Abbau und biozide Wirkung von Pflanzenschutz-und Schädlingsbekämpfungsmitteln im Boden am Beispiel von Kelevan

Degradation and biocide effect of chemical plant protecting agents and pesticides in soils by the example of the insecticide Kelevan By the example of the insecticide Kelevan it is proved that by means of a combined test plan degradation and biocide effect of chemical plant protecting agents and pesticides in soils can be tested simultaneously. For this test two different test soils as described in leaflet No. 36 of the Biologische Bundesanstalt (BBA), Braunschweig, are each divided in test samples of about 200 g dry matter. To answer the question whether besides the biotic an abiotic degradation of Kelevan and its primary subsequent products takes place in top soil, too, one part of the soil samples was sterilized by overheated steam. Afterwards these and the non-sterilized soil samples were treated with known amounts of Kelevan[cage-U-¹⁴C] and in accordance to leaflet No. 36 of the BBA stored in the dark at 22°U65% r. h. or under field conditions for different periods. To investigate the effect of Kelevan and its metabolites on microorganisms in top soil, further soil samples were treated with increasing amounts of Kelevan and also stored for different periods. At the end of storage periods on an average W,2 % of applicated radioactivities were recovered in the soil samples with Kelevan[cage-U-¹⁴C]. Whereas readioactivities of sterilized soil samples were nearly quantitatively extractable, increasing radioactivity amounts were held back under the same extraction conditions by the native soil samples, which were present as organic residue components of Kelevan(cagc-U-¹⁴C) and not as ¹⁴C-containing carbonate. During degradation, in both test soils as well under laboratory conditions as under field conditions, about one third of Kelevan[cage-U-¹⁴C] was transferred within 30 months via Kelevan acid[cage-U-¹⁴C] to Chlordecon[cage-U-¹⁴C] and about two thirds were transferred into various unknown ¹⁴C-labelled degradation products. The results of microbiological investigation prove that microorganisms were evidently neither selected nor decimated in both test soils by Kelevan and its degradation products.     

Vergleichende Betrachtung von Verfahren zur Auswertung von Nährstoffsteigerungsversuchen am Beispiel Phosphor

Comparison of two procedures to evaluate phosphate‐fertilizing field trials Growth response of agricultural crops to different input levels (e.g., fertilizer rates) can be described by the “law of diminishing increments”, which has been formulated mathematically amongst others by Mitscherlich (1928) and von Boguslawski and Schneider (1962, 1963, 1964). In the present paper, the economically optimal phosphate‐fertilizer requirements in 43 long‐term phosphate (P)‐fertilization experiments were calculated using equations on the basis of the yield functions of Mitscherlich or von Boguslawski and Schneider, respectively. For three field trials with linear or disproportionately high yield responses on P fertilization, none of the two procedures could be used. The same held for four trials with maximum yields already appearing at the first fertilization level. Similar P‐fertilization optima were calculated for 36 trials following the “law of diminishing increments”, resulting in a highly significant correlation (R² = 0.946) between both procedures. The correlation coefficients between the phosphate balance at the calculated optimum profitability and CAL‐P content in the soils at trial start were R² = 0.70 (Mitscherlich, 1928) and R² = 0.65 (von Boguslawski and Schneider, 1962, 1963, 1964), respectively. An optimal soil P content of 8–10 mg CAL‐P (100 g soil)^–1 was deduced. Both methods are applicable to calculate the optimum phosphate‐fertilizer requirement if yield effects due to P fertilization follow the “law of diminishing increments” and the increments of fertilization levels in each trial are established in a way that diminishing yield increments can be expected.     

Aufnahme und Verlagerung von Natrium bei zwei Sorten von Lolium perenne

Uptake and translocation of sodium in two cultivars of Lolium perenne The uptake and translocation of Na was investigated in two Lolium perenne cultivars (Dolewi and NFG). With increasing Na⁺ concentration in the nutrient solution (0, 1, 2 and 4 mMNa) the Na⁺ uptake per pot increased from 1.4 to 11.9 me/1 Na⁺ for Dolewi and from 1.1 to 6.9 me/l Na⁺ for NFG. The higher Na uptake by Dolewi can only partly be explained by better growth, the higher Na⁺ selectivity playing also an important role. In another experiment plants of both types were grown in solution cultures for 41/2 weeks at 15°C and 25°C, respectively. Hereafter the plants were supplied with 1.25 mM ²⁴NaCl for six hours under equal conditions. Again the higher Na uptake and also a higher Na translocation (of about 20%) was found in Dolewi, whereas only 10% of the ²⁴Na uptake had been translocated by NFG. When plants were grown in a nutrient solution with a lower temperature (at 15°C) the root lipids showed a higher linolenic acid and oleic acid content than the plants grown in a medium at 25°C. At the same time the 24Na uptake was higher in the plants grown at the lower temperature, yet the relationship between root lipids and Na uptake still remains to be elucidated.     

Die Ermittlung des Bulk-Stomata-Widerstandes und der aktuellen Evapotranspiration aus Saugspannungsmessungen des Bodenwassers - dargestellt am Beispiel von Acker-Unkrautgesellschaften auf Hochflutlehm

The determination of bulk stomata resistance from tensiometric measurements of soil water - represented at the example of field weed societies on high flood loam It was shown that the computation of actual evapotranspiration from water losses above the zero flux layer is reliable enough to determine as well the bulk stomata resistance, used in Monteith's formula, as the shape of the reduction of potential to actual evapotranspiration. For field weed societies the bulk stomata resistance was determined to 37 s/m and, assuming a leaf area index of 3.0, the according plant resistance was calculated to 28 s/m. The reduction function from potential to actual evapotranspiration was linear one, starting at a water content of 70% of the available field capacity and ending at permanent wilking point. Both results are in good agreement with data from literature.     

Entwicklung,Eigenschaften und Klassifikation von Dünenböden der Ostfriesischen Inseln – am Beispiel Spiekeroogs

Pedogenesis, properties, and classification of dune soils of the East Frisian Islands (southern North Sea coast of Germany)—exemplified by the island Spiekeroog The aim of this study was a detailed pedological investigation and exact classification of dune soils of the East Frisian Islands. The following soil‐forming processes were identified on a laboratory‐data basis: humus accumulation and dislocation, carbonate loss, acidification, modification of exchangeable cations, and base‐saturation decrease. A slight iron oxide accumulation was visible in the field, but not confirmed by laboratory data. Applying the qualitatively and quantitatively defined horizons from the German classification, these soils cannot be classified as Regosols, Braunerden, and Podsols but they fit perfectly in the Arenosols as defined in the WRB.     

Phosphataufnahme und -Verwertung von drei Inzuchtlinien des Welschen Weidelgrases (Lolium multiflorum Lam.) und ihren Hybriden

Uptake and utilization of phosphorus by three inbred lines of Lolium multiflorum L. and their hybrids Three Lolium multiflorum inbred lines A, B and C and their hybrids (AB, AC, BC) were tested for their shoot dry matter (DM) production, P uptake (mg P pot^?1), P utilization (mg DM · mg P^?1) and P influx (P uptake rate per cm root length) by growing in plastic pots for a maximum period of 92 days at two P levels in a loess loam soil. The acid phosphatase activity of roots of inbreds A and C grown in nutrient solutions with 1.10 and 100 μmol P · L^?1 was also determined using the hydrolysis of Nitrophenyl phospate (NPP). Compared to the average of the inbreds DM production of the hybrids was 8 % higher at high and 12 % higher at low P level. With an increase of 14% and 25% DM respectively hybrid BC had the highest heterosis effect. The biomass production corresponded with the P uptake. Therefore, the P utilization efficiency of the hybrids was nearly the same as that of the inbreds. The increase in P uptake of the hybrids was related to the increase of root length. This means that the P uptake efficiency, i.e. the influx per unit of root remained unchanged between the inbreds and their hybrids. It can thus be concluded that the heterosis effect corresponds to an increase of P uptake caused by an increase of the size of the root system. The activity of the root phosphatases increased with declining P status of shoots and being absolutely higher in inbred A than C. Both inbreds responded within 3 days to a decreased P supply (from 100 to 1 μmol P · L^?1).     

Einfluß der Kalkung und Düngung auf den Ionenaustausch und die chemische Zusammensetzung der Bodenlösung am Beispiel von vier Waldstandorten im Hessischen Bergland

Impact of liming and fertilization on ionic exchange and chemical composition of soil solutions from four forest sites in the colline region of Hesse Between February 1985 and July 1987 soil seepage experiments were carried out on fertilizer trial plots in mature beech stands of four forest districts of Hesse. Encompassed by this study are in addition the most important results from soil-chemical analyses of the subsequent years 1988 to 1991. Aim of the investigations was to study the influence of liming and K/Mg-fertilization on the chemical composition of soil and soil solution under different site conditions. In the percolated soil solution liming did not led to a significant pH increase in subsequent years. In contrast, in some cases the pH level dropped by 0.1 to 0.2 units on average and Al-concentration increased correspondingly. In most cases, fertilization led to a significant increase in soil solution concentrations of the metal cations potassium, calcium and magnesium, especially at a depth of 50 cm. On those trial plots where a pH decrease was observed, the concentrations of K, Ca and Mg exhibited either a slight or no increase at all. Furthermore on some trial sites with freely drained soils, liming led to a faster mineralisation of the humus layer and thus to an increase of nitrate contents in the percolated soil solution from about 1–2 mg/l to 10–20 mg/l on average. Increased concentrations of sulfate and in most cases also of heavy metals (Mn, Zn, Cu. Cd) were observed in the soil solution which was attributed to the mobilizing effect of Ca-fertlization. In general, the mobility of most chemical parameters showed a slight increase following liming and soil tillage. Even after 5 to 8 years considerably higher pH-values and base saturation were evident in limed and fertilized soils, especially in the top 15 cm of soil profiles.     

Abbau und Umwandlung von Pflanzenrückständen und ihren Inhaltsstoffen durch die Mikroflora des Bodens

Degradation and transformation of plant residues and their components by the microflora of the soil This review describes recent results of publications in this area. It condsiders the dynamics of degradation under field and laboratory conditions and indicates some of the problems of simulation models. The preponderant part of transformation processes apparently takes place in a relatively small fraction of soil organic matter which also includes the biomass. Methods for the quantitative measurements of the biomass have been considerably improved. The turnover rates of plant residues are effectively influenced by their chemical composition, for instance by their C/N ratio and their content of lignin or polysaccharides. C/N ratios also seem to influence the socalled priming effect and the transformation of increasing amounts of plant residues added to the soil. Some progress has been also made in the transformation of plant, residues under different climatic conditions. Experiments with polysaccharides and glucose have indicated that a major portion of the residual carbon residues in soil are contained in the biomass or N-containing microbial metabolites. A small part is also present in the phenolic constituents of humic compounds. Root excretions also contribute carbohydrates. Recent experiments indicated the transportation of a considerable amount of photosynthetic products from sprouts through roots into the soil. They cause intensive microbial turnover processes in the root zone. N-containing compounds are stabilized in the soil biomass. Proteins and aminopolysaccharides are furthermore stabilized by sorption on humic compounds or clay particles. They are even more effectively stabilized by linkage into humic compounds. Plant residues contain appreciable amounts of free and polymerized phenols which are degraded by microorganisms or incorporated into humic compounds. Easily oxidisable phenols are more slowly degraded in soil than the more stable ones. This is especially true for low concentrations of phenols added to the soil. The pH-values of the soil and its content of humic compounds influence essentially the degradation rate. Lignins belong to the most important natural biopolymers. Methods for their specific labelling with 14°C have essentially promoted studies about their degradation and transformation in soil and have enlarged the knowledge about lignin degrading organisms. Beside lignins and other plant polyphenols, melanins may play an important role in the formation of humic compounds. These melanins are synthesized form carbohydrates by some microscopic fungi through secondary metabolic reactions. They are formed from phenols, quinones, polyenes, aminoacid and aminosugar derivatives. Similar to humic acids they are relatively stabile against rapid microbial degradation. Analytical methods developed in the last years indicate that both groups of polymers contain similar building blocks.     

Unterschiede von Toneigenschaften in Tonstein der fränkischen Lias- und Doggerlandschaften und ihren Böden

Distinctions of Clay Properties in Claystone of the Franconian Lias-and Doggerlandscape and Their Soils Pelosols and Pseudogleys derived from the sediments of the Amaltheen Clay (lias δ), Posidonia Shale (lias δ) and Opalinus Clay (dogger æ) formations in the forelands of the Alb Mountains in Franconia were separated using 16 properties (seven textural and nine chemical properties, the latter of which indicate clay specific properties). Multivariate discriminant analysis was able to distinguish sediments from sediments, sediments from soils and soils from soils. Eight properties were important for discriminating the samples into several groups. Properties with the greatest discriminating quality were the effective buffering capacity for K (BCKe in mval/100 g soil and 100 g clay/M^1/2), the K-fixation (mg K/100 g soil and clay), and the labile K (mval K/100 g soil). The mobile K (ARo in M^1/2) was also an important property. The Pseudogleys were most significantly separated from the Amaltheen Clay and Opalinus Clay sediments. Furthermore, the Pelosols could be significantly separated from Amaltheen Clay and Opalinus Clay on one side and Posidonia Shale on the other. The statistically significant increase of the BCKe and the decrease of ARo as well as some X-ray diagrams suggest that in Pseudogleys derived from Amaltheen Clay and Opalinus Clay and in Pelosols derived from Posidonia Shale expandable forms of 2 : 1 minerals were formed from 10 A-minerals.     

Über die räumliche und zeitliche Variabilität scheinbar fixer Wasserhaushaltsgrößen am Beispiel von Bodenaggregaten

Temporal and spatial variability of hydrological parameters of single soil aggregates The hydrological parameters determined for a single soil profile are usually not assumed to be variable and are often taken to represent a larger area and longer period of time, without consideration of spatial and temporal changes in the environment like cultivation or weather. Naturally structured and homogenized, subsequently restructuring aggregates from a “Stagno-haplic Luvisol” (FAO, 1991) with different possibilities of swelling were analysed with regard to the characteristics of the water retention curve and hydraulic conductivity. The experiments verified that the pattern of the water retention curve with respect to single aggregates was not constant but depended on the aggregate's initial intensity and frequency of desiccation. Additionally, effects on the hydraulic conductivity were determined. The measured values varied with the amount of swelling and shrinking, to which the aggregates were exposed. Thus, the calculation of hydraulic conductivity according to the model of Van Genuchten (1987) is doubtful. Therefore, the quantification of ecological characteristics from such parameters has to be questioned. The main cause for the described effects can be seen in the induced and only partly reversible structuring process, i.g. aggregate compaction due to shrinkage and rearrangement of particles inside the aggregate during repeated swelling and shrinkage. Additionally, physico-chemical hydrophobicity was supposed to have a major influence under certain circumstances.     

Verlagerung und Dispersion von Chlorid-, Bromid-, Nitrat- und SulfatTracern in zwei typischen Auenböden

Translocation and dispersion of chloride, bromide, nitrate and sulfate tracers in two typical Fluvi-Eutric Cambisols Chloride, bromide, nitrate and sulfate were applied as tracers on two weakly to moderately acidic Fluvi-Eutric Cambisols. The soil solution was sampled by ceramic suction cups down to a soil depth of 180 cm. At definite time intervals also soils material was taken from different depth to produce the soil saturation extract. The concentrations of the non-adsorbed anions chloride, bromide and nitrate were very similar in the suction cup solutions and in the saturation extracts, whereas the concentrations of the weakly adsorbed sulfate partially showed considerable differences. Obviously both methods extract in acid soils different fractions of the dissolved sulfate. By comparison of marked sulfate peaks with those of chloride, bromide or nitrate, which occur at the same time in different soil depth, a Kd value of 0.16 1/kg can be calculated for the Ap horizon and of 0.02 1/kg for the subsurface horizons of one Fluvi-Eutric Cambisol. Values of the dispersivity of the different horizons were estimated by varying the values of the dispersivity reported in the literature until the best fit of the simulated anion depth distribution to the measured values was found. The estimated dispersivities varied between 1.0 cm in the Ap horizon and 1.8 and 10.0 cm in the subsurface horizons.     

Vergleich von zwei nicht-destruktiven Methoden zur Bestimmung von Wurzeloberflächen

Comparison of two non-destructive methods for determination of root surface areas In order to study root growth and development continuously in water culture experiments, two non-destructive rapid methods of estimating root surface area were compared. In the methylene blue method roots are stained for 30 seconds in methylene blue solution (74.7 mg/l). After washing off adhering methylene blue the adsorbed cationic dye is exchanged with Ca²⁺ by incubating the stained root in 0,1 M CaCl₂ solution. The amount of exchangeable methylene blue is determined photometrically at 668 nm. In the ink method, roots are stained for 1 minute with a 1:100 diluted solution of drawing ink. Excess ink is removed by carefully rotating the plant, and adhering ink is allowed to diffuse into destilled water. The quantity of ink is determined photometrically at 500 nm. The root surface area of potato plants estimated with these two methods correlates highly significantly with the root surface area calculated from root volume and root length. In the case of the ink method the calibration curve obtained with potato roots may also be used for other plant species like maize. This is not possible with the methylene blue method. A correction factor depending on the cation exchange capacity of the roots would be needed for this method. With the ink method overestimation of root surface area may occur if abundant root hairs are present. This is due to the formation of droplets in the root hair zone. However for repeated measurements during a growth period the ink method is more suitable since with this method no negative effect on root growth and nutrient uptake can be observed.     

Raten der Deposition,der internen Produktion und des Umsatzes von Protonen in zwei Waldökosystemen

Rates of deposition, of soil internal production and of turnover of protons in two forest ecosystems The rates of deposition, of turnover and of soil internal production of protons are calculated from the flux balance of chemical elements within two forest ecosystems (Dystic Cambisols from loess/sandstone with beech or spruce). The rates of interception deposition vary significantly throughout the season and determine the rates of total deposition to a large extent. The comparison of the actual rates of proton load with the buffer rates possible in the soils leads to the conclusion that soil acidification up to the level of the Al-buffer range is unavoidable in most forest soils in Middle Europe. The behaviour of the incoming S in the soil is related to the dissolution and precipitation of Al-hydroxo-sulfate. The accumulation of S within the soil of the spruce stand was found to be reversible and was followed by a phase of strong leaching of S and Al from the soil. The processes that account for the rates of soil internal proton-net-production are quantified. More than 70% of the total proton load results from the deposition of air pollutants while only less than 30% is of soil internal origin.     

Cu‐, Zn‐ und Cd‐Aneignungsvermögen von zwei Spinatgenotypen in Abhängigkeit von der P‐Versorgung und Wurzelexsudation

Cu, Zn, and Cd acquisition by two spinach cultivars depending on P nutrition and root exudation Within a spectrum of 11 spinach cultivars (cvs) differences in the Cu, Zn, and Cd contents of shoots had been noticed. The aim of this study was therefore to analyze in more detail the acquisition of Cu, Zn, and Cd by the most differing cultivars (Tabu and Monnopa) in dependence on P nutrition. The plants were grown in a low phosphorus Luvisol (pH 6.3; total contents Cu: 89, Zn: 297, Cd: 2.4 mg kg^—1) with two phosphorus levels in pots under natural conditions. For the determination of inflow, root length/shoot weight ratio and of the Cu, Zn, and Cd concentration in the soil solution (rhizosphere) plants were harvested 26 and 40 days after sowing. Root exudation of organic acids of the two cvs was measured 35 days after growing in quartz sand with different P supply. Both cultivars responded to P fertilizer by doubling their shoot weight. With increased P supply (0.68—0.77% P in shoot‐DM) both cultivars showed similar heavy metal contents in the shoot resulting from similar root length/shoot weight ratios (RSR) and net uptake rates of the three elements as well as the same element concentrations in the rhizosphere soil solution. Under P deficiency, however, cv. Tabu (0.52% P in shoot‐DM) showed in comparison with cv. Monnopa (0.48% P) higher Cu, Zn, and Cd contents of shoots although its RSR was smaller than that of cv. Monnopa. However, the inflow for Cu was higher and for Zn and Cd significantly higher compared with cv. Monnopa. This result of cv. Tabu corresponded with higher concentrations of Cu, Zn, and Cd of its rhizosphere soil solution, and its higher exudation rates of oxalate, citrate, and malate (3.9; 1.0; 0.7 nmol cm^—1 h^—1). The corresponding values for cv. Monnopa were: 1.7; 0.3; 0.4 nmol cm^—1 h^—1. The mobilization of Cu, Zn, and Cd by the excreted organic acids seems to be responsible for the higher Cu, Zn, and Cd inflow of cv. Tabu.