Der Umsatz von Pflanzenwurzeln im Laufe der Vegetationsperiode und dessen Beitrag zur „Bodenatmung”︁

The Turnover of Plant Roots during the Growth Period and its Influence on “Soll Respiration” Mustard and wheat plants were grown under ¹⁴CO₂, their roots being tightly separated from the shoot sphere. Root formation, root respiration, and root decomposition could thus be followed during the plant development by radiometric methods. The total quantity of organic root matter in soil at harvest time turned out to be 20–50% larger than the amount of root residues as determined by ordinary washing procedures. Depending on the plant and duration of the experiment, an additional amount of up to three times more than this remaining root carbon was already mineralized during the vegetation period. Only one fifth of this ¹⁴CO₂-production could be attributed to the respiration of living root tissue, all the remainder seemed to be due to the microbial decomposition of dead roots, root residues and root excretions. Root respiration and root decomposition together produced almost four fifths of the total evolving CO₂-quantity, whilst the contribution from soil organic matter breakdown did not exceed one fourth of it. According to these data, the total rhizo-deposition amounts to 3–4 times as much organic substance than what can be found as root residues at harvest time. This rich supply of readily decomposable organic matter leads to a most intensive turnover in the rhizosphere, which should be of considerable influence on the dynamic processes in soil.     

Gefügebildung durch Bodentiere in „konventionell”︁ und „biologisch”︁ bewirtschafteten Ackerböden

Fabric formation by soil animals in “technically farmed” and in “organically farmed” arable land At 4 ecologically different sites in south-western Germany one “organically” and one adjoining “technically” farmed field were investigated. Samples of the Ap horizons of these 4 pairs of comparison were taken before the start of the vegetative period and again after harvest. The fabric formation by earthworms and by Enchytraeid worms (and Collembola) was evaluated on polished blocks by quantitative micromorphologic characteristics. – Significant differences appeared at one pair of comparison only, in part at a second one also. The two pairs of comparison which did not exhibit significant differences were para-brown earthes of loess in somewhat warmer climates. – An increase of Enchytraeid (and Collembola) droppings during the vegetative period was found as a by-result.     

Die „Baumfuß-Methode”︁, dargestellt anhand einer Untersuchung der Immissionsbelastung von Nordwest-Jugoslawischen Buchenwäldern

The “Trunk Base Method”, Demonstrated by an Investigation on Immission Load of Beech Stands in Northwestern Yugoslavia Due to stemflow, the soil area close to the stem of old beech trees (Fagus sylvatica) differs from the soil farther from the stem as a consequence of higher input rates of all elements. It is postulated that the level of deposition determines the degree of deviation in soil chemical properties of the trunk base area (“Baumfußbereich” = “micro-habitat”) compared with soil which is not influenced by stemflow water (“Vergleichsstandort” = “macro-habitat”). The paper attempts to estimate the relative load of air pollution in 10 beech stands (mainly Rendzinas and Cambisols from limestone and dolomite) of northwestern Yugoslavia. In each plot 10 micro- and macro-habitats were chosen, for analysis of soil samples of Ah horizons for pH and exchangeable cations after percolation with NH₄Cl. The differences in pH, base saturation and saturation of (H+Fe) between trunk base area and related soil are used to determine acid loading. The saturation of (H+Fe) turned out to be the most appropriate indicator to describing the acidification. The results indicate high acid deposition rates at sites 1–5,9 and 10, but low rates at stands 6–8. It is assumed, that the main sources of pollutants reaching the plots 1–5, which are located at the western declivity of Risnjak, are industrial plants in northern Italy and towns at the Adriatic coast. The sources of pollutants reaching the sites 9 and 10, which are located at the eastern declivity of Gorski Kotar, respectively Lika region, are the industrial plants in northern Yugoslavia and Hungary.     

Zu Eigenschaften,Horizontaufbau und Gliederung der „Haftnässepseudogleye”︁

Properties, horizons and classification of the “Haftnässepseudogleye” (Stagnosols periodically waterlogged with capillary water) The term “Haftnässe” (soil wetness due to capillary moisture) can be used in describing soils with Sg-horizons in which long-term waterlogging and anaerobic conditions occur in the absence of gravitational water. “Haftnässe” is caused by water held in pores with an equivalent diameter of 0.2–50 μm by soil-water tension (pF) between 1.8 and 4.2, when the air capacity of the horizons is very low. “Haftnässe” moves primarily by capillary forces and is available to plants (available water). In some soils, the horizon below the Sg-horizon contains large pores, is well aerated and tends to impede the movement of capillary water. This type of horizon is often wetter than the overlying and underlying horizons, due to the presence of capillary water in the immediately overlying Sg-horizon. The symbol “So” is proposed for such horizons. In these soils, in the Sg-horizon reduced iron compounds are oxidized and precipitated, forming rusty mottles. The sequence of horizons developed in the “Haft(nässepseudo)-gleye” (Stagnosols periodically waterlogged with capillary water) typically affects the continuity of the pathways along which capillary water normally moves. The “Haft(nässepseudo)gleye” are divided into two subtypes on the basis of the sequence of horizons in the soil profile:

• Typical “Haft(nässepseudo)gley” (Shn) exhibits a sequence Ah/Sg/(II)So and shows transitions to Luvisol and Glossisol,
• Thick “Haft(nässepseudo)gley” (Shm) exhibits a sequence Ah/Sg and shows transitions to “Stau(wasserpseudo)gley” (Gleysol periodically waterlogged due to perched water), Gleysol, Fluvisol and tidal marsh soil.

     

Die Bewertung der Pedofunktion „Pflanzliche Produktion”︁ in Schleswig-Holstein

Evaluation of the pedofunction “plant production” in Schleswig-Holstein The actual pedofunction “plant production” could be determined by longrunning yield measurements. If we take into consideration the field crops grain, sugarbeet and potatoes, only grain shows a relation between physiographic units and yield. The grain-yield in Schleswig-Holstein has a range of 40% (of maximum yield), about 20% could be explained by different types of soils, further 20% by the water-saturation-deficit of the air (sum of the May and June averages). Decreasing deficits of about one mm go along with increasing yields of about 5%. From a special exploitation of the Specific Crop Estimation results y = ?3,7x + 98 for the relation between relative grain yield and saturation deficit. For winterrye the results of the general exploitation are verified (see above). In contrast winterwheat shows a clear difference: The relative yield scatters about 50%, the relation between relate yield and saturation deficit is not linear, it depends additional on rainfall in summer and the waterholding capacity of soils. Pseudogleys (=Gleyic Luvisols) show a yield depression if the rainfall is less than 350 mm despite decreasing saturation deficits under 8 mm. For Braunerde-Pseudogley-Lessivés (=Cambisol-Gleyic Luvisol- Orthic luvisol) areas this values are 370 mm rainfall in summer and 10 mm saturation deficit. This investigation shows that the pedofunction “plant production” could be determined by the soil type distribution and some few climatic data.     

Über Veränderungen im Proteingehalt einzelner Pflanzenteile der Sonnenblume im Laufe einer Vegetationsperiode bei normaler Ernährung,bei Kupfer- und bei Stickstoffmangel

Litho- and Pedogenesis of slope positions of the Sandstone Odenwald Hilly slope positions of the Odenwald in SW-Germany are characterised by solifluction deposits which were formed from mesozoic sandstone during the glacial age. The evaluation of texture and heavy mineral analysis showed different amounts of loess in different layers of the solifluction deposits. Clay migration seems to be the main reason for differences in clay content between soil horizons and took place mainly in deposits with low loess contents. These are also the deposits in which a pronounced podzolization took place.     

Einfluß von Makrobicyclus „Kryptofix 222”︁ auf die Calcium- und Strontium-Aufnahme von Buschbohnen-Keimpflanzen

Influence of macrobicycle ?Kryptofix 222”? on calcium- and strontium-uptake of bush bean seedlings Macrobicycle ?Kryptofix 222”? (4,7,13,16,21,24-Hexaoxa-1,10-diazabicyclo-8,8,8-hexacosane) is the only known organic compound which chelates Sr (pK = 8.0) stronger than Ca (pK = 4.4). Therefore it was proved in experiments with 10 days old seedlings of bush beans, whether Kryptofix enables plants to discriminate between the physiological important Ca and the undesired Sr in favour of Ca. The following results were obtained: 1. At a constant (equimolar) supply of CaCl2 + SrCl₂ (50 μM/l each) increasing levels of Kryptofix raised the Ca/Sr-ratio of the seedlings from 0.8 (without Kryptofix) to 2.7 (with 150 μM Kryptofix/l) by reducing their Sr-content and increasing their Ca-content correspondingly. 2. Despite of reduced Sr-uptake the translocation of Sr to the primary leaves was promoted by Kryptofix (presumably via preventation of Sr fixation by the xylem vessels and in the surrounding tissue), whereas no influence exists on the movement of Ca. 3. At low CaCl₂ + SrCl₂ supply (5 μM/l each) the bean seedlings showed similar Ca and Sr-contents (Ca/Sr-ratio about 1.07), both in the presence or absence of equimolar Kryptofix concentrations. 4. With increasing CaCl₂ + SrCl₂ supplies (25–125 μM/l each), bean seedlings without Kryptofix increasingly favours Sr- against Ca- uptake (reaching a Ca/Sr-ratio of 0.49). On the contrary, in the presence of equimolar concentrations of Kryptofix (50–250 μM/l) there is an increasing preference of Ca versus Sr-uptake (Ca/Sr = 1.89).     

Genauigkeit von Bodenfeuchtemessungen mit „Time Domain-Reflektometrie” und., Frequency Domain-Sensoren”︁ in heterogenen Waldböden

Precision of soil moisture measurements done with “Time Domain Reflectometry” and “Frequency Domain Probes” in heterogeneous forest soils Using “Time Domain Reflectometry” (TDR) and “Frequency Domain” (FD) technique soil moisture of a homogenized soil- substrate of silty loam was measured in the lab as well as soil moisture of the same silty loam and of two soils with coarser texture and more heterogeneous structure in situ. These measurements were compared with gravimetric soil moisture measurements done at the same measuring sites. Thus the measuring errors caused by soil heterogeneities should be assessed. The standard error of both, the TDR- and the FD- probes amounted to less than 1 Vol%, at the in situ measurements as well as in the homogenized substrate. In the homogenized substrate under relatively dry conditions soil moisture was overestimated to about 2 Vol% by both electronical methods, which is most likely the result of compactions in the contact zone between rods and the soil caused by the insertion of the rods. In the field both electronical methods, however, underestimated the soil moisture up to 14 Vol%. This applied especially to the surface of the mineral soil and under the influence of high stone contents. This deviation is interpreted as an effect of gaps along the rods, caused by the insertion. In loosely packed and stony upper soils we propose therefore to install the rods in homogenized autochtoneous soil material having settled to its natural bulk density instead of inserting them into the natural layered soil.     

Einfluß exogen veränderter „source-sink”︁-Beziehungen auf die Anzahl der Endospermzellen und die Kornentwicklung bei Sommerweizen

Influence of an exogenously changed source-sink relationship on the number of endosperm cells and grain development in spring wheat In 2 years pot experiments with spring wheat the source-sink ratio was changed by shading the plants at different times after anthesis, by removal of flag leaf blades, and by phytohormone treatment of the ear. The effect of the different treatments was recorded by determining the number of endosperm cells per grain, the single grain weight and the grain yield. In grains of normally illuminated plants the maximum number of endosperm cells was reached 2 to 3 weeks after anthesis. The storage of assimilates within these cells depends on the intensity of illumination during the entire grain filling period. Shading the plants between anthesis and maturity led to a 23 to 34% decrease in grain yield, but only to a 7 to 16% decrease in the number of endosperm cells. The same drop in the endosperm cell number was observed in plants shaded for only 15 days from the start of anthesis. A subsequent period of normal illumination till maturity led to a marked increase in the single grain weight. No decrease in the endosperm cell number was seen in plants shaded from the 15^th day after anthesis till maturity. There was, however, a 12–13% reduction in the single grain weight and grain yield in these plants as compared with the control. Removal of the flag leaf at anthesis reduced the number of endosperm cells by 6 to 11%, the single grain weight by 10 to 29% and the grain yield by 15 to 25%. CCC and Ancymidol treated plants in the shading trials showed the same decrease in the endosperm cell number but a more pronounced reduction in the single grain weight compared with control plants. Their reactions to the various shading trials followed the same general pattern as the control plants. The results of the shading experiments confirm that the endosperm cell number is not the only determinating factor for the single grain weight. The application of kinetin and abscisic acid to the ear had no effect on the number of endosperm cells and single grain weight. Abscisic acid, however, reduced the number of graines per ear.     

Chemische und mikrobiologische Veränderungen in einem Rigosol nach mineralischer Düngung im langjährigen Feldversuch und kurzzeitigen aeroben Inkubationsversuch

Chemical and microbiological changes in a Rigosole after mineral fertilization in long-term field experiments and short-term aerobic incubation trials A sandy clay loam which often showed priming effects in a differently fertilized (control, 120 kg N/ha, 240 kg N/ha) long-term field experiment, was aerobicly incubated (25°C) and analysed for chemical and microbial parameters. The total nitrogen and C_org contents in the 240 kg N/ha treatment were markedly lower than in the unfertilized as well as in the 120 kg N/ha treatment. Long-term fertilization with 240 kg N/ha increased the dehydrogenase activity by about 34% in comparison to the control and about 54% to the 120 kg N/ha variant and enhanced the population of amino acid ammonifying and proteolytic bacteria. After analogous fertilization in model trials, positive as well as negative priming effects were shown. Thereby no linear dependence occurred in relation to the amount of nitrogen added. The effects on biological criteria were similar both under laboratory conditions as well as in long-term field experiments. The total nitrogen and C_org contents of humus fractions partly showed differences in dependence on fertilization.     

Oxidation von „unverändertem”︁, methyliertem und hydriertem Lignin in Gegenwart von SiO2 and Hydrochinon (1,4-Dihydroxybenzol)

Oxidation of ?unalterated”?, methylated and hydrogenated lignin in the presence of SiO₂ and hydroquinone (1,4-dihydroxybenzene) Under the conditions choosen, which were similar to those in soils, peats and composts, the oxidation by hydroquinone and its (aut-) oxidation products was generelly greater on the methylable than on the hydrogenable structures of lignin. Especially phenolic and enolic hydroxy as well as aldehyde groups, but also single aliphatic double bonds in propene side chains, phenyl cumarone systems, stilbenoide structures as well as such conjugated to aldehyde and ceto groups forced the O₂-absorption on lignin.