Extraktion eines kupferbelasteten Bodens unter Verwendung eines aminosäurehaltigen Reststoffhydrolysats. 1. Cu-Elutionsdynamik und bindungsspezifische Freisetzung

Extraction of a copper contaminated soil material by an amino acid containing residue hydrolysate. 1. Time course of copper elution and characterization of reactive binding forms A copper contaminated (Cu content: 294 mg kg^?1) soil material sampled from an area formerly cultivated with hops (Humulus lupulus), was extracted within sixteen days in a column test facility (soil packing per column: 4.1 kg dry weight) by the percolation of an amino acid containing blood meal hydrolysate. The objectives of the study were to record the time course of copper elution, to determine the resulting degree of copper removal and to examine the specific extractability of the various copper binding forms. Until the maximum Cu concentration in the column effluent was reached, the time course of the Cu release went parallel to the throughput of the amino acids. As a consequence, the velocity of the copper mobilization and transport seems to be ruled by the hydrodynamic flux of the percolate mainly. In total 62% of the soil bound copper were removed by the hydrolysate. Above-average amounts were extracted from the binding forms 2–4 defined according to Zeien and Brümmer (1989). As a result, the copper forms, which are mostly responsible for potential ecotoxicological effects, could be widely diminished.     

Simultane Bestimmung von N-Transformationsraten in Bodensäulen unter Verwendung von 15-N: Stickstoffmodell für eine Terra fusca-Rendzina

Simultaneous determination of nitrogen transformation rates in soil columns using 15-N: N-Model of a Terra fusca-Rendzina soil Rates of ammonification, nitrification, immobilization, and denitrification were determined in undisturbed columns of a Terra fusca Rendzina soil. A steady input of 15-N labelled ammoniumsulfate with the irrigation water created a steady state of the turnover processes in the soil resulting in a constant output of 15-N-nitrate. In this state the rate constants (8°C) were K₁ = 0.64 for the netto-N-nitrification, K₂ = 0.11 for the netto-N-denitrification, and K₃ = 0.25 for the netto-N-immobilization. 64% of the nitrate was leached, 25% immobilized in organic matter, and 11% denitrified. Relating these rate constants to the turnover of the soil nitrogen one can calculate the mean annual rates for the different processes of a forest soil, using the mean annual temperature. For the Göttinger Wald situation (T = 6.9°C) the following rates were calculated; Ammonification = 183 kg N·ha^?1·a^?1, immobilization = 44 kg N·ha^?1·a^?1, netto N-denitrification = 19 kg N·ha^?1·a^?1, and netto-N-mineralization = 120 kg N·ha^?1·a^?1.     

Simulation des Anionen-Transports in ungestörten Bodensäulen unter stationären Fließbedingungen

Simulation of anion transport in undisturbed soil cores under steady-state flow conditions Miscible displacement experiments with undisturbed soil columns were carried out in the laboratory. Objective of the experiments was to collect information about the transport of Cl^? and NO₃^? through field soils. The experiments were carried out with a forest soil and an agricultural soil. The flow velocity of the chloride and the nitrate solution was either 1 cm/day or 0,3 cm/day. Of each soil there were 5 replicates. The effluent of each of the columns was analyzed and the collected data were used for model calculations. It was found that the breakthrough curves of Cl^? and NO₃^? were similar in shape. For the well-aggregated forest soil the apparent diffusion coefficient was much larger than for the agricultural soil. For both soils practically all of the chloride could be recovered in the effluent, but for nitrate considerable losses within the soil column were noted. It was also found that the chloride breakthrough could be described with a simple convection-dispersion equation. However a reduction of the total pore space, accounting for anion exclusion, was needed. Furthermore it was observed that for nitrate an additional sink term in the convection-dispersion equation was needed to account for the observed nitrate losses. It appears that the transport of nitrate and chloride through the soils that were studied can be described mathematically, provided the anion exclusion space and the rate of nitrate losses are known. The nature of the anion exclusion and the nitrate transformation needs further study.     

Denitrifikation eines gemüsebaulich genutzten Bodens in Abhängigkeit von der Einarbeitung frischer Erntereste

Denitrification losses from a horticultural soil as affected by incorporation of fresh plant residues Denitrification in the A_p-horizon of a Luvisol under horticulture as affected by fresh cauliflower residues (Brassica oleracea L. var. botrytis) was measured using the acetylene inhibition technique. The residues were chopped and ploughed in 25 cm deep. Denitrification rates, soil temperature, moisture, nitrate and watersoluble carbon were determined from the end of July until the end of September. One day after incorporation of plant residues the denitrification rate showed a rapid increase to the highest value (5.15 kg N · ha^?1 · day^?1) of the experimental period. During the following 57 days the rates declined to the level of the untreated control. The highest denitrification rates occurred in the experimental sites which received plant residues. The estimated N-loss for the whole experimental period (57 days) totalled 43.6 kg N · ha^?1 in the treatment with plant residues and 2 kg N · ha^?1 in the treatment without plant residues. Coefficients of variation of denitrification rates were high (29–206%). Within the treatment ‘with plant residues’ denitrification rate and watersoluble carbon were positively correlated.     

Menge und Verteilung des Stickstoffs in Fulvo-, Humin- und Kieselsäure-Huminsäuren eines Müll-Klärschlamm-Kompostes

Amount and distribution of nitrogen in fulvic-, humic- and silico humic acids from a garbage-sewage sludge compost During the course of composting for 106 days of a mixture of solid wastes and sewage sludge subsamples were taken at different time intervals. They were extracted for fulvic-, humic- and silico-humic acids which in turn were fractionated for different nitrogen fractions. Basic nitrogen fractions such as amino acids (AS), amino sugars (AZ), real amide nitrogen (ADe), pseudo amide nitrogen (ADp), remainder nitrogen of the hydrolysate (RNHY) and total nonhydrolyzable nitrogen (ΣNnhy) have been determined. The most pronounced transformations of nitrogen within the organic matter of the compost took place during the first 10–14 days of composting.     

Einfluß langjähriger Gülledüngung auf den Nährstoffhaushalt des Bodens. 2. Mitteilung: Bindung und Löslichkeitskriterien der Bodenphosphate

Influence of long-term slurry application on soil nutrients. 2. Fractions and solubility criteria of soil phosphorus Fractions and solubility criteria of soil phosphorus accumulated by long-term slurry application were investigated. The following results were obtained:

• – Slurry application mainly resulted in higher concents of inorganic phosphorus, especially Fe-Al-P, even in deeper soil layers.
• – The accumulation of inorganic phosphorus resulted in an increase of phosphorus availability in all conventional extraction methods used, as well as in higher phosphorus concentration of the soil solution.
• – In the upper soil layers of luvisols and in the deeper soil layers of diluvial sandy soils organic phosphorus was enriched, but did not significantly influence phosphorus intensity and delivery.
• – Compared to soils supplied with mineral fertilizers there are no particularities in phosphorus dynamics, from which differences in the interpretation of “available” phosphorus values with respect to phosphorus recommendation scales could be concluded.

     

Verhalten von Schwermetallen in Böden. 2. Extraktion mobiler Schwermetalle mittels CaCl2 und NH4NO3

Behaviour of heavy metals in soils. 2. Extraction of mobile heavy metals with CaCl₂ and NH₄NO₃ 156 soil samples from arable fields, grassland and forest stands were analysed for the CaCl₂^? and NH₄NO₃^? extractable contents of Cd, Zn, Mn, Cu and Pb. The average amounts of Cd, Zn, Cu and Pb extracted with CaCl₂ are higher compared with NH₄NO₃ whereas the relation for Mn is vice versa. The proportion of the NH₄NO₃^? extractable contents in percent of the CaCl₂^? extractable contents of Cd, Zn and Pb decrease with increasing pH, whereas the contents of Mn and Cu increase. Inspite of a differing extraction behaviour of the two salt solutions the CaCl₂^? and NH₄NO₃^? extractable amounts of Cd, Mn, Zn und Pb are highly correlated and can be converted one into another. The mobile (CaCl₂, NH₄NO₃) proportion of the corresponding total, EDTA and DTPA heavy metal contents is in close relation to the pH of the soils. Using CaCl₂ solution the threshold pH values for an increasing mobility decrease in the order Cd > Mn > Zn > Cu > Pb, using NH₄NO₃ as extractant the order is Mn > Cd > Zn > Cu > Pb. In the case of CaCl₂ as extractant soluble chloro-Cd-complexes will be formed so that the Cd mobility in soils will be overestimated in most cases.     

Zur Verwendung von Gesteinsmehlen in der Landwirtschaft. I. Chemisch-mineralogische Zusammensetzung und Eignung von Gesteinsmehlen als Düngemittel

The use of rock powders in agriculture. I. Chemical and mineralogical composition and suitability of rock powders for fertilization Five different rock powders were investigated in order to test their suitability for agricultural fertilization. The fertilization effect of rock powders is greatly influenced by the mineralogical composition and the intensity of grinding, but less by the total content of nutrients. The low content of soluble nutrients (less than 1%) and the high portion of elements without any importance for plant nutrition (more than 70% oxigen-bound Si, Al and Fe) raises the question if rock powders can be successfully applied as fertilizers, at least in annual cropping systems. Because of the enormous differences between the investigated rock powders the term “rock powder” does not describe any specific characteristics for the user.     

Die Rolle der mikrobiellen Biomasse und des mineralisch fixierten Ammoniums bei den Stickstoff-Transformationen in niedersächsischen Löß-Ackerböden unter Winter-Weizen. I. Poolgrößenveränderungen

Significance of microbial biomass and non-exchangeable ammonium with respect to the nitrogen transformations in loess soils of Niedersachsen during the growing season of winter wheat. I. Change of pool sizes Nitrogen transformations in loess soils have been examined by laboratory and field experiments. After straw application (· 8 t · ha^?1), N in microbial biomass (N_mic) increased by about 20 mg · kg^?1 soil (· 90 kg N · ha^?1 · 30 cm^?1) after 9 days of incubation (20 °C). Another laboratory experiment yielded an increase of about 400 mg of NH₄+-N · kg^?1 fixed by minerals within 1 h after addition of 1 M NH₄+-acetate. Defixation of the recently fixed NH₄+ after addition of 1 M KCl amounted to only 60 mg · kg^?1 within 50 days. In a field experiment with winter wheat 1991, an increase in N_mic of about 80 kg N · ha^?1 · 30 cm^?1 was observed from March to June. After July, growth of the microbes was limited by decreased soluble carbon concentrations in the rhizosphere. Different levels of mineral N-fertilizer (0, 177 and 213 kg N · ha^?1) did not affect significantly the microbial biomass. The same field experiment yielded a decrease of non-exchangeable ammonium on the “zero”-fertilized plot in spring by 200 kg N · ha^?1 · 30 cm^?1. The pool of fixed ammonium increased significantly after harvest. After conventional mineral N-fertilizer application (213 kg N · ha^?1). NH₄+-defixation was only about 120 kg N · ha^?1 · 30 cm^?1 until July.     

N-Wirkung von Rindergülle unter Zusatz von Dicyandiamid bzw. Stroh in Gefäß- und Lysimeterversuchen

Utilization of N in cattle slurry after addition of Dicyandiamide resp. straw in pot and lysimeter trials In a pot and lysimeter trial, leaching of nitrate of cattle slurry applied at different times (August, September, October, March) was tested with and without addition of DCD, and utilization of N by the following crop was determined. In a pot trial (sandy silt loam), the effect of additional straw manuring was also investigated. Pots were exposed to natural weather conditions from start of experiment (August) until sowing of rye grass (April). Application of straw as well as addition of DCD to slurry reduced leaching of N considerably. DCD addition with and without straw resulted in significantly higher N removals by rye grass. Unlike ammonium nitrogen “preserved” by DCD, slurry nitrogen biologically fixed by the rotting straw, however, was not yet available to the following rye grass crop (May to July). Slurry + straw + DCD generally led to higher amounts of residue N in the soil as a result of N balance. Also in the lysimeter trial, DCD reduced leaching of nitrate especially in vegetationless periods and thus improved the effect of cattle slurry applied in August resp. November (higher yields and N removals by silage maize).     

Akkumulation und Mobilisation von Phosphaten in einer Schwarzerde im Statischen Dauerversuch Lauchstädt - Betrachtung der P-Bilanz nach 84 Versuchsjahren

Accumulation and Mobilisation of Phosphate in Haplic chernozem of the Static Long-Term Experiment at Lauchstädt - Consideration of the P-Balance after 84 Years Phosphate balance was calculated and various soil P parameters of a long-term field experiment at Lauchstädt were determined in which mineral fertilizer and farm yard manure were applied in rates of 0 to 54 kg P/ha/year. The various fertilizer treatments resulted in a considerable variation of the P balance sheet ranging from -738 to 2652 kg P/ha. This implies that 59 % of the applied P (cumulated maximum 4477 kgP/ha) remained in the soil, the rest was taken up by crops. Assuming a balanced P supply in which crop P uptake equaled the P fertilizer rate, a rate of 12, 9 kgP/ha/year would be required. This rate was approximately calculated for the various treatments having received farm yard manure. Phosphate mobilized from the soil (up to 738 kg P/ha) was related to factors which had an impact on crop yield. The decrease of total P in the upper soil layer (0 to 25 cm) was lower than the cumulative P uptake of crops. It is therefore assumed that a considerable proportion of P taken up by crops came from the subsoil. The change in the P balance sheet obtained during 84 years was clearly reflected by various soil parameters including the maximum P adsorption capacity which was highest in the treatment with the largest P deficit (NK treatment).     

Die Rolle der mikrobiellen Biomasse und des mineralisch fixierten Ammoniums bei den Stickstoff-Transformationen in niedersächsischen Löß-Ackerböden unter Winter-Weizen. II. Umsetzung von 15N-markiertem Stickstoff

Significance of microbial biomass and mineral fixed ammonium with respect to the nitrogen transformations in loess soils of Niedersachsen during the growing season of winter wheat. II. ¹⁵N-turnover Field experiments 1988/89 on a fallow plot of the southern Niedersachsen loess area with straw application (δ 10 t · ha^?1, homogeneously incorporated by hand) yielded an increase in microbial biomass-N (N_mic) by 60 kg N · ha^?1 · 30 cm^?1 until March 1989 and further 40 kg N · ha^?1, till May which was almost completely remobilized until harvest. For a cropped plot (with winter wheat and 10 t · ha^?1 straw incorporation), N immobilization was of similar magnitude. Up to 18% of the applied ¹⁵N-fertilizer (185 kgN · ha^?1) were microbially immobilized. In contrast to 1988/89, no significant mass change of N_mic occurred in 1991 due to straw application (δ 10t · ha^?1). Variations in the amount of N_mic were nearly independent on the treatment (crop, with 140 kg fertilizer-N · ha^?1 or without N-fertilizer, respectively; fallow plot without fertilizer-N) within a range of 225-400 kg N · ha^?1 · 30 cm^?1. Directly after N-application (each 70 kg N · ha^?1 in March and in May), up to 100% of the fertilizer-N were assimilated by the microbes. Subsequently, remobilization of the immobilized nitrogen occurred within 2 (in March) or 6 weeks (in May), respectively. Simultaneously, organic soil-N was mineralized after each N-application and minerally fixed for us biggest part. Between March and June, the fixed NH₄+ decreased by about 112 kg · ha^?1 · 30 cm^?1.     

Schätzung der Denitrifikation in landwirtschaftlich genutzten Böden. II. Ergebnisse und Bewertung

Estimating denitrification in agriculturally used soils: II. Results and evaluation This is the second of two papers describing a denitrification model. Whereas in the first paper the model approach was described, the second paper deals with results obtained with the model. To evaluate the model's performance, 14 profiles in the catchment area of a water-work were studied in detail. For each site the potential and the actual annual denitrification rates were estimated. It was found that the least favorable conditions for denitrification occurred in the sandy soils of the study area. Consequently, estimated denitrification rates were lowest (< 10 kg N ha^?1 a^?1) in these soils. Estimated denitrification rates were highest (50 kg N ha^?1 a^?1) in peal and river plain soils, with either a high amount of organic matter and/or a high groundwater table. In silty loess soils, denitrification losses were estimated to be 20 to 35 kg N ha^?1 a^?1. With use of the anion concentrations in the surface layer of the groundwater, a plausibility study was conducted to evaluate the estimated denitrification losses. Its results show that the values obtained are realistic. However, a true calibration of the model is still necessary.     

Atmosphärische Deposition von Bioelementen in Agrar-Ökosysteme 2. Mitteilung: Schwefel-Interception eines Getreidebestandes

Atmospheric deposition of bioelements in agrar-ecosystems 2. Report: Sulphur interception by barley To measure the sulphur interception of cereals, small lysimeters were used as ?Wirkdosen”?. The crop was barley. During the vegetation period (soving to harvest) the small lysimeters were deposited in a barley field of about 1000 m². The investigation was carried out with 4 repetitions. The sulphur interception was determined from the sulphur balance. No sulphur interception by barley was measured. Due to the limited accuracy of the measurement an interception of 3–4 kg S/ha could be possible, but this quantity would have no ecological importance for agriculture. It is assumed, that all plants of low growth do not intercept sulphur in measurable quantities. This is a significant difference between agrar- and forest-ecosystems.