Vorräte und Nachlieferung an Mineralstickstoff im Boden eines Meliorationsexperiments zu Kiefer

The influence of soil amelioration procedures on the content and production of mineral nitrogen in the soil of a formerly litter raked pine stand in Upper Palatia In 1964 a soil amelioration experiment was started in a 87-year-old, Scots Pine stand of site class III.8., situated in the growth district ?Oberpfälzer Jurarand”?, East Bavaria. The soil, degraded in former times by litter removal, is a podsolic pseudogley, derived from cretaceous sediments with diluvial loess depositions. The trial comprised of the following treatments: NPKCaMg-fertilization, the N-input was repeated three times (I- ?Volldüngungsvariante”?); PKCaMg-fertilization and tillage to a depth of 20 cm (II–?Fräsvariante”?); PKCaMg-fertilization, tillage and underplanting of the perennial legume Lupinus polyphyllus (III-?Lupinenvariante”?); control (O). In the 15^th vegetation period after the beginning of the experiment and 6 years after the last N-fertilization respectively, the effects of these amelioration procedures on the content and production of mineral nitrogen (incubation in the field) were investigated. The mean N-net mineralization rate in the upper soil increased in the following sequence: control 100% – Fräsvariante 114% – Volldüngungsvariante 400% – Lupinenvariante 628%. A significant linear correlation could be detected between N_min-production and the nitrogen content in pine needles; methodical problems of incubation however caused an underestimation of the absolute mineralization level on all treatments. The nitrification was promoted by N-fertilization and lupine treatment. On the ?Volldüngungsvariante”? the N_min-production rose in the organic layer, on the ?Lupinenvanante”? in the mineral soil. Characteristic of lupine treatment were a low actual content of mineral nitrogen at the beginning of vegetation period and a rapid mineralization during springtime. The highest actual N_min-contents in the upper soils were generally observed in the summer. On the ameliorated treatments a significant decrease occurred in the late summer, followed by a small increase in the autumn.     

Biotisch und abiotisch gesteuerter Abbau von organischer Substanz im Boden

Biotic and abiotic decomposition of organic matter in soils The problem area of organic matter decomposition in soils by biotic, abiotic and photochemical mechanisms is tested under administration of uniformly ¹⁴C-labelled wheat straw, humic of fulvic acids; furthermore by the use of conventional methods. In four separate test runs, based on Hapludalf-Ah soil, formed in loess, as well as on Ah soil of a spodic Dystrochrept in pleistocene sand, measurements over years - altogether 57 measurement cycles - revealed similar decomposition rates of ¹⁴C fulvic and 14C humic acid. The approximate magnitudes of turnover were: biotic: abiotic (Hg-sterilization): biotic + UV-irradiation: abiotic + UV-irradiation = 100:20:70:50. The sterilized samples continued to release CO₂. Biotic + UV showed losses, compared with biotic, by partial UV sterilization. Abiotic + UV indicated increasing CO₂ release, compared with abiotic only, due to additional photochemical decomposition. In a larger program with radioactive as well as conventional methods of CO₂ measurement decomposition rates in different soils were tested under biotic, abiotic and photochemical condition in presence of metal ions, such as iron, aluminium, copper, zinc, lead and mercury. The impact by the added metals can be summerized as follows: Calcium and aluminium are favoring the organic matter decomposition under biotic conditions, while mercury, lead, copper, zinc and iron are rather inhibitive. Contrary, under biotic/steril conditions copper and especially mercury, further zinc and lead, at lower extent also calcium, impede CO₂ liberation. Since there are but small differences among the various test soils, soil own parameters seem to exert under abiotic conditions low importance only. Under UV irradiation calcium had in the biotic milieu high, in the steril/abiotic milieu a lower increasing effect upon COz liberation. Also iron indicates a stimulating effect under contemporary UV irradiation, which at lower level applies to lead and mercury too, particularly in connection with the sandloess Hapludalf of Harburg. Based on the observed CO₂ release also under abiotic/steril conditions final tests were conducted with calcinated quartzsand in contrast to soil, otherwise again under biotic, abiotic, as well as biotic or abiotic + UV conditions. Also in these calcinated sands ¹⁴CO₂ release from the ¹⁴C labelled straw continued. Addition of increasing amounts of aluminiumlactate causes decreasing ¹⁴CO₂ rates. An even stronger inhibition was produced by addition of zinclactate.     

Wirkungen organischer Substanzen auf Boden- und Düngerphosphat. Teil 2: Einfluß verschiedener organischer Stoffe auf die Mobilität von Dünger-P

Effekt of various organic substances on the mobility of fertilizer P Using model trials, studies were carried out on the influence of long-term organic manuring as well as incubation with rotted straw, maize roots, and slurry, on both the diffusion of ³²P from added (NH₄)₂H³²PO₄ in a ‘soil block’and the fixation rate of fertilizer phosphate in the soil. 1. In the “soil block experiment”, preincubation for 7 days with slurry (added to a low-P brown earth soil at a rate of 5% D. M.) increased diffusion of P as compared to an equivalent amount of added inorganic P. Preincubation with rotted straw resp. maize roots had only insignificant effects. 2. Long-term organic manuring with farmyard manure (P-long-term field trials Weihenstephan) had a significant positive effect on the diffusion of P in the soil block in contrast to annual application of mineral P. Effects of straw manuring were markedly less. 3. Addition of maize roots (5% D. M. to a non P-treated or P-enriched brown earth soil) resulted in a reduced fixation of labelled fertilizer phosphate (by 2–8%), longer preincubation periods, however, increased fixation. Preincubation with rotted straw increased P fixation by 2 to 4% as compared to an equivalent addition of inorganic P (diammonium phosphate).     

Der Einfluß agrochemischer Substanzen auf den Stroh- und Zelluloseabbau im Boden

The influence of agrochemical compounds on the decomposition of straw and cellulose in soil Supplementary to earlier investigations the decay of large amounts of straw-material with normal quantities of pesticides and normal amounts of straw-material with large quantities of pesticides was proved in a gasanalytical instrument and in pot-experiments. At the same time the straw-decay was tested in pot-experiments. The soil used in these pots has been untreated or treated for several years with different kinds of plant-Protecting-solutions. Finally there was made a test about the decay cellulose (KOZOVA 1963) with the same and different investigation materials. The results are as follows: 1. The use of plant-protection in wheat does not diminish the decay of straw even if the double quantity of straw treated with a medium-quantity of pesticides is added and normal quantities of straw treated with high quantities of pesticides are added to the soil. 2. Agricultural soils, which are cultivated for many years by using pesticides, do not show less straw-decay. 3. The decay of pure cellulose in the laboratory tested by the method of Kozova (1963) was diminished in soils, which had been treated for many years with herbicides and herbicides added with other plant-protection-means. This restriction seems to depend on unfavorable food-conditions for microorganisms eating cellulose in a soil without weed, since the direct dipping of cellulose in herbicid-liquid is not causing any decay-restriction. 4. On the other hand the direct sprinkling of the cellulose-filter-discs with fungicid-solutions of normal concentration diminished the decay strongly. However the decay was not restricted under field-conditions. This seems to be due to the fact that in the growing plants the fungicides have been transformed to a large extend and only small amounts could reach the soil.     

Einfluß unterschiedlicher Gehalte an organischer Bodensubstanz auf das Konsistenzverhalten verschiedener Mineralbodensubstrate

Effect of organic matter content on the consistency of several mineral substrates The effect of organic matter content on the consistency of soils different in texture was investigated. The shifts of the values of the consistency limits towards higher moisture contents are explained by different organic matter contents. The consistency limits of plasticity and liquidity. were significantly dependent on the content of organic matter.     

Einfluß der Bodenentwicklung auf den Zusammenhang zwischen Lagerungszustand und vertikaler Spannung im Boden

Effect of soil formation on packing and on vertical stresses in soils The relationship between void ratio and vertical stress was investigated for 34 profiles (loess, glacial till, sands) mostly under forest and some under meadows. Development in terrestric forest soils obviously results in ?non overconsolidated”? structure. The stress distributions as a function of depth partly point to constant shear parameters, partly to differences in the profile, especially clear in the case of Podsol and Sandbraunerde. Whereas the absolute value of the void ratio can be explained by the soil-own shear parameters, the decrease of void ratio as a result of equal load increments will be explained by the extent of translation, which is necessary to increase the mean number of grain contacts.     

Der Einfluß von Cadmium im Boden auf den Ertrag verschiedener Pflanzenarten und deren Cadmiumgehalt

Influence of Cadmium in Soil on the Yield of Various Plant Species and their Cadmium Content In pot experiments the influence of increasing quantities of cadmium in the soil (< 250 mg Cd/kg) on the growth of carrot, bushbean, tomato, ray grass and the cadmium content of various plant parts were studied. Considerable differences of the various plant species are observed. Sensitivity increases in the order: tomato (low) < broccoli < oat < lettuce < ray grass = carrot root < radish < bushbean = pea < spinach (very sensitive). Symptoms of toxicity are found in bush beans only. Fruit, seeds and roots accumulate less cadmium then leaves and straw.     

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.     

Einfluß variierter Temperatur und Feuchte auf mikrobielle Aktivitäten im Boden unter Laborbedingungen

Influence of varied soil temperature and moisture on microbial activities under laboratory conditions Under laboratory conditions the influence of temperature (10°C, 20°C, fluctuation from 5° to 30°C within 12 h with additional freezing for 3 days) and soil moisture (30%, 60% w.h.c., remoistening to 60% for 1 week) on several microbial activities was investigated. The biomass-related, glucose-induced short-term respiration and the dehydrogenase activity (TTC reduction) were higher at 10°C in most cases as compared to 20°C. Independent of freezing fluctuating temperature caused the lowest activities. The nitrogen mineralization (including nitrification), however, was affected in the opposite way. No marked influences were observed with β-glucosidase, arylsulfatase, and alkaline phosphatase. In the sandy loam nearly no effects of the soil moisture occurred and in the loamy sand especially the dehydrogenase activity was higher at 30% w.h.c., whereas the nitrogen mineralization was lower. From the results it can be concluded, that ecological conditions favouring mineralization without substrate addition may even reduce microbial biomass by decomposition.     

Auswirkungen der Gamma-Bestrahlung und Pasteurisierung von Klärschlamm auf seine mikrobiellen Eigenschaften und die Mineralisierung im Boden

Effect of γ-irradiation and pasteurization of sewage sludge to the microbiological properties and the mineralization in soil Hygienic aspects of sewage sludge application in agricultural practice are of increasing importance. Because parasites are extremely sensitive to γ-irradiation a dose of 300 krad is equivalent to pasteurization. The total bacteria count of the sewage sludge is reduced by this dosage by 90 to 99%. Enzymic activity is reduced after radiation at a rate of about 39%. Especially amylase, catalase, and alkaline phosphatase are extremely sensitive to irradiation. Mineralization studies of sewage sludge with different pretreatments in different soil types indicated no significant differences.     

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.     

Die Wirkung von Stroh- und Klärschlammdüngung auf das Huminstoffsystem einer Braun- und einer Schwarzerde

The influence of fertilization with straw and sewage sludge on the humic system of a brunizem and a chernozem The influence of fertilization with straw, sludge and mineral nitrogen on the humic system of a black and a brown soil was determined. Soil samples from a polyfactoriel pot experiment lasting two years were analyzed using a photometric analysis of the humic system. Sewage sludge increased extractable humic substances in both soils; straw increased chernozem humic substances but not brunizem humic substances. The other factors tested had no influence. Fertilization with straw, sludge and mineral-N each caused a degradation of the humic system of both soils, as was the case with the combined treatmetns on the brown soil. On the black soil, however, the combined treatment with straw and sludge caused a pronounced aggregation of the humic system. Additional fertilization with mineral-N resulted in an aggregation already with the lower sludge-treatment.     

Abbau und biozide Wirkung von Pflanzenschutz-und Schädlingsbekämpfungsmitteln im Boden am Beispiel von Kelevan

Degradation and biocide effect of chemical plant protecting agents and pesticides in soils by the example of the insecticide Kelevan By the example of the insecticide Kelevan it is proved that by means of a combined test plan degradation and biocide effect of chemical plant protecting agents and pesticides in soils can be tested simultaneously. For this test two different test soils as described in leaflet No. 36 of the Biologische Bundesanstalt (BBA), Braunschweig, are each divided in test samples of about 200 g dry matter. To answer the question whether besides the biotic an abiotic degradation of Kelevan and its primary subsequent products takes place in top soil, too, one part of the soil samples was sterilized by overheated steam. Afterwards these and the non-sterilized soil samples were treated with known amounts of Kelevan[cage-U-¹⁴C] and in accordance to leaflet No. 36 of the BBA stored in the dark at 22°U65% r. h. or under field conditions for different periods. To investigate the effect of Kelevan and its metabolites on microorganisms in top soil, further soil samples were treated with increasing amounts of Kelevan and also stored for different periods. At the end of storage periods on an average W,2 % of applicated radioactivities were recovered in the soil samples with Kelevan[cage-U-¹⁴C]. Whereas readioactivities of sterilized soil samples were nearly quantitatively extractable, increasing radioactivity amounts were held back under the same extraction conditions by the native soil samples, which were present as organic residue components of Kelevan(cagc-U-¹⁴C) and not as ¹⁴C-containing carbonate. During degradation, in both test soils as well under laboratory conditions as under field conditions, about one third of Kelevan[cage-U-¹⁴C] was transferred within 30 months via Kelevan acid[cage-U-¹⁴C] to Chlordecon[cage-U-¹⁴C] and about two thirds were transferred into various unknown ¹⁴C-labelled degradation products. The results of microbiological investigation prove that microorganisms were evidently neither selected nor decimated in both test soils by Kelevan and its degradation products.     

Einfluß von Stroh und Nitrapyrin auf den verfügbaren Stickstoff im Boden,den Ertrag und den Stickstoffentzug von Lolium multiflorum

Effect of straw and nitrapyrin application on the nitrogen availability in the soil and the yield and nitrogen uptake of Lolium multiflorum. In pot experiments the effect of straw and nitrapyrin application on the turn-over of fertilizer NH and on the nitrogen availability in the soil was investigated. The investigation comprised two sections: an incubation experiment in which straw and nitrapyrin together with NH-N were incorporated into a brown podsolic soil and a subsequent pot experiment with ryegrass. Nitrapyrin inhibited the nitrification and reduced the nitrogen loss of the soil. Compared with the treatments without nitrapyrin application, nitrapyrin resulted in a lower dry matter yield and in a lower nitrogen uptake of the ryegrass. Straw application reduced the nitrate content in the soil significantly. This effect was particulary evident in the treatments which did not receive nitrapyrin. Accordingly, nitrogen uptake and yield of ryegrass were significantly lower in the ‘straw treatments’ as compared with the treatments without straw. It is suggested that the impared nitrogen availability in the ‘straw treatments’ was mainly due to nitrogen losses caused by denitrification.     

Die Bedeutung der Festigkeitsverteilung in Einzelaggregaten für den Wasser- und Stofftransport im Boden

Relevance of strength distribution within aggregates to the movement of soil water and soil solution Different transport processes exist not only between the total soil and single aggregates, but also within individual aggregates. To clarify the structure of single aggregates without thin-sectioning, resistance to penetration was repeatedly measured on the same aggregate at a predefined soil water tension. The aggregates were sampled from the G_{o 2} horizon of a Typic Fluvaquent (Φ 15-25mm) and from the B_{g 2} horizon of an Aquic Chromudert (Φ 30-50mm) and equilibrated with water tensions ranging from roughly OhPa to 1000hPa. The strength distributions within individual aggregates were calculated using penetration resistance values of all measurements on one aggregate at a single water tension. These distributions, as exemplified by those at 300hPa and 1000hPa. show that the aggregates are surrounded by a thin, but very strong mineral skin which may be discontinuous, especially for aggregates from the Aquic Chromudert soil. In these aggregates, slickenside-like friction planes were found to penetrate through the skin. The deviation in the skin composition from that of the inner-aggregate described in literature, together with the finding of its strength, suggest that the exchange of water and solutes between the inter-aggregate and intra-aggregate pores is strongly impeded. The weaker parts within the skin, however, must be interpreted as preferred pathways, perhaps resulting in some fingering within aggregates at the prevailing matrix potential. The significance of different pathways within aggregates for the general transport of matter in soils is briefly discussed.     

N-Umsatz von verschiedenem Pflanzenmaterial im Boden in Gefäß- und Feldversuchen

Turnover of nitrogen of different plant material in the soil in pot and field trials In pot and field trials, effects of various plant materials like green rape, sugar beet leaves, potato foliage, straw of wheat, maize, or field beans, on the turnover of N in the soil (mineralization, N_min-concentrations, NO₃-leaching) and on yield and N uptake by some crops was tested in relation to mineral N fertilizer application. In both experiments, widely corresponding results were obtained: Irrespective of the N contents of the plant material, biological immobilization of N always was combined with beginning mineralization (pot trial: decrease of NO₃ leaching in late fall). Green rape (C/N = 12/1) showed already after 4 weeks in the field trial a marked net mineralization (N_min) of 20–30% of the added nitrogen which was quantitatively reflected in higher removals of N. Beet leaves (C/N = 20/1) were decomposed at a much slower rate in combination with an increase in N removals of subsequent crops by 6-20 % depending on the rate of mineral fertilizer application. All types of straw (CM = 57-8611) and potato foliage (CM = 73/1) caused a marked biological immobilization of N which resulted in reduced N removals depending on turnover rate (potato foliage: fast, wheat straw: slow) and N contents of the organic material. Different plant residues (straw, leaves) were applicated on a harvested field with cereal to test comparatively one part of the total value of different preceding crops; at onset of vegetation the N_min-contents in soil, depending on the climatic conditions during the non-growing season for mineralization, were analyzed.