: July 2010

The successful use of winter cover crops (WCCs) in short rotations depends on adequate management of their residues. To improve management decisions, there is a need to understand the factors controlling WCC residue decomposition rates and nutrient release rates. A 2‐yr study was conducted to estimate residue decomposition and C and N release rates using principal‐component regression (PCR) based on WCC biochemical fractions at the time of WCC killing. Rye (Secale cereale L.), hairy vetch (Vicia villosa L.), and rye–hairy vetch biculture were planted as WCCs in the fall and chemically killed in the spring before no‐till–planting corn (Zea mays L.). At killing time, residues were analyzed for total C and total N concentrations, neutral detergent fiber (NDF) and acid detergent fiber (ADF), and C and N concentration in the NDF and ADF. Concentration of C and N in neutral detergent soluble fractions (NDSOLC and NDSOLN, respectively) and acid detergent soluble fractions (ADSOLC and ADSOLN, respectively) were calculated. Principal components (PCs) 1, 4, 5, and 7 were selected as significant predictor variables for biomass decomposition and C and N release rates. The PC1 scores suggest that large concentrations of NDF and ADF are associated with low biomass decomposition and slow C and N release rates. Other important fractions are C and N concentration in the NDF and NDSOLC, NDSOLN, ADSOLC, and ADSOLN. The availabilities of C and N, rather than their total concentration in the residue, play a critical role in residue decomposition and nutrient release.
A Method to Investigate Within‐Field Variation of the Response of Combinable Crops to an Input
Authors: Lark R. M. , Wheeler H. C.
Published: July 2010

Precision agriculture is based on the hypothesis that the optimum rate of inputs to a crop varies spatially within fields. Evidence for this hypothesis is scarce due to the practical and theoretical difficulties of designing appropriate experiments. This paper proposes a procedure for testing the hypothesis of precision agriculture for crops that may be harvested with a combine harvester equipped with a yield monitor. An input is applied according to a randomized block design. Yield monitor data may be treated as a convolution of yield with a function that characterizes the smoothing effect of processes in the combine on the mass flow rate at the sensor. The input rates, determined by the experimental design, are transformed using the combine's smoothing function and a preselected yield response function. The parameters of the response function for the whole field or a local neighborhood can be estimated from these transformed rates and the yield monitor data. A null hypothesis, that the spatial variation in one of these parameters (that determines the local optimum rate) may be attributed to random yield variation about a uniform response function, may be tested. A wheat crop (Triticum aestivum cv. Consort) was treated with varying rates of N fertilizer in a case study in the south of England. Analysis of the yield data showed that the observed variation in the response could not be explained as random fluctuation around the field‐scale response function. The economic optimum rate of N varied from zero to greater than 200 kg ha−1
Soybean Agronomic Response to Management Systems in the Upper Midwest
Authors: Pedersen Palle , Lauer Joseph G.
Published: July 2010

There has been a rapid increase of soybean [Glycine max (L.) Merr.] production in cropping systems in Wisconsin. The objective of this research was to determine the influence of five management systems on agronomic traits for three soybean cultivars grown at two different planting dates. An older cultivar (Hardin) and two newer cultivars (DeKalb CX232 and Spansoy 250) were grown in five management systems between 1997 and 2000. Four management systems were located on a silt loam soil and consisted of conventional and no‐tillage systems with and without irrigation. The fifth management system was located on a sandy loam soil that was irrigated. A planting date × cultivar interaction was observed on the silt loam soil where CX232 yielded 7% greater for the early planting date (4.37 Mg ha−1) than for the late planting date, but no planting date effect was observed for Hardin and Spansoy 250. Over all cultivars, yield was 4% greater for early planting on the silt loam soil. Grain yield and other agronomic traits were not influenced by cultivar and planting date on the sandy loam soil. Tillage and irrigation did not affect grain yield or most of the other agronomic traits. Regression of cultivar means on management system indicated an equal stability for yield among the cultivars tested with Hardin tending to be the most stable. It was concluded that soybean cultivar decisions in the Upper Midwest should be based on selecting the highest yielding cultivars adapted to a particular geographic region and location regardless of management system.
EVIDENCE OF CONTAMINATION OF PEDIGREED CANOLA (BRASSICA NAPUS) SEEDLOTS IN WESTERN CANADA WITH GENETICALLY ENGINEERED HERBICIDE RESISTANCE TRAITS
Authors: Friesen Lyle F. , Nelson Alison G. , Van Acker Rene C.
Published: July 2010

The objective of this study was to survey pedigreed canola (Brassica napus L.) seedlots for contaminating herbicide resistance traits because of complaints from farmers regarding glyphosate [N‐(phosphonomethyl)glycine]‐resistant canola volunteers occurring unexpectedly in their fields at densities and in patterns that suggested that pollen‐mediated gene flow from neighboring fields in previous years was not the source of contamination. Twenty‐seven unique, commercial certified canola seedlot samples were collected. Glyphosate‐resistant seedlot samples were not collected. Canola samples were planted in the field, and when the canola had two to four true leaves, glyphosate, glufosinate [2‐amino‐4‐(hydroxymethylphosphinyl)butanoic acid], and thifensulfuron {methyl 3‐[[[[(4‐methoxy‐6‐methyl‐1,3,5‐triazin‐2‐yl)amino]carbonyl]amino]sulfonyl]‐2‐thiophenecarboxylate} herbicides were applied. Surviving canola plants were counted. Of the 27 seedlots, 14 had contamination levels above 0.25% and therefore failed the 99.75% cultivar purity guideline for certified canola seed. Three seedlots had glyphosate resistance contamination levels in excess of 2.0%. Unexpected contamination (even at 0.25%) can cause problems for producers that practice direct seeding and depend on glyphosate for nonselective, broad‐spectrum weed control. To avoid unexpected problems and costs, it is important that farmers are cognizant of the high probability that pedigreed canola seedlots are cross‐contaminated with the various herbicide resistance traits.
Effect of Strip Tillage on Corn Nitrogen Uptake and Residual Soil Nitrate Accumulation Compared with No‐Tillage and Chisel Plow
Authors: Al‐Kaisi Mahdi , Licht Mark A.
Published: July 2010

Tillage and N management systems can have a significant effect on N use by corn (Zea mays L.) and nitrate (NO3–N) movement through the soil profile. Potential water quality and NO3–N loss problems associated with conventional tillage and fall‐applied N have prompted this study. The objective is to evaluate strip tillage effect on corn N uptake and NO3–N movement through the soil profile compared with chisel plow and no‐tillage systems. The three tillage systems implemented in this study were strip tillage, no‐tillage, and chisel plow along with two N application timings (fall and spring) of 170 kg N ha−1 for corn in a corn–soybean [Glycine max (L.) Merr.] rotation on two Iowa fields in 2001 and 2002. The three tillage systems were implemented every year for both crops (corn and soybean). Crop response, N uptake, and other soil NO3–N measurements were conducted on a randomized complete block design experiment. Grain yields and grain N uptake showed no significant improvement under strip tillage compared with no‐tillage or chisel plow systems. Tillage and N treatments caused no significant differences in NO3–N accumulation at the lower depths of the root zone (1.2 m). Strip tillage and no‐tillage resulted in lower residual soil NO3–N buildup than chisel plow in the 0‐ to 1.2‐m soil profile after 2 yr of tillage implementation. Tillage and N treatments did not cause significant differences in NO3–N concentration in water leachate collected at the 1.2‐m depth.
Early‐Maturity Soybean in a Late‐Maturity Environment: Economic Considerations
Authors: Popp M. , Edwards J. , Purcell L. , Manning P.
Published: July 2010

Over the last several years, farmers in the midsouthern USA have been planting earlier maturing soybean [Glycine max (L.) Merr.] cultivars. Maturity Group (MG) IV cultivars have become increasingly popular for reasons of drought avoidance and labor scheduling. Recently, research has been conducted to examine the agronomic characteristics and profitability of even earlier maturing cultivars. This study examines the economic considerations of MG 00 through MG IV soybean for two locations in Arkansas with different soil (silt loam vs. clayey soils) and weather conditions using both irrigated and nonirrigated production practices. Field trials were conducted over the period of 1999 to 2002. Net returns above direct and total expenses were calculated using cost of production estimates and experimental yields. Care was taken to isolate the impact of seasonal price effects as well as costs associated with irrigation, planting, and weed control as the remainder of production practices is similar across MG choice. Sensitivity analysis demonstrated that MG choice was driven mainly by yield differences and that seasonal price effects as well as changing seed cost, weed control practices, and irrigation costs had little impact. Producers may therefore choose to evaluate MG choice by following trends in yield potential. However, the analysis did not consider the farm‐specific potential for labor cost savings that may occur due to changes in the timing of labor requirements. Further, the analysis does not explicitly consider seeding rate and glyphosate tolerance effects on MG choice.
Lint Yield and Fiber Quality of Cotton Fertilized with Broiler Litter
Authors: Tewolde H. , Sistani K. R. , Rowe D. E. , Adeli A. , Johnson J. R.
Published: July 2010

Poultry litter is generated in large quantities in the same southeastern U.S. states where cotton (Gossypium hirsutum L.) is a dominant field crop, but is rarely used as a primary cotton fertilizer partly because of lack of adequate management recommendations. This research was conducted to determine adequate rates of broiler litter and whether supplementation with inorganic N would be necessary for optimum cotton lint yield and fiber quality. The research was conducted from 2002 to 2004 on two commercial farms representing conventional‐till (CT) and no‐till (NT) systems. The treatments consisted of an unfertilized control, a farm standard (STD) fertilized with inorganic fertilizers, and broiler litter of 2.2, 4.5, and 6.7 Mg ha−1 in an incomplete factorial combination with 0, 34, or 67 kg ha−1 N as urea–ammonium nitrate solution (UAN). Litter without supplemental UAN–N increased yield by 23 to 110 kg lint ha−1 for every 1.0 Mg ha−1 litter under both CT and NT. The often‐recommended litter rate of 4.5 Mg ha−1 was not adequate to increase yield to be equivalent to that of the STD that received 101 to 135 kg ha−1 as UAN. It was necessary to supplement this or the other litter rates with 34 or 67 kg ha−1. UAN–N to support yield equal to or greater than the yield of the STD. The most consistently well‐performing treatment under both tillage systems in all years was the 4.5 Mg ha−1 litter supplemented with 67 kg ha−1. UAN–N. Lint yield was highly correlated (r2 = 0.83–0.97) with applied total plant‐available N (NTPA) under both systems. Fiber quality, fiber length and micronaire in particular, also responded to NTPA, but the responses were smaller than lint yield. Litter when adequately supplemented with UAN–N did not adversely affect fiber quality. These results show broiler litter as much as 4.5 Mg ha−1 should be supplemented with inorganic N fertilizers when used as a primary cotton fertilizer and when the expected yield is ≈1700 kg ha−1 under CT and ≈1500 kg ha−1 under NT.
Tests of Some Methods for Detecting Antibiotics in Soil
Authors: Witkamp M. , Starkey R. L.
Published: July 2010

Various methods of testing soils for antibiotics were compared using soils to which antibacterial substances (penicillin, streptomycin, chloramphenicol) or antifungal substances (cycloheximide, candicidin, nystatin) had been added. Chloramphenicol, penicillin, and cycloheximide could be tested by direct diffusion from soil through a cellulose film into assay agar. All of the antibiotics could be determined in soil‐agar mixtures. Whith this method, some antibiotics were more active in nearly neutral media than in acid media. The antifungal antibiotics and streptomycin showed decreasing activity against certain test organisms with an increase in the amount of colloidal material in the soil. There was little or no such effect with chloramphenicol and penicillin.
Effect of Nitrogen, Potassium, Calcium, and Magnesium on Mineral Composition of Lakeland Fine Sand in Relation to Mineral Content of Tung Leaves
Authors: Barrows Harold L. , Drosdoff Matthew
Published: July 2010

Eight‐year‐old tung trees growing on Lakeland fine sand were treated from 1949 to 1955 with factorial combinations of 3 sources of N and 2 levels each of N, K, Ca, and Mg. Soil samples collected in October 1954 showed that exchangeable K was increased to a depth of 36 inches (lowest depth sampled) by the high level of applied K, but was reduced by the high level of Mg. Exchangeable Ca was increased by the high level of Ca, but was reduced by the high level of K or Mg. Exchangeable Mg was increased by the high level of Mg in the 0‐ to 6‐inch depth only. Below 6 inches, it was reduced by the high level of K or Mg.

The chemical analyses of leaves collected in 1955 show the same general trends as those found in the soil. The polynomial equations of degrees n = 1, 2, 3, and 4 were calculated for the regression of the concentration of K, Ca, and Mg in the leaves on saturation percentage of these elements in the soil. The linear equation for K was significant for each soil depth and the equations of higher degree show no significant improvement. The linear equations for Ca were significant at all depths, but the second‐degree equations were an improvement on the linear in the top 18 inches of soil. The linear equations for Mg were significant in the top 18 inches of soil. The second‐degree equations were an improvement on the linear in the 6‐ to 12‐ and 12‐ to 18‐inch depths.
Field Determination of Hydraulic Conductivity Above a Water Table With the Double‐Tube Method
Authors: Bouwer Herman
Published: July 2010

Theory and principles of the double‐tube method, as presented in a previous paper, were applied and tested in laboratory and field studies. The former were carried out in a sand box, where the hydraulic conductivity of 3.87 cm. per min. obtained with the double‐tube principle agreed closely with the known conductivity of 4.10 cm. per min.

Field equipment and procedures for practical application of the double‐tube method are discussed in detail. A specially developed hole cleaner for obtaining an undisturbed soil surface at the bottom of the auger hole is described. It is shown how sufficient depth of saturation and corresponding consistency in resulting hydraulic conductivity values can be ascertained in the field without calculating the hydraulic conductivity after each set of measurements.

Results from the double‐tube method in the field compare favorably with hydraulic conductivity data obtained in the laboratory from soil samples taken at the bottom of the auger hole after completion of the field tests. The double‐tube method appears to be a suitable tool for in situ measurement of hydraulic conductivity of soil that is not saturated prior to the time of measurement.
Growth Responses of Pine and Spruce Seedlings to Regimes of Soil Moisture and Fertility
Authors: McClain K. M. , Armson K. A.
Published: July 2010

The growth of jack pine (Pinus banksiana Lamb.), black spruce (Picea mariana (Mill) B.S.P.), and white spruce (Picea glauca (Moench) Voss.) seedlings at 4 fertility levels and 3 soil moisture regimes was studied under greenhouse conditions. Weekly height measurements were made and after a treatment period of 12 weeks dry weight and root area indices were determined. For the tops root ratios were calculated from dry weights. Growth increased with increased moisture but increased, then decreased with fertility increase. Soil fertility × moisture interaction significantly (P = 0.01) increased the dry weight of black spruce and white spruce. Maximum growth for all species occurred in the wettest moisture regime. For the spruce this occurred with the first increment in fertility above the control and with the second increment in fertility above the control for jack pine.
Errors in Concentrating Ammonium Samples Prior to Isotope‐Ratio Analysis
Authors: Reeder J. D.
Published: July 2010

Errors during 15N analysis can result from NH+4‐N loss, isotopic fractionation, or atmospheric contamination during the distillation and concentration of samples prior to mass spectrometric analysis. The effectiveness of three trapping acids were compared at two different evaporation temperatures for their capacity to rapidly and efficiently concentrate large numbers of samples with minimum error in 15N measurements due to fractionation or contamination. Standard samples containing 1 mg of N as either (NH4)2SO4 or NH4Cl, at 15N concentrations of 0.366, 3, or 10 atom %, were acidulated with one of three trapping acids (2 mL of 0.1M HCL; 2 mL of 0.04M H2SO4; or 2 mL of 0.04M H2SO4 + 2 mL of 2% H3BO3) and evaporated to dryness on either a 95°C waterbath or an 87°C dry‐bath. Significant fractionation errors occurred in samples acidulated with HCl when the evaporation procedure was prolonged and a film of NH4Cl was allowed to form on the walls of sample vials. Samples acidulated with H2SO4 were significantly contaminated with atmospheric ammonia when the evaporation procedure was prolonged. The presence of boric acid in evaporating samples resulted in erratic 15N values which were thought to be partially due to incomplete dissolution of the samples prior to mass spectrometric analysis.
A Simple, Low‐Cost Vacuum System
Authors: Boyle F. W. , Strong W. R. , Wierenga P. J.
Published: July 2010

Vacuum pumps are used extensively in soil research, but often vacuum is not available or the vacuum system makes too much noise in a shared work area. A simple, low‐cost vacuum pump can be made from an air‐tight container, such as a desiccator, an aquarium air pump, and some tubing. These units have been operated reliably for periods exceeding 16 wk in the field, laboratories, and greenhouses. The pump has provided vacuum levels equal to about 0.03 MPa. The low cost (about $100.00) allows several systems to be made so that they can provide backup capabilities to each other.
Kinetics and Mechanisms of Molybdate Adsorption/Desorption at the Goethite/Water Interface Using Pressure‐Jump Relaxation
Authors: Zhang Peng Chu , Sparks Donald L.
Published: July 2010

Pressure‐jump (p‐jump) relaxation with conductivity detection was used to ascertain the kinetics and mechanisms of MoO4 adsorption/desorption on goethite. A postulated reaction mechanism consisting of two consecutive elementary steps was examined and verified through kinetic and equilibrium studies. The first step is the formation of an ion‐pair complex through the electrostatic attraction between the protonated surface and the MoO4 anion. The second step involves a ligand exchange process, whereby 1 mol of H2O is replaced by 1 mol of adsorbed MoO4 from the surface. It is much slower than the first step. The forward and backward intrinsic rate constants for steps 1 and 2 are: kint1 = 4019.2 mol−1 L s−1, kint‐1 = 391.5 s−1, kint2 = 1.888 mol−1 L s−1, and kint‐2 = 42.34 s−1. A slightly modified triple layer model (TLM) was employed to calculate the distribution of ionic species on the goethite surface, in the α and β layers, and in the bulk solution at equilibrium and electrical parameters for the charged surface. Both equilibrium and kinetic data fit the postulated mechanism for the reaction steps and the modified adsorption model well.
Sorption Isotherm‐Sequential Extraction Analysis of Heavy Metal Retention in Landfill Liners
Authors: Salim Imad A. , Miller Carol J. , Howard Jeffrey L.
Published: July 2010

The chemical partitioning of heavy metals in soil materials is of great importance in risk assessment, landfill bottom liner design, and remedial investigation. The sorption characteristics of clayey calcareous sediments used to construct landfill bottom liners at four sites in southeastern Michigan were studied using a new method: combined sequential extraction‐sorption isotherm analysis (CSSA). After spiking to simulate high levels of contamination, the sediments sorbed large quantities of Pb (∼1480–145 000 mg kg‐1), Ni (∼750–8100 mg kg‐1), and Cd (∼980–5070 mg kg‐1). Sequential extraction data indicated that Pb and Ni were principally in a carbonate‐occluded form, whereas Cd was mainly in an exchangeable form at high levels (>1000 mg kg‐1) of contamination. these results suggest that Pb and Ni will be immobilized by the liner materials but Cd will probably be highly mobile. By applying sequential extraction analysis after spiking, Langmuir sorption isotherms were constructed successfully for most of the individually targeted phases. Thus, CSSA appears to be a promising method for predicting the attenuation capabilities of soils and sediments because it allows the sorption capacities of individual phases to be determined while together in a natural system.
Spatial Relations between Oat Residue and Ceramic Spheres when Incorporated Sequentially by Tillage
Authors: Allmaras R. R. , Copeland S. M. , Copeland P. J. , Oussible M.
Published: July 2010

Spatial characterization of crop residues and agrichemicals incorporated by tillage is needed to interpret biomass‐related soil processes. This study presents such a characterization. We first described oat residue (Avena sativa L.) and green‐sphere distributions produced by chisel plow (CP) and moldboard plow (MP) tillage and then described red‐sphere distributions when incorporated during secondary tillage. Finally the co‐location of incorporated oat residue and colored spheres was characterized. Green and red ceramic spheres were surrogates for shoot residue and incorporated agrichemical, respectively. Characterizations were derived from weights of soil and residue and counts of spheres in soil cores (1.84 cm diam. by 30 cm long, sectioned into 15 sublengths each 2 cm long). Penetration with MP was 25 cm, CP was 15 cm, and cultivator was 17 cm. The MP incorporated 67% of residue in the 10‐ to 20‐cm depth, while more that 90% of the incorporated residue in the CP was between 1 and 11 cm deep. Secondary tillage had negligible influence on these depth distributions. Green‐sphere distributions were related more closely to tool penetration than those of oat residue because root and shoot tissue were not distinguished. Fractional porosity of the 5.32‐cm3 volumes, adjusted to account for oat residue and sphere volumes, was increased ≈12% due to these materials. Many 5.32‐cm3 volumes contained no oat residue, whereas only a few volumes had concentrations ≥4 times the mean residue concentration. Although oat residue was incorporated with primary tillage, residue and herbicide surrogates were co‐located in 35% of the volumes, many of which contained large concentrations of residue. Exclusive use of either primary tillage with the same secondary tillage produces an environment for characteristically different bioactivity in the upper 10 cm.
Improving Numerical Modeling of Two‐Dimensional Water Flow in Variably Saturated, Heterogenous Porous Media
Authors: Pan Lehua , Wierenga Peter J.
Published: July 2010

Previous work has shown that a transformation of the pressure head greatly improved the efficiency of the algorithms for simulating one‐dimensional infiltration into very dry heterogenous soils. We expanded the approach to solve two‐dimensional problems and introduced an adaptively optimum relaxation procedure to improve the efficiency and the robustness of the numerical solutions. A theoretical framework was developed for analysis of convergence problems in solving Richards' equation. Based on this framework, several simple calculation methods are proposed to estimate the relative convergence of different transformation methods. They can also be used to select “good” transformation parameters and a “good” time steps. Two transformation‐based methods, Kirkland's ϕ‐based method and Ross' p‐based method, as well as Celia's h‐based method are used as comparisons. Test cases are infiltrations into very dry heterogenous porous media. The results show that the Pt‐based method is the most effective of the four methods and the simplest of the three transformation methods. It is several orders of magnitude faster than the h‐based method and also reduces the truncation error using the same grid. The proposed adaptively optimum relaxation procedure enhances the efficiency and robustness of all four methods to different degrees. Combination of the Pt‐based method with the adaptively optimum relaxation procedure results in a very efficient and robust algorithm. Using a coarser grid in the horizontal direction can further improve the efficiency in both computer time and memory requirements of the two‐dimensional model without loss of accuracy.
Return of the Leviathan? Hydropolitics in the developing world revisited
Authors: Movik Synne
Published: July 2010

The paper focuses on the evolution of water management regimes, water scarcity, and the transition to a new water legislation in South Africa that occurred with the passing of the 1998 National Water Act. It takes issue with the analysis offered by Turton & Meissner in their 2002 article ‘The hydrosocial contract and its manifestation in society: A South African case study’ (in Hydropolitics and The Developing World (2002), African Water Research Unit, Pretoria, pp. 37–60) who argue that the relations between resource users and the State may be conceived of as a ‘hydrosocial contract’, and that the nature of this relationship has changed from constituting a Hobbesian form of social contract where the State is all-powerful (the Leviathan), to a more Lockean form, where the emphasis is on individuals' willingness to cede some of their autonomy in order to be governed. The main argument against Turton & Meissner's analysis is that it ignores policy and legislative aspects, which, if included, would substantially alter their conclusion.
The quest for Roualeyn Gordon Cumming's rhinoceros horns
Authors: ROOKMAAKER KEES
Published: July 2010

The longest horn ever recorded for the White Rhinoceros (Ceratotherium simum) was one measuring 158cm, shot by Roualeyn Gordon Cumming (1820–1866) in the South African interior between 1843 and 1848. The quest for the present whereabouts of this trophy led from Gordon Cumming's museum in Fort Augustus, Scotland (which existed from 1858 to 1866), to auction sales in Inverness and London, across the ocean to the American Museum run by circus magnate P. T. Barnum in New York. While the horn actually remained in family custody, it apparently disappeared recently.
Distribution and conservation ofGrallariaandGrallariculaantpittas (Grallariidae) in Ecuador
Authors: FREILE JUAN F. , LUIS PARRA JUAN , GRAHAM CATHERINE H.
Published: July 2010

The current ranges of many tropical species of conservation concern are poorly known, yet this information is critical for assessing their conservation status against the IUCN Red List criteria and implementing species-level management. Antpittas in the generaGrallariaandGrallariculaare elusive, ground-foraging insectivores, highly susceptible to a range of threats. For these genera, we combine environmental niche modelling with expert knowledge in order to predict species’ geographic distributions, and we use current estimates of deforestation to evaluate their conservation status in Ecuador. We use BIOCLIM to generate a first pass geographic prediction, which was further aided by expert knowledge of their natural history. This methodology allowed us to assess the conservation status of each species, revising previous assessments at the national level and making recommendations for revision of global IUCN Red List categories. Based on inferred rates of population decline, derived from estimates of loss of suitable habitat, we suggest ranking three species as ‘Endangered’ in Ecuador, one as 'Vulnerable', and three as ‘Near Threatened’. Predicted national ranges vary in size from 56.05 km2to 112,745 km2. Patterns of range loss were different for each Andean slope, with higher deforestation on the western slope. The combination of niche modelling and knowledge of habitat loss can be a powerful tool to aid conservation efforts in the face of a poor understanding of population demographics, as is the case for many Neotropical taxa. We hope the methodology and results provided here will increase our understanding, and focus future attention on the conservation of this poorly known avian group.
Validierung der deutschen Version der Compulsive Acquisition Scale
Authors: Mueller Astrid , Crosby Ross D. , Linsenbühler Simone , Bleich Stefan , Osen Bernhard , Glaesmer Heide , de Zwaan Martina
Published: July 2010

Zusammenfassung. Theoretischer Hintergrund: Nach Frost und Kollegen (2009) können pathologisches Kaufen und die zwanghafte Mitnahme kostenloser Dinge zu dem Konstrukt zwanghafter Erwerb zusammengefasst und mit der Compulsive Acquisition Scale (CAS; Frost et al., 2002 ) erhoben werden. Fragestellung: Überprüfung der psychometrischen Gütekriterien der deutschen CAS. Methode: Die CAS sowie weitere konstruktnahe und konstruktferne Fragebögen wurden von einer bevölkerungsbasierten Stichprobe sowie mehreren Vergleichsstichproben beantwortet. Ergebnisse: Die 2-Faktorenstruktur der Originalversion konnte nicht repliziert werden. Die CAS-Summenskala erwies sich als reliabel und valide und differenzierte gut das Ausmaß zwanghaften Erwerbs zwischen kaufsüchtigen Patienten, Mitgliedern von Messie-Selbsthilfegruppen, anderen Patientengruppen und Kontrollpersonen. Schlussfolgerung: Die deutsche CAS-Summenskala ermöglicht mit Fragen zum pathologischen Kaufen und zur exzessiven zwanghaften Mitnahme kostenloser Dinge die Erhebung von zwanghaftem Erwerb.
Risikofaktoren für Untreue – warum Partner fremdgehen
Authors: Plack Kristin , Kröger Christoph , Allen Elizabeth S. , Baucom Donald H. , Hahlweg Kurt
Published: July 2010

Zusammenfassung. Theoretischer Hintergrund: In überwiegend US-amerikanischen Studien konnten individuelle, partnerschaftliche und kontextuelle Faktoren identifiziert werden, die das Eingehen einer außerpartnerschaftlichen Beziehung beeinflussen. Fragestellung: Welche der identifizierten Risikofaktoren können als Prädiktoren für das Eingehen von Untreue anhand einer deutschen Stichprobe repliziert werden? Methode: Fragebogenerhebung an einer Stichprobe von N = 768 jungen Erwachsenen im Alter von 18–40 Jahren. Erfasst wurden soziodemografische, individuelle (Einstellungen, Religiosität, Bindungsstil), partnerschaftliche (partnerschaftliche und sexuelle Zufriedenheit, Dauer der Partnerschaft) sowie kontextuelle Faktoren (beruflich bedingte Reisetage, Gelegenheiten). Ergebnisse: Eine niedrige partnerschaftliche sowie sexuelle Zufriedenheit, eine gering ausgeprägte Religiosität und als hoch eingeschätzte Gelegenheiten erhöhen die Wahrscheinlichkeit für das Eingehen einer Außenbeziehung. Weiterhin erwiesen sich das Alter, die Dauer der primären Partnerschaft und die Anzahl der beruflich bedingten Reisetage als signifikant bedeutsame Prädiktoren. Schlussfolgerungen: Die Ergebnisse stehen weitgehend in Einklang mit den Befunden der US-amerikanischen Untersuchungen. Spezifische Implikationen für zukünftige Fragestellungen werden diskutiert.
The endocannabinoid system links gut microbiota to adipogenesis
Authors: Muccioli Giulio G , Naslain Damien , Bäckhed Fredrik , Reigstad Christopher S , Lambert Didier M , Delzenne Nathalie M , Cani Patrice D
Published: July 2010

Obesity is characterised by altered gut microbiota, low‐grade inflammation and increased endocannabinoid (eCB) system tone; however, a clear connection between gut microbiota and eCB signalling has yet to be confirmed. Here, we report that gut microbiota modulate the intestinal eCB system tone, which in turn regulates gut permeability and plasma lipopolysaccharide (LPS) levels. The impact of the increased plasma LPS levels and eCB system tone found in obesity on adipose tissue metabolism (e.g. differentiation and lipogenesis) remains unknown. By interfering with the eCB system using CB1 agonist and antagonist in lean and obese mouse models, we found that the eCB system controls gut permeability and adipogenesis. We also show that LPS acts as a master switch to control adipose tissue metabolism both in vivo and ex vivo by blocking cannabinoid‐driven adipogenesis. These data indicate that gut microbiota determine adipose tissue physiology through LPS‐eCB system regulatory loops and may have critical functions in adipose tissue plasticity during obesity.
Modulation of Intracellular Cyclic AMP Levels by Different Human Dopamine D4 Receptor Variants
Authors: Asghari Vida , Sanyal Suparna , Buchwaldt Saskia , Paterson Andrew , Jovanovic Vera , Van Tol Hubert H. M.
Published: July 2010

Abstract: To investigate whether polymorphic forms of the human dopamine D4 receptor have different functional characteristics, we have stably expressed cDNAs of the D4.2, D4.4, and D4.7 isoforms in several cell lines. Chinese hamster ovary CHO‐K1 cell lines expressing D4 receptor variants displayed pharmacological profiles that were in close agreement with previous data from transiently expressed D4 receptors in COS‐7 cells. Dopamine stimulation of the D4 receptors resulted in a concentration‐dependent inhibition of the forskolin‐stimulated cyclic AMP (cAMP) levels. The potency of dopamine to inhibit cAMP formation was about twofold reduced for D4.7 (EC50 of ∼37 nM) compared with the D4.2 and D4.4 variants (EC50 of ∼16 nM). Antagonists block the dopamine‐mediated inhibition of cAMP formation with a rank order of potency of emonapride > haloperidol = clozapine ≫ raclopride. There was no obvious correlation between the efficacy of inhibition of forskolin‐stimulated cAMP levels and the D4 subtypes. Dopamine could completely reverse prostaglandin E2‐stimulated cAMP levels for all three D4 receptor variants. Deletion of the repeat sequence does not affect functional activity of the receptor. The data presented indicate that the polymorphic repeat sequence causes only small changes in the ability of the D4 receptor to block cAMP production in CHO cells.
Electronic excitation energy calculation by the fragment molecular orbital method with three-body effects
Authors: Chiba Mahito , Koido Tetsuya
Published: July 2010

A scheme for full quantum electronic excited state calculation is proposed that is based on the fragment molecular orbital (FMO) method with three-body effects. The accuracy and efficiency of this scheme is checked by calculating the excitation energy of hydrated formaldehyde and hydrated phenol. In all cases, three-body effects improved the excitation energy by the one- and two-body FMO methods with small computational cost, and the excitation energy approached more closely the full calculation value. The results also show that the three-body effects were relatively large and cannot be neglected.
Mach–Zehnder interferometry method for decoupling electro-optic and piezoelectric effects in poled polymer films
Authors: Greenlee Charles , Guilmo Anael , Opadeyi Ayodeji , Himmelhuber Roland , Norwood Robert A. , Fallahi Mahmoud , Luo Jingdong , Huang Su , Zhou Xing-Hua , Jen Alex K.-Y. , Peyghambarian Nasser
Published: July 2010

A Mach–Zehnder interferometer (MZI) is utilized to decouple the electro-optic and piezoelectric tensor effects occurring in a poled polymer film. This method has significant advantages over the commonly used Teng-Man reflection ellipsometry technique by allowing for the independent determination of the Pockel’s coefficients r13 and r33 and the piezoelectric coefficient d33. The r33 value of a guest host polymer that consists of AJLZ53 amorphous polycarbonate was found to be 122.69 pm/V and 123.03 pm/V using the MZI and reflection ellipsometry method, respectively. The r33 data fits well to the dispersion of the second order susceptibility tensor based on the two-level model approximation.