Carbon and nitrogen turnover in two acid forest soils of southeast Australia as affected by phosphorus addition and drying and rewetting cycles

The effects of adding P and of drying and rewetting were studied in two acid forest soils from southeast Australia. The soils were a yellow podzolic with a low soil organic matter content (3.75% C) and a red earth with a high organic matter content (13.5% C). C and N mineralization and microbial C and N contents were investigated in a laboratory incubation for 151 days. Microbial C and N were estimated by a hexanol fumigation-extraction technique. Microbial C was also determined by substrate-induced respiration combined with a selective inhibition technique to separate the fungal and the bacterial biomass. The results obtained by the selective inhibition technique were not conclusive. Adding P to the soil and drying and rewetting the soil reduced microbial N. This effect was more pronounced in rapidly and frequently dried soils. Microbial C was generally less affected by these treatments. Compared with the control, the addition of P caused a reduction in respiration in the red earth (-13%) but an increase in the yellow podzolic soil (+12%). In the red earth net N mineralization was highest following the addition of P. In the yellow podzolic soil highest N mineralization rates were obtained when the soil was subjected to drying and rewetting cycles. In both soils increased N mineralization was associated with a decrease in microbial N, indicating that the mineralized N was of microbial origin. Nitrification decreased with rapid drying and rewetting. The addition of P promoted heterotrophic nitrification in both soils.     

Behavior of manganese in some acid soils in Western Germany in relation to pH and air-drying

The relationships of pH to Mn concentrations in equilibrium soil solutions of strongly acid soils (pH < 4.5) were studied. The values of Mn concentrations did not conform to the solubility relationships of MnO₂, Mn₂O₃ or Mn(OH)₃. On the othr hand, a significant relationship between pMn and exchangeable Mn (r = 0.636^**, N =43) was observed. This suggest that the levels of Mn in solution are primarily controlled by exchangeable Mn in response to pH changes.

Mineral soil samples when air-dried showed a 1.5 to more than 8-fold increase in amounts of NH₄Cl-extractable Mn. This increase was not observed in soil samples rich in organic matter (> 5% organic carbon), thus excluding the possibility of release of Mn from the organic fraction of the soil. The increase is considered a consequence of increased solubility of Mn-oxides.     

Large Headsetts and Improved Cultivar Enhance Growth and Development of Taro (Colocasia esculents [L.] Schott) During Establishment

Small, medium and large headsetts of a traditional ( Nine ) and an improved ( Alafua Sunrise ) cultivar of taro were grown for 33 days in pots in a screenhouse.
Differences between the cultivars were greatest in root growth where density of root primordia, number of primary roots and root surface area at the final harvest were 53, 82, and 60 % greater respectively in the improved over the traditional variety. Relative rate of leaf elongation and leaf appearance rate were about 30 % faster in the improved variety. Correlation between leaf area and root surface area was cultivar dependent.
Large headsetts produced more primary roots and a larger root surface area than small headsetts. They also produced 46 % more leaf area than small headsetts because of larger individual leaves, but not the rate of leaf appearance.
Dry matter and nitrogen content declined in petioles, remained relatively constant in corm and accumulated in new shoot and root during establishment. Losses of N were similar but accumulation was greater in new growth of Alafua Sunrise than Niue.
We conclude that differences in productivity between the improved and traditional cultivars used in this experiment are at least partly attributable to differences in rate of development of new shoot and root during establishment. Previously reported correlations between corm yield and size of planting material are probably due to large headsetts producing a greater area of leaf and root than small headsetts during early growth.     

Summary of the first round analyses of the Third International Workshop on Swine Leukocyte Differentiation Antigens.

The reactivity of 155 monoclonal antibodies submitted to the Third International Workshop on Swine Leukocyte Differentiation Antigens, together with 41 internal standards, was analysed by flow cytometry on 29 different pig cell targets as well as two human cell targets as a means of establishing suitable panels of monoclonal antibodies for more detailed clustering analyses by the various subsections of the workshop. Results were collected either without further gating, with gating based on FS/SS characteristics or with gating based on the co-expression of a reference antibody in two-colour flow cytometry. The CD or SWC reactivity of the internal standards had been established in previous workshops. Data sets were subsequently analysed by statistical clustering using the Leucocyte Typing Database IV software. The resulting 18 cluster groups were allocated to the appropriate second round sections of the workshop, after reviewing the overall cellular reactivity of each cluster as well as the specificity of known standards which clustered in a group.     

Designing sustainable agriculture education: Academics’ suggestions for an undergraduate curriculum at a land grant university

Historically, land grant universities and their colleges of agriculture have been discipline driven in both their curricula and research agendas. Critics call for interdisciplinary approaches to undergraduate curriculum. Concomitantly, sustainable agriculture (SA) education is beginning to emerge as a way to address many complex social and environmental problems. University of California at Davis faculty, staff, and students are developing an undergraduate SA major. To inform this process, a web-based Delphi survey of academics working in fields related to SA was conducted. Faculty from colleges and universities across the US were surveyed. Participants suggested that students needed knowledge of natural and social science disciplines relating to the agri-food system. In addition, stakeholders suggested students learn through experiences that link the classroom to field work, engaging a broad range of actors within applied settings. Stakeholders also emphasized the need for interdisciplinary and applied scholarship. Additionally, they proposed a range of teaching and learning approaches, including many practical experiences. Given the diverse suggestions of content knowledge and means of producing knowledge, the survey presented unique challenges and called into question the epistemological and pedagogical norms currently found in land grant colleges of agriculture. This study has implications for land grant universities seeking to develop undergraduate curriculum appropriate to the field of SA. Damian M. Parr is a doctoral student of Agricultural and Environmental Education, in the School of Education at the University of California at Davis. His professional interests include organic farming, sustainable agriculture, experiential and transformational learning, critical pedagogy, and participatory action research. He is currently working on linking on-campus student initiated sustainable farm and food systems projects to curricula at land grant universities Cary J. Trexler is an assistant professor of Agricultural and Environmental Education at the University of California at Davis where he teaches courses in the history of agricultural education, experiential learning, and research methods for practicing teachers. His research focuses on experiential learning, sustainable agriculture education, and needs of teachers and informal educators within the context of the agri-food system Navina R. Khanna is a graduate student pursuing an MS in International Agricultural Development at the University of California at Davis. She is committed to facilitating community dialogue and education about sustainability issues. Her work at the university focuses on the process and goal of sustainability in agricultural education and campus food system sustainability. Her primary professional interests include democratic participatory process in agri-food system sustainability and urban revitalization Bryce T. Battisti is a doctoral student of Agricultural and Environmental Education, in the School of Education at the University of California at Davis. His research interests include the development of alternative models for university education that are founded on student-centered experiential learning. Specifically, he studies models of permaculture education that lead toward accredited degrees and relates these models to sustainable agriculture degree programs     

Formation of Al13I-: evidence for the superhalogen character of Al13

Al13- is a cluster known for the pronounced stability that arises from coincident closures of its geometric and electronic shells. We present experimental evidence for a very stable cluster corresponding to Al13I-. Ab initio calculations show that the cluster features a structurally unperturbed Al13- core and a region of high charge density on the aluminum vertex opposite from the iodine atom. This ionically bound magic cluster can be understood by considering that Al13 has an electronic structure reminiscent of a halogen atom. Comparisons to polyhalides provide a sound explanation for our chemical observations.     

Potential of plant growth-promoting rhizobacteria-plant interactions in mitigating salt stress for sustainable agriculture: A review

Soil salinization affecting different crops is one of the serious threats to global food security.Soil salinity affects 20%and 33%of the total cultivated and irrigated agricultural lands,respectively,and has been reported to caused a global crop production loss of 27.3 billion USD.The conventional approaches,such as using salt-tolerant varieties,saline soil scrapping,flushing,leaching,and adding supplements (e.g.,gypsum and lime),often fail to alleviate stress.In this context,developing diverse arrays of microbes enhancing crop productivity under saline soil conditions without harming soil health is necessary.Various advanced omics approaches have enabled gaining new insights into the structure and metabolic functions of plant-associated beneficial microbes.Various genera of salt-tolerating rhizobacteria ameliorating biotic and abiotic stresses have been isolated from different legumes,cereals,vegetables,and oil seeds under extreme alkaline and saline soil conditions.Rapid progress in rhizosphere microbiome research has revived the belief that plants may be more benefited from their association with interacting diverse microbial communities as compared with individual members in a community.In the last decade,several salt-tolerating plant growth-promoting rhizobacteria (PGPR) that improve crop production under salt stress have been exploited for the reclamation of saline agrosystems.This review highlights that the interaction of salt-tolerating microbes with plants improves crop productivity under salinity stress along with potential salt tolerance mechanisms involved and will open new avenues for capitalizing on cultivable diverse microbial communities to strengthen plant salt tolerance and,thus,to refine agricultural practices and production under saline conditions.     

Pyrazole and induction of fatty liver by a single dose of ethanol

Pyrazole (4 millimoles per kilogram or 272 milligrams per kilogram of body weight), given to fasted rats 10 minutes before gavage with ethanol (4 grams per kilogram), completely prevented both the disappearance of ethanol from the blood over a 16-hour period and the ethanol-induced reduction in the ratio of oxidized to reduced hepatic nicotinamide-adenine dinucleotide. However, it did not affect the accumulation of triglycerides in the liver after the administration of ethanol. These results indicate that metabolism of ethanol is not required for production of fatty liver by a single, large dose of ethanol.