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.     

Prognose der mechanischen Belastbarkeit und der auflastabhängigen Änderung des Lufthaushaltes in Ackerböden anhand von Bodenkarten

Prediction of soil strength of arable soils and stress dependent changes in ecological properties based on soil maps Based on a database of at present 160 mechanical soil profile datasets, the site and horizon dependent mechanical soil strength expressed as precompression stress can be predicted by multiple regression analysis and used for documentation in maps at different scales. Stress dependent changes in air permeability or air capacity can be derived for the virgin compression stress range as well as the effect of stress propagation in soils or stress attenuation capacity and depth dependent changes of ecological properties. Thus, areas with defined mechanical sensitivity as a function of depth can be derived and recommendations for site adjusted farming techniques can be given. In addition it allows the agricultural machine industry to develop site adjusted machines to support the ideas of good farming practice, defined by the soil protection law of Germany.     

Ordination von Waldökosystemen nach Stoffkonzentrationen der Lösungsphase und bodenchemischen Tiefengradienten

Ordination of forest ecosystems using element concentrations of the solution phase and soil chemical depth gradients Using data sets from 16 forest ecosystems the possibilities of an ordination procedure with respect to matter budget parameters are demonstrated. Principal component analysis was selected as method of ordination. Ordinations were carried out separately for (i) depth gradients of base saturation, for (ii) average element concentrations in the soil solution at two different depths, and (iii) for element concentrations in the bulk deposition and the throughfall. In the majority of cases the procedure yields plausible and interpretable arrangements of the ecosystems along the first and the second principal component axes. These two components contain over 80 percent of the total variance in the datasets. Compared to other methods of ecosystem characterization the ordination procedure is advantageous concerning practicability and objectivity. It is suggested to apply the method to a larger set of forest ecosystems with the aim of grouping the systems according to their individual states. An additional application is the analysis of temporal changes as attempted in ecosystem monitoring.     

Eine Methode zur Ermittelung der wasserspannungsabhängigen Änderung des Sauerstoffpartialdruckes und der Sauerstoffdiffusion in einzelnen Bodenaggregaten

A method to determine oxygen partial pressure and oxygen diffusion in single soil aggregates as a function of soil moisture tension Anaerobic zones occur even in unsaturated soils of silty or clayey texture, that are aerated sufficiently in their macropore system. These zones can be related to the inner parts of soil aggregates. To describe the oxygen balances in soils it is necessary to measure not only in soil profiles but as well in single soil aggregates within a range of soil matrix potentials. Therefore oxygen partial pressure in single soil aggregates of different texture was measured continuously as a function of soil matrix potential. For that purpose we developed an oxygen sensitive microelectrode with a tip diameter of 0.5 mm, that is sturdy enough to measure even in sandy soils. One microtensiometer (diameter of the tip < 0.5 mm) and one oxygen microelectrode were placed in water saturated soil aggregates. Soil water potential and oxygen partial pressure were measured continuously during soil drying. The results show an aeration of primarily anoxic soil aggregates at different soil matrix potentials due to different texture and structure. The clayey polyhedral aggregates of the Vertisol were aerated at significantly lower soil matrix potentials than the loamy prisms of the Fluvisol. These show higher values of oxygen partial pressure even at soil water potentials less than 150 hPa. In the aggregates of the Vertisol, that have a fine texture, values of rel. aparent diffusion D_s/D_o were in the range of 1 · 10^?3 at soil water potentials < ?     

Mathematische Modellierung der Funktionen des Bodens im Stoffhaushalt von Ökosystemen

Mathematical modelling of the role of soil in ecosystem functioning The structure of ecosystems and the parameters necessary for their characterization are discussed under the aspect of matter balances. The main weight is layed on the regulatory role of transport processes and storage changes in soil. It is postulated that the quantitative ecological analysis of landscapes requires the application of computer models of the regulatory processes in soil as a method for minimizing the measuring expense. The basic equations describing transport processes and storage changes are discussed and their application for special problems of the balance of water and chemical elements is demonstrated.     

Theoretische Betrachtung des Ionenkreislaufs in Waldökosystemen

Theoretical consideration of the ion cycle in forest ecosystems From the law of mass conservation and the principle of electrical neutrality it is deduced for forest ecosystems being in steady state that proton production or -consumption during ion uptake is balanced by opposite proton turnover during mineralization. With a beech (Fagus silvatica) forest ecosystem in the Solling as an example it is shown that the turnover of nitrogen plays a key role in this respect. Temporal and spatial discoupling of the ion cycle cause acidification pushes and deacidification phases. It is distinguished between seasonal acidification pushes, which are regulated by weather conditions, and climatic acidification pushes, which are regulated by climate fluctuations. Strong long lasting reductions of the phytomass production, as caused by strong changes in climate or by human interaction, can lead to instationary states. It is distinguished between two consecutive instationary states, which are connected with soil acidification: humus-disintegration and podzolization. It is concluded that an acute podzolization in its beginning stage, which appears at present in deciduous forest and older stands of spruce and pine, cannot be caused by ecosystem internal reasons, but is the consequence of acid precipitation.     

Pflanzenverfügbarkeit der Phosphatvorräte ackerbaulich genutzter Böden. -Langfristige Feldversuche zur Nutzbarkeit des Bodenphosphors und zur Bewertung der Bodenuntersuchung -

Availability of Phosphate Reserves in Arable Soils - Long Term Field Experiments for Assessing Soil P Reserves and Critical Soil Test Values - The objective of this work is to quantify the plant availability of soil P reserves accumulated by former fertilizer applications, the possibility of utilizing them by arable field crops and to determine critical soil test values. For this purpose several long term field experiments with large plots without replicates were initiated in 1977 on luvisols from loess (pH 6.8 – 7.4) in Lower Saxony with a sugar beet - winter wheat - winter barley/winter wheat crop rotation. Annual P applications were 0, 45, 90, 135 and 180 kg P₂O₅/ha as triple phosphate. Application of other fertilizers and plot management were according to farmer's practice. Despite of high yield levels phosphate response of plants was only 2 % at its maximum in the average of all crops in 15 years. This was confirmed by small plot experiments with four replicates placed into the large plots after 9 years, when soil P levels had been differentiated under the influence of plant P removal and P application. Herewith in agreement, shoot P concentration was found within the range generally regarded sufficient. It is therefore concluded that plant P demand has been fully satisfied by soil P reserves. Soil P test values, monitored by the P(H₂O) method of Sissingh, decreased markedly in 15 years, when no P was applied, they remained approximately constant when P application was equal to P removal and they increased when P addition was higher than P removal. Plants on a site with 4 mg P(H₂O)/L initially had severe P deficiency. Maximum yield was obtained when the soil P level was raised to 11 mg P(H₂O)/L. It is concluded that P reserves, which are often high in German arable soils, can be utilized by field crops and thus be lowered to about 10 mg P(H₂O)/L by reducing or omitting P dressings. For practical purposes it is suggested to restrict P application, if necessary at all, to the sugar beet crop in the rotation because they often respond more than small grain.     

Die Bestimmung repräsentativer Mittelwerte von Schwermetall-Konzentrationen in den Niederschlägen und im Sickerwasser von Wald-Standorten des Soiling

Heavy metals in precipitation and seepage water from forest sites in the Soiling: Determination of representative averages of heavy metal concentrations Concentrations of Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd and Pb were determined in open land precipitation, in precipitation below canopy and in seepage water in two different soil depths, over the period of 3 years, in monthly and half-yearly intervals, in a beech and a spruce forest of the Soiling mountains. The results of the concentration measurements and the element fluxes calculated from these data were treated statistically. The coefficients of variation of the concentrations and the fluxes within a given time period often exceeded 100%. It is proposed that, in order to determine meaningful average values, weighted samples are taken in half-year or year intervals, over the time span of several years, in a number of local replicates sufficient to reduce the error of the mean to less than 30%. For the investigation of time variations in the concentrations and fluxes the sampling of single rain events or of seepage water within short time periods (a few days) is suggested.     

Rekonstruktion des Paläomilieus und der Geo‐Pedogenese kalkfreier Marschböden Niedersachsens

Reconstruction of the paleo‐environment and geopedogenesis of non‐calcarous marshland soils (Eutric Gleysols) of Lower Saxony The genesis of non‐calcarous marshland soils is still controversially. For clarification, the paleo‐environments of two Eutric Gleysols were reconstructed by using X‐ray fluorescence spectroscopy, light microscopy, and scanning electron microscopy. Profile 1 shows seven facies. The diatom composition reveals paleo‐environments variable in time with lacustrine, brackish, and marine conditions. Pyrite was found at the transition of clastic material and peat and within the peat, indicating together with frequently found small Zr:Al and Si:Al ratios and small Ca:Sr ratios calm, brackish, and lagoonal sedimentation conditions with reed‐peat formation. Profile 2 shows two facies; their transition is very sharp and characterized by a sudden change in diatom composition, geochemical quality, and carbonate contents. The diatom flora and Ca:Sr ratios of the lower facies reveal a tidal creek habitat with a connection to the sea and exceptional small Si:Al and Zr:Al ratios. The results, particularly for many facies of profile 1, suggest a decalcification during geopedogenesis. Two genetic phases of this decalcification are therefore likely for today non‐calcarous marshland soils, either during early geopedogenesis or during later terrestrial development.     

Förderung des Wachstums und der Nährstoffaufnahme bei kruziferen Ölund Zwischenfrüchten durch inokulierte Rhizosphärenmikroorganismen

Promotion of plant growth and nutrient uptake of cruciferous oil- and intercrops by inoculated rhizosphere microorganisms The vegetative growth of rape, oil radish and mustard was repeatedly stimulated by isolates of Pseudomonas fluorescens (PsIA12), P. putida (A1 A2), Stenotrophomonas maltophilia (PsIB2, Psl2), Agrobacterium rhizogenes (A1A4) and Rhizobium trifolii (R39) by improved root development and nutrient uptake (N. P. K. Mg) in pot and field experiments on loamy sand and sandy loam at different yield levels. The seed yield of rape could be increased only by 2 isolates (PsIA12, PsIB2). The growth stimulating bacteria produced phytohormones (auxins and partly cytokinins). No direct relations between plant growth stimulation and the potential microbial metabolic activities nitrogenase, nitrate reductase, P-mobilization, pectinase, cellulase could be found. Effective bacteria are in close association with the plants and can survive in the rhizosphere.     

Bilanzierung jährlicher Elementflüsse in Waldökosystemen im Solling

Balances of annual element fluxes within forest ecosystems in the Solling region Based on measurements of element fluxes the annual changes of element storage within the compartments ?Stand”?, ?Humus layer”? and ?Mineral soil”? are calculated for a beech and a spruce stand. In spite of high rates of N-deposition insufficient N supply especially for the beech stand is obvious. The H⁺ buffering capacity of the stands is very limited and is greater for the spruce than for the beech stand. The accumulation of C, N, P and Ca within the humus layer of both stands seems to be due to far reaching changes of decomposition conditions caused by acid precipitation. The mineral soil reacts as a sink for H⁺ and S and as a source for Ca, Mg, Mn and Al. From the cation-anion-balance for the changes of element storage the annual H⁺-production within the mineral soil was calculated. The sum of H⁺ ions produced ecosystem internal within the humus layer and the mineral soil ist greater for spruce than for beech. For the spruce stand the total H⁺-load from deposition and from internal sources is about twice as big as the one of the beech stand.     

Veränderungen der Blattspreiten und des Chlorophyllgehaltes der Fahnenblätter von Winterweizen durch Wachstumsregulatoren

Changes of leaf-blades and chlorophyll content of flag leaves from winter wheat due to growth regulator application In pot experiments with winter wheat at two N-levels the effect of CCC and Ancymidol on the morphology, the chlorophyll content and the slope of the chorophyll degradation after anthesis were studied. The area of the blades and the number of flag leaves per pot were increased by the higher N-supply and by the growth regulators as well, resulting in a larger leaf area of flag leaf-blades per pot. In all cases the mixture of CCC + Ancymidol at the higher N-level reached the maximum values. The late intermediate harvesting showed distinct differences in the chlorophyll concentration of the flag leaf-blades and the total amount of chlorophyll of all flag leaf-blades per pot, whereby a delay of senescence in the growth regulator trials compared with the control could be proved.     

Vergleich der Verteilungen der Wasserleitfähigkeit und des Porenvolumens von waagrecht und senkrecht entnommenen Stechzylinderproben

Evaluation of the distribution of hydraulic conductivity and porosity measured at horizontally and vertically orientated core samples At 90 core camples taken vertically and 90 taken horizontally from 9 horizons of luvisols from loess hydraulic conductivities (h. c.) and porosities were determined. Frequency distribution of porosity showed but little influence of sample orientation, h. c.-values however showed marked difference. Most frequent values of horizontal distribution was approximated by lowest value of vertical distribution. This result was confirmed by evaluation of measurements given by Bailly (1969) and by Baumgart (1967).     

Zur Interpretation erhöhter Schluffgehalte in Böden des Bayerischen und des Oberpfälzer Waldes

On the interpretation of raised silt contents in soils of the Bavarian and Upper Palatinate Forest For the Bavarian and Upper Palatinate Forest (Bavaria), 41 representative pedons were examined for aeolian components using grain‐size analysis. Soils derived from loess (three pedons) are only available in the foreland of the Bavarian Forest near to the river Danube. Soils with aeolian fractions (one pedon) also exist in the adjacent part of the Bavarian Forest. No indication for loess components (37 pedons) were found in all other parts of this mountain range: these soils are missing a coarse‐silt maximum in their upper layer as should be expected for loess‐influenced soils. However, 17 of these pedons have a medium‐silt maximum in their upper layer interpreted as a result of intense physical weathering. Therefore, the widely occurrence of soils with aeolian components cannot be confirmed for this low‐mountain range of E Bavaria.     

Der Einfluß des NO3 : NH4 -Verhältnisses in der Nährlösung auf Ertrag und Gehalte an organischen und anorganischen Ionen von Tomatenpflanzen

The influence of the relation between NO₃ and NH₄ in the nutrient solution on yield and organic and inorganic ion contents of tomato plants. . Tomato plants were grown in aerated media of oppositly varying supply of (NH₄)₂SO₄-and NaNO₃ with a constant N-quantity of 15 meq/1 or a quantity of NH₄-, NO₃ or (NO₃ + NH₄) increasing from 3 to 30 meq.N/1. Yield and ion content were determined. A maximum yield was achieved by a mixed N-supply i.e. 4 to 5 parts NO₃, 1 part NH₄-N and 7, 5 meq N/l. The “(C-A) value” was calculated by the content of the cationions “C” (=K⁺ + Na⁺ + Ca⁺⁺ + Mg⁺⁺ + NH₄⁺) and the inorganic anions “A” (= NO₃^? + Cl^? + H₂PO₄^? + SO₄^–). The “(C-A)” value is equivalent to the content of the organic anions. Furthermore we determined the citrate, malate, oxalate, and pektinate content. These make up 60–80% of the (C-A) value. The NO₃- and K content increase considerably, the Ca-, Mg-, Na-, Citrate, Malate and Oxalate content increase less pronounced, the Cl-, H₂PO₄- and SO₄- content decrease as the NO₃ content increases from 0–80%. If the medium contains 80–100% NO₃ - N, the NO₃ and K content remain almost constant, while the Ca-, Mg-, citrate, malate and oxalate content especially increase in this case. The K content decreases in the presence of a high (NH₄)₂SO₄ supply. Parallel to this the value (C-A) decreases greatly, so that it is less than the sum of the determined organic anions. In this case the content of organic anions obviously does not correlate with the (C-A) value. The yield correlates with the carboxylate contents. (C-A) values of 150–170 mval/100 gm. d. m. cause a lowering of the yield. The plants contain an almost equal amount of citrate, malate and oxalate. Depending on the N-concentration of the medium, the malate content will be a bit more than the amount of citrate in case of maximum yield. If there is a lack or toxicity in the medium the citrate content will be higher than the malate content. The yield per dry weight correlates positivly with the quotients of citrate and malate.