bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamics of surface sealing, runoff formation and interrill soil loss as related to rainfall intensity, microrelief and slope
Authors: Roth Christian H. , Helming Katharina
Published: February 2007

The aim of this study was to determine what effect rainfall intensity, microrelief roughness and slope have on the interactions between sealing, runoff formation, rainsplash detachment and interill soil loss by wash from air dry soil surfaces. Soil material from the plough horizon of a loess‐derived Haplic Luvisol was subjected to simulated rainfall to measure these effects.

Irrespective of the above three treatments studied, rates of runoff, splash, and interill soil loss were found to follow three distinct stages, confirming earlier work. Splash rates as a function of rainfall energy indicated a distinct maximum before leveling off, while both runoff and soil loss displayed asymptotic curves, the respective rise of rates coinciding with the maximum splash rates. Rainfall intensity had the greatest effects on the studied parameters, high intensities increasing final infiltration rates at the expense of overproportionally higher soil loss rates. Rough soil surfaces diminished both splash and soil loss, while slope only affected soil loss. In an additional treatment with a pre‐crusted soil surface, dispersion of the crust due to air slaking was believed to be the cause of increased runoff rates and a decrease in equilibrium splash and soil loss rates.

Seal erosion by runoff, dissipation of rainfall energy due to puddling, increased cohesion of the soil surface as a result of sealing are some of the factors involved in the interactions studied, and the extent to which these single processes counteract or compensate each other depends on the type of force acting and the flow conditions at the soil surface.
Factors controlling Al‐activity in soil solutions in an acid forest soil of the German Solling area
Authors: Matzner Egbert
Published: February 2007

The forests of the German Solling area are heavily impacted by acidic deposition. Analysis of soil solutions derived from suction lysimeters in the field reveal strong vertical gradients of Al‐activity in the soil solution and increasing activity with soil depth. Temporal pattern of Al‐ activity in soil solutions under field conditions cannot easily be predicted by equilibrium models using Al(OH)3 dissolution. Percolating disturbed soil samples under laboratory conditions with artificial acid soil solutions undersaturated to Al(OH)3 solids resulted in high rates of Al release in the 30–40 cm layer and revealed Al(OH)3 as a possible Al‐activity controlling solid. The laboratory findings are not in coincidence with field observations. This discrepancy with respect to the regulation of Al activity in the 30–40 cm layer is attributed to the effect of soil structure and the interaction of macropores and micropores under field conditions. Al activity of the soil solution in the 0–10 cm layer seems to be regulated by exchange reactions with organic substances.
Properties and composition of soil organic matter in forest and arable soils of Schleswig‐Holstein: 1. Comparison of morphology and results of wet chemistry, CPMAS‐13C‐NMR spectroscopy and pyrolysis‐field ionization mass spectrometry
Authors: Beyer Lothar , Schulten Hans‐Rolf , Fründ Rüdiger
Published: February 2007

Properties and composition of 25 soil samples (0.8–51% Corg) were determined by morphology, wet chemistry, CPMAS‐13C‐NMR‐spectroscopy and pyrolysis‐field ionization mass spectrometry (Py‐FIMS). The recovery rate of organic carbon was 102% (±15%). The correlation between the litter compound/humic compound ratio and humification grade, estimated with morphological observations, was strong (r2 = 0.502***). A typical classification of horizons (L, O, H, Ah+M) with regard to organic compounds (wet chemistry and 13C‐NMR) was not always significant. The pyrolysis‐mass spectra confirmed and extended on the basis of molecular chemical structures the results of wet chemistry, especially with polysaccharides, nitrogen compounds, lignin, lipids and alkylaromatics (r2 = 0.818–0.937***). A correlation between the NMR‐aliphatics, the humic compounds isolated by wet chemistry, and the long‐chain aliphatic carbon units in the pyrolysis‐mass spectra was established.
Dissolution of Poorly Crystalline Iron Oxides in Soils by EDTA and Oxalate
Authors: Borggaard Ole K.
Published: February 2007

Poorly crystalline iron oxides in soils are often estimated by 2 hours oxalate extraction at pH 3 and less often by 3–7 months EDTA extraction at pH 7.5–10.5. Calculated solubility products (Ksp) of iron oxides in equilibrium with EDTA and oxalate showed EDTA to dissolve only iron oxides with Ksp > 10−40‐10−41 at pH > 10, whereas at pH 3 oxalate (and EDTA) should theoretically dissolve all iron oxides. The different pHs could largely account for the great difference in extraction speed between the two methods.

Although EDTA and oxalate seem to act by surface complexation, where the adsorbed ligand by attenuating lattice Fe‐O bonds causes iron detachment, the mechanisms are considered to be different. Possibly EDTA forms tetranuclear surface complexes, which are considered to inhibit dissolution of well crystallized but not poorly crystallized iron oxides due to differences in bond strengths. Oxalate forming binuclear and mononuclear surface complexes can probably also act as an electron bridge between iron(II) in solution and surface iron(III) leading to iron(II) catalyzed dissolution of iron oxides. This mechanism is obviously of particular importance in the dissolution of magnetite and maghemite.

Despite the great theoretical differences the published methods with EDTA and oxalate dissolve comparable amounts of iron from many soils and the dissolved iron corresponds to poorly crystalline (highly reactive) iron oxides, mainly ferrihydrite.
Long‐term trapping efficiency of a vegetated filter strip under agricultural use
Authors: Schauder Horst , Auerswald Karl
Published: February 2007

In a hops‐producing area long‐term average trapping‐effectiveness of a grassed filterstrip under agricultural use was measured. Copper, applied as fungicide, was used to identify the colluvium in a meadow below a hop garden. 9,5 t material were trapped during 17 years per m width of the filterstrip. This annual accumulation of 540 kg/m width represents a trapping efficiency of 55% of the computed annual soil loss of the hop garden. The results agree with other publications which report the trapping efficiency for a longer period, whereas the reported results of short‐term experiments largely overestimate the efficiency.
Bildung schlechtkristalliner bis amorpher Verwitterungsprodukte in stark bis extrem versauerten Waldböden
Authors: Veerhoff Michael , Brummer Gerhard W.
Published: February 2007

Mit Hilfe röntgenographischer (RDA), röntgenfluoreszenzanalytischer (RFA), elektronenoptischer (REM, EDAX) und chemischer Analysen wurde versucht, die als Folge einer weitflächigen extremen Versauerung von Waldböden durch Silicatverwitterung gebildeten amorphen bis schlechtkristallinen Abbauprodukte mineralogisch und chemisch näher zu kennzeichnen. Die Untersuchungen erfolgten an fünf stark bis extrem versauerten Waldböden (verschiedene Parabraunerden, ein Parabraunerde‐Pseudogley und ein Parabraunerde‐Podsol) mit unterschiedlichem Ausgangsmaterial (Löß, Sandlöß und Geschiebesand/lehm) aus Nordrhein‐Westfalen und Schleswig‐Holstein. Wie die Ergebnisse zeigen, hat in den sehr stark bis extrem versauerten Oberböden sowie in den B‐Horizonten von Waldstandorten eine starke Zerstörung von Tonmineralen und anderen Silicaten und damit verbunden eine Anreicherung schlechtkristalliner bis amorpher Verbindungen stattgefunden. Die gebildeten Abbauprodukte liegen zumeist als flächenhaft auftretende kieselsäurereiche Aggregatüberzüge und Verkittungen oder in Form von kleinräumigen Ausfällungen auf Mineraloberflächen vor. Neben Si enthalten die Überzüge auch geringe Anteile an Al und Fe.
Wechselwirkungen zwischen Boden‐Huminstoffen und Metall‐Ionen III. Komplexbildung von Boden‐Huminsäuren und Boden‐Fulvosäuren mit Metall‐Ionen
Authors: Finger Wilfried , Klamberg Horst
Published: February 2007

Es wurde die Komplexbildung zwischen isolierten und analytisch eingehend charakterisierten Boden‐Huminstoffen aus zwei Horizonten eines Podsols und einer Reihe ausgewählter Metall‐Ionen untersucht. Mit Hilfe der Ionenaustausch‐Methode wurden zunächst bei drei verschiedenen pH‐Werten Bedingungs‐Stabilitätskonstanten für die Komplexe von zwei Boden‐Huminsäuren mit den Metall‐Ionen Ca2+, Mn2+, Cu2+ und Zn2+ ermittelt. Danach wurden für die Komplexbildung von zwei Boden‐Fulvosäuren mit der um die Ionen Al3+ und Fe3+ erweiterten Auswahl an Metall‐Ionen bei konstantem pH‐Wert Bedingungs‐Stabilitätsfunktionen bestimmt. Durch Auswertung der gefundenen Stabilitätsfunktionen der Metall‐Fulvosäure‐Komplexe konnte zwischen der Metallbindung an Niederenergie‐ und Hochenergie‐Bindungsstellen vom Phthalsäure‐ bzw. Salicylsäure‐Typ unterschieden werden. Aus den Stabilitätsfunktionen wurden außerdem maximale Stabilitätskonstanten für die Komplexbildung an den unterschiedlichen Bindungsstellen sowie Hinweise auf die vorliegenden Komplex‐Stöchiometrien entnommen. Die erhaltenen Komplexbildungsparameter und ihre Bedeutung für die Beschreibung der Fixierung und des Transports von Metall‐Ionen im Boden werden abschließend diskutiert.
Iron deficiency stress responses amongst citrus rootstocks
Authors: Treeby Michael , Uren Nick
Published: February 2007

Seedlings of citrus rootstocks differing in lime tolerance were grown in nutrient solution with and without Fe. Proton efflux, release of phenolic compounds and Fe reducing substances and root‐mediated reduction of FeIII in FeEDTA and freshly precipitated Fe(OH)3 in response to Fe deficiency were determined.

Sweet orange, Carrizo citrange and trifoliate orange, the three least tolerant rootstocks used in the study, did not decrease nutrient solution pH in response to Fe deficiency. The more lime tolerant rootstocks, rough lemon, Cleopatra mandarin and sour orange, did decrease nutrient solution pH. But in CaSO4 solution only sour orange increased H+ efflux significantly under Fe deficiency.

In response to Fe deficiency, the release of phenolic compounds was increased significantly in rough lemon and Cleopatra mandarin seedlings, while the release of reducing substances was increased significantly in rough lemon, sour orange and trifoliate orange.

Rough lemon was the only rootstock to respond to Fe deficiency with an increase in root‐mediated reduction of chelated FeIII at pH 6.5. At pH 8.0, both Fe‐deficient rough lemon and Cleopatra mandarin roots reduced higher amounts of FeIII from freshly precipitated Fe(OH)3 than Fe‐sufficient seedlings.

Iron reduction by detached roots of Fe‐deficient and Fe‐sufficient rough lemon did not follow Michaelis‐Menten kinetics at high substrate concentrations. Rates of Fe reduction at low substrate concentrations were inconsistent with the existence of an inducible ferric reductase in response to Fe deficiency.
Retention of Ni, Zn and Cd by Si‐associated goethite
Authors: Gerth Joachim , Brümmer Gerhard W. , Tiller Kevin G.
Published: February 2007

Synthetic goethite used to study the effects of reaction time and temperature on the pH‐dependent sorption of Ni, Zn and Cd was associated with amorphous silica. Ni interacted with dissolved Si and formed a Ni/Si precipitate on the goethite surface. Individual metals added at a concentration of 0.5 μmol g−1 and sorbed during a reaction period of 504 hours (21 days) at 35°C were extracted by 0.7 M HNO3 for 14 days. At the end of this period 11,28 and 40 percent of Ni, Cd and Zn, respectively, were not extracted whereas 20 percent of the total Fe content of the goethite and 39 percent of the associated Si were dissolved. During the sorption process metals became immobilized in the goethite particles. This effect can be related to a diffusion of metal ions into micropores. A total mobilization of sorbed metals can only be achieved by a complete dissolution of the goethite. The strong fixation of Ni, Zn and Cd by goethite suggests that additions of this Fe oxide could be used to ameliorate highly contaminated sludges or soils.
Effect of pH on Zinc Adsorption and Solubility in Suspensions of Different Clays and Soils
Authors: Metwally A. I. , Mashhady A. S. , Falatah A. M. , Reda M.
Published: February 2007

Zinc solubility in clay and soil suspensions was controlled by chemisorption at pH 4.5 – 7.0. The solubility in clay mineral suspensions was in the order palygorskite < montmorillonite « kaolinite and reflected the high affinity of zinc to palygorskite and the high CEC of montmorillonite. The solubility in soil suspensions was in the order Haplustoll < Torrifluvents and reflected the effect of high CEC and organic matter content of the first. The slopes of the pH‐pZn curves, calculated zinc potential and sequential desorption data suggested that Zn++ − Zn(OH)2 aqueous controlled the solubility of zinc in soil and clay mineral suspensions at pH 7.5 – 9.0. The slopes of the pH–pZn curves of two soils were, however, modified by the possible peptization of organic matter and Zn(OH)2.
Long‐term nitrogen balance for pearl millet (Pennisetum glaucum L.) in an acid sandy soil of Niger
Authors: Hafner Hermann , Bley Joachim , Bationo André , Martin Peter , Marschner Horst
Published: February 2007

On acid sandy soils of Niger (West Africa) fertilizer N recovery by pearl millet (Pennisetum glaucum L.) is often more than 100 per cent in years with normal or above average rainfall. Biological nitrogen fixation (BNF) by N2‐fixing bacteria may contribute to the N supply in pearl millet cropping systems. For a long‐term field experiment comprising treatments with and without mineral fertilizer (F) and with and without crop residue application (CR) a N balance sheet was calculated over a period of six years (1983‐1988).

After six years of successive millet cropping total N uptake (36‐77 kg N ha−1 yr−1) was distinctly higher than the amount of fertilizer N applied (30 kg N ha−1 yr−1). The atmospheric input of NH4‐N and NO3‐N in the rainwater was about 2 kg N ha−1 yr−1, 70 % in the form of NH4‐N. Gaseous NH3 losses from urea (broadcast, incorporated) were estimated from other experiments to amount to 36 % of the fertilizer N applied. Nitrogen losses by leaching (15 to > 25 kg N ha−1 yr−1) were dependent on the treatment and on the quantity and distribution of single rainfall events (>50 mm). Decline in total soil N content (0‐60 cm) ranged from 15 to 48 kg N ha−1 yr−1. The long‐term N balance (1983‐1988) indicated an annual net gain between 6 (+CR‐F) and 13 (+CR+F) kg N ha−1 yr−1. For the control (‐CR‐F) the long‐term N balance was negative (10 kg N ha−1 yr−1). In the treatment with crop residues only, the N balance was mainly determined by leaching losses, whereas in treatments with mineral fertilizer application the N balance depended primarily on N removal by the millet crop. The annual net gain in the N balance increased from 7 kg ha−1 with mineral fertilizer to 13 kg ha−1 in the combination mineral fertilizer plus crop residues.

In both the rhizosphere and the bulk soil (0‐15 cm), between 9 and 45% of the total bacterial population were N2‐fixing (diazotrophic) bacteria. The increased N gain upon crop residue application was positively correlated with an increase in the number of diazotrophic and total bacteria. The data on bacterial numbers suggest that the gain of N in the longterm N balance is most likely due to an N input by biological nitrogen fixation. In addition, evidence exists from related studies that the proliferation of diazotrophs and total bacteria in the rhizosphere due to crop residue application stimulated root growth of pearl millet, and thus improved the phosphorus (P) acquisition in the P deficient soil.
Leaf nutrient analysis in Salix viminalis (L.) energy forest stands growing on agricultural land
Authors: Rytter Lars , Ericsson Tom
Published: February 2007

The seasonal pattern of morphological leaf characteristics, leaf nutrient and carbohydrate contents in two energy forest stands growing on fertile clay soil and consisting of Salix viminalis (L.) was investigated. One of the stands was irrigated and liquid fertilized (IL) daily from May to August while the other stand was untreated (C). The study was carried out on shoots growing for their second year on five‐year‐old roots.

A pronounced seasonal variation in length, weight, and area of leaves of the same developmental stage was observed, while differences between the stands were small. The leaf content of carbohydrates and starch was low. Nitrogen was the only nutrient that was significantly higher in the IL stand compared with the C stand throughout the growing season. The small differences between stands were most probably an effect of the initially high soil fertility. Different bases for expressing plant nutrient status during the growing season, i.e. nutrient amount per leaf dry weight with and without carbohydrates, nutrient amounts per leaf or leaf area, nutrient proportions in leaves, and nutrient amounts in the total canopy, were compared and discussed. It was concluded that the common expression, nutrient weight per dry weight of leaves, without correction for non‐structural carbohydrates, was adequate to describe the nutrient situation in well‐growing basket willow plantations. The most appropriate time for leaf sampling was proposed to be the phase of most intensive growth.
Measurement of ammonia emissions after liquid manure application: I. Construction of a windtunnel system for measurements under field conditions
Authors: Braschkat J. , Mannheim T. , Horlacher D. , Marschner Horst
Published: February 2007

A windtunnel system is presented applicable for measuring ammonia emissions under field conditions. With this system two objectives are achieved:

No alteration of the microclimatic conditions in the testing area

Reliable determination of the volumetric air flow and the ammonia concentration

The use of a transparent foil, the precise adjustment of the flow velocity to the windspeed outside, and the constant cross‐sectional area over the whole length of the tunnel are the most important constructional details of the system.
Mikrobielle Aktivitäten in landwirtschaftlich genutzten Böden Niedersachsens. I. Einfluß der ackerbaulichen Nutzung
Authors: Frank Thomas , Malkomes Hans‐Peter
Published: February 2007

Auf drei Ackerböden an zwei niedersächsischen Standorten wurden vier Jahre lang verschiedene mikrobielle Aktivitäten untersucht. Häufig reagierte die Glucose‐induzierte Kurzzeitatmung und die Dehydrogenaseaktivität am empfindlichsten auf Umwelteinflüsse. Unter Getreide wurden meistens höhere Aktivitäten beobachtet als unter Zuckerrüben. Die einzelnen mikrobiellen Aktivitäten wurden unterschiedlich durch die Böden und die Vegetationsperiode beeinflußt. Pflanzenschutzmittel‐Spritzfolgen führten unter Zuckerrüben zeitweise zu einer Verringerung einiger mikrobieller Aktivitäten.
Kinetics of soil phosphate desorption as affected by citric acid
Authors: Gerke Jörg
Published: February 2007

Citrate can accumulate in the rhizosphere of phosphate (P) deficient plants. Therefore, P desorption was investigated in relation to citrate concentrations applied in a single or sequential mode to a Luvisol and a Podzol. Cumulative P desorption increased up to 20 times that of the control, the absolute increase being higher in the Podzol. The rate of P release was closely related to the rate of Fe+Al release indicating that desorption originated mainly from Fe/Al associated P. The mode of citrate loading affected the P desorption in an ambiguous manner. P‐diffusion coefficients were calculated from the desorption data. The coefficients strongly increased with citrate loading, the increase being more pronounced in the Podzol.
Evaluation of Chemical Indices of Soil Pb Availability in Calcareous Soils
Authors: Al‐Afifi M. A.
Published: February 2007

The objective of this study was to compare six soil tests (1 M KNO3, 1 M NH4OAC, 0.005 M DTPA, 0.1 M EDTA, 1 M HNO3and 0.025 M Ca DTPA B4O7) as extractants for soil Pb and as predictors of plant available Pb for wheat (Triticum aestivumL.) in the greenhouse. The soils recieved 0, 200 and 400 mg Pb kg−1as Pb(NO3)2and are referred to as Pb0, Pb1and Pb2treatments respectively. Of the six soil extractants, 1 M HNO3was the most effective extractant for Pb from Pb0treatment whereas 0.1 M EDTA and 0.025 M Ca DTPA‐B4O7were the best and equally effective in their ability to extract Pb from Pb1and Pb2treatments. Regression analysis was used to develop two variable models for predicting Pb uptake by wheat as a function of extractable Pb and selected soil properties. The 0.025 M Ca DTPA‐B4O7extractant was the best in predicting uptake by wheat in Pb0(r = 0.791***significant at p = 0.001) and Pb1(r = 0.726***) and Pb2(r = 0.942***) treatments.
The effect of ultrasound on the stability of mesoaggregates (60–2,000 μm)
Authors: Tippkötter Rolf
Published: February 2007

A standardized ultrasonic dispersion is presented with reference to soil structure. It is suggested that the parameters of aggregate stability can be expressed by the input of ultrasound energy which causes a soil‐dependent process of aggregate dispersion. Preliminary results for soils of different land use and parent materials show that, for the soils examined, the stability of mesoaggregates (60–2,000 μm) lowers in the sequence forest > grassland > wasteland >arable land and limestone > basalt > loess > glacial till. Close correlations were also found to the content of carbon and clay.
Die flächenhafte Variabilität bodenphysikalischer Parameter und des Corg‐Gehaltes in den Pflugsohlen je eines Ton‐, Sand‐ und Lößstandortes
Authors: Immler Ludwig G. , Zahn Michael T.
Published: February 2007

Auf jeweils einem landwirtschaftlich genutzten Ton‐, Sand‐ und Lößstandort wurden mit Hilfe von Rasterbeprobungen in der Pflugsohle das Gesamtporenvolumen (PV), der Grob‐ und der Feinporenanteil (gPV (> 10 μm) bzw. fPV (< 0,2 μm)), die nutzbare Feldkapazität (nFK) und der Gehalt an organischem Kohlenstoff (Corg) flächenhaft bestimmt sowie statistisch und geostatistisch ausgewertet. Das Gesamtporenvolumen zeigte auf alien Standorten eine geringe Variabilität (Variationskoeffizient v = 5,9% bis 11,9%). Sein Mittelwert kann auf allen drei Untersuchungsflächen bereits bei einer Probendichte von 2/ha mit einem Standardfehler von Δa <10% geschätzt werden. Die Variabilität von fPV und gPV sowie der nFK und des Corg‐Gehaltes war bei der Ton‐ und der Sandfläche vergleichsweise hoch, so daß 10–20 Proben/ha für einen Standardfehler Δa <10% erforderlich sind.

Eine Auswertung von Variogrammparametern zeigte, daß erst bei hohen Probendichten (> 100 Proben/ha) niedrige Nuggetwerte für genaue Kriging‐Interpolationen erreicht werden. Mit der geostatistischen Block‐Kriging‐Interpolation kann die flächenhafte Verteilung von Bodenparametern jedoch auch bei relativ geringen Probendichten (ca. 10/ha) deutlich realistischer dargestellt werden, als dies mit der klassischen inverse‐distance‐Interpolation möglich ist, wie ein Vergleich beider Verfahren zeigt.
Significance of microbial biomass for carbon and nitrogen mineralization in soil
Authors: Kaiser Ernst‐August
Published: February 2007

C and N mineralization was quantified in an incubation experiment with two samples containing different amounts of microbial biomass. The samples from two layers (0–20, 20–30 cm) of an arable luvisol from loess were fertilized with nitrate, mixed with14C‐labelled straw and incubated for 52 days at different O2levels. Decreasing O2concentrations (21, 2, 1 and 0% O2) in soil conducted a decrease in C and N mineralization. More C and N were mineralized in samples with a higher initial microbial biomass. The differences in microbial biomass were still present at the end of the experiment, but more proliferation was detected in samples with the lower initial microbial biomass, leading to equal ratios between microbial biomass‐C and soil organic C in both soils.
The excretion of citric and malic acid by proteoid roots of Lupinus albus L.; effects on soil solution concentrations of phosphate, iron, and aluminum in the proteoid rhizosphere in samples of an oxisol and a luvisol
Authors: Gerke Jörg , Römer Wilhelm , Jungk Albrecht
Published: February 2007

Organic acid concentration in the proteoid rhizosphere of White Lupin in different soil samples (Oxisol‐Ap = Ox, Luvisol‐Ap and Luvisol‐C = LA and LC) was determined in order to study the influence of root‐released carboxylates on the mobilization of phosphate, aluminum, and iron in the rhizosphere. In the LC, organic acids were accumulated as Casalts extractable with water. In the proteoid rhizosphere of this soil sample 55 μmol citrate and 8 μmol malate per g soil were found. In the Ox, no water extractable organic acids were present. However, determination of citrate in the solid phase of this soil by Diffuse Reflectance Infrared Fourier Transform Spectroscopy gave concentrations of 88 and 68 μmol citrate per g soil without and with P application, respectively. Displaced soil solution from the proteoid root rhizosphere of the Ox and the LA increased in Fe and Al concentrations from <50 μmol/L (soil from reference pots without plants) to more than 600 μmol Fe+Al/L. The concentration of P was increased by a factor of 2 despite of P uptake by the proteoid roots. The mobilization of Al, Fe, and P is attributed to ligand exchange of phosphate against citrate and to the solubilization of Al and Fe as carboxylate complexes.
Der Einfluß der Expositionszeit auf die Höhe der Bodenatmung bei Anwendung der Lundegardhmethode
Authors: Kleber Markus , Stahr Karl , Henning‐Müller I.
Published: February 2007

Zur Beurteilung der Rolle, die speziell kohlenstoffreiche Böden bei einer potentiellen Klimaveränderung spielen werden, sind weit mehr Daten erforderlich, als bisher verfügbar. Nicht an jedem Standort kann jedoch ein beliebig hoher technischer und personeller Aufwand getrieben werden. Es wurde daher in der vorgelegten Untersuchung das alte und einfach anzuwendende Lundegardh‐Verfahren zur Messung von Kohlendioxidemissionen aus Böden, das für Zeiträume bis zu 24 Stunden allgemein als Standard akzeptiert ist (Anderson, 1982), daraufhin geprüft, ob es auch bei längeren Installationszeiten verwertbare Information liefert Zu diesem Zweck wurden an sieben aufeinander folgenden Tagen je sechs Lundegardhglocken für jeweils einen Tag installiert (Behandlung B) und die Mittelwerte aus den sechs Wiederholungen zu einem Wochenwert addiert. In unmittelbarer räumlicher Nähe wurden parallel dazu je 6 Glocken für die Dauer von einem bis zu sieben Tagen installiert (Behandlung A). Dies wurde sowohl in der warmen, als auch in der kalten Jahreszeit vorgenommen. Der Vergleich der Variante A mit der Variante B ergab einen linearen Zusammenhang, der es erlaubt, kumulierte Tagesdaten durch Werte von mehrtägig installierten Glocken zu substituieren. Dies setzt die Berücksichtigung des “Kammereffektes”, einer vonTesarovaundGloser(1976) gefundenen Überschätzung der Respiration durch die längerfristig installierten Glocken voraus. Die dort angegebene Überschätzung um 16% pro Tag wurde im Sommer in der identischen Höhe gefunden, während im Winter, bei wesentlich niedrigeren Absolutwerten und damit einhergehend größerer statistischer Bedeutung von Ausreißern, eine Überschätzung von 46% auftrat.
Small Scale Heterogeneity of Soil Chemical Properties. I. A Technique for Rapid Aggregate Fractionation
Authors: Kayser Achim T. , Wilcke Wolfgang , Kaupenjohann Martin , Joslin John D.
Published: February 2007

Several recent studies have observed physical, chemical and microbiological heterogeneities on the scale of soil aggregates. The publications emphasize the ecological importance of these small scale gradients. This paper introduces a method for the rapid fractionation of soil structure units into a surface fraction and a core fraction. The technique combines a rapid freezing in liquid N2 and standardized wet sieving of the structure units. During the sieving process the aggregate surfaces begin to thaw and are consequently washed through the sieve. The soil passing the sieve during a specified time is termed aggregate surface fraction, the remainder is the aggregate core fraction.

Samples from 18 forest soil profiles were taken to study the precision and accuracy of the method, as well as factors determining the efficiency of fractionation. The precision of aggregate fractionation as determined by parallel fractionations yielded coefficients of variability of 5.3 to 7.5% and 6.5 to 11.4% for the amount of core and surface fraction, respectively. Furthermore, the proposed technique yielded results comparable to those obtained by manual razor‐peeling of the aggregate surfaces. The variation of concentrations of chemical parameters in water extracts of both aggregate fractions was up to six times greater than in soil solutions obtained from mixed samples. Increasing soil organic C resulted in a decrease in the proportion of the aggregate surface soil collected under fixed sieving conditions, while clay content correlated positively with the amount of the aggregate surface fraction collected.
Regulation of enzymes involved in the sulphur‐assimilatory pathway
Authors: Hawkesford Malcolm J. , Schneider Andrea , Belcher Ann R. , Clarkson David T.
Published: February 2007

The regulation of enzymes involved in sulphate assimilation in plants has been investigated. Extractable activity of ATP sulphurylase (the first enzyme of the assimilatory pathway) has been shown to be regulated by sulphate availability and O‐acctylserine (OAS) supply. OAS addition to the medium increased extractable activity and was able, at least partially, to overcome the repression of extraclable activity observed by supply of sulphate and cysteine. Cysteine synthase, the final enzyme of the cysteine biosynthetic pathway, was not regulated under these conditions.
Ermittlung bodenphysikalischer Kennwerte in Abhängigkeit von Bodenart, Lagerungsdichte und Humusgehalt
Authors: Krahmer Ulrich , Hennings Volker , Müller Udo , Schrey Heinz‐Peter
Published: February 2007

Die Neuauflage der Bodenkundlichen Kartieranleitung als 4. Auflage enthält ein neues Bodenartendiagramm mit 31 zum Teil neu definierten Bodenarten. Sie verzichtet auf die vorher frei wählbaren alternativen Bezeichnungen bei Ton‐Schluff‐Gemengen, trägt neueren bodenkundlichen Erkenntnissen Rechnung und soll für die neuen und alten Bundesländer verbindlich sein. Da die Bodenart für nahezu alle bodenkundlichen Bewertungen eine elementare Ausgangsgröße ist, mußten einige aus ihr ableitbaren bodenphysikalischen Kennwerte neu berechnet und auf eine breitere Datenbasis gestellt werden. Für die vorliegende Auswertung standen 6352 Datensätze aus acht Bundesländern zur Verfügung. Aus ihnen wurden für die meisten Bodenarten repräsentative, statistisch gesicherte Werte der Luft‐, Feld‐, nutzbaren Feldkapazität und Wasserdurchlässigkeit als Funktion der Rohdichte, trocken, effektiven Lagerungsdichte sowie des Humusgehaltes zugeordnet und in tabellarischer Form dargestellt.
Luftkapazität, nutzbare Feldkapazität und Feldkapazität von Substrat‐Horizontgruppen ‐ eine statistische Auswertung von Labordatenbanken
Authors: Riek Winfried , Wessolek Gerd , Renger Manfred , Vetterlein Eberhard
Published: February 2007

Die vorliegende Auswertung basiert auf mehr als 6000 Bodenhorizontdaten, die den Labordatenbanken der geologischen Dienste mehrerer Bundesländer entstammen. Zur statistischen Bearbeitung wurden Dateien mit einer gezielten Differenzierung nach geologischen Ausgangssubstraten bzw. petrographisch‐genetischen Angaben angelegt. Die Abschätzung des Einflusses von Bodenart, Humusgehalt und Trockenrohdichte auf die Kennwerte Feldkapazität, nutzbare Feldkapazität und Luftkapazität erfolgte regressionsanalytisch für Substrat‐Horizont‐Gruppen. Unter geogenetischen Aspekten konnte ein Vergleich mit den bodenphysikalischen Angaben der Bodenkundlichen Kartieranleitung (AG Bodenkunde 1982) angestellt werden. Zur Ableitung der Kenngrößen FK, nFK und LK wird exemplarisch für Lößböden ein Schätzrahmen vorgestellt, der die Bodenhorizontierung berücksichtigt.
Migration of Cesium‐137 in typical soils of North Germany ten years after the Chernobyl accident
Authors: Giani Luise , Helmers Heinz
Published: February 2007

Ten years after the Chernobyl disaster the Cs‐137 migration of typical soils of North Germany (Folic Histosol, Haplic Podzol, Dystric Gleysol, Eutric Fluvisol) has been investigated and compared to their Cs distribution in 1986. In 1986 nearly 90% of the Cs‐137 occurred in the upper 1–5 cm soil sections, whereas it was 50–70% in 1996. The more regular distribution ten years after the accident shows that migration processes have taken place. The Podzol presented a high migration with marked Cs‐137 losses in the top soil. The Gleysol showed the lowest migration down to 10 cm depth. A nearly similar pattern at the top was found within the Histosol, however, a ratio of 10% Cs‐137 in the 10–15 cm section indicated a deeper migration. Despite the large clay content, the Fluvisol showed a regular Cs distribution within its profile, probably resulting from cattle steps and/or peloturbation.
Estimation of ammonia losses after application of liquid cattle manure on grassland
Authors: Braschkat Jörg , Mannheim Thomas , Marschner Horst
Published: February 2007

Field experiments under various conditions were carried out in Hohenheim and the Allgäu to measure the effects of liquid manure properties and meteorological factors on ammonia losses. The micrometeorological method (IHF) and the wind tunnel method were used. Depending on the prevailing conditions the ammonia losses varied between 14 and 99% of the applied ammonium nitrogen. The relationship between the ammonia loss and the logarithm of the dry matter content of liquid manure was highly significant. The dry matter content also influenced the time course of the ammonia loss. Solar radiation was the other major factor affecting ammonia loss. Compared to dry matter content and‐solar radiation, effects of other factors such as ammonium content and pH of liquid manure, air temperature, relative humidity and wind speed were small in the given range tested. Based on the relationships between the various parameters a simple model for estimation of ammonia loss was developed.
Ammoniakemissionen aus alternden Pflanzen und bei der Zersetzung von Ernterückständen
Authors: Mannheim Thomas , Braschkat Jörg , Marschner Horst
Published: February 2007

Die unter naturnahen Bedingungen mit der Windtunnelmethode gemessenen NH3‐Emissionen aus Pflanzenbeständen betrugen zwischen Blüte und Reife 0,8 bis 1,4% des Nt‐Gehaltes der oberirdischen Pflanzenmasse, entsprechend 1,1 bis 2,9 kg NH3‐N ha−1. Die höchsten Emissionen wurden bei Ackerbohnen gefunden; die Emissionen aus Winterweizen, Sommerraps und Senf lagen auf niedrigerem Niveau. Durch Entfernen eines Teiles der Ähren (Sink‐Reduktion) wurde die Höhe der NH3‐Emission nicht verändert, jedoch vorverlegt ebenso wie die Seneszenz. Dies läßt darauf schließen, daß die NH3‐Emission in enger Beziehung zur Seneszenz steht.

Die NH3‐Emissionen aus Ernterückständen betrugen zwischen 0,9 und 3,7% des Nt‐Gehaltes. Während aus wasserreichen Zuckerrübenblättern und aus Kartoffelkraut Verluste von 8,6 bis zu 12,6 kg NH3‐N ha−1 auftraten, emittierte aus N‐reichem Ackerbohnenstroh, wahrscheinlich aufgrund des hohen Trockensubstanzgehaltes, verhältnismäßig wenig NH3 (3,1 kg N ha−1; 0,9% des Nt‐Gehaltes). Durch Einarbeitung von Zuckerrübenblatt in den Boden konnte die NH3‐Emission um 81% reduziert werden, durch Mulchen um 63%.
Specific surface area and surface charges of some argentinian soils
Authors: Sánchez R. M. Torres , Falasca S.
Published: February 2007

The specific surface areas of nine argentinian soils obtained by adsorption followed the order N2 < ethylene glycol < H2O, attributed to the presence of smectites (verified by XRD analysis) and some organic coating. The H2O2 treatment of these soils modified the former order of surface area determined by different absorbents. This order was modified because the mineral surface was evidenced and an increase of cation adsorption was produced by organic matter removal. This fact was supported by the decrease of PZC values of soils after H2O2 treatment.

The specific surface area of initial soils obtained by water and ethylene glycol adsorptions showed a good correlation with carbon content and CEC of untreated soils and with the PZC of protonated soils.
Ammonium fluxes into plant roots: Energetics, kinetics and regulation
Authors: Glass Anthony D. M. , Erner Yair , Kronzucker Herbert J. , Schjoerring Jan K. , Siddiqi M. Yaeesh , Wang M.‐Yuan
Published: February 2007

Ammonium uptake across the plasma membranes of seedling roots of intact rice plants is thermodynamically active at low external concentrations, and consequently, electrogenic uniport is an unlikely mechanism for influx. At higher NH4+ concentrations uptake is passive and electrogenic uniport is a possibility. While passive permeation of NH3 is also possible at high external [NH4+], influx measurements at 10 mM NH4+ demonstrated a pH dependence which was inconsistent with significant NH3 permeation. Kinetic studies using 13NH4+ established that influx at low external [H4+] occurred via high affinity transport systems (HATS) in rice and spruce, while at higher [NH4+], influx was mediated by low affinity transport systems (LATS), that showed linear concentration dependence. Ammonium influx via the HATS was shown to be up‐regulated or down‐regulated in response to changes of N status, whereas influx in the LATS was insensitive to N status. The identity or identities of the regulatory signals responsible for controlling influx are discussed.
Manipulating the pathway of ammonia assimilation in transgenic non‐legumes and legumes
Authors: Hirel Bertrand , Phillipson Belinda , Murchie Erik , Suzuki Akira , Kunz Caroline , Ferrario Sylvie , Limami Anis , Chaillou Sylvain , Deleens Eliane , Brugière Norbert , Chaumont‐Bonnet Muriel , Foyer Christine , Morot‐Gaudry Jean‐François
Published: February 2007

In this paper we discuss the ways in which our understanding of the nature of the molecular controls of nitrogen assimilation has been increased by the use of non‐leguminous and leguminous plants with genetically‐altered capacities for ammonia assimilation. Using tobacco or Lotus as model plants, Glutamine synthetase (GS) and glutamate synthase (GOGAT) activities have been altered by stimulating or inhibiting in an organ‐ or tissue‐specific manner the expression of the corresponding genes. In a few selected examples, the physiological impact of these genetic manipulations has been studied on plants grown under different nitrogen regimes. The use of such genetically‐modified plants will allow us to better understand the molecular control of this metabolic pathway. It is also potentially of great importance in agriculture if such internal and stable modifications are beneficial in terms of nitrogen use efficiency, thus avoiding an excessive utilization of fertilizers or herbicides (GS inhibitors). Our current knowledge and prospects for future development are explored.
Aluminum and iron(III) species in the soil solution including organic complexes with citrate and humic substances
Authors: Gerke Jörg
Published: February 2007

The solubility of Al and Fe in soil is of relevance for their toxicity and availability, respectively, to plant roots. Humic substances as the main part of stable soil organic matter and citrate which is often excreted by P deficient plants are strong complexants of Al and Fe(III). Therefore, equations were developed to calculate the Al and Fe(III) species distribution in the soil solution in the presence of humic substances and citrate as organic ligands.

Calculations in the pH range 4.0–7.0 showed that at higher pH humic‐Al complexes were the most important species whereas AlOH‐citrate− dominated between pH 4.0 and 5.4. Free monomeric Al and AlSO4+ were of minor relevance.

Iron(III) species calculations showed that humic‐Fe complexes were the main species in the pH range 4.0–7.0. But if mugineic acid, a Fe complexing phytosiderophore released into the rhizosphere by graminaceous plant species, was present in the soil solution (10−6 M), Fe‐mugineic acid complexes accounted for most of the Fe in solution. Fe‐citrate− was relevant at lower pH but contributed little to Fe(III) species at pH > 6.0.

The results demonstrate the strong importance of the considered organic ligands for Fe and Al in the soil solution.
Changes of Al and Heavy Metal Concentrations in Slovak Soils During the Last 25 Years
Authors: Berghofer Ralf , Wilcke Wolfgang , Linkeš Vladimír , Nestroy Otmar , Zech Wolfgang
Published: February 2007

The objective of this study was to investigate changes of total concentrations and various extract‐defined Al and heavy metal fractions in Slovak agricultural soils during the last 25 years. We compared 7 stored soil samples collected between 1966 and 1970 with samples collected in 1994 at the same sites. Seven fractions of Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn were determined with a sequential extraction procedure in all samples. Total concentrations of Cd, Zn, Mn, Ni, and Cu were lower in the 1994 samples; those of Al, Fe, Pb, and Cr were higher. Based on the initial concentrations, the average total concentration changes were: Cd(‐10,3%)<Zn(‐7,2%)<Mn(‐4,8%)<Ni(‐2,3%)<Cu(‐1,4%)<Al(+2,1%)<Fe(+2,9%)<Cr(+7,4%)<Pb(+8,3%). This row is consistent with the decrease in metal mobility. The differences in salt‐extractable metals showed the same pattern; however, changes were more pronounced than for total concentrations. The results suggest that decreases during the last 25 years are caused by higher leaching than deposition rates and increases vice versa. The highest increase in Cr and Pb concentrations is observed in the EDTA‐extractable fraction, which mainly characterizes organically bound metals.
Cd translocation into generative organs of linseed (Linum usitatissimum L.)
Authors: Becher Monika , Wörner Annke , Schubert Sven
Published: February 2007

Linseed is able to accumulate considerably high concentrations of Cd in generative organs, the dietary critical value of 0.3 μg Cd/g seed often being exceeded. Differences between genotypes of linseed in this respect, however, have been observed but the underlying mechanisms responsible for these differences are unknown. The aim of the present work was to identify these mechanisms by studying the Cd accumulation of the linseed genotypes Antares and McGregor which differ in their ability to accumulate Cd in the seeds. Cultivar Antares is a high and cv. McGregor a low Cd accumulator which was confirmed in a pot experiment. It was found that the differences between these genotypes were Cd‐specific and were caused neither by single seed weight nor by Cd translocation into the shoot. The distribution pattern of Cd within mature capsules between the pericarp and the seeds differed from that of Ca which was used as a phloem‐immobile reference ion. From these results we conclude that Cd was translocated from the pericarp into the seeds via the phloem. This conclusion was supported by direct Cd determination in collected phloem sap from linseed stems. As sources of seed‐Cd we identified the pericarps of capsules and the leaves. The genotype differences concerning the Cd concentrations in the seeds may be explained in terms of differences in phloem translocation of Cd.
Relationship of apple vitamin C and antioxidant contents to harvest date and postharvest pathogen infection
Authors: Davey Mark W , Auwerkerken Annemarie , Keulemans Johan
Published: February 2007

A surprisingly strong correlation between the date of commercial harvest and the mean vitamin C (L‐ascorbate, L‐AA) contents of fruits from Belgian‐grown Malus × domestica cultivars was reported recently (Davey MW and Keulemans J, J Agric Food Chem 52:8031–8038 (2004)). The study has been extended to show that this correlation remains consistent over different production years and that harvest date is also significantly correlated with fruit L‐AA and total antioxidant activities but not with glutathione (GSH) levels or other physiological parameters of fruits. L‐AA concentrations were also found to be negatively correlated with mean preharvest daytime temperature; however, since preharvest temperature and harvest date themselves are closely linked, it was not possible to definitively separate the relative contributions of genetic and environmental factors to these traits. It is also shown that the susceptibility of fruits of different apple genotypes to postharvest infection with Botrytris cinerea decreases with increasing harvest date and that this susceptibility is correlated with fruit vitamin C but not GSH levels. There is no such relationship underlying the susceptibility of fruits to postharvest infection with Gloeosporium fructigenum. These results are discussed in the context of low‐input breeding for improved fruit quality and disease resistance via selection of fruits with improved antioxidant defence capabilities. Copyright © 2007 Society of Chemical Industry
Reproducibility of the Italian ISQ method for quality classification of bread wheats: An evaluation by expert assessors
Authors: Foca Giorgia , Ulrici Alessandro , Corbellini Maria , Pagani Maria Ambrogina , Lucisano Mara , Franchini Gian Carlo , Tassi Lorenzo
Published: February 2007

The great variety of different bakery products in Italy has led to the development of a method, the Synthetic Index of Quality (Indice Sintetico di Qualità, ISQ), for the classification of bread wheats in different quality categories. Based on chemical and rheological properties, each wheat sample is assigned to the most suitable class by an expert assessor. In many cases this procedure is not straightforward, making the class assignation uncertain, thus leading to the possibility of controversies during the trading phase. In the present study, in order to have a quantitative estimate of the validity and reliability of this procedure, a panel composed of nine expert assessors was utilised for the repeated evaluation of 100 samples of bread wheats of various qualities. The results suggest that the proposed approach can be used both to monitor the reliability of the single assessors, and to identify samples whose class assignation is reasonably indubitable, e.g. to be used for the development of automated classification methods. Moreover, the analysis of the most uncertain assignation cases can be useful in order to enhance the ISQ classification method itself. Copyright © 2007 Society of Chemical Industry
Carotenoid pigments in kale are influenced by nitrogen concentration and form
Authors: Kopsell Dean A , Kopsell David E , Curran‐Celentano Joanne
Published: February 2007

The objective of these experiments was to investigate the effects of N rate and form on the accumulation of lutein, β‐carotene and chlorophyll pigments in the leaf tissues of kale. Winterbor, Toscano and Redbor kale cultivars were greenhouse grown using nutrient solution culture. In the first study, N treatments were 6, 13, 26, 52 and 105 mg L−1 at a constant 1 NH4‐N:3 NO3‐N ratio. On a fresh weight basis, plant pigment concentrations (lutein, β‐carotene and chlorophylls) were not affected by N rate. When calculated on a dry weight basis, however, carotenoid pigments increased linearly in response to increasing N rate. In a second study, N rate was held constant at 105 mg L−1 and N form was changed as follows: 100% NH4‐N:0% NO3‐N, 75% NH4‐N:25% NO3‐N, 50% NH4‐N:50% NO3‐N, 25% NH4‐N:75% NO3‐N and 0% NH4‐N:100% NO3‐N. Increasing NO3‐N in nutrient solutions from 0 to 100% resulted in increases in both lutein and β‐carotene concentrations. Increases in carotenoid concentrations would be expected to increase the nutritional value of kale. Therefore N management should be considered in crop production programmes designed to increase the concentrations of nutritionally valuable carotenoids. Copyright © 2007 Society of Chemical Industry