Zur Abhängigkeit des Bodenwasserpotentials von der Temperatur

Soil-water-potentials depending on temperature The soil-water-potential · of different soils has been measured in dependence of temperature. Between about — 0.2 · 10⁶ and — 0.7 · 10⁶ erg cm^?3 (corresponding to a pressure head of 2 resp. 7 m water) all soils show a significant dependence of the soil-water-potential on temperature always in connection with hysteresis phenomena. With soils rich in clay or sand the dependence is most pronounced. At very high suction values (< — 0.7 · 10⁶ erg cm^?3) the dependence becomes small. Thus the measurements agree well with psychrometric evaluations of Campbell and Gardner (1971) on the no-temperature-dependence of the soil-water-potential in the range of about — 3 ·10⁶ to — 20 ± 10⁶ erg cm^?3.     

Dicyandiamidabbau im Boden in Abhängigkeit von der Temperatur

Effect of temperature on the breakdown of dicyandiamide in the soil The breakdown of dicyandiamide in a soil (sandy silty loam, pH 6.2, 0.13 % N) was investigated in relation to temperature. 1. The rate of conversion of dicyandiamide (DCD) (20 mg DCD-N/100 g soil) to guanylurea increased with rising temperature (10°–90°C). After 20 days, 14–100 % of the added DCD was metabolized. Small amounts of DCD (0.67 resp. 1.34 mg DCD-N/100 g soil) were broken down completely within 20–80 days at 8°–20°C. 2. Guanylurea was transformed to guanidine and then to ammonium. Increasing temperature in the region of 10° and 30°C accelerated the transformation. At higher temperatures (up to 70°C) an accumulation of guanidine occurred.     

Der Wasserhaushalt von Fichte in Abhängigkeit von Boden und Atmosphäre

The water regime of spruce in relation to soil and atmosphere Simple observations of the water regime of potted spruce trees and measurements in the field are reported, followed by a discussion of spruce water potential in relation to soil and atmosphere water potentials. When the soil is sufficiently moist water regime of spruce is determined by the atmosphere. As higher the atmospheric demand and as lower the hydraulic conductivity of the soil as more difficult it is for a spruce plant to supply transpired water and more and more the potential transpiration rate is reduced. For short term aspects water storage in leaf tissues is of high importance. Observations show the possibility of water uptake by needles if wetted by rain or dew. The maximum amount of this way of water absorption is also given by the internal storage capacity.     

Wasserhaushalt und Dickenwachstum von Kiefern in Abhängigkeit des Grundwasserflurabstandes

Water budget and annual ring growth of pines for different groundwater depth conditions Relation between annual ring width and water supply was examined for different groundwater depth in an old pine stand on a sandy soil. The quotient Ereal/Epot is a suitable parameter to quantify water stress. Multiple regression analyses were used to describe the dependence between annual ring width and water stress. Mean growth of basal area can be expressed by Ereal/Epot of the actual and previous year. This site specific function was used to quantify growth reduction affected by ground-water lowering for various soil conditions.     

Stärkegehalte von Kartoffelknollen in Abhängigkeit von Kalium-Ernährung und Knollenentwicklung

Starch content of potato tubers in relation to K nutrition and tuber growth In a pot experiment with potato (cv Saturna) K content in tubers increased from 1.0 to 2.6 % of tuber-DM due to increasing rates of K fertilizer. Simultaneously starch in tuber fresh matter decreased from 21 to 15 %. Highest starch content in tuber dry matter was obtained in that K treatment which gave the highest yield in dry tubers. Measuring starch accumulation during tuber growth revealed that already in the flowering stage differences exist in the starch contents of the tuber dry matter between the lowest and highest K treatments, namely 69 % for K₁ as compared with 64 % for K₅. The rate of starch accumulation between flowering and final harvest, however, was similar in all K treatments. This suggests that K supply affects the storage tissue at an early stage of tuber development probably via different water relations of tubers.     

Ermittlung bodenphysikalischer Kennwerte in Abhängigkeit von Bodenart,Lagerungsdichte und Humusgehalt

Evaluation of soil physical parameters as a function of soil texture, effective density and humus content The latest, 4. edition of the Soil Mapping Instruction presents a new soil texture diagram with 31 partially newly defined soil textures. This diagram works without alternative names of clay silt mixtures, it takes into account the latest scientific findings and should obligatory be used in the new and old Bundesländer of the BRD. Though the soil textures define almost all soil specific valuations, the soil physical parameters depending from texture had to be recalculated on an enlarged database. 6352 records from 8 Bundesländer were used on this calculation. Out of these records most of the 31 soil textures could be characterized by representative and statistically proved values of air capacity, available water capacity, field moisture capacity and mean water permeability as a function of bulk density, dry, effective density and humus content. The values are presented in tables.     

Der Bulk-Stomata-Widerstand von Ackerbohnen und seine Abhängigkeit vom Bodenwassergehalt

Bulk stomatal resistance of Vicia faba and its dependence on soil water content Bulk stomatal resistance of beans (Vicia faba L.,) as a function of soil water content was estimated for 41 days by comparison of potential transpiration, determined from meteorological data, and actual transpiration, determined from soil water losses. The resistance of beans is about 46 s/m if soil water content is above 70 % of available field capacity and increases strongly in dryer situations. This behaviour can be described by an exponential function.     

Nitrifikation von Gülle-N in Abhängigkeit von Ausbringungstermin,pH-Wert des Bodens und Dicyandiamidzusatz

Nitrification of slurry N as dependent on application time, soil pH and addition of dicyandiamide Formation of nitrate after slurry application was investigated in relation to soil pH and dicyandiamide application in model trials at simulated outdoor temperatures of October or November till July. In the soil of pH 5.7, a supplement of 20 mg/kg DCD to slurry applied in October was sufficient to remarkably reduce nitrification which started not before March. In the soil of pH 7.2, formation of nitrate without DCD mainly occurred before winter, but was retarded by 20 mg/kg DCD till April/May. Higher amounts of DCD further delayed nitrification for about another month. After slurry application end of November (soil temperature 0°C), nitrification was retarded by dicyandiamide for up to 3 month.     

Aufnahme und Verlagerung von 15N-Stickstoff bei Sommergerste in Abhängigkeit von K-Ernährung und Mehltaubefall

¹⁵N uptake and distribution by spring barley in relation to K nutrition and mildew attack Barley cv. Aramir was grown in complete nutrient solution containing 0,5 (K₁), 1,5 (K₂) and 4,5 mM K (K₃) respectively till maturity. Part of the plants was infected by mildew (Erysiphe graminis), whereas control treatments were kept mildew-free by fungicide sprays. Symptoms of mildew attack were less at K₂ and K₃ and grain yields of infected plants were raised from 98 (K₁) to 160 (K₂) and 165 g/pot (K₃). In control treatments grain yields were 130 (K₁), 164 (K₂) and 163 (K₃) g/pot. During anthesis nitrogen in the nutrient solution was labelled with ¹⁵N for two days and ¹⁵N metablism was studied within 7 consecutive days. The aim of this pulse-chase experiment was to find out, how mildew attack and K nutrition influence N metabolism. The following results were obtained: a) ¹⁵N uptake increased from K₁ to K₂ in infected and healthy plants, though at slightly lower levels in the infected treatments. b) During 7 days after the ¹⁵N pulse up to 17,1% of the ¹⁵N absorbed were translocated into the grains. Better K status as well as spray treatments stimulated nitrogen translocation. c) Mildew attack of leaves does not seem to influence the conversion of grain-¹⁵N into grain proteins. Better K supply stimulates the rate of protein synthesis in the grain. d) In mildew infected leaves relatively more of the ¹⁵N absorbed is incorporated into leaf proteins. But this may be a consequence of slower grain growth, because already 7 days after anthesis infected plants in all K treatments had significantly lower grain yield. In spite of the short duration of the experiment the ¹⁵N data do not indicate that the visible depression of mildew attack by better K nutrition of the crop might inter alia be due to K stimulated defense reactions within N metabolism. This is in agreement with a previous experiment.     

Zusammenhang zwischen hydraulischer und mechanischer Bodenstabilität in Abhängigkeit von der Belastungsdauer

Interaction between mechanically and hydraulically affected soil strength depending on time of loading Soil‐deformation analysis often only considers the direct effects of mechanical stress on changes in void ratio or pore functions while the interaction between hydraulic and mechanical processes is seldomly mentioned. Thus, we analyzed the effect of mechanical stress and time of soil settlement on changes in soil strength and the corresponding interactions between stress‐dependent changes in pore water pressure on precompression stress for a clayey silt. Disturbed samples with a bulk density of 1.4 g cm^–3 and a water content of 25 g (100 g)^–1 were compressed for four time steps (10–240 min) at eight stresses (20–400 kPa) with four replications. During the experiments, the changes of pore water pressure and void ratio were registered. With increasing time of stress application, we determined an increased soil strain. The higher the stress‐application time, the smaller gets the void ratio and the precompression stress value. Parallel to these variations in settlement, we also found changes in the pore‐water‐pressure values. This is a consequence of decreasing pore diameter while the water saturation increases. Thus, the proportion of neutral stresses on total stress increases which coincides with a change of water suction (= unsaturated) conditions up to even positive pore‐water‐pressure values (from less negative to positive pore water pressure values). From our experiments, we can conclude that the changes in pore‐water‐pressure values already occur at normal stress values smaller than the precompression stress. This underlines the increasing sensitivity of soil deformation processes close to the internal soil strength. The results support the idea, that in order to quantify the mechanical strength of structured unsaturated soils, we always have to determine the changes in pore‐water‐pressure values, too.     

Molybdängehalte einiger Acker- und Grünlandpflanzen Schleswig-Holsteins in Abhängigkeit von Bodenfaktoren

Mo contents of some crops and grassland plants of Schleswig-Holstein in relation to soil factors . The Mo content of about 170 plant samples of typical soils of Schleswig-Holstein were in the range of 0,2–11 ppm, increasing from grass to red clover, white clover and rape. By comparison with limiting values for adequate Mo supply (0,3 ppm Mo for red clover and probably also for the other three plants), a fairly good supply of the plants investigated can be deduced. The factors responsible for the varying Mo contents of plants are first of all the pH-value, furthermore the content of active iron and available phosphorus in the soil. The different contents of oxalat-soluble Mo had apparently no influence in this range of good supply. Whereas the correlation between one soil factor and plant Mo content was high only in some cases, coefficients of determination of up to 80% resulted from the use of several factors by multiple correlation.     

Umsatz von 15N markiertem Nitratstickstoff im Boden in Abhängigkeit von Strohdüngung und Bodenfeuchte

Turnover of ¹⁵N labelled nitrate nitrogen in soil as related to straw application and soil moisture In incubation experiments the effect of straw application on the turnover of ¹⁵N labelled nitrate has been studied at two soil moisture levels (brown podzolic soil). High ¹⁵N losses were found at the high soil moisture level. These losses are supposed to originate from denitrification. At both soil moisture levels straw application reduced significantly the ¹⁵N losses. Straw application resulted in a remarkable decrease of the ¹⁵NO₃ content in the soil and promoted the incorporation of ¹⁵N into the organic soil fraction. The incorporation of ¹⁵N into α-amino N and particularly into the rest hydrolyzable-N fraction was favoured by straw, while the incorporation into the amide-N fraction was hampered. Exhaustive cropping (Lolium multiflorum and Sinapis alba) on the soil incubated before with ¹⁵N, showed that the ¹⁵N incorporated into the organic fraction was poorly available. Thus straw application resulted in significant yield depression. It is assumed that the fraction of the rest hydrolyzable N is hardly available to plants.     

Verteilung und Löslichkeit von Bor in Helianthus annuus in Abhängigkeit vom Bor-Angebot

Distribution and Solubility of Boron in Different Organs of Sunflower Plants in Relation to the Boron Concentration of the Nutrient Solution The distribution of boron in different plant organs and its solubility in various extractants was investigated in sunflowers supplied with different concentrations of boron in the nutrient solution. 1. The distribution of boron within the plant differs depending on boron supply. Under deficiency conditions the boron content of younger tissues is decreased (compared with older tissues) while under conditions of boron toxicity an accumulation in the older leaves results. 2. A cell in need of B takes the B from the solutions continuum of its surroundings. Under conditions of poor B supply almost all the B is converted to a form which is not soluble in water. A large part of this B is soluble in chloroform; a similar amount is chloroform-extractable from chloroplasts. The remainder is neither soluble in chloroform nor in inorganic extractants. 3. Surplus boron is not accumulated in all cells. It remains in the solutions-continuum until it is deposited at the end of the transpiration stream. Here it remains soluble in water or unspecifically occluded and is soluble in soda or acids. The distribution of surplus boron follows the pattern of a toxification. 4. In a plant adequately supplied with B only the boron in the transport pathways seems to be soluble in water.     

Anorganisch-katalytische Umsetzungen von Cyanamid und dessen Metaboliten in Quarzsand II. Cyanamidabbau unter dem Einfluß von Metalloxiden und Temperatur

Inorganic catalytical breakdown of cyanamide and its metabolites in quartz sand II. Cyanamide breakdown as influenced by metal oxides and temperature The inorganically catalysed breakdown of cyanamide with addition of water in presence of metal oxides was studied in quartz sand. Cyanamide breakdown and the formation of metabolites was investigated in relation to the kind and quantity of metal oxides as well as temperature.

• 1 The oxides or hydroxides of Mn, Cu, Zu, Ni, Co influenced the rate of cyanamide breakdown very differently.
• 2 Decreasing the quantity of oxides (amorphous Fe(III) – hydroxide, ochre, rust) from 0.5 to 0.1 g or 0.05g/100g of quartz sand retarded cyanamide breakdown in an oxide specific formation of urea and dicyanamide.
• 3 The influence of temperature (5 and 18°C) on the breakdown was not so great as that of moisture (5% and 150% of the water capacity).
• 4 A low temperature (5°C) and high moisture regime (150% of the water capacity) retarded cyanamide breakdown considerably almost completely stopping it. The type and concentration of the metal oxide (iron oxide) as well as the moisture and temperature of the reaction medium are very important in the inorganically catalysed cyanamide and water reaction leading to the formation of urea or dicyanamide.

     

Aufnahme und Verlagerung von 42K und 86Rb bei jungen Gerstenpflanzen in Abhängigkeit von einer Calcium-Behandlung der Wurzeln

Uptake and translocation of ⁴² and ⁸⁶Rb by young seedlings in relation to different calcium levels in the root medium The uptake of ⁴²K and ⁸⁶Rb by 8-d.-old barley seedlings was studied after 4 h period in solutions containing either ⁴²K or ⁸⁶Rb (1 mmol ⁴²KNO₃ + 1 mmol KCl; 1 mmol ⁸⁶RbCl + 1 mmol RbNO₃). The amount of ⁴²K was 56% and 20% higher than that of ⁸⁶Rb in the roots and shoots respectively (Pict. 1). Increasing the level of Ca in the root medium enhanced ^{42 86}Rb uptake. However the translocation rate of ⁸⁶Rb in the shoot was relatively lower than that of ⁴²K. In view of the content in the roots both elements were translocated to the shoot in a similar percentage (Table 1).