Sorption/desorption behaviour of sulfonylurea herbicides as affected by the addition of fresh and composted olive cake to soil

The olive industry generates residues which can be applied as amendments to soils in their original form (olive cake) or after composting or vermicomposting processes. The addition, fresh or incubated, of these amendments to soil and of their different organic fractions was studied in relation to the sorption/desorption of three sulfonylurea herbicides, bensulfuron‐methyl, chlorsulfuron and prosulfuron. Herbicide sorption was low or very low, slightly promoted by the addition of the agricultural by‐products, especially olive cake, and mainly affected by pH of the soil solution, with the organic carbon content having no significant effect on herbicide retention. Desorption was only reduced when fresh olive cake was added. The incubation of soil and amendments for 3 months did not modify herbicide sorption, but made desorption reversible except for olive cake. The transformation of the organic matter of the amendments due to humification and maturity processes are likely to be responsible for this behaviour. Different organic fractions were removed to assess the influence of each fraction on sulfonylurea sorption. Only the removal of all studied organic fractions increased herbicide sorption, revealing the role of humin and mineral fractions in this process. Therefore, the use of organic amendments is not useful for reducing the risk of movement of ionisable molecules in soil.     

Long-term agroecosystem experiments: assessing agricultural sustainability and global change

Long-term agroecosystem experiments can be defined as large-scale field experiments more than 20 years old that study crop production, nutrient cycling, and environmental impacts of agriculture. They provide a resource for evaluating biological, biogeochemical, and environmental dimensions of agricultural sustainability; for predicting future global changes; and for validating model competence and performance. A systematic assessment is needed to determine the merits of all known experiments and to identify any that may exist in tropical and subtropical environments. The establishment of an international network to coordinate data collection and link sites would facilitate more precise prediction of agroecosystem sustainability and future global change.     

Towards achieving functional ecosystem mimicry with respect to water cycling in southern Australian agriculture

The southern Australian landscape is characterised by large climatic variability and an old, weathered surface with generally low hydraulic gradients. Many of these landscapes are prone to salinisation. The original ecosystems have strategies to cope with this environment in ways which minimise runoff and groundwater recharge. Replacement of these ecosystems with conventional agriculture has resulted in large-scale disruption of the natural water cycle with severe environmental, economic and social consequences. Sustainable agricultural systems aimed at mimicking natural hydrology must either minimise groundwater recharge over most of this landscape or intercept groundwater discharge in lower parts of the landscape prior to salinisation to restore the original hydrological balance. Empirical and theoretical analyses suggest that however vegetation is managed in the landscape, effective water balance control will be achieved only at a leaf area index approaching that of the natural state, indicating revegetation of most or all parts of the catchment with either trees or plants with similar ecohydrological characteristics as trees. There are at present few economically- attractive agricultural systems able to achieve hydrologic mimicry likely to be adopted at the necessary scale. This revised version was published online in June 2006 with corrections to the Cover Date.     

An In Vitro Biomechanical Study of a Multiplanar Circular External Fixator Applied to Equine Third Metacarpal Bones

The biomechanical characteristics of a 4-ring circular multiplanar fixator applied to equine third metacarpal bones with a 5 mm mid-diaphyseal osteotomy gap were studied. Smooth Steinmann pins, either 1/8 inch, 3/16 inch, or 1/4 inch, were driven through pilot holes in the bone in a crossed configuration and full pin fashion and fastened to the fixator rings using cannulated fixation bolts. The third metacarpal bone fixator constructs were tested in three different modes (cranial-caudal four-point bending, axial compression, and torsion). Loads of 2,000 N were applied in bending and axial compression tests and a load of 50 N ± m was applied during testing in torsion. Fixator stiffness was determined by the slope of the load displacement curves. Three constructs for each pin size were tested in each mode. Comparisons between axial stiffness, bending stiffness, and torsional stiffness for each of the three different pin sizes were made using one-way analysis of variance. There was no visually apparent deformation or permanent damage to the fixator frame, and no third metacarpal bone failure in any of the tests. Plastic deformation occurred in the 1/8 inch pins during bending, compression, and torsion testing. The 3/16 inch and 1/4 inch pins elastically deformed in all testing modes. Mean (±SE) axial compressive stiffness for the 1/8 inch, 3/16 inch, and 1/4 inch pin fixator constructs was: 182 ± 16 N/mm, 397 ± 21 N/mm, and 566 ± 8.7 N/mm; bending stiffness was 106 ± 3.3 N/mm, 410 ± 21 N/mm, and 548 ± 12 N/mm; and torsional stiffness was 6.15 ± 0.82 N.m/degree, 7.14 ± 0.0 N±m/degree, and 11.9 ± 1.0 N.m/degree respectively. For statically applied loads our results would indicate that a 4-ring fixator using two 1/4 inch pins per ring may not be stiff enough for repair of an unstable third metacarpal bone fracture in a 450 kg horse.     

In vitro amino acid absorption using hydrolysed sardine muscle or soybean meal at different intestinal regions of the Pacific bluefin tuna (Thunnus orientalis)

The amino acid (AA) absorption along the intestinal tract of the Pacific bluefin tuna (Thunnus orientalis) was evaluated using two hydrolysed protein sources (fresh sardine muscle and soybean meal) with the everted intestine technique. Pork pepsin and pancreatic enzyme extract from the bluefin tuna were used to hydrolyse the protein from fresh sardine (FSH) and soybean meal (SMH) under optimal bluefin tuna fish physiological conditions. Both of the hydrolysate solutions were tested within three intestinal sections from the bluefin tuna. The everted intestinal fractions immersed in the hydrolysate solutions were sampled at different times to analyse for AA and absorption rate calculations. Fresh sardine and SMH contained greater amounts of essential amino acids (EAA) than those of non‐essential amino acids (NEAA); however, the profiles of AA absorbed showed higher absorption of NEAA in both cases. Using a similar concentration solution, the absorption rates within the intestinal fractions showed a preferential absorption in the proximal and distal regions for Arg and His when FSH was used. However, the absorption rates for Lys resulted in a decreasing proximal‐to‐distal gradient between the different intestinal regions for FSH and SMH. The possibility of a catabolic role of certain AAs in the enterocytes being able to explain the differences in absorption is discussed.     

楚源果业优质鲜食猕猴桃产业化开发的实践与体会

“楚源果业”（长沙楚源果业有限公司的简称）从2003年起开始实施湖南省优质鲜食猕猴桃产业化工程。公司按照产业化经营的思路和集中成片、规模发展的原则，选择丰悦、翠玉等优良品种，在省内旅游区周边交通便利、农业生产管理水平较高的中低海拔地区建立生产基地，并以公司为龙头，按行业协作组织的形式将各生产基地组织起来，统一技术管理和果品营销。现已建立产业化基地约200hm^2，并在湘中、湘北、湘西北及湘西建立了鲜食猕猴桃重点示范基地。两年来，湖南省优质鲜食猕猴桃产业化开发从无到有，从小到大，极大地促进了湖南省猕猴桃产业的整体发展。     

Baryons at the edge of the X-ray-brightest galaxy cluster

Studies of the diffuse x-ray-emitting gas in galaxy clusters have provided powerful constraints on cosmological parameters and insights into plasma astrophysics. However, measurements of the faint cluster outskirts have become possible only recently. Using data from the Suzaku x-ray telescope, we determined an accurate, spatially resolved census of the gas, metals, and dark matter out to the edge of the Perseus Cluster. Contrary to previous results, our measurements of the cluster baryon fraction are consistent with the expected universal value at half of the virial radius. The apparent baryon fraction exceeds the cosmic mean at larger radii, suggesting a clumpy distribution of the gas, which is important for understanding the ongoing growth of clusters from the surrounding cosmic web.