bluuebunny/crossref_metadata_2025 huggingface dataset:
Grain Position Affects Grain Macronutrient and Micronutrient Concentrations in Wheat
Authors: Calderini Daniel F. , Ortiz‐Monasterio Ivan
Published: July 2014

Little is known about nutrient distribution within the spike of bread wheat (Triticum aestivum L.). This knowledge is important for determining breeding strategies aimed at increasing grain yield without affecting nutritional quality. The objective of this study was to gain a better understanding of how grain position affects nutrient concentration, dry matter distribution, and water dynamics of grains. An experiment using two sowing dates was performed under field conditions. Dry weight and concentrations of macronutrients (Ca, Mg, K, P, and S) and micronutrients (Cu, Fe, Mn, and Zn) in grains from the basal (BS), central (CS), and apical spikelets (AS) of two cultivars and one synthetic hexaploid line were determined. Grain water dynamics and nutrient and dry matter concentrations were also measured throughout the grain‐filling period for the second sowing date. Genotypes showed different distributions of dry matter in different grain positions. Grain macronutrient and micronutrient concentrations in all genotypes decreased at grain positions more distal from the rachis. This reduction was as great as 30% (Ca) but varied by nutrient (e.g., Zn = −18%; S = −10%; K = +1%). Grain water content did not differ between grains. The observed differences in grain weight and nutrient concentration between grain positions could have important implications for wheat breeding. They suggest that it might be more effective to select for higher grain yield by increasing individual grain weight rather than grain number, a strategy that, in addition, would be less likely to affect the balance of nutrient concentrations within the spike.
Soil Inorganic Nitrogen under Fertilized Bermudagrass Turf
Authors: Lee David J. , Bowman Daniel C. , Cassel D. Keith , Peacock Charles H. , Rufty Thomas W.
Published: July 2014

Managed turfgrass acreage in the southeastern USA is steadily increasing. There is public concern that fertilization of turfgrass systems, particularly additions of N on golf courses, might be adversely affecting groundwater quality due to nitrate leaching. This study was conducted to measure soil nitrate levels in situ under continuously managed bermudagrass (Cynodonspp.) and to evaluate influences from fertilization and mineralization. Two experimental sites were established on 50‐ and 75‐yr‐old golf course fairways in the Neuse and Cape Fear River basins in eastern North Carolina. Soil sampling was done seasonally. Results indicate that nitrate‐N levels were consistently low (1 to 4 mg kg−1soil) and similar to adjacent natural areas throughout the 120‐cm sampling depths during the 2‐yr experiment at both sites. Levels were relatively uniform with depth and across several landscape positions. The soil nitrate levels under fertilized fairways were similar to those in adjacent nonfertilized natural areas, indicating minimal influence from turf management practices. From laboratory mineralization studies and soil temperature data, it was estimated that 60 to 154 kg N ha−1would be released from organic N pools during the bermudagrass growing season (May to October). Because of similar temperature responses, it appeared that N release from mineralization would be synchronized with bermudagrass growth. Substantial bermudagrass growth in nonfertilized plots provided direct evidence that mineralization was a significant contributor to turf nutrition. There was no evidence that N fertilization or the ecology of the bermudagrass system posed inherent risks to water quality and the environment.
Condensed Tannin Concentration of Rhizomatous and Nonrhizomatous Birdsfoot Trefoil in Grazed Mixtures and Monocultures
Authors: Wen L. , Roberts C. A. , Williams J. E. , Kallenbach R. L. , Beuselinck P. R. , McGraw R. L.
Published: July 2014

Condensed tannins in forage legumes can be beneficial or detrimental to ruminant livestock performance, depending on concentration. The objective of this research was to determine condensed tannin concentration in birdsfoot trefoil (Lotus corniculatus L.) without rhizomes (BFT) and with rhizomes (RBFT) from grazed monocultures and mixtures. An additional objective was to investigate possible fluctuation of condensed tannin concentrations through the spring grazing season. In 1997, ‘Norcen’ BFT and ‘ARS‐2620’ RBFT were sown into pastures located at Columbia, MO; pastures were pure stands or mixtures with tall fescue (TF; Festuca arundinacea Schreb). Pastures were grazed in 1998 and 1999, and the BFT and RBFT components were hand clipped every 14 d throughout the spring of 1998 and 1999. Samples were analyzed for condensed tannin concentration by near infrared (NIR) reflectance spectroscopy with calibrations based on the vanillin−HCl colorimetric method. Condensed tannin concentrations of grazed BFT were lower in this study than concentrations reported in other studies. Averaged over both years, BFT contained 11.4 g catechin equivalents (CE) kg−1 DM, and RBFT contained (P < 0.05) three times that amount (38.6 g CE kg−1 DM). Also, condensed tannin concentrations of the BFT component were 100% higher when BFT was grown in a mixture instead of a pure stand (P < 0.10); in 1999, they were 55% higher (P < 0.05). Finally, condensed tannin concentration fluctuated over the spring of 1998 (P < 0.05), but not the spring of 1999. We concluded that condensed tannins in BFT are much lower than in RBFT, that condensed tannins in BFT decrease when grown with a tall fescue companion grass, and that concentrations can fluctuate in the spring as they do in the autumn.
Development of Species‐Specific SCAR Markers in Bentgrass
Authors: Scheef Elizabeth A. , Casler Michael D. , Jung Geunhwa
Published: July 2014

Bentgrass species (Agrostis spp.) are cool season turfgrasses that are tolerant of continuous, close mowing heights because of their prostrate growth habit. Some bentgrass species are difficult to distinguish because of similar morphological characteristics and genetic compatibility. Specific DNA technology, such as the use of SCAR (sequence characterized amplified region) markers, can be used to differentiate between some species of bentgrass. SCAR markers were created by sequencing a single RAPD (random amplified polymorphic DNA) band and designing primers to amplify the band of specific size. Two SCAR primer pairs were designed to identify colonial (Agrostis capillaris L.) and creeping (Agrostis palustris Huds.) bentgrass species. The colonial SCAR primers amplify a band of 400 base pairs (bp) and are designated Col400F and Col400R. The creeping SCAR primers amplify a band of 700 bp and are designated Creep700F and Creep700R. Testing with 17 cultivars (140 plants) representing four bentgrass species, single unique bands were correctly amplified for creeping and colonial bentgrass species by their respective SCAR primer pair. Differentiating these species by SCAR markers is useful for screening large numbers of clones collected from superior patches of naturalized populations on old golf courses and lawns. These SCAR markers also have useful potential for identifying progenies derived from artificial interspecific hybridizations among bentgrass species, especially between colonial and creeping bentgrass.
Estimating yield depression caused by nonuniformity of spatial plant patterns
Authors: Hühn Manfred
Published: July 2014

Agricultural plant stands at harvest are characterized by more or less irregular spatial distributions of their individual plants. The objective of this study was to quantify the yield depression caused by nonuniformity of spatial plant patterns. On the basis of several assumptions, a stochastic approach is proposed that allows an estimation of the effects of irregular spatial patterns of the distribution of individual plants on yield (Y). The variables, single plant yield (S) and individual area per plant (A) estimated by the area of Thiessen polygons, were evaluated. Yield was calculated theoretically by the expectation of the ratio S/A On the basis of a nonlinear relationship between single plant yield and individual area per plant, yield can be represented by two additive terms. The first term depends on the mean of individual plant areas. The second term is negative, depends on the mean and variance simultaneously, is proportional to the variance of individual plant areas, and can be interpreted as the effect of variable individual plant areas on yield. This provides the amount of yield depression caused by nonuniformity of spatial distribution of plants across the area. Theoretical concepts and results were applied to an experimental yield data set of winter oilseed rape. The amount of yield depression was 5.3%.
Genetic and Environmental Effects on Seed Weight and Seed Yield in Switchgrass
Authors: Boe A.
Published: July 2014

A positive correlation exists between seed weight and seedling vigor. The objective of this study was to determine genetic and environmental effects on seed weight and seed yield within two switchgrass (Panicum virgatum L.) cultivars. Thirty half‐sib families of ‘Sunburst’ (large seeded) and ‘Summer’ (small seeded) were evaluated for 3 yr in Kentucky bluegrass (Poa pratensis L.) sod (competitive) and tilled (noncompetitive) spaced‐plant nurseries at Brookings, SD, and in a tilled spaced‐plant nursery at Highmore, SD. Parents were evaluated in a separate nursery. Significant differences were found among families within both cultivars for 100‐seed weight, but significant family × environment interactions indicated nonuniformity in responses of families to environmental variability. Narrow‐sense heritability estimates for 100‐seed weight were 0.88 for Sunburst and 0.58 for Summer. Seed weight increased in response to increased ambient moisture, but was similar for competitive and noncompetitive environments (grand means were 101 and 175 mg 100 seeds−1 for Summer and Sunburst, respectively) at Brookings. However, mean plasticity for seed weight was evident from markedly reduced seed weights for both cultivars at Highmore. Magnitude and direction of plasticity for seed weight differed for the two cultivars. Plastic families of Summer generally had heavier seeds in the competitive environment, whereas those of Sunburst had heavier seeds in the noncompetitive environment. Significant differences were found among families within both cultivars for seed yield. Summer had 70% higher mean seed yields than Sunburst, and annual seed‐yield means varied by greater than 80%. Seed weight was highly responsive to temporal and spatial environmental variation, but genetic variation was adequate to expect progress from selection within both cultivars.
Cold Tolerance in Oilseed Rape over Varying Acclimation Durations
Authors: Rife C. L. , Zeinali H.
Published: July 2014

Winter rapeseed (Brassica napus L.) promises to be an important crop in the southern Great Plains. To increase the crop's consistency in the region, cultivars with improved winter hardiness and management recommendations that utilize all of a genotype's winter hardiness need to be developed. Better understanding of the variability in cold tolerance over the winter season need to be determined to help achieve these goals. The objectives of this study were to evaluate variability in cold tolerance over prolonged acclimation durations in oilseed rape by means of laboratory freezing tolerance procedures, and determine changes in freezing tolerance brought about by high temperature treatments. A warming period to simulate possible deacclimation events was included both before and after vernalization saturation had taken place. Maximum cold tolerance was achieved by 3 d of acclimation in the spring cultivar and between 6 and 9 d in the winter cultivars. A 7‐d warming period reduced cold tolerance in all lines tested, but it did not reduce cold tolerance to the level of unacclimated plants. All tested lines were able to recover cold tolerance to the same level as before the deacclimation treatment after reexposure to 5°C conditions for 7 d. Cold tolerance did tend to decrease with prolonged acclimation durations. This information can help in the planning of strategies to develop rapeseed lines better adapted to the winter conditions of the southern Great Plains.
Inheritance of Low‐Phytate Phosphorus in Soybean
Authors: Oltmans Sheilah E. , Fehr Walter R. , Welke Grace A. , Cianzio Silvia R.
Published: July 2014

A reduction in the phytic acid (phytate) content of soybean [Glycine max (L.) Merr.] seed would improve the bioavailability of P in rations of nonruminant animals containing soybean meal. A soybean mutant with low phytate and increased inorganic P was developed by the USDA‐ARS and Purdue University. The objective of this study was to determine the inheritance of low phytate in a line derived from the mutant. The low‐phytate line was crossed reciprocally to a line with normal phytate. The F1 seeds from the reciprocal crosses had normal phytate, indicating complete dominance for the wild‐type alleles and no maternal effects. The segregation of 210 F2 seeds satisfactorily fit a phenotypic ratio of 15:1 normal to low phytate. The F2–derived lines satisfactorily fit a ratio of 7:8:1 homogeneous normal phytate to segregating to homogeneous low phytate. The segregation ratios indicated that low phytate was controlled by recessive alleles designated pha1 and pha2 at two independent loci that exhibited duplicate dominant epistasis. Both of the alleles must be homozygous to obtain low‐phytate seed.
Genetic Variability and Trait Relationships in Switchgrass
Authors: Das Modan K. , Fuentes Roger G. , Taliaferro Charles M.
Published: July 2014

Greater knowledge of the magnitude of genetic variability for biomass yield and yield components in switchgrass, Panicum virgatum L., and relationships among the biomass yield component traits would facilitate the breeding improvement of the species. Accordingly, we conducted two replicated experiments to assess genetic variation for biomass yield and yield components and quantify relationships among those traits in different switchgrass populations. In Exp. 1, 228 half‐sib families from SU C3 and 261 from NU C3 populations were evaluated at Perkins, OK, while 278 half‐sib families from the SL C0 population were evaluated at Stillwater, OK. Exp. 2 comprised 11 lowland switchgrass populations tested at Chickasha and Perkins, OK, in 1998. Substantial differences (P < 0.01) in biomass yield per plant existed among half‐sib families within the respective SU C3, NU C3, and SL C0 populations. Estimates of genetic variance for biomass yield were significant for each population. However, significant family × year and family × block variance estimates indicated substantial environmental influence in each of the populations. In Exp. 2, significant (P ≤ 0.05) variation existed among the 11 populations over locations for biomass yield per plant, tiller number per plant, tiller length, leaf blade length, and leaf blade width. Phenotypic correlation between biomass yield and tiller number per plant was positive (r = 0.68* at Chickasha and r = 0.60* at Perkins). Path coefficient analyses revealed that number of tillers per plant had the highest positive direct effect on biomass yield at both locations (0.74 at Chickasha and 0.66 at Perkins). Adequate genetic variability was present within the switchgrass populations to allow breeding improvement of biomass yield. Selection for increased number of tillers per plant would be the most effective means of indirectly increasing biomass yield.
Climatic and Water Availability Effects on Water‐Use Efficiency in Wheat
Authors: Abbate P. E. , Dardanelli J. L. , Cantarero M. G. , Maturano M. , Melchiori R. J. M. , Suero E. E.
Published: July 2014

In Argentina, wheat (Triticum aestivum L.) is cropped over a wide range of climatic conditions. Considerable variability in the ratio of dry weight produced per unit of transpired water, usually referred to as water‐use efficiency (WUE), is expected as variation in climatic factors affects photosynthesis and transpiration in different ways. Also, previous studies have shown that water supply limitations may affect WUE in wheat. The objective of this study was to quantify the effects of climatic environment and water availability on WUE in wheat crops. Six experiments were conducted at different locations of the Argentine wheat belt and crop dry weight and water use were measured in periods when water use was dominated by transpiration. Three of the experiments included both irrigated and rainfed treatments. Mean daily values of (i) pan evaporation, (ii) relative humidity, (iii) potential water use, and (iv) vapor pressure deficit, were used to find a general relationship that explained effects of the climatic environment on WUE. For experiments with high water availability, daytime vapor pressure deficit was better related to WUE than the other climatic factors. WUE was greater for experiments with water limitation, probably because stomatal closure to restrict transpiration rate occurred around midday when vapor pressure deficit was highest. As a consequence, relative dry weight under water limitation was not linearly related to relative water use as proposed in previous studies. A quadratic relationship that better represented this response was derived.
Dollar Spot Resistant Hybrids between Creeping Bentgrass and Colonial Bentgrass
Authors: Belanger F. C. , Bonos S. , Meyer W. A.
Published: July 2014

Creeping bentgrass (Agrostis stolonifera L.) is an important turfgrass species used extensively on golf courses. It is highly susceptible to the fungal pathogen Sclerotinia homoeocarpa F.T. Bennett, the causal agent of dollar spot disease. There is a wide range in degree of susceptibility among current cultivars, with a limited number that have improved resistance. Colonial bentgrass (A. capillaris L.), a related species, has good resistance to dollar spot. We have produced interspecific hybrids between creeping bentgrass and colonial bentgrass and field‐tested them against dollar spot. Some of the hybrids had excellent dollar spot resistance, exhibiting essentially no disease symptoms. This is the first formal report of evaluation of interspecific hybrids between creeping bentgrass and colonial bentgrass for an agronomically important trait. The results presented here suggest that the use of interspecific hybrids may be a useful new approach in Agrostis breeding programs.
Assessment of Low Light Tolerance of Seashore Paspalum and Bermudagrass
Authors: Jiang Yiwei , Duncan Ronny R. , Carrow Robert N.
Published: July 2014

Low light (LL) stress is a major problem that influences turfgrass quality. Low light tolerance of seashore paspalum (Paspalum vaginatum Swartz) has not been assessed and information is needed to develop management strategies and to maximize turf performance. The objectives of this study were to: (i) evaluate responses of seashore paspalum to reduced light intensity and to identify the most tolerant entries; (ii) compare low light responses between paspalum and hybrid bermudagrass (Cynodon dactylon L.× C. transvaalensis Burtt Davy) cultivars. Eight entries of seashore paspalum and two hybrid bermudagrass cultivars were evaluated under full sunlight control (FL), and constant 70% and 90% LL provided by shade shelters in the field from August to October in 2001 and July to September in 2002 at Griffin, GA. Significant differences in turf quality, color, density, canopy photosynthetic rate (Pn), canopy chlorophyll index (Chl), canopy spectral reflectance, and leaf dry weight were observed in paspalum entries and hybrid bermudagrass cultivars under 70 and 90% LL treatments. Among all grasses, turf quality declined 9 (the best) to 22% (the worst) under 70% LL and 13 to 28% under 90% LL, respectively, compared with the control with FL. Canopy photosynthetic rate was reduced 10 to 43% under 70% LL and 27 to 67% under 90% LL; and normalized difference vegetation index (NDVI) decreased 14 to 31% and 20 to 45% for 70% LL and 90% LL treatments, respectively. Most paspalum entries exhibited better low light tolerance than hybrid bermudagrasses under 70 and 90% LL, and ‘Sea Isle 1’ paspalum ranked as the most tolerant cultivar under both LL conditions. The ranking for the most low light tolerant entries under two LL conditions were: ‘Sea Isle 1’ paspalum (best) > Cloister paspalum = ‘Sea Isle 2000’ paspalum > Temple 1 paspalum = ‘Salam’ paspalum > Q 36313 paspalum = 561‐79 paspalum = Hybrid 5 paspalum > ‘TifSport’ bermudagrass = ‘TifEagle’ bermudagrass (worst). Large variations observed among paspalum entries and bermudagrass cultivars in response to LL conditions could potentially be used for enhancing management practices.
Isozyme Diversity in Wild Red Clover Populations from the Caucasus
Authors: Mosjidis Jorge A. , Greene Stephanie L. , Klingler Kimberly A. , Afonin Alexandr
Published: July 2014

The amount of genetic variation within species and populations and the distribution of genetic diversity (GD) among populations are important to breeders and biologists. The objective of this study was to assess GD on the basis of isozymes in 15 wild red clover (Trifolium pratense L.) populations collected in the Caucasus Mountains, Russia. Isozymes assayed were esterase, β‐glucosidase, phosphoglucomutase, peroxidase, diaphorase, phosphoglucoisomerase, and superoxide dismutase. Ten isozyme loci with 26 alleles were detected. Ninety percent of the loci were polymorphic in at least one population. Percent polymorphic loci within populations ranged between 50 and 90%. At the species level, the number of alleles per polymorphic locus was 2.89 and effective number of alleles per locus was 1.84. Within‐population averages were 2.75 and 1.70, respectively. Genetic diversity was 0.353 at the species level and the mean value for the populations was 0.323. Some of the populations such as PI 604728 and PI 604735 were unique at the at the isozyme level. The other 13 accessions could be consolidated into one accession. Diversity measurements indicated that this species has a high level of variability that resides mostly within populations. Gene flow expectations based on predictions using topographic maps developed using interpolated digital and climatic surfaces coincided with gene flow estimates obtained using isozymes. This supports the use of GIS tools and remotely sensed data to develop maps that help germplasm collection and post‐collection efforts to understand patterns of GD in collected germplasm.
Pasture Soil and Herbage Nutrient Dynamics through Five Years of Rotational Stocking
Authors: Jones Gordon B. , Tracy Benjamin F.
Published: July 2014

If nutrients are efficiently recycled within pasture systems, soil nutrient concentrations should change minimally over time. This process, however, has not been well documented in rotationally stocked tall fescue– [Schendonorus phoenix (Scop.) Holub] based pastures. The study objectives were to: (i) examine temporal changes in plant‐available soil nutrient concentrations in two creep grazing systems grazed by cows that differed in size, (ii) determine how winter hay feeding and use of improved forages for creep grazing affected soil and herbage nutrient concentrations, and (iii) examine the relationship between and variability within soil and herbage nutrient concentrations. From 2008 to 2012, soil and herbage samples were collected from 102 paddocks across four grazing system treatments. Significant differences in soil nutrient concentration between creep grazing systems were observed before the initiation of grazing (p < 0.05) and were consistent through time. Soil pH and soil P, K, Ca, Mg, and B concentrations declined significantly with time (p < 0.05). Increased concentrations of soil P, K, Fe, and Cu were found in hay feeding paddocks. Soil P and K showed greater variation across samples than did herbage P and K concentrations. The correlations between soil and herbage nutrient concentrations were weak. Because of variability in soil nutrients within paddocks, herbage nutrient analysis may provide a better assessment of pasture fertility status. Though year‐to‐year changes in soil nutrient concentration were small, monitoring the nutrient status of pasture systems is essential for achieving optimal forage yields, improving livestock health, and limiting nutrient losses to the environment.
Measured and Predicted Solute Leaching from Multiple Undisturbed Soil Columns
Authors: Logsdon S. D. , Keller K. E. , Moorman T. B.
Published: July 2014

Preferential flow may cause rapid leaching of solutes. The preferential flow model MACRO is a flexible, transient‐state preferential flow model. The objective of this study is to compare measured and predicted Br and tritium leaching for multiple soil columns. We collected 48 undisturbed columns (0.35 m long and 0.20 m in diameter), that represented three soils (Mollisols), two tillage treatments (no‐till and chisel), and two rainfall application rates for the first rain. We applied Br to the soil 2 d before the first rain, which contained tritium. There were four rain events, each 1 wk apart with drainage and evaporation between rains. We determined effluent breakthrough curves. We determined input parameters from soil properties measured on three extra columns for each soil and tillage combination and from calibration. For the first rain event, measured Br loss was 175% larger than tritium loss. Predicted bromide leaching for the first rain was 2% smaller than tritium loss. Tritium retention could have reduced tritium leaching. Concentrations of tritium and bromide were usually overpredicted for the first flush and underpredicted for the end of the first rain event through the start of the third rain event. The root mean square error values were as much as four times as high as a treatment mean for bromide, and up to eight times as high for tritium. Lack of agreement between measured and predicted bromide and tritium leaching may suggest further important mechanisms should be incorporated into MACRO.
Effect of Water Regime on Aggregate‐tensile Strength, Rupture Energy, and Friability
Authors: Munkholm Lars J. , Kay Bev D.
Published: July 2014

The effect of water regime on aggregate‐tensile strength, rupture energy, and friability index was studied in two experiments on sandy loam soils (Glossic Phaeozem/WRB 1998). In Exp. 1, soil from a long‐term, 5‐yr crop rotation receiving animal manure (dairy farm and grass, DFG) was compared with a soil (continuous cereal crop, CCC), which had grown almost continuous cereals and not received animal manure. In Exp. 2, soil from compacted plots (PAC) and uncompacted reference plots (REF) was sampled. The soil was air‐dried and separated into four aggregate‐size classes (i.e., 1–2, 2–4, 4–8, and 8–16 mm). Aggregate‐tensile strength and rupture energy were measured on air‐dry aggregates and on aggregates adjusted to −10, −30, −100, −350 kPa, and −166 MPa pressure potential. Soil friability index was estimated from the tensile strength or specific rupture energy results. Aggregate density was determined on 2‐ to 4‐, 4‐ to 8‐, and 8‐ to 16‐mm aggregates. The CCC soil displayed a greater increase in strength and specific rupture energy with increased dryness than the DFG counterpart. This may be related to differences in organic matter content and dispersible clay. Generally, the relationship between tensile strength or specific‐rupture energy and pressure potential could be described by a power function. However, the rupture energy results could not be fitted by a power function for the Exp. 2 soils. The Exp. 2 soils differed in the stress–strain relationship, i.e., the compacted soil displayed the highest Young modulus, (Y/ε) in all cases. Maximum values of the friability index were found between −10 and −100 kPa.
Temperature and Moisture Effects on Nitrification Rates in Tropical Rain‐Forest Soils
Authors: Breuer Lutz , Kiese Ralf , Butterbach-Bahl Klaus
Published: July 2014

Intact soil cores from three tropical rainforest sites on the Atherton Tablelands, Australia, were sampled at different hygric seasons to determine the effects of soil temperature and soil moisture on gross nitrification using the barometric process separation technique (BaPS). Parameterization experiments revealed that gross nitrification was positively correlated to increases in soil temperature, but negatively correlated to increased rates of water‐filled pore space (WFPS) because of simulated rainfall. Pronounced seasonal variations of gross nitrification rates were observed at all three sites with lowest values during the dry season (1.9–9.7 mg NH+4‐N m−2 h−1) and highest values during the transition period between dry to wet season (14.8–27.6 mg NH+4‐N m−2 h−1). Highest nitrification activities were found for two sites characterized by a narrow C/N ratio and a high total C content in the mineral soil, whereas the site with a wider C/N ratio and lower C content in the soil showed significantly lower nitrification rates. Gross nitrification was positively correlated to in situ N2O‐emission rates indicating that nitrification is a key regulating process of N2O‐production and emission in these tropical soils.
Yield and Soil Fertility Trends in a 20‐Year Rice–Rice–Wheat Experiment in Nepal
Authors: Regmi A. P. , Ladha J. K. , Pathak H. , Pasuquin E. , Bueno C. , Dawe D. , Hobbs P. R. , Joshy D. , Maskey S. L. , Pandey S. P.
Published: July 2014

The rice (Oryza sativaL.)–wheat (Triticum aestivumL.) cropping system occupies about 13.5 million ha in South Asia and is important for the region's food security. We examined the long‐term yield trends, changes in soil nutrient fractions (both total and available), and nutrient balances in a 20‐yr rice–rice–wheat experiment conducted in the Indo‐Gangetic plain of Nepal. The yield of first rice crop fertilized with recommended NPK fertilizer or farmyard manure (FYM) declined an average of 0.09 or 0.07 Mg ha−1yr−1, respectively. These 20‐yr trends explained only 20 to 21% of the variability in yield, and inexplicable shorter‐term yield trends were observed. Likewise, wheat yield declined at 0.05 Mg ha−1yr−1(with both NPK and FYM) over the 20 yr. However, the yield of second rice crop did not decline over that period. The total and available N and P, and total and labile C contents of soil from Year 10 to 20 were either maintained or increased, but total K and available K declined. The apparent K balance showed net losses of 62.3 and 15.2 kg K ha−1yr−1with NPK and FYM treatments, respectively. Depletion of soil K and inadequate K fertilization seems to be the primary reasons of limited and declining yield of first rice and wheat crop. In addition, the yield of wheat declined because of a delay in sowing, which was estimated to be 0.04 Mg ha−1for each day delay in sowing. The study showed that the current local fertilizer recommendations, particularly for K, for the rice–rice–wheat system are inadequate.
Pedogenesis of Vesicular Horizons, Cima Volcanic Field, Mojave Desert, California
Authors: Anderson K. , Wells S. , Graham R.
Published: July 2014

An existing model of desert pavement formation suggests desert pavement clasts rise vertically on an accreting eolian mantle and the underlying vesicular horizon coevolves with pavement formation. Results presented here support this model and provide a mechanism whereby eolian material is transported from the ground surface to ped interiors, thereby increasing the thickness of the vesicular horizon underlying desert pavements. Basaltic desert pavements in the Cima Volcanic Field are underlain by a vesicular horizon with strong coarse columnar and strong medium platy soil structure. Peds collected from three sites along a topographic gradient were subsampled into seven ped domains to quantify physical, chemical, and micromorphological properties within peds and along the topographic transect. Ped interiors have up to 40% clay and 12% CaCO3whereas sediments adhering to ped sides have <7% clay and 2% CaCO3Argillans and siltans lining platy surfaces in ped centers and bottoms indicate desert dust is translocated vertically along the macropores between peds and horizontally along platy boundaries to ped interiors. Once soils develop a strong columnar and platy structure, translocation to ped interiors is enhanced. Calibrated radiocarbon ages between 5440 and 5045 BP for Av ped centers suggest enhanced dust flux and pedogenesis occurred during the drier middle Holocene, an inference supported by luminescence dating and correlations with regional eolian chronologies.
Brazil's Soil Carbon Stocks
Authors: Bernoux Martial , da Conceição Santana Carvalho Maria , Volkoff Boris , Cerri Carlos Clemente
Published: July 2014

Soil organic carbon (C) stocks to a depth of 30 cm were estimated for Brazil on the basis of a map of different soil‐vegetation associations (SVA) combined with results from a soil database. The SVA map was derived by intersection of soil and vegetation maps. The original soil and vegetation classification were simplified to six soil and 15 vegetation categories. The SVA map comprised 21 111 map units (MU) that were spread into 75 different SVA categories. Mean representative C stocks (RCS) of the SVA categories ranged from 1.51 to 41.78 kg C m−2More than three fourth of all SVA areas had an associated RCS varying between 3 and 6 kg C m−2Because these data represent sites with native vegetation in the absence of significant disturbances, they represent a valuable baseline for evaluating the effect of land‐use change on soil C stocks for Brazil. In total, about 36.4 ± 3.4 Pg C was stored in the 0‐ to 30‐cm soil layer.
Cultivation‐Induced Effects on Belowground Biomass and Organic Carbon
Authors: Slobodian N. , Van Rees K. , Pennock D.
Published: July 2014

Land conversion and cultivation effects on belowground biomass and C were assessed at a fescue (Festuca altaica Trin. ssp. hallii) prairie site and an adjacent cultivated field seeded to spring wheat (Triticum aestivum L.). Belowground biomass and soil organic C (SOC) were measured in three landform element groups (upper level and convex shoulder elements [UL], low‐catchment‐area footslope elements [FS], and low‐elevation level and high‐catchment‐area footslope elements [LL]) at both sites. Upper level, FS, and LL landscape positions in the prairie had, respectively, eight, 12, and 13 times more belowground biomass in the top 60 cm of soil than their cultivated field counterparts. In the upper 1.8 m of soil, belowground biomass in the prairie grassland increased downslope (UL = 1849 ± 306, FS = 2533 ± 899, and LL = 3663 ± 1248 g m−1). In the cultivated field, LL landscape positions had higher levels of belowground biomass than either UL or FS positions (UL = 228 ± 54.5, FS = 200 ± 47.0, and LL = 294 ± 76.8 g m−2). Losses of C from belowground biomass accounted for 17.6% of total SOC losses in UL landscape positions, and 71.7% of losses in FS positions after cultivation. Lower level positions had the greatest loss of belowground plant C (−15.6 Mg ha−1) but overall the SOC had increased by 9.0 Mg ha−1 In these position the loss of belowground C was offset by significantly higher SOC additions to the surface through soil redistribution. On a whole landscape basis, the C loss because of changes in belowground biomass is a large part of the C change that occurs during the transition from native prairie to arable agriculture.
Bermudagrass Management in the Southern Piedmont USA. III. Particulate and Biologically Active Soil Carbon
Authors: Franzluebbers A. J. , Stuedemann J. A.
Published: July 2014

Quantifying the effects of forage management on soil C cycling improves our understanding of greenhouse gas emissions, agronomic productivity, and changes in soil quality in pasture ecosystems. We evaluated the effects of N fertilization strategy (inorganic only, crimson clover [Trifolium incarnatum L.] cover crop plus inorganic, and broiler litter) and forage harvest strategy (unharvested, low and high grazing pressure, and hayed; representing a gradient from low to high utilization) on particulate organic C (POC), soil microbial biomass C (SMBC), and potential C mineralization (CMIN) during 4 yr on a previously eroded site dominated by Typic Kanhapludults. Accumulation of POC, SMBC, and CMIN with time was greatest at a depth of 0 to 2 cm and was not different among fertilization strategies. To a depth of 6 cm, POC accumulated at a rate of 65 to 73 g m−2 yr−1 under unharvested or hayed strategies and at a rate of 136 to 144 g m−2 yr−1 under cattle grazing strategies. Accumulation rate of SMBC was also dependent upon forage utilization, averaging 5.1, 9.6, 11.9, and 7.4 g m−2 yr−1 under unharvested, low grazing pressure, high grazing pressure, and hayed strategies, respectively. The portion of total organic C as CMIN during 24 d increased from 16 g kg−1 initially to 44 ± 5 g kg−1 (mean ± standard deviation among 12 treatments) at the end of 4 yr, without significant treatment effects. Particulate and biologically active soil C pools increased under all forage management strategies, although cattle grazing imparted the greatest increase partly because of the return of feces to soil.
Soil Survey Mapping Unit Accuracy in Forested Field Plots in Northern Pennsylvania
Authors: Drohan P. J. , Ciolkosz E. J. , Petersen G. W.
Published: July 2014

The use of Natural Resources Conservation Service (NRCS) Soil Survey Geographic Database (SSURGO) digital data and soil survey report data in geographic information system (GIS) models is becoming more common as the mapping becomes NRCS SSURGO certified. How accurate this data is in reflecting the actual field situation is an essential aspect of the GIS model. This study was conducted to determine how well NRCS official series descriptions (OSDs) matched field data from 30 forested plots in northern Pennsylvania. If plots proved to match OSD data well, then a model of sugar maple (Acer saccharum Marsh.) decline could be developed from U.S. Forest Service (USFS) Forest Inventory and Analysis (FIA) data using this data. Soil descriptions of the plots sampled in 1998 were compared with the NRCS OSDs. Plot variability was assessed with four exploratory soil pits and detailed field characterization was done on the most representative pit to a depth of 1.2 m. Results indicate that field soil data from plots matched OSD data well (less than two parameters outside the range) 80% of the time and very well (less than or equal to one parameter outside the defined data range of six properties) 63% of the time. Properties that fell outside the data range were almost always very close to the range of characteristics for the named series. Plots with more than two properties outside the range of the mapped series often occurred in landscape positions (backslope or toeslope [near streams]) prone to disturbance that could have resulted in large variability in the properties under observation. These data indicate that NRCS OSD data for the six properties in this study in forested areas of Pennsylvania can be used for GIS modeling.
Using Soil Phosphorus Profile Data to Assess Phosphorus Leaching Potential in Manured Soils
Authors: Kleinman Peter J. A. , Needelman Brian A. , Sharpley Andrew N. , McDowell Richard W.
Published: July 2014

Transport of P by subsurface flow pathways can be an important mechanism of P transfer from land to water, particularly in manured soils that are artificially drained. This study was conducted to determine whether detailed description and interpretation of soil P profile data provide adequate insight into P leaching potential. Evidence of P translocation within soil profiles of a tile‐drained Buchanan (fine‐loamy, mixed, semiactive, mesic Aquic Fragiudult)‐Hartleton (loamy‐skeletal, mixed, active, mesic Typic Hapludults) catena was assessed by measuring oxalate‐extractable P, P sorption saturation, Mehlich‐3 P, water‐extractable P in bulk and clay film samples obtained from individual horizons. Tile‐drain monitoring and column leaching experiments were conducted to evaluate interpretations derived from soil P profile data. Soil P fractions were not correlated with P losses in lysimeter studies, indicating the limited potential of using soil profile P data for quantitative prediction of leaching losses. Application of manure to the soil surface resulted in significant increases in leachate P concentrations from the lysimeters. Soil profile P data did, however, provide some evidence of long‐term P leaching. While bulk horizon samples did not indicate significant long‐term P translocation to soil depths corresponding with artificial drainage, some clay film samples had significantly elevated oxalate P, P sorption saturation and Mehlich‐3 P at lower depths. Elevated P concentrations in clay films may be associated with preferential transport of P along soil macropores, although, not all clay films sampled in this study were necessarily associated with active macropores. Thus, soil P profile data appear to provide limited insight into P leaching potential.
Roughness Measurements of Soil Surfaces by Acoustic Backscatter
Authors: Oelze Michael L. , Sabatier James M. , Raspet Richard
Published: July 2014

The measurement of the roughness of soil surfaces on centimeter scales is important to modeling local soil erodibility. An acoustic backscatter technique was examined for its ability to quantify the roughness of porous soil on centimeter scales. Acoustic backscatter offers the possibility of an inexpensive, mobile, and rapid means of estimating statistical properties of soil surfaces. Four soil plots were constructed with varying amounts of roughness. Surface roughness of the four soil plots was measured with the acoustic backscatter technique and a laser microreliefmeter. The roughness power spectra for the surface plots were obtained from surface profiles measured by the laser microreliefmeter and by the acoustic backscatter technique. Statistical values of the RMS (root mean square) height and correlation length of surface roughness for each plot were calculated from the acoustic backscatter power spectra and laser microreliefmeter power spectra and compared. Agreement between the two techniques for estimating roughness statistics was shown to be good (<13% difference) when an adequate amount of data points were used to map out the roughness power spectra. The acoustic backscatter technique appears to be a potential alternative to rapidly and inexpensively quantify the roughness of soil surfaces.
The Spectral Reflectance Properties of Soil Structural Crusts in the 1.2‐ to 2.5‐μm Spectral Region
Authors: Ben-Dor E. , Goldlshleger N. , Benyamini Y. , Agassi M. , Blumberg D. G.
Published: July 2014

A controlled investigation of the spectral signature of soil's structural crust in the 1.2‐ to 2.5‐μm spectral region was conducted to investigate the feasibility of accounting for the crust status solely from the spectral information. This research was conducted because there is no valid method for in situ assessment of soil‐crust characteristics in agricultural fields while and after the crust is formed. Through the use of a laboratory rainfall simulator and a sensitive spectrometer, we showed that significant spectral differences occurred between the crust and the bulk soil for three selected soils from Israel. The study was divided into two parts: Part 1, in which qualitative observations of the three soils were conducted under one level of rainstorm energy, and Part 2, where a selected soil was further investigated under varying levels of rain energy. The spectral differences obtained for the crusted soil are related to the texture and mineralogy of the soil's surface. It was concluded that the relationship between structural crust and soil reflectance spectroscopy can be used as a tool for estimating soil properties governed by the physical crust formation, such as infiltration rate, soil runoff, and erosion. It was further suggested that this methodology be tested within a remote sensing domain, using field, air, or spaceborne hyperspectral sensors.
Gas Diffusivity in Undisturbed Volcanic Ash Soils
Authors: Moldrup Per , Yoshikawa Seiko , Olesen Torben , Komatsu Toshiko , Rolston Dennis E.
Published: July 2014

Soil‐water‐characteristic‐dependent (SWC‐dependent) models to predict the gas diffusion coefficient, DP, in undisturbed soil have only been tested within limited ranges of pore‐size distribution and total porosity. Andisols (volcanic ash soils) exhibit unusually high porosities and water retention properties. The Campbell SWC model and two Campbell SWC‐based models for predicting DP in undisturbed soil were tested against SWC and DP data for 18 Andisols and four Gray‐lowland (paddy field) soils from Japan. The Campbell model accurately described SWC data for all 22 soils within the matric potential range from ≈ −10 to −15000 cm H2O. The SWC‐dependent Buckingham‐Burdine‐Campbell (BBC) gas diffusivity model predicted DP data well within the same matric potential range for the 18 Andisols. The BBC model showed a minor but systematic underprediction of DP for three out of the four Gray‐lowland soils, likely due to a blocky soil structure with internal fissures. A recent DP model that also takes into account macroporosity performed nearly as well as the BBC model. However, DP in the macropore region (air‐filled pores >30 μm) was consistently underpredicted, likely due to high continuity of the macropore system in both Andisols and Gray‐lowland soils. In agreement with previous model tests for 21 European soils (representing lower porosities and water retention properties), both SWC‐dependent DP models gave better predictions for the 22 Japanese soils than soil‐type independent models. Combining DP and SWC data, a so‐called gas diffusion fingerprint (GDF) plot to describe soil aeration potential is proposed.
One-Pot Synthesis of Dibenz[b,f][1,4]oxazepines via Mg(ClO4)2-Catalyzed Ugi Four-Component Reaction and Microwave-Assisted Intramolecular SNAr
Authors: Luo Jialu , Wu Jinlong , Dai Wei-Min
Published: July 2014

A general one-pot synthesis of dibenz[b,f][1,4] oxazepine-11(10H)-carboxamides is described. The Ugi four-component reaction (U-4CR) of 2-aminophenols, cyclohexyl isocyanide, 2-chloro-5-nitrobenzaldehyde, and 2-bromobenzoic acids in MeOH in the presence of 25 mol% Mg(ClO
Classifications of acute pancreatitis: to Atlanta and beyond
Authors: Pallisera Anna , Adel Farah , Ramia Jose
Published: July 2014

Until Atlanta Classification (AC) made in 1992, there was not any classification of acute pancreatitis (AP). Last twenty years AC let us compare results and papers. But the increasing understanding of the pathophysiology of AP, improvements in diagnostic methods and the development of minimally invasive tools for radiological, endoscopic and surgical management of local complications, several authors have called for the AC to be reviewed. Last months, two new classifications of AP have been published. We made a historical review of AC, the two new classifications and a comparison between them.