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Published in Agron. J. 105:1–10 (2013) doi:10.2134/agronj2012.0221 Available freely online through the author-supported open access option. Copyright © 2013 by the American Society of Agronomy, 5585 Guilford Road, Madison, WI 53711. All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. T global arable land base is estimated at 1.351 billion hectares which amounts to about 0.19 ha per person based on a population of 7 billion (World Fact Book, 2012). With the projected population increase to 9 billion by 2050, the per capita arable land amount will be 0.15 ha per person but in actual fact much less because an extra 2 billion people will require additional land for infrastructure. Also, the fact that 93 to 99% of the food consumed by humans comes from the land (Pimentel and Pimentel, 2000; Smil, 2000) implies that food production per unit area will have to increase. However, 45% of global arable soils are aff ected by degradation (Lal, 2007). Th e Food and Agriculture Organization endorses conservation agriculture as the key step to meeting the long-term global demand for food, feed, and fi ber for the projected 9 billion people by 2050 (Mackenzie, 2009). Irrigated land comprises about 7% of the total arable land area (World Fact Book, 2012) and land under irrigation will probably not increase to make up for short falls in food production because of competing fresh water needs by a growing population. Th erefore dry land farming systems will need to become more productive which means more water effi cient. Th e positive benefi ts of no-till production systems on crop production (Lafond et al., 1996, 2006b), economic performance (Gray et al., 1996; Zentner et al., 2002; Holm et al., 2006) and energy use effi ciency (Zentner et al., 2004) are well recognized in the Northern Great Plains. More recent no-till studies have demonstrated additional yield increases in spring wheat (Triticum aestivum L.) and canola (Brassica napus L.) as length of time under no-till increases (Lafond et al., 2011). Additional benefi ts from no-till can be obtained if crops are seeded into tall stubble. Increases in grain yield and water use effi ciency have been observed for spring wheat (Cutforth and McConkey, 1997), canola (Cutforth et al., 2006), fi eld pea (Pisum sativum L.), lentil (Lens culinaris Medik.), and chickpea (Cicer arietinum L.) (Cutforth et al., 2002) when seeding into >30 cm tall stubble. Tall stubble reduces water loss from evaporation at the soil surface and increases water available for transpiration, thereby explaining the greater reported crop water use effi ciencies and grain yields when compared to shorter or no stubble. Growing crops into tall stubble combined with long-term no-till represents an important approach to increasing crop production under semiarid dryland farming conditions. Given the reported benefi ts of no-till production systems, seeding into standing stubble and through surface residues has challenges. One solution to reduce plugging is to increase the row spacing. Th e common accepted knowledge is that narrow row spacing gives greater grain yields in cereal crops (Austenson and Larter, 1969; Briggs, 1975; Bauder, 1990; Chen et al., 2008). However, other studies have shown that it is possible to use wider spacing without experiencing grain yield losses. Research with no-till winter wheat showed equivalent yields between 18 and 36 cm under semiarid conditions (McCleod et al., 1996) and among 10-, 20-, and 30-cm row spacing under subhumid conditions (Lafond and Gan, 1999). With spring wheat, no diff erences in yield were observed among 10-, 20-, and 30-cm row spacing under no-till (Lafond, 1994; Bailey et al., 1998) and conventional till systems (Lafond and Derksen, 1996) and between 23 and 30 cm with no-till (Johnston and Stevenson, 2001) under subhumid conditions. No grain yield diff erences were observed among 10-, 20-, and 30-cm spacing in barley with no-till (Lafond, 1994; Bailey et al., 1998) and conventional till (Lafond and Derksen, 1996) under subhumid ABSTRACT

Published in Agron. J. 104:1501–1509 (2012) Posted online 6 Aug. 2012 doi:10.2134/agronj2011.0339 Copyright © 2012 by the American Society of Agronomy, 5585 Guilford Road, Madison, WI 53711. All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. N practices can improve soil organic matter, soil moisture, and total and available soil N, and have benefited farming systems of the northern Great Plains (Sharifi et al., 2008; Lafond and Clayton, 2010; Lafond et al., 2011). Results from studies at different locations in this region suggest that increases in C, N, and water holding capacity of NT soils along with aging of the NT system continue to improve the quality of NT soils. Across the three major soil zones of Saskatchewan, continuous NT increased potentially mineralizable soil N by 16 to 40 kg ha–1 compared to a conventional-till (CT) treatment (Liang et al., 2004). In the black soils of this province, Schoenau et al. (2008) measured greater soil available N and P following 28 yr of continuous NT compared to 5 yr of continuous NT history in the same field. As a result of improved soil quality and soil moisture, the BNF of legume crops has gradually increased in NT systems (Matus et al., 1997; van Kessel and Hartley, 2000). However, NT practices and other crop managements can increase the level of soil N to the point where soil NO3–N can inhibit legume BNF. Legumes preferentially use N from soil than taking N from the atmosphere, as the latter requires more energy (Graham and Vance, 2003). Moreover, a high level of soil NO3–N strongly inhibits nitrogenase activity and thereby lowers BNF (Peoples et al., 1995; Lucinski et al., 2002). In faba bean (Vicia faba L.), the proportion of plant N derived from the atmosphere (%Ndfa) was strongly inhibited by soil NO3–N (Lopez-Bellido et al., 2006). Doughton et al. (1993) found that the BNF of chickpea (Cicer arietinum L.) was inhibited by high soil NO3–N after chemical fallow compared to after sorghum [Sorghum bicolor (L.) Moench]. Yet, a reduction in BNF will not manifest itself in plant biomass, N content and grain yield if the reduction in BNF is compensated by soil N uptake (George et al., 1988; Doughton et al., 1993; Reiter et al., 2002). In addition to the effect on BNF, accumulated soil N due to long-term NT can stimulate vegetative growth, lower HI, and affect yield production of the field crops. As an indeterminate crop, lentil simultaneously develops leaves, flowers and pods until stress terminates vegetative growth (Erskine and Goodrich, 1991). Therefore, response of lentil yield to high soil N can be different from that of field crops with determinate growth habits. In soybean [Glycine max L.(Merr.)], application of 150 kg ha–1 N fertilizer increased vegetative biomass, resulted in lodging, and lowered grain yield of an indeterminate cultivar, whereas it improved the yield of semi-determinate cultivars (Wallace et al., 1990). Application of 90 kg ha–1 N fertilizer increased lentil biomass by 50% and reduced HI by 6% compared to a nonfertilized treatment; however, grain yield was increased or remained independent of the N fertilizer treatments (Bremer et al., ABSTRACT

The year-to-year variability of seed yield in annual canarygrass ( Phalaris canariensis L.) is a major concern among growers. A field experiment was conducted at 13 site-years across Saskatchewan to determine the response of annual canarygrass seed yield to K and Cl, and to provide better recommendations to producers on the use of KCl fertilizer in annual canarygrass based on soil test results. Potassium did not affect the yield or development of annual canarygrass over a range of 155 to 717 kg K ha -1 in the top 15 cm of soil. Chloride had a large impact on annual canarygrass seed yield; seed yield increased by approximately 24% when Cl was added in the form of KCl or CaCl 2 when averaged across all sites. The seed yield increased because the application of Cl increased panicle size (seeds panicle -1 ). The magnitude of the response tended to increase as level of Cl in the soil decreased. Annual canarygrass growers need to measure Cl when using soil tests to determine fertilizer requirements. It is recommended that 9.1 kg Cl ha -1 in the form of 20 kg ha -1 of KCl be applied when the Cl level in the surface soil (0-15 cm) is below 70 kg Cl ha -1 . The findings encourage growers to conduct individual field test strips to determine the strength of the Cl response.

Including grain-legumes in cropping systems contributes to a reduction in greenhouse gas emissions and enhances agronomic and economic performance of cropping systems. The objective was to examine the potential for increasing the frequency of field pea (Pisum sativum L.) (FP) in a spring wheat (Triticum aestivum L.) (W)-based cropping system. Three crop rotations, continuous pea (C-Pea), W-FP, and W-W-FP, were evaluated over a 10-yr period (1998―2007) at Indian Head, SK. During the FPphase of C-Pea and W-FP, three starter N rates (5, 20, 40 kg N ha ―1 ) were applied. One rate of N (80 kg N ha ―1 ) was used in W. Rotation and N had similar effects on plant densities in either crop. Field pea grain yields were 25% lower with C-Pea than W-FP or W-W-FP but similar between W-FP and W-W-FP. Starter N had some effect on FP grain yields at the higher N rate in W-FP but not C-Pea. Spring wheat grain yields were 3% greater on FP than W stubble. Grain protein in FP was 3.1% higher on C-Pea than W-P or W-W-FP while grain protein in W was 1 g kg ―1 higher on FP than W stubble. Crop water use efficiency in FP and W was not affected by crop rotation. Based on the results of this study, we conclude that the frequency of FP in cropping systems in the subhumid and semiarid areas can be increased intermittently with only a 1-yr cereal break between FP crops when combined with proper integrated crop management practices.

Hybrid structures based on superconducting Nb and highly coercive ferromagnetic SmCo 5 films grown on MgO(100) substrates were fabricated by pulsed laser deposition under UHV conditions. Thin film architectures of SmCo 5 on Nb and the reversed system both with and without Cr spacer layer between superconductor and ferromagnet were examined by transmission electron microscopy and X-ray diffraction concerning their microstructure and epitaxial relationship, respectively. For SmCo 5 on Nb with thick intermediate Cr spacer the epitaxial relationship MgO(001)[100]//Cr(001)[110]//Nb(001)[110]//Cr(001)[110]// SmCo 5 (11-20)[0001]//Cr(001)[110] was found. With decreasing thickness of the Cr spacer layer the strength of the texture decreases and finally crystallinity of SmCo 5 is lost. In the reversed layer system, Nb on Cr on SmCo 5 , with decreasing thickness of the Cr spacer layer the epitaxial relationships change from SmCo 5 (11-20)[0001]//Nb(001)[110] to local SmCo 5 (11-20) [0001]//Nb(110)[1-11] and the Nb texture changes from the (001)[110] component to a 〈110〉 fibre. The orientation relationships observed are discussed with regard to elastic strain energy minimization.

The crystallographic and magnetic texture of epitaxial, hard magnetic Sm 2 Co 7 films prepared on Cr-buffered MgO single-crystal substrates are analyzed. Substrate symmetry, deposition temperature, and deposition rate are systematically varied, resulting in a variety of different, but epitaxial orientations. On Cr-buffered MgO(001), Sm 2 Co 7 grows with three different types of orientations: one inplane orientation with the c-axis aligned in the substrate plane parallel to MgO[100] and [010], and two tilted orientations, where the c-axes of the Sm 2 Co 7 crystals have a 45° and 60° orientation to the substrate plane. The volume fraction of the tilted orientations decreases with decrease in the Sm 2 Co 7 deposition temperature. A lower limit is given by the epitaxial growth temperature, which is necessary to form a fully crystalline, epitaxial film. This temperature can be reduced by lowering the deposition rate. Thus, almost completely inplane aligned films can be achieved by a low-rate/low-temperature deposition. On a Cr-buffered MgO(01 1) substrate Sm 2 Co 7 grows with a single orientation, i.e., with the c-axis aligned onto the substrate plane parallel to MgO[100]. The findings are discussed considering elastic strain minimization, thermodynamics and kinetics of film growth, surface faceting, and Co-particle formation.

Crop residues are considered the feedstock of choice for the production of ethanol, but removing crop residues may negatively impact soil productivity. The objectives were to quantify the proportion of total aboveground crop residues removed through baling and to evaluate the effects of 50 yr of straw removal with baling on soil quality and wheat (Triticum aestivum L.) production. The first study evaluated three harvesting systems and their impact on straw removal with baling. The second study measured straw removal after 50 yr on soil quality and wheat production using a fallow-spring wheat-spring wheat rotation (F-W-W) with three different treatments imposed. One treatment was not fertilized with straw retained, and the other two were fertilized with N and P but one treatment retained the straw while the other had the straw baled every year during the cropping years. The proportion of total aboveground residues other than grain removed with baling ranged from 22 to 35% or 26 to 40% depending on the method of calculation based on the first study. Measurements of soil organic carbon (SOC) and nitrogen (SON) showed no differences after 50 yr of straw removal, and spring wheat grain yields and grain protein concentration were also not affected based on the second study. The potential therefore exists to use crop residues for ethanol production or other industrial purposes without adversely affecting the long-term productivity of medium- to heavy-textured soils providing that

Information regarding the impact of P and KCl rate and placement in conjunction with N rate on durum wheat (Triticum turgidum L. var. durum) is limited in the Great Plains. Our objectives were to determine the effects ofN, P, and KCl fertilizer rate and P and KCl placement on grain yield and quality of durum wheat grown on low P soils. Nine combinations of N and P fertilizer and five combinations ofN, P, and KCl applied with the seed and in a side band, were compared over 3 yr at Indian Head, SK, in fields with soil P levels

The behaviour of the upper critical field Hc2 of the multiphase magnetically ordering superconductor HoNi2B2C presents numerous features arising from the three distinct magnetically ordered phases of the material that form at temperatures below the superconducting critical temperature Tc, i.e. within the superconducting phase. A detailed investigation of the Hc2 of this material in the form of high-quality biaxially textured thin films has been conducted, including the only full set of angle-dependent measurements currently available. The results reveal a number of additional features that have hitherto been overlooked, in particular a far higher degree of anisotropy of the material throughout the entire temperature range below Tc than is commonly reported. By correlating these features with the known phase diagrams of the material, an explanation of the observed behaviour can be postulated, and the apparent loss of anisotropy attributed to the transition of the material into a different magnetic phase. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Samples of cube textured Ni tapes were oxidized in flowing oxygen at different temperatures. Crystal orientation maps (COMs) of the resulting oxide layers were produced by electron backscatter diffraction. The oxide layers were also analysed by X-ray diffraction (XRD), scanning electron microscopy and atomic force microscopy (AFM). The oxide grain size of a sample oxidized at 600 degrees C was similar to that of the substrate and the oxide was highly textured, both indicating epitaxial growth. The orientation relationship between the substrate and the oxide was directly observed from XRD to be (111)NiO//(001)Ni, [101]NiO//[110]Ni with four, equivalent, in-plane variants. In each variant, the oxide has both110- and211-type directions parallel to the Ni110directions. Differences in oxide thickness and surface roughness on neighbouring grains were revealed by AFM and these were attributed to the existence of a range of oxide growth conditions resulting from small differences in the orientation of each substrate grain. Similar macrotexture and microstructure were observed on a sample oxidized at 1300 degrees C, but additional, facetted oxide crystals had formed at the oxide grain boundaries. COMs showed that these crystals were either cube or 45 degrees rotated cube orientated, a texture different to that of the large oxide grains. The grain boundary crystals were thought to form by inward diffusion of oxygen at defects in the growing oxide scale.

Poor stand establishment resulting in lower yield is a major constraint to expanding winter wheat (Triticum aestivum L.) land area across the semiarid temperate regions of the northern Great Plains. We conducted a direct-seeded study at nine sites across western Canada totaling 26 environments (site-years) over three growing seasons (2011–2013) to observe the responses of the winter wheat cultivar CDC Buteo to five levels of seed treatment (i) Check–no seed treatment, (ii) tebuconozole [(RS)- 1-(4-Chlorophenyl)-4,4-dimethyl-3-(1H, 1,2,4-triazol-1-ylmethyl)pentan- 3-ol], (iii) metalxyl {2-[(2,6-dimethylphenyl)-(2-methoxy-1-oxoethyl) amino} propanoic acid methyl ester], (iv) imidacloprid (N-{1-[(6-Chloro-3-pyridyl)methyl]-4,5-dihydroimidazol-2-yl}nitramide), and (v) dual fungicide/insecticidal seed treatment: tebuconozole, + metalxyl + imidacloprid; and two levels of fall-applied fungicide (i) Check–no application or (ii) foliar-applied prothioconazole {2-[2-(1-chlorocyclopropyl)-3-(2-chlorophenyl)-2-hydroxypropyl]-1H-1,2,4-triazole-3-thione} performed in mid-October. The check and the fungicide seed treatment, metalaxyl, produced similarly low grain yield resulting in lower net returns, whereas the dual fungicide/insecticide seed treatment provided the highest yield and net returns (CAN+$13 ha–¹). Fall-applied fungicide improved yield (0.06 Mg ha–¹), but decreased net returns (–$12 ha–¹). Plant density increased slightly (13 plants m–²) when seed treatments included the insecticide component, imidacloprid. Fall foliar fungicides generally improved spring plant density; however, no benefit was observed in seed treatments containing imidacloprid. Greater yield and plant stand stability was observed with fall-applied foliar fungicide applications; however, fall foliar would be cost prohibitive. The benefits of a fall foliar fungicide application requires further exploration in the context of an added input or as an alternative to a spring application as the net returns of a fall foliar compared to no application in the system render the input cost-prohibitive.

Oxygen sensing was investigated in rat pheochromocytoma PC12 cells. They respond to hypoxia with an increased intracellular generation of reactive oxygen species (ROS), measured by oxidation of dihydrorhodamine 123. This increase is abolished by intracellular superoxide scavenging by Mn(III)-tetrakis(1-methyl-4-pyridyl)-porphyrin, and reduced or absent in the presence of the flavoprotein/complex I inhibitors, diphenyleneiodonium and rotenone. The same inhibitors, but neither intra- nor extracellular (superoxide dismutase) superoxide scavenging, abolish the hypoxia-induced increase in tyrosine hydroxylase (TH) gene expression. Thus, ROS production increases in PC12 cells during hypoxia, but this is not the cause of hypoxic TH mRNA upregulation that involves a flavoprotein.

The refractive indexes of CsCl, CsBr, and CsI show a strong nonlinear density dependence. This behaviour can be related to the closure of the band gap by means of a constant-joint-density-of-states model for the dielectric function. The results are discussed with respect to the dielectric properties of other AB compounds.

Energy dispersive X-ray diffraction on Ce in the range of pressures up to 14 GPa and temperatures up to 625 K identifies the structures in the previously proposed phase diagram and thereby disproves some of the more speculative phase diagrams from the literature, primarily concerning possible boundaries for the f.c.c. phase at high temperatures.

The equilibrium phase diagram of boron nitride thermodynamically calculated by Solozhenko in 1988 has been now refined on the basis of new experimental data on BN melting and extrapolation of heat capacities of BN polymorphs into high-temperature region using the adapted pseudo-Debye model. As compared with the above diagram, the hBN ⇆ cBN equilibrium line is displaced by 60 K toward higher temperatures. The hBN−cBN−L triple point has been calculated to be at 3480 ± 10 K and 5.9 ± 0.1 GPa, while the hBN−L−V triple point is at T = 3400 ± 20 K and p = 400 ± 20 Pa, which indicates that the region of thermodynamic stability of vapor in the BN phase diagram is extremely small. It has been found that the slope of the cBN melting curve is positive whereas the slope of hBN melting curve varies from positive between ambient pressure and 3.4 GPa to negative at higher pressures.

A special pressure cell for Raman spectroscopy is described which contains a sample chamber with special scattering geometry and a ruby manometer for in situ pressure measurements. Typical results are given for the fundamental vibrational Raman spectra of matrix-isolated nitrogen molecules.