Einfluß von Bodenreaktion,Redoxbedingungen und organischer Substanz auf die Phosphatgehalte der Bodenlösung

Influence of soil reaction, redox conditions and organic matter on the phosphate content of soil solutions Samples of seven agriculturally used soils of different composition (A_p-horizons), one marine underwater soil and two garbage composts were adjusted in suspensions (soil-water-ratio 1:3) to different pH values between 3 and 8 by additions of NaOH or HCl. By a different degree of aeration the redox potential was kept constant at selected values between +600 and ?300 mV. After an incubation period of 22–24 days under controlled E_h-pH-conditions the content of total phosphate and orthophosphate was measured in the equilibrium solutions. At oxidizing conditions all soil and compost samples show the lowest phosphate content in solution at pH S6. At higher and lower pH values the phosphate content increases. The results indicate that the phosphate concentration is determined by adsorption/desorption processes – mainly connected with iron oxides – and not by dissolution or precipitation of definite phosphorus compounds. Under reducing conditions the phosphate content increases in the equilibrium solutions of all samples. Especially in samples with high content of sulphides a considerable increase of the phosphate concentration could be measured at Eh values below +300 mV at pH 5, +200 mV at pH 6, and ± 0 mV at pH7 and 8. Below these values phosphate containing iron(II1) oxides were reduced and – with further decreasing redox potentials – transformed to iron sulphides. In samples without sulphide formation the phosphate mobilization is much lower. With increasing amount of soluble organic matter the phosphate content of the solutions also increases because of phosphate desorption by organic anions or complexation of aluminium and iron from phosphate adsorbing compounds. But also the content of soluble organically bound phosphate increases and may amount to 70 % of the total phosphate content in solution.     

Lysimeterstudie zum Einfluss von Düngung und Bewirtschaftung auf die Ertragsbildung,den Wasserhaushalt und die Nährstoffauswaschung im Trockengebiet der Uckermark

Lysimeter study about the effect of fertilization and management on yield, water balance, and solute leaching in the dry region of the Uckermark Results are presented of a lysimeter study on the effects of fertilization and management on yield, seepage rate, and solute leaching in the dry region of the Uckermark (Northeast Germany) from 1992 to 1999. The crop rotation included sugar beet, summer barley, pea, and winter wheat with fertilization of 280 and 400 kg N ha^—1 within the crop rotation. Additionally to the mineral fertilization, sugar beet was fertilized with the sugar beet leaf or slurry. The average annual seepage rate was 13.7 mm, the nitrogen leaching was 4.3 kg N ha^—1, and the phosphorus leaching was 0.008 kg P ha^—1. Differences between the treatments were negligible and insignificant. The amount of the precipitation from April to September had a significant influence on yields. Furthermore, results of water use efficiency and the effect of different nitrogen rates on yields are presented.     

Einfluß von Natriumchlorid und Mycostatin auf den Mineralstoffgehalt im Blattgewebe und die Feinstruktur der Chloroplasten

Effect of Sodium Chloride and Mycostatin on the Mineral Content of Leaf Segments and on the Fine Structure of Chloroplasts Leaf segments of bean, barley and sugar beet were treated for several hours with 25 meq NaC1 or with the antibiotica mycostatin. The effect of these treatments on the content of potassium, sodium, calcium, magnesium and chloride in the leaf segments and on the fine structure of chloroplasts was studied. In bean sodium chloride treatment induced strong efflux of potassium and swelling of the chloroplasts. Sodium sulfate or mycostatin had the same effect. Despite of the strong efflux of potassium the content of calcium and magnesium in the segments was practically unaffected. Addition of 1 meq calcium to the external solution prevented the effect of sodium chloride on efflux of potassium as well as on the fine structure. In barley sodium chloride or mycostatin also induced efflux of potassium and swelling of the chloroplasts. These effects, however, were less pronounced than in bean. Again the content of calcium and magnesium in the segments was practically unaffected, and the addition of 1 meq calcium compensated the effect of sodium chloride. In sugar beet both mycostatin and sodium chloride did not induce efflux of potassium, despite of a strong influx of sodium in the sodium chloride treatment. In both treatments no change in the fine structure of the chloroplasts was observed. It was proved by isolation of chloroplasts that the typical sodium chloride induced differences in efflux of potassium from the leaf segments is also reflected in efflux of potassium from the chloroplasts. The results indicate the causative connection between efflux of potassium and change in the fine structure of the chloroplasts. Differences between the three plant species with respect to efflux of potassium induced by sodium chloride or mycostatin are reflections of different membrane properties. The presence of calcium in the external solution is much more important for the membrane stability of bean than it is for sugar beet e. g. The results obtained with leaf segments are a good reflection of the different tolerance of these three plant species to high sodium chloride concentrations under field conditions.     

Düngung,N-Umsatz und Pflanzenwachstum in ihrer Wirkung auf die langfristige Protonenbilanz von Böden

Influence of fertilization, nitrogen transformation and plant growth on the long-term proton balance in soils In view of results of recent publications the influence of fertilization, nitrogen transformation and plant growth on proton balance in soil is discussed. One reason, why acidity in the soil increases after plant growth can be traced back to the fact, that plants take up more N-free cations than N-free Anions from the soil. Thus the more nitrogen fertilization as well other fertilization practices will increase plant yield the more the process of soil acidification will be enhanced. There ist no influence on soil pH by forms of applied fertilizer nitrogen like NH₄NO₃, HNO₃, NH₄OH, urea or biologically fixed N. However, accompanying ions of nitrogen fertilizers depending whether they are metal cations or sulfate or chlorid anions will decrease or increase proton production. For the calculation of the amount of produced acid in the soil during the uptake of nutrients by plants the yield of the plants and the alcalinity of plant ash will be needed. The calculation of the amount of produced acid both from the fertilization and the plant growth will be falsified by the unknown amount of nitrate which is leached beneath the rooting zone.     

Der Einfluß der natürlichen organischen Substanzen auf die Metallverteilung zwischen Boden und Bodenlösung in einem sauren Waldboden

The influence of organic matter in the translocation of metals between soil and soil solution of an acid forest soil Water extracts were prepared from soil samples which were collected from a soil profile showing very little variation in the texture down to a depth of 120 cm and thus only little translocation of clay in the soil profile. The aim of the study was to describe the distribution between soil and soil solution of several metals like Cu, Pb, Cd, Zn, Al and Mn as a function of humic substances, electrolyte concentration and pH. From the experimental results the following hypothesis on the reaction mechanisms involving metals and humus derived substances has been deduced. The metals Cu, Fe, Al and Pb are mobilized through complexation by soluble humus substances in addition to the usual pH dependent desorption and dissolution of hydroxides. This mobilization determines the solution concentration of Cu and Fe at pH > 3.7 and Al and Pb at pH > 4.2. Al, Fe and Pb are complexed selectively by high molecular weight humus derived substances which undergo adsorption on soil mineral surfaces. Cu interacts with low molecular weight humus derived substances which are not easily adsorbed by the mineral surfaces. Zn, Cd and Mn primarily undergo sorption and are thus controlled by pH and electrolyte concentration of solutions because their complexation with humus derived substances seems to be weak or nonexistant. It is further postulated that the humus derived substances mobilize Al³⁺ and Fe³⁺ ions. By this, other metals like Cd, Zn, Mn, Ca and Mg can occupy the free exchange sites.     

Einfluß der Kaliumdüngung auf die Verfügbarkeit des Kaliums in K-fixierenden Böden im Verlaufe der Vegetationszeit

Effect of potassium fertilization on K-availability in potassium fixing soils over the vegetative period The effect of potassium fertilization on the K-availability over the course of the vegetative period was tested on nine potassium fixing soils over two years. The availability of potassium fertilized at the beginning of vegetative period falls (on a soil with 50% clay) to half of the original amount within one month. The availability decreases especially during the time without vegetation. Only after fertilization with 1200 kg K₂O/ha are substantial amounts of potassium available for the plants until the end of the vegetative period (determined by electroultrafiltration). An annual application of 300 kg K₂O/ha only slightly increased the CAL-K and exchangeable K in comparison with the unfertilized plots, although the plants showed marked yield responses. A significant improvement in potassium supply was not obtained with less than 600 kg K₂O/ha. The potassium wet fixation values are relatively constant on the plots without or with low K-fertilization: after high potassium application they show considerable fluctuation. The fixation potential is considerably reduced with an annual application of 1800 kg K₂O/ha, but is not completely removed. Potassium can be removed by repeated extraction with a dilute CaCl₂-solution but the rate at which it is released into the soil solution is too slow compared to the needs of rapidly growing crop plants. The rise in the level of available potassium by fertilization is reverse to the clay content. There was considerable variation between the different available potassium forms over the vegetative period on the highly fertilized plots; consequently a soil test made annually can only give a rough idea of the K-level in potassium fixing soils.     

Zusammensetzung und Speziierung der Bodenlösung eines mit Schwermetallen belasteten kalkreichen Bodens

Composition and Speciation of Soil Solution collected in a Heavy Metal polluted calcareous Soil Close to a brass foundry, which had emitted heavy metal containing dusts for over 80 years, soil water was collected in the topsoil (18 cm) and in the subsoil (40 cm) of a severely polluted Calcic Fluvisol by means of polyethylen suction cups over a period of 2 years. The total metal content of the topsoil (extracted with 2M HNO₃ at 100 °C for 2 hours) was 38 nmol g^?1, 24 μmol g^?1, and 25 μmol g^?1 for Cd, Cu, and Zn, respectively. The mean heavy metal concentrations of the soil solution were 0.5 mol L^?1, 300 nmol L^?1, and 200 nmol L^?1 in the topsoil and 0.6 nmol L^?1, 90 nmol L^?1, and 30 nmol L^?1 in the subsoil for Cd, Cu, and Zn, respectively. Solubility calculations showed that the soil solutions were undersaturated with respect to heavy metal carbonates as well as to hydroxides. It seems that the heavy metal concentration is determined by sorption processes rather than by precipitation. The composition of the soil solution has been shown to be governed by the presence, of calcite, by the soil temperature and by the partial pressure of CO₂ in the soil air. The pCO₂ in the soil air (in both depths) has been estimated at 2 mbar during the winter term and at 20 mbar during the summer term. A corresponding increase of the concentration of macroelements (Ca, Mg, Na) as well as of total dissolved carbonate and of dissolved organic matter (DOC) has been measured in the summer half year. No significant seasonal variations of the heavy metal concentrations were detected and no correlations with concentrations of other components could be found.     

Einfluß unterschiedlicher Düngung auf pH,N, C und die Gehalte an CAL-extrahierbarem K und P im Boden

Influence of different fertilization on pH, N, C and CAL-extractable K and P in the soil The influence of different fertilization (mineral fertilizer, different kinds and quantities of farmyard manure and biocompost, horn meal) on soil properties was studied during 8 years of cultivation. The plots were planted and harvested as practised under local farming conditions. The pH of the non-fertilized plots decreased from 5.84 to 5.69, while it was increased by fertilization with farmyard manure or biocompost. N_t in the soil was not influenced by different fertilization. C_t was increased by high biocompost application, stayed constant on the other fertilized plots but decreased on the nonfertilized plots from 1.08 to 0.99%. Without fertilization, plant available nutrients were diminished from 7.3 to 4.3 mg P(CAL) 100 g^?1 and from 22.5 to 13.9 mg K(CAL) 100 g^?1. However, if the plots were fertilized with mineral or organic fertilizer, the nutrient content remained on the initial level. Storing farmyard manure under roof or covering with straw or polyethylene sheet did not affect the criteria of soil studied.     

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.     

Einfluß der Probenvorbereitung auf die Adsorption von Cd und Cu in sauren Waldböden

Influence of Soil Sample Preparation on Cd and Cu Adsorption in Acid Forest Soils The influence of soil sample preparation on Cd and Cu adsorption was investigated using six acid forest soil samples and comparing adsorption isotherms for fresh and air-dried samples. While no influence of sample preparation on Cd adsorption capacity was found, air-drying resulted in a significant decrease in Cu adsorption density in all six soil samples under investigation at ecotoxicologically relevant concentrations in the soil solution.     

Einfluß der N-Düngung von Apfelkulturen auf Nitratgehalte im Boden,stickstoffhaltige Reservestoffe im Baum und Ertrag

Effect of N-fertilization in apple orchards on soil nitrate contents, nitrogenous reserves in the tree, and crop yield It should be investigated how nitrate supply affects crop yields and incorporation and mobilization of nitrogenous reserves with Golden Delicious' apple trees on M 7 and M 9, and whether N fertilizer needs are influenced by N reserves in the trees. Two trials were carried out in 1981–1983. In the first one on al loess soil increasing N levels (0, 40, 80, 120 kg N/ha) were applied. In the second one, on a podsolic sandy soil, N was applied either in spring and/or in August (0/0, 80/0, 40/40, 0/80 kg N/ha). N fertilizers were applied to the herbicide strips only. Both orchards were in their best cropping age. Soil nitrate contents were mainly influenced by N-fertilization. Precipitation and drip irrigation caused translocation of nitrate and leaching from the soil layer investigated (0–90 cm). Thus, on the sandy soil almost no nitrate was left in spring, whereas on the loess soil various amounts of nitrate were still available in the subsoil depending on N fertilization in the preciding year. In plots where N fertilization was at optimum, the soil nitrate contents varied between 65 and 130 kg N per hectare herbicide strip over the main growing season (May–August). In the bark N reserves were mainly proteins, but almost equal amounts of protein and soluble N were found in the wood. N reserves were incorporated into the bark mainly between October and December, but even earlier than September in the wood. They were mobilized from April through July. Arginine was stored in the wood in considerably higher amounts than in the bark. Asparagine contents showed a sharp increase immediately after blossom time, particularly in the bark. There was almost no significant influence of the different fertilizer patterns on incorporation and mobilization of nitrogenous compounds. The N-reserves had no effect on crop weight. Highest crop yields were obtained whenever at least 40 kg N/ha were applied in spring. Additional N supply in August did neither increase incorporation of N-reserves nor crop yields. The nitrogenous reserves in the trees can be ignored in estimating N-fertilizer needs. On the other hand, the soil nitrate contents at bud break in April should be taken into account.     

Einfluß einer Düngung auf den Diffusionsfluß nicht gedüngter Kationen

Effect of Mineral Fertilizer Application on the Diffusion of Cations that have not been Added with the Fertilizer . Mineral fertilizer application increases the concentration of all cations in the soil solution, because the cations added displace partly those cations occupying exchange positions into the soil solution. In pot experiments, therefore, the K concentration could be raised by Mg-fertilization and vice versa. In the first experiment the response of alfalfa to Mg fertilization was to be studied. 1.2 g Mg/pot (12 kg soil/pot) was applied before sowing and 0.5 g/pot after each cut. 1.0 g P/pot as CaHPO₄ was added, but no K was added in the first year (except soil No. 6 K). In the 2^nd year 1 g K/pot was added after each cut. At 3 sampling dates soil samples were taken for diffusion measurements. In a second experiment K availability was tested at different K and soil water contents. 4 K treatments were included (0, 9, 29 and 49 mg K/100 g). K and Mg diffusion were measured. In the first experiment an increase of K concentration in the soil solution was recorded (Tab. 1) and in the second one an increase of Mg concentration (Fig. 1). This increase of concentration took place without altering the amounts present in the soil, but it led to an increase of the diffusive flux of the cations in question (Tab. 1 Fig. 2). This is taken as further evidence that cation diffusion takes place in the soil solution and depends mainly on the cation concentration in the soil solution. In those cases in which the cation availability depends mainly on cation diffusion to the roots mineral fertilizer application may affect the supply of cations that have not been added to the soil. This effect will be important in pot experiments to which large amounts of fertilizer are applied and which are not subject to leaching. It cannot be detected by most of the conventional soil testing methods because the amounts of cations - except, of course, those that have been added - have not changed. Only an analysis of the soil solution will reveal whether this ?salt effect”? is significant or not in a specific case.     

Einfluß von Bodeneigenschaften,Bodennutzung und Bodentemperatur auf die N-Mobilisierung von Kulturböden

Influence of soil characteristics, agricultural use and soil temperature on the N-mobilization of cultivated soils A new N-mobilization model, which considers also the short term and seasonal N-supplying capacity of soil is presented. At a fixed time the potential mobilizable N (N-MOB) is a sum of difficultly mobilizable N (N-MOB_s) originating from the pool of difficultly mobilizable N (N_s) and the easily mobilizable N (N-MOB₁) originating from the pool of easily mobilizable N (N₁). It is possible to characterize soil according to their M₁, N-MOB_s and v (N-MOB_s per day) values. Usefulness of these parameters in N-nutrition and ground water burden from N has been discussed. Basic parameters of this model have been experimentally determined independently with the help of two different experiments i. e. laboratory incubation and column lysimeter using surface soil samples. The easily mobilizable N pool (N₁) values were found in the range of 142 to 814 kg N ha^?1 which corresponded to 1.2 to 7.4 % of organic N content of these soils. The difficultly mobilizable N per day (i. e. v = N-MOB_s per day) in an incubation experiment (35°C) were found in the range of 1.5 to 24kg N ha^?1. However, in the column lysimeter experiment, in contrast, these values at 10°C ranged between 0.05 to 0.9 kg N ha^?1. These values correspond to N-MOB_s values in the range of 11–182 kg N·ha^?1 for a period of 200 days which approximate to a vegetation period. For practical purposes, the N₁ and v values could be calculated by just measuring 3–4 points after 14 days of incubation at 35°C. The results show that N-MOB_s values strongly correlated compared to N₁ values to total N, organic carbon and clay content and non significantly to pH and silt content. The results of an laboratory incubation experiment carried out to assess the effect of temperature on N-mobilization show that even at 0°C there was N-mobilization. The results revealed that in the temperature range of 0–8°C (a range of soil temp. usually observed in winter months) and in the range of 25–40°C (range of summer months temp. for surface arable soil), a small change in the soil temperature would result in enormous increase in the quantity of mobilized N. The highest mobilized N quantity was found above 60°C.     

Wirkungen organischer Substanzen auf Boden- und Düngerphosphat Teil 1: Einfluß von Stroh- und Maiswurzelextrakten auf die Löslichkeit von Boden-und Dünger-P

Effects of organic substances on soil- and fertilizer phosphate Part 1: Influence of straw or maize-root extracts on the solubility of soil and fertilizer P The effects of straw and maize-root extracts on the solubility of soil and fertilizer phosphate were tested in incubation trials. The following results were obtained. 1. Addition of an extract of unrotted straw (10 g straw/100 g soil) to incubate a brown-earth soil, (high or low in P) for 1–14 days did not have any significant effects on the H₂O and CAL P-fraction as compared to a KH₂PO₄ control, but markedly increased transformation of ‘easily soluble’Fe- and Al-phosphates (?15 to ?40 ppm) into ‘less soluble’forms (+15 to +20 ppm). Addition of an extract of rotted straw decreased the amounts of water extractable P and ‘easily soluble’Fe- and Al-phosphates but CAL-extractable P and ‘less soluble’Fe- and Al-phosphates were increased. 2. Incubation of the same soil (P-enriched) with an extract of maize roots (roots: soil = 1:3) for 1 day resulted in a reduction in the fixation of fertilizer phosphate (34 as compared to 42%) and in a decrease of fertilizer P recovered as ‘less soluble’Fe- and Al-P (from 31 to 11%); however, fixation was markedly increased after 14 days.     

Einfluß der Löslichkeit verschiedener Phosphatdüngemittel auf die Phosphataufnahme und den Ertrag von Sommerweizen

Solubility of various phosphate fertilizers in a brown podzolic soil and their effect on phosphate uptake and yield of spring wheat. The solubility of various phosphate fertilizers (Superphosphate, Rhenaniaphosphate, Novaphos, Carolonphosphate and Hyperphosphate) was studied in an incubation experiment, and P uptake and yield effect of these fertilizers were investigated in a pot experiment. The soil used was a carbonate free brown podzolic earth (C horizon) with a neutral pH and low in available phosphate and humus. The quantities of P extracted from the soil by the EUF technique were the lower, the higher the amount of non processed phosphate of the incubated P fertilizers. This clear differentiation in the solubility of the various P-fertilizers was not obtained by the DL extraction. The P uptake of plants was highly correlated with the P quantities extracted by EUF (r = 0,95***), while the correlation between P uptake and the P of the DL extract was less narrow (r = 0,64*). The yield, particularly the grain yield, decreased with an increase of the non processed P in the fertilizers tested. Grain yield and EUF extractable P were highly correlated (r = 0,86***); while the relationship between grain yield and the DL extractable P was poorer (r = 0.62*). The experiments have shown that mainly the easily soluble phosphate is of decisive importance for the yield formation.