Comparison of different laboratory methods with lysimetry for soil solution composition — experimental and model results

Compositions of soil solution obtained by the following methods were compared with those obtained by lysimetry: centrifugation; 2:1 extracts of air dried (2:1_dried) and field moist (2:1_moist) samples; saturation extracts; the ‘equilibrium soil pore solution’︁ method using columns with undisturbed (ESPS) and composited soil (ESPS_comp); and a method using pressure. Two soil depths of a Spodic Dystric Cambisol at Solling, Germany, were sampled with 10 to 12 replications. A coupled equilibrium model was used to describe the effect of soil to solution ratio on the solution composition. The model included multiple cation exchange and inorganic complexation, and for the subsoil solubility products of AlOHSO₄ and Al(OH)₃. Saturation extracts gave similar results as lysimetry and thus may be useful for calculating output fluxes. However, biological transformations (N mineralisation, solubilisation of organic matter) occurred during the preparation of saturation extracts. Composition of soil solutions obtained by either 2:1_dried extracts or centrifugation differed greatly from the results of other methods, indicating that these two methods may not be the best means to investigate equilibrium soil solutions. The values of molar ion ratios depended largely on the method used to obtain soil solutions: Ca²⁺/Al³⁺ ratios for each depth ranged from less than 0.3 (which suggests that liming is required urgently) to greater than 1 (liming not necessary). Modelling described the effect of soil to solution ratio on element concentrations for the methods pressure, saturation extracts, ESPS_comp and 2:1_moist extracts qualitatively with a few exceptions. The model suggested that differences in element concentrations using these methods may be mainly due to dilution, cation exchange and solubilisation of sparingly soluble salts, depending on the soil to solution ratio used.     

Effect of K+ nutrition,leaf age and light intensity on apoplastic K+ in leaves of Vicia faba

The infiltration-centrifugation method is valuable for the estimation of ion concentrations within the leaf apoplast because it opens up the possibility of differentiating between free and bound cations. The K⁺ concentration in the apoplast of intact leaves of Vicia faba reflects the nutritional status with respect of this ion and can be monitored by the infiltration-centrifugation technique. Transfer into a nutrient solution without K⁺ led to a significant decrease in apoplastic K⁺ within two days. Under K⁺ deficiency, the K⁺ concentration in the leaf apoplast was maintained at 2 mM. Regardless of K⁺ supply, young leaves had higher K⁺ concentrations in the apoplast than older ones. Data on diurnal variations in apoplastic K⁺ suggest that the leaf apoplast is a transient pool for K⁺ accumulation within the leaf prior to absorption into the symplast or retranslocation to other growing tissues.     

Formation of mineral N (NH4+, NO3—) during mineralization of organic matter from coal refuse material and municipal sludge

In 1994, the 14 hectare plateau of a coal refuse bank in Landsweiler‐Reden (Southwest‐Germany) was covered with a mixture consisting of 80% (v/v) refuse materials, 10% (v/v) composted wood and 10% (v/v) of sewage sludge as part of a reclamation project. The amount of sludge dry matter applied was approximately 450 Mg ha⁻¹ to a depth of 2 m. The approximate amount of nitrogen (N) applied with the substrate was 20 Mg ha⁻¹ (total N). From April 1996 until November 1997, contents of mineral nitrogen and nitrogen mineralization were monitored down to a depth of 2 m. Nitrogen mineralization was monitored by means of a modified buried bag procedure using a retrievable cylindrical receptacle. The contents of NH₄⁺‐ and NO₃⁻‐N were largest at the beginning of the observation period, reaching a peak value of 650 kg ha⁻¹ in May 1996. Then, mineral N stabilized in 1997 at a level of 200 kg N ha⁻¹, with the soil profile below 150 cm contributing about 75% to this amount. Net nitrogen mineralization was characterized by the same depth distribution. Other than in surface horizons, mineralization activity at the bottom of the profile continued into 1997 with the same intensity as in 1996. Variability among replicate buried bag incubations was high (CV > 100% on several occasions). Nitrogen loss through leaching was estimated at 630 kg N ha⁻¹ over the observation period, averaging at 360 kg N ha⁻¹ a⁻¹. The reclamation procedure used in this study may have the potential to contaminate ground water in hydrologically sensitive areas.     

Determination of pH in Pre rigor Fish Muscle – Method Matters

ABSTRACT

The determination of post mortem muscle pH are often carried out in studies on how pre-slaughter handling influences the development of rigor mortis and the quality of the fish products. The analysis might be performed by inserting a pH-electrode into the intact flesh or using a suspension containing a minced muscle sample. Although it has been known for a long time that mincing muscle tissue accelerates glycolysis and breakdown of adenosine triphosphate (ATP), more recent studies quite commonly determine pH after mincing pre rigor muscle without including an enzyme inhibitor that arrests glycolysis. This may have resulted in anomalously low pre rigor muscle pH. The aim of the present work was to compare the two methods of pH determination in pre rigor fish muscle and to highlight the importance of including the enzyme inhibitor when homogenizing pre rigor fish muscle prior to pH analysis.     

Dietary map of Nile tilapia using stable isotopes in three tropical lakes,Ethiopia

Comprehensive analysis of food webs requires identifying dietary sources that support the production of all major organisms within the food web/food chain. Here, we use stable isotope ratios (δ¹³C, δ³⁴S and δ¹⁵N) to assess the relative contribution of different basal carbon sources to the diet of Nile tilapia (Oreochromis niloticus L.) in three tropical lakes Hawassa (also Awasa in literature), Ziway and Koka (Ethiopia). Computations were carried out with Stable Isotope Analysis in R (SIAR) model to quantify the dietary proportion of each prey for the tilapia fish. Basal food sources were distinguishable based on their δ¹³C, δ³⁴S and δ¹⁵N values. In Lake Ziway, macrophytes (64%) were the dominant assimilated diet of tilapia while particulate organic matter (POM) and zooplankton contributed only 20% and 16%, respectively. In parallel, Nile tilapia in Lake Hawassa assimilated macrophytes (35%), POM (33%) and zooplankton (32%) at comparatively equal proportion. The dietary sources of the fish in Lake Koka were POM (49%) and zooplankton (51%). In contrast with earlier studies based on gut content analysis, the present results reveal that macrophytes contributed more and phytoplankton less than previously reported especially in macrophyte‐dominated lakes Ziway and Hawassa. The ecological condition of the lakes might have been predominantly accountable for the diet change of the tilapia. As dietary data are prerequisite for food web/food chain analysis and aquaculture industry, re‐evaluating the diet of aquatic organisms appear relevant.     

The potential of soil functions and planner-oriented soil evaluation to achieve sustainable land use

Purpose  

Since application of ecological soil evaluation is not widely introduced in planning processes, a need for harmonisation of soil evaluation methods and spatial planning is evident. Conflicts are caused by the discrepancy between a holistic and site-specific approach of soil evaluation and the demand of spatial planners for easy-to-handle planner-oriented evaluation methods. Planners require less differentiation of pedological aspects but a detailed consideration of land use aspects. The aim of this paper is to illustrate the evolution of the concept of soil function and the development of the understanding of the soil functionality with time, respectively. This is reflected before the background of its applicability for spatial planning. Restrictions and deficits are highlighted, and strategies for further research work are sketched. The relation of soil functions and soil evaluation is examined exemplarily with algorithms of the TUSEC method applied for typical but fictive planning situations.     

Arthroscopic approaches to the fetlock joint of adult cattle: A cadaver study

The objective of the present study was to describe the arthroscopic anatomy of the bovine fetlock joint using one palmar/plantar and three dorsal joint approaches. A comparative anatomic, ultrasonographic and arthroscopic study using 20 cadaveric feet from 13 non-lame adult dairy cows was performed. Arthroscopy was accomplished using a rigid arthroscope to view the synovial cavities with their synovial villi and parts of the following structures: the distal ends of the metacarpal/metatarsal III/IV bones with their trochleae and sagittal ridges, synovial grooves, the articular surfaces of the proximal sesamoid bones, the proximal aspects of the first phalanges, the lateral and medial collateral ligaments, the suspensory ligament and the interdigital ligaments as parts of the interosseus muscle, the cruciate sesamoidean ligaments, the communication site between the lateral and medial pouch in the palmar/plantar area, and dorsally the septum between the lateral and the medial pouch. The technique allowed a good overall view of most relevant structures in the sound cadaver joint. Further investigations are warranted to evaluate the diagnostic, therapeutic and prognostic applications of these techniques in the treatment of septic arthritis.     

Using Very-Large-Scale Aerial Imagery for Rangeland Monitoring and Assessment: Some Statistical Considerations

The availability of very-large-scale aerial (VLSA) imagery (typically less than 1 cm ground-sampling-distance spatial resolution) and techniques for processing those data into ecosystem indicators has opened the door for routinely using VLSA imagery in rangeland monitoring and assessment. However, for VLSA imagery to provide defensible information for managers, it is crucial to understand the statistical implications of designing and implementing VLSA image studies, including consideration of image scale, sample design limitations, and the need for validation of estimates. A significant advantage of VLSA imaging is that the researcher can specify the scale (i.e., spatial resolution and extent) of the images. VLSA image programs should plan for scales that match monitoring questions, size of landscape elements to be measured, and spatial heterogeneity of the environment. Failure to plan for scale may result in images that are not optimal for answering management questions. Probability-based sampling guards against bias and ensures that inferences can be made to the desired study area. Often collected along flight transects, VLSA imagery lends itself well to certain probability-based sample designs, such as systematic sampling, not often used in field studies. With VLSA image programs, the sample unit can be an entire image or a portion of an image. It is critical to define the sampling unit and understand the relationship between measurements and estimates made from the imagery. Finally, it is important to statistically validate estimates produced from VLSA images at selected locations using quantitative data of the same scale and more precise and accurate than the VLSA image techniques. The extent to which VLSA imagery will be useful as a tool for understanding the status and trend of rangelands depends as much on the ability to build the imagery into robust programs as it does on the ability to quickly and relatively easily collect VLSA images over large landscapes.     

A Strategy for Rangeland Management Based on Best Available Knowledge and Information

Adapting what we currently know about ecosystems to a future where rangelands are changing is a new frontier in rangeland management. Current tools for knowledge discovery and application are limited because they cannot adequately judge ecological relevance of knowledge to specific situations. We propose development of integrated knowledge systems (KSs)—collections of resources (e.g., data, analytical tools, literature) drawn from disparate domains and organized around topics by process-based conceptual models. An integrated KS would define relevance by ecological attributes (e.g., soils, climate, vegetation) and location as a flexible mechanism for organizing, finding, and applying knowledge to rangeland management. A KS provides knowledge sources within a decision-making framework that defines what knowledge is needed and how it will be used to make decisions. Knowledge from a KS can identify appropriate spatial and temporal scales to address specific resource questions or objectives. Several factors currently limit KS development and implementation. These include limited interoperability of disparate information and knowledge systems; lack of consistent geographic referencing of knowledge; incomplete and inconsistent documentation of the origin, history and meaning of data and information; underexploited application of remote sensing products; limited ability to extrapolate and share local knowledge and unstructured information; and lack of training and education of professionals that can link ecological and technical fields of study. The proposed KS concept and recommendations present an opportunity to take advantage of emerging technologies and the collective knowledge of rangeland professionals to address changing ecosystems and evolving threats. If we keep on with a “business as usual” approach to finding and using information, we will struggle to meet our responsibilities as rangeland professionals.     

Changes in soil organic carbon fractions in a tropical Acrisol as influenced by the addition of different residue materials

Residues of Leucaena (Leucaena leucocephala (L), Senna siamea (S) and maize stover (M) were tested to evaluate their effect on soil organic matter accumulation and composition under sub-humid tropical conditions. On an Imperata cylindrica (I) dominated grass fallow, a total amount of 30?Mg?ha^?1 DM were applied within 18?months. Two months after the last application, changes in the light and heavy soil organic carbon fraction (LF and HF) and in the total soil organic carbon content (LF?+?HF) in the topsoil were observed. All organic materials increased the proportion of the LF fraction in the soil significantly. The increase in HF was 39 to 51% of the increase in total organic carbon, depending on the source of the organic material. The potential of the tested organic materials to increase total soil organic carbon content (including all soil organic carbon fractions) was in the order L?>?S?>?M?>?I, whereas the order of increase of the HF fraction was L?=?S?>?I?>?M. Cation exchange capacity of the newly formed heavy soil organic carbon was highest with L and lowest with M. Ranking of the transformation efficiency of applied plant residues into the heavy soil organic carbon fraction was I?>?L?=?S?>?M. Transformation efficiency of the residues could neither be explained by lignin nor lignin/N ratio, but rather by extractable polyphenols (Folin?CDenis extraction). The results show that accumulation of the HF fraction in tropical soils is feasible through the application of large quantities of plant residues, but depends strongly on the composition of the applied materials.