Agricultural lands occupy 37% of the earth's land surface. Agriculture accounts for 52 and 84% of global anthropogenic methane and nitrous oxide emissions. Agricultural soils may also act as a sink or source for CO 2 , but the net flux is small. Many agricultural practices can potentially mitigate greenhouse gas (GHG) emissions, the most prominent of which are improved cropland and grazing land management and restoration of degraded lands and cultivated organic soils. Lower, but still significant mitigation potential is provided by water and rice management, set-aside, land use change and agroforestry, livestock management and manure management. The global technical mitigation potential from agriculture (excluding fossil fuel offsets from biomass) by 2030, considering all gases, is estimated to be approximately 5500-6000 Mt CO 2 -eq. yr K1 , with economic potentials of approximately 1500-1600, 2500-2700 and 4000-4300 Mt CO 2 -eq. yr K1 at carbon prices of up to 20, up to 50 and up to 100 US$ t CO 2 -eq. K1 , respectively. In addition, GHG emissions could be reduced by substitution of fossil fuels for energy production by agricultural feedstocks (e.g. crop residues, dung and dedicated energy crops). The economic mitigation potential of biomass energy from agriculture is estimated to be 640, 2240 and 16 000 Mt CO 2 -eq. yr K1 at 0-20, 0-50 and 0-100 US$ t CO 2 -eq. K1 , respectively.

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. 1994. Root penetration profiles of wheat and barley as affected by soil penetration resistance in field conditions. Can. J. Soil Sci. 74: igZ-ZOO. e stuOy was conducted on three Manitoba soils (Marquette heavy clay, Fortier silty clay loam, and Souris loamy sand) with the objectives of: (a) assessing the effects of contrasting tillagesystems on various soil physical properties; and O) ielating root penetiation of cereals to these properties. The zero tillage (ZT) and conventional tif^fale (Cf) treatments hadbeen esta'blished between 3 (Marquette and Souris) and 10 (Fortier) years prior to the initiation of the stridy. Penetrometer resistance (PR), bulk density (BD) and pore size distribution (PSD) were measured at various depths and iimes during two growing ,"uronr. The effects of tillage systems on soil properties were generally small, particularly in the poorly strucirred S-ouris l6amy sand. PR in the top 10 cm of soil tended to be higher under ZT than^under C1.. pR uarleO mart 100^1m in diameter) near the soil surface tended to be higher under ZT ihan under CT. There was no evidence of any detrimenlal effect of poor aeration on the final root penetration p.oFtl.r of wheat. The proportion of roots penetrating the soil was inversely relatec to iR. Soil strength critical for root penetration was determined to be 2 MPa and was independent of soil type. In most situations' however, roots were able to grow inio soil with mechanical impedance greater than 2 MPa, possibly by making use of biochannels and spatial and temporal heterogeneity in the soil stmcture.

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This study examined the possible relationship between emotional competence and transformational leadership in K-12 school leaders as a function of self-other agreement. The study found that, for those school leaders whose self-assessment of their leadership agreed with that of their subordinates, the self-ratings of emotional competence were strongly and significantly correlated with the self-ratings of transformational leadership. However, the correlations between emotional competence and leadership self-ratings were not significant for those school leaders who either over-or under-estimated their transformational leadership. In contrast, the correlations of others' ratings of the leaders' emotional competence and transformational leadership were equally strong and significant for all leaders. Furthermore, this study demonstrated that those leaders who agreed with their subordinates in the assessment of their transformational leadership also agreed with their subordinates in the rating their social and emotional competence, whereas leaders who over-estimated their transformational leadership were likely to rate their emotional competence higher than were their subordinates. These identified relationships have potential implications for professional development programming for school leaders and for furthering establishing the degree to which development of emotional competence promotes the development of transformational leadership.

Gentile, R. M., Martino, D. L. and Entz, M. H. 2003. Root characterization of three forage species grown in southwestern Uruguay. Can. J. Plant Sci. 83: 785-788. Forage crops are widely grown in the mixed cropping system of southwestern Uruguay. There is renewed interest in the use of forages for soil improvement and carbon sequestration, but the root growth of forages has received little study. Field observations were made of the root systems of tall fescue (Festuca arundinacea Schreb.), alfalfa (Medicago sativa L.) and chicory (Cichorium intybus L.). Soil core samples were used to measure root count and biomass distributions to a depth of 1 m. Roots were detected to a depth of 1 m for all species, although half of the root biomass for each species was located in the top 20 cm of the soil. The distribution of root counts differed with the greatest number of root axes found above a depth of 20 cm for tall fescue and chicory, and below 20 cm for alfalfa. Si on recommence à s'intéresser aux fourrages pour amender le sol et mieux piéger le carbone, on sait peu de choses sur la croissance des racines des espèces fourragères. Les auteurs ont étudié le système racinaire de la fétuque élevée (Festuca arundinacea Schreb.), de la luzerne (Medicago sativa L.) et de la chicorée (Cichorium intybus L.) sur le terrain. Pour dénombrer les racines et calculer la répartition de la biomasse, ils ont prélevé des carottes de sol à 1 m de profondeur. Toutes les espèces ont des racines à cette profondeur, bien que la moitié de leur biomasse se situe dans les 20 premiers centimètres du sol. La répartition des racines varie, le plus grand nombre d'axes radiculaires ayant été observé à 20 cm de profondeur pour la fétuque et la chicorée et à plus de 20 cm pour la luzerne.

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