Phosphatformen in Unterwasserböden Ca-reicher Fließgewässer

Forms of phosphates in underwater soils of Ca-rich running waters Underwater soils of small carbonaceous rivers in Upper Bavaria have phosphorus contents between 300 ppm in oligotrophic creeks and more than 0.2% in heavily polluted waters. The (Al,Fe)-P and the Ca-P occupied 20–35% and 28–38% of total phosphorus (P_t) resp., so that inorganic phosphates represent 53 to 64% of P_t. The correlation between P_t and carbonate is negative, but is positive between P_t and oxalate Fe or organic substance. Addition of P results in a relative increase of (Al,Fe)-P compared with other forms. Approximately 7 to 15% of total P is subject to isotopic exchange with ³²P.     

Makrosymptome an Mais und Tomate bei unharmonischen N- und P-Angeboten

Microsymptoms in maize and tomatoes resulting from imbalanced nitrogen and phosphorus supply The inducing factors of visible symptoms are not easy to identify in cases of ?complex”? symptoms. ?Complex”? symptoms originate from simultaneous multiple nutrient deficiencies, nutrient deficiency and excess, or multiple nutrient toxicities. Microsymptoms are well known for nitrogen and phosphorus deficiency supply as well as for nitrogen excess supply. The aim of the present paper was to study whether these microsymptoms can be helpful in diagnosing visible symptoms which are difficult to identify in cases of ?complex”? symptoms. The experiments were carried out with maize and tomatoes under controlled experimental conditions in solution culture. Microsymptoms which occur in response to nitrogen or phosphorus stress – deficiency or excess – occur in the same way in plants that are suffering from imbalanced nitrogen and phosphorus supply. In cases of multiple toxicities further microsymptoms occurred. These symptoms mainly depended on the nutrient concentration in the solution.     

PH-Verteilung und Pufferung von Böden

PH-distribution and buffering of soils A frequency distribution of the pH values of 927 soils clearly reflects the three soil buffer ranges (carbonate, pH-dependent charge and aluminium release) by higher frequencies within these ranges and lower frequencies between them.     

Effect of soil acidity on the entomophilic nematode Steinernema kraussei Steiner

Summary The free-living stages of Steinernema kraussei (Rhabditida), an endoparasite of Cephalcia abietis L. (Hymenoptera), are exposed to different soil conditions when searching for host nymphs. Field studies and laboratory experiments showed that soil acidity plays a major role in the nematode's ability to parasitize Cephalcia nymphs. Under field conditions in Picea abies forests positive correlations between soil pH and both nematode density and insects parasitized were found. Acidic soil with pH levels below 4.0 may limit the nematode's host-finding. Controlled experiments in the laboratory under different pH conditions confirmed these correlations.Dedicated to the late Prof. Dr. W. Kühnelt     

Extraktion eines kupferbelasteten Bodens unter Verwendung eines aminosäurehaltigen Reststoffhydrolysats. 2. Elutionsdynamik und Bilanzierung der Aminosäuren nach kontinuierlichem Eintrag in Bodensäulen

Extraction of a copper contaminated soil material by the percolation of an amino acid containing residue hydrolysate. 2. Time course of amino acid elution and input/output balance of amino acids During 16 days an amino acid containing blood meal hydrolysate (amino acid concentration: 188 mMol·L^?1) was percolated through a column packed soil material (soil content per column: 4.1 kg dry weight, four parallels). The copper contaminated material (soil type: Typic Udifluvent, soil texture: sandy loam, loamy sand) was sampled from an area formerly used for cultivation of hop (Humulus lupus). Besides the investigation of the copper liberation the experiments aimed to determine the elution dynamic and input/output balance of amino acids (time span for amino acids balance 14 days). In total 11.7 L of hydrolysate, containing 2.2 Mol of amino acids, were introduced into each column. The mean amino acid output with the column effluent was 1.13 Mol. This corresponds to an elution degree of 51.2%, related to the sum of applicated amino acids, and to a mean substance specific elution degree of 48.4% reflecting the elution of 15 compounds. The substance specific elution ranged from 9.6% (serine) to 75.5% (valine). The highest concentrations of serine and threonine were determined in the effluents after two days, whereas the histidine concentration was highest at the last sampling. The differences in the percolation properties of the amino acids are discussed in terms of important retention and elimination processes (biodegradation, ad-/desorption, intercalation).     

Ein Elektrodensystem zur Messung des Redoxpotentials im Kontaktbereich Boden/Wurzel

An electrode matrix for Eh measurements in the root/soil interface For redox potential measurements in the rhizosphere an electrode matrix was constructed from a teflon disc, in which 37 short Pt wires were placed with a 3.5 mm distance between two electrodes. The potentials of these electrodes were recorded periodically by a data logger and were stored on punched tape. With this arrangement, redox potential patterns for the rhizosphere of single roots could be recorded and plotted by a small computer.