Veränderung der Ionenkonzentration der Bodenlösung bei intensiv genutzten Braunerden der Geest im niederschlagreichen Sommer 1984

Changes in the soil solution ionic concentration of intensively cropped sandy dystric cambisols of NW-Germany in the rainy summer of 1984 Of 6 fields (barley, oats, corn, beets) soil samples of the layers 0–30 cm and 30–60 cm were collected 7 times with intervalls of 5 to 12 days from May until July. Soil water was centrifuged from the soil (Fig.1), and analysed for Ca, Mg, K, Na, NO₃ and Cl. From an initial high level the ionic concentrations in 0–30 cm (Tab. 1) were lowered drastically, and raised accordingly in 30–60 cm (Fig.3 and 5) by 90 mm rain within 10 days. The decrease in K-concentration by dilution was considerably less than that of Ca and Mg as would be expected if exchange equilibrium is reached. AR-values after Beckett (equalled those calculated from soil solution ion activities) did not change with K displacement, however, markedly with K plant uptake (Tab. 2). The theoretical chances of reducing unavoidable K displacement from the root zone at the cost of Ca and Mg are discussed.     

Untersuchungen zur Stickstoff-Immobilisation in mineralisch gedüngten Ackerböden aus Löß während der Vegetationszeit von Winter-Weizen

Experiments on nitrogen immobilization in minerally fertilized soils from loess during the growing season of winter wheat The nitrogen regime has been simulated during the growing period of winter wheat 1984/85 on a stagnigleyic cambisol using a simple, functional computer model. The model includes N mineralization from soil organic matter, transport of water and nitrate as well as growth of wheat and N uptake by the crop. Simulation starts at harvest of the previous crop. Simulated and measured N supply (soil mineral nitrogen plus N uptake by the plant) were in good agreement between september and december 1984. On this loess plot as well as on 10 other ones an over-estimation of mineral nitrogen in the soil up to 40 kg/ha was observed with beginning of december/january 1984/85 reflecting a seasonal trend. Experiments with ¹⁵N enriched Ca-nitrate 1984/85 on microplots of the same field point to a non-consideration of nitrogen immobilization. Fertilizer-N-immobilization amounted up to 35 kg/ha in the soil and to further 15 kg/ha in the straw material. The pool of fixed ammonium was of no importance with respect to the mobilization-immobilization-turn-over of fertilizer nitrogen. Experiments 1988/89 on microplots of a colluvial loess soil indicate a change of biomass nitrogen being responsible for the seasonal N-immobilization. An increase of biomass-N of about 30 kg/ha was observed under the growing wheat crop. An additional N-immobilization of nearly 40 kg/ha was observed with straw incorporation. A similar increase of microbial biomass nitrogen under winter wheat has been observed during the growing period 1987/88.     

Eigenschaften und Entstehung der Humuskörper typischer Wald- und Ackerböden Schleswig-Holsteins

Characteristics and genesis of humus substances of typical forest and arable soils of Schleswig-Holstein The humus substances of Luvisols and Podzols (forest, conventional and ecological farming system) were investigated wet chemically with “Streu- und Humus-Stoffgruppenanalyse” just as macro- and micromorphologically. Low nutrient contents and reduced bioturbation retard the decomposition of litter in the forest soils. Humus accumulation and transfer of humic substances are larger in the Podzol than in the Luvisol. Under arable land use the amount of humus decreased more under conventional farming. Organic fertilization stimulates the bioturbation and decomposition of litter.     

Zur Frage der N-Formen im Grund- und Bachwasser aus hydromorphen Böden

N-sources in groundwater and outlet channels of hydromorphic soils NO₃- and NH₄-concentration was observed in the surface flow (1972–74) and in groundwater (1974–76) of the catchment area “Honigau” with a size of 1375 ha. During summer with low surface discharge and groundwater tables high NH₄-concentration was measured as compared to NO₃-concentration. High ammonium content during summer appears to be typical for many hydromorphic soils, as confirmed by N-content in Sphagnum peat soils and marsh soils. During winter season only a correlation exists between surface discharge and NO₃-content in the Honigau area. This correlation disappears during very high discharge levels.     

Stickstoffumsatz in einigen obstbaulich genutzten Böden Südwestdeutschlands

Nitrogen turnover in some orchard soils of South West Germany Investigations in several orchards in South West Germany led to the following results: The actual content of mineral nitrogen as well as the rate of mineralization showed a marked dependence on the nature of soil, weather and soil management. Frequently the rate of mineralization had a distinct annual course following soil temperature. During summer additional oscillations partially were related to water and air contents of the soils. As a rule under old sward the rate of mineralization was distinctly higher than in the same soil being cultivated or treated with herbicides. Under mulched sod not only higher rates of mineralization, but also distinctly higher actual contents of mineral nitrogen could be found as compared with data under cropped sod. This ran parallel with higher nitrogen supplies to the trees and distinctly higher yields, but also with a worse storage quality of the fruits and conspicuously increased wash-out rates of nitrate (provided that manuring was continued with the primary amount of nitrogen). The total content of soil nitrogen depended much more on the method of soil management (swarded or not swarded) than on the amount of nitrogen fertilizers. It seems that the total nitrogen content of a soil tends towards a certain level corresponding to the conditions of site and soil managements and that this level cannot be raised constantly by manuring. From these results the following conclusions for practical fruit growing can be drawn: With modern forms of commercial fruit growing using mulched sward for soil management the nitrogen output is much less than with cultivating the same soil as arable land or intensive grassland. Due to cropping of the grass in former times nitrogen deficiency of fruit trees was not unusual, but since the grass under the trees has been mulched there is more danger of excessive nitrogen supply if manuring has been left as it was. Unlike the situation known of sand cultures with low nitrogen reserves in orchards with high mineralization rates the time of manuring is not of great consequence.     

Methoden zur Ermittlung von Grenzwerten der Phosphor-, Kalium- und Magnesium-Gehalte in Ackerböden

Assessment of critical values of phosphorus, potassium, and magnesium contents in arable soils Long-term fertilizer field experiments were carried out in order to calibrate soil test values for P, K, and Mg. In several years treatments gradually resulted in differences of soil nutrient contents. This made it possible to investigate the effect of fertilizer application on the relation between yield of plants and soil nutrient content. Methods were suggested to evaluate these relationships and to calculate critical soil nutrient contents. Emphasis was mainly directed towards the definition of level 3 of nutrient supply because it represents the aim of economic fertilizer application.     

Schätzung der Denitrifikation in landwirtschaftlich genutzten Böden. I. Grundlagen

Estimating denitrification in agricultural soils: I. Basic assumptions Despite a common interest of soil scientists, groundwater hydrologists, agronomists, and climatologists in quantifying soil nitrogen losses through denitrification, these are often neglected when the nitrogen turnover of agricultural soils is modelled. This is the first of two papers describing a semi-quantitative denitrification model that has been derived from data collected from soils of a catchment area near Viersen in the Lower Rhine Valley in West Germany. A field study was conducted to study the soil environment of denitrifying microorganisms. The results of this study were used to evaluate the effect of soil water, soil air and soil temperature, of the amount and quality of the organic matter, and of the pH-value on denitrification. To this end an existing model to quantify denitrification was extended. Provided the seasonal nitrogen excess of a field is known, the model in its new form enables an estimation of the extent of field-specific denitrification rates. This paper describes the effects of the parameters under consideration on denitrification, the model components used to describe these parameters, and the development of the denitrification model.     

Reisböden aus Kolluvium basaltischen Ursprungs im Hochland von Madagaskar

Paddy soils from basaltic colluvium in the Highland of Madagascar Three soils under lowland rice cultivation, found on the Highland of Madagascar, in the Vakinankaratra region, were investigated, in order to help understanding their ecology and to assess their fertility. The parent material of the three soils consists of basaltic colluvium. According to the FAO-UNESCO (1988), these soils have been classified as Ferralic Cambisol (D2) and Dystric Gleysol (D3 et D4). They are very poor in alkali cations, and rich in aluminium, iron and clay. The clay is mainly composed of gibbsite, kaolinite as well as of little amounts of goethite and quartz. This composition underlines the high degree of intensive soil weathering. The low fertility of the investigated soils is due to very low contents of available P, Ca, Mg, K and N, as well as to the high content of iron and manganese, which are toxic for rice plants under the anaerobic conditions of the soils during flooding. We therefore recommend to add to the soil beside NPK fertilizers, limestone powder in order to obtain a pH-value between 6 and 7. This will lead to an increase of Ca, Mg, and K as well as to a better plant availability of phosphorus and a decrease of the toxic effects of iron and manganese.     

Auswirkung unterschiedlicher Bodenbearbeitung auf die mechanische Belastbarkeit von Ackerböden

Effect of different tillage systems on the mechanical compressibility of arable soils The influence of different tillage systems (Zero-tillage, minimum tillage with rotary tiller and conventional tillage with moldboard plow) on the mechanical compressibility of two soils, a Regosol from loess-colluvium, and a Vertisol from mesocoic clay has been investigated as well as the causes and consequences for penetration resistance and air permeability. In addition the bulk density and the pore size distribution of aggregates have been investigated with regard to a possible explanation for the often described difference in stability in untilled or minimum tilled soils when compared to tilled ones. The results clearly demonstrate the higher mechanical stability of the untilled or minimum tilled soils as compared to tilled soils, which may result in better growing condition for plants. The higher stability is the result of a more vertical oriented pore geometry and stress distribution and can be explained by measured differences in the bulk density and pore size distribution within the aggregates too.     

Nährstoffauswaschung aus Weinbergsböden an der Mittelmosel

Leaching of plant nutrients from vineyard soils Leaching of plant nutrients particularly of nitrate from vineyard, arable, and forest soils of the Middle-Mosel have been investigated over a two-year period. Nitrate concentration in the leachate of vineyards amounted to an average of 326 mg NO₃/l and was about 10 to 20 times higher than the nitrate concentration in the leachate of arable and forest soils. According to the hydro-dynamic model assumptions on groundwater flow in the slates of the Rhenish Massif, the data obtained for the groundwater recharge (158-180 mm/year as gained in spring) and leaching of nitrate (144 kg N/ha/year) must be considered as minimum values. Hydrodynamic model assumptions suggest nitrate leaching rates of about 200 kg N/ha. Main reasons for the high leaching of nutrients are heavy fertilizer application and high mineralization rates in the vineyard soils favoured by relatively high soil temperatures and a high soil permeability.     

Mikrobielle Aktivitäten in landwirtschaftlich genutzten Böden Niedersachsens. I. Einfluß der ackerbaulichen Nutzung

Microbial activity of arable soils in Lower Saxony, Germany. I. Influence of agricultural practice A range of microbial functions were measured over four years in field trials on three soil types in Lower Saxony. Generally, glucose-induced short-term respiration and dehydrogenase activity were most susceptible to environmental influences. Higher microbial activity occurred under cereals than under sugar beets. Some microbial functions were affected by soil type and vegetation period. Furthermore, pesticide treatments of sugar beets inhibited some microbial functions.     

Anwendung des Agrarökosystemmodells EPIC zur Prognose des Wasser- und Nährstoffhaushaltes von landwirtschaftlich genutzten Flächen auf Sandböden in Ost-Brandenburg

Predictions of water and nutrient dynamics from agricultural sites on sandy soils in East- Brandenburg The validity of the agroecosystem model EPIC was tested for two agricultural sites on sandy soils without groundwater located at the moraine landscape in East-Brandenburg. Measurements of soil moisture, soil nitrate, above ground plant biomass and yield from these two agricultural investigation sites were compared with the corresponding simulation results of the model. The calculations of the soil water balance show a good fit between simulated and observed soil moisture values. The comparison between simulated and measured above ground plant biomass presents an underestimation of biomass by the model at the beginning of crop growth in spring and an overestimation at the end of the vegetation period. EPIC shows also an overestimation of yield in this study. The observed and the simulated soil nitrate values show no fit. Probably one reason for this fact might be the kind of process modeling included in EPIC, which was designed for long term calculations up to 50 years. Another possible reason could be the over estimation of N-uptakes of plants in comparison with estimates of the N-demand of plants based on the simulated yields. However a clear reason for the insufficient calculations of soil nitrate status by the model could not be found in this study. Further analysis of mineralization, N-uptake of plants and N-Ieaching in EPIC must be done in future.     

Die Bestimmung der Konsistenzgrenzen an einigen Vulkanaschenböden aus Südchile

The consistency limits of some volcanic ash soils of south Chile. Consistency limits of 15 different soils with high volcanic ash contents, located in Southern Chile, were tested by means of the DIN-18.122 procedure and the liquid limit also by the cone penetrometer method. The liquid limit of holocenic volcanic ash soils is profoundly influenced by carbon content, and the plastic limit by exchangeable cation capacity and carbon content. In pleistocenic volcanic ash soils, the liquid limit is determined by silt and carbon contents, the plastic limit by carbon content and the plasticity index only by clay content. No significant correlation was found between the Casagrande method and that of the cone penetrometer.     

Zum jahreszeitlichen Nitratgehalt und zur Nitratauswaschung von landwirtschaftlich genutzten Böden in Baden-Württemberg

Seasonal nitrate content in, and nitrate leaching from, agricultural soils of Baden-Wuerttemberg The behavior of soil nitrate was investigated at five field locations in the State of Baden-Wuerttemberg between 1984 and 1987. It was found that the amount of nitrate in the upper 90 cm of soil was not a constant, but fluctuated throughout the year with maxima in the spring and in the fall. Additionally, it was found that the amount of nitrate leaching during winter (from November through April) was correlated to, but not identical with the mineral nitrogen content of the previous fall. It further appeared that nitrate leaching in light sandy soils is mainly a mixing process, whereas in heavy soils it seems to be more a miscible displacement phenomenon.     

Die Bedeutung der Umsetzung von Weizenstroh im Hinblick auf den C- und N-Haushalt von Löß-Ackerböden

The significance of wheat straw decomposition with regard to the C- and N-cycle of a cultivated loess soil In 1984/85, a microplot experiment with ¹⁵N-enriched fertilizer was carried out on a field of the Calenberg loess area near Hannover (surface area of the plots: 1 ± 2 m; experimental soil: stagnigleyic cambisol from loess). On the one hand, the extent of immobilization as well as remobilization of native soil- and fertilizer-N associated with straw incorporation (± 8 t/ha) was quantified. On the other hand, the turnover as well as the alteration of C- and N-masses in the decomposing straw material was studied. About 70% of the initial dry organic matter of straw was mineralized within one year. An enrichment of fertilizer-N as well as native soil-N in the residues of up to 20 kg/ha was observed as compared to the initial N-mass. On a microplot cropped with winter-wheat, microbial N-immobilization of about 30–40 kg/ha (native soil-N and fertilizer-N) occured in the soil after straw incorporation. The immobilization extended to march 1985. Subsequent, associated with a C/N-ratio in the straw of 43, N-remineralization as well as -extramineralization was observed with 40 kg/ha at maximum in december 1985.     

Quantitative Mineralbestimmung in der Schlufffraktion von Böden auf der Grundlage der chemischen Analyse und unter Anwendung der Karl-Fischer-Titration. II. Ergebnisse bei Böden aus Geschiebedecksand,Geschiebemergel und Löß

Quantitative estimation of the mineralogical composition from silt-fractions of soils on the basis of the chemical analysis and by application of the Karl-Fischer-titration. II. Results obtained with soils from glacial sand, boulder marl and loess The contents of micas and feldspars were quantified in the silt-fractions from horizons of a podsolic brown earth developed on glacial sand and of lessives on loess as well as on boulder marl by using a method that has been described in detail in part I. Three components each of micas and of feldspars, namely muscovite (Ms), phlogopite (Phl), annite (Ann), orthoclase (Or), albite (Ab) and anorthite (An) were determined. The silt fractions of the three investigated soils are similar in their mineralogical composition. Feldspars are composed of equally high amounts of Or and Ab. Micas are dominated by the Ms-component. Apparently the mica content of the silt fractions is reduced during soil development, whereas no significant changes can be found for feldspars. The loss of micas is responsible for the decreasing potassium content of the silt fractions.     

Eine Vegetationstechnik zur quantitativen Bestimmung der Wasseraufnahme durch Wurzeln aus versalzten Rhizoböden

A vegetation technique to study the water uptake by roots from salinized rhizospheric soils The paper presents a vegetation technique to study the water uptake rate by roots, which are exposed to rhizospheric soils (soil in close vicinity of roots) of different combinations of soil osmotic and soil matrix water potential. The vegetation technique consists of two growth periods, a period of preculture and an experimental period. The aim of the preculture is to obtain series of homogenous plants growing each in a small pot filled with a densely rooted soil. At the end of the preculture all plants are very similar with respect to shoot and root development. The aim of the experimental period is to study the effects of various combinations of soil osmotic and matrix water potential on the water supply of plants. Thus the experimental period starts with supplying all pots with the same amount of water up to field capacity. In order to obtain different osmotic water potentials of the soil solutions, the water is differently salinized. Then the plants are exposed to constant climatical growth conditions. During the following days the water loss of the pots is determined hourly. The development of the matrix, osmotic and total soil water potential, the water uptake rate of the roots, the transpiration rate and growth rate of the shoots can be calculated from the water losses.     

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.