摘要:

Calculation of labile phosphate from phosphate buffer curvesA procedure to calculate labile P from phosphate buffer curves (Q/I curves) is presented. It treats the buffer curves as Langmuir adsorption isotherms and calculates the labile P by extrapolation to zero. In a long term P fertilizer trial the labile P calculated in this way was nearly equal to the increase in plant available P as extracted by calcium lactate. From a heavily fertilized vineyard soil, on the other hand, more P was extracted by 3 · 10−3M CaCl2during the first extractions than calculated from the buffer curves whereas on further extractions the two quantities approached each oth

ISSN:0044-3263    

DOI:10.1002/jpln.19761390302

出版商:WILEY‐VCH Verlag    

年代:1976

数据来源: WILEY

摘要:

Investigations on the significance of the nutritional status of plants for their salt toleranceIn order to explain the causes of salt damages on crops in the Sibari Plain (Southern Italy) the nutrient contents of plants were used in addition to soil data.Increasing Na‐ and Mg‐salinity reduced the K‐contents of wheat plants during sprouting below the (preliminary) critical value of 30%oand the Ca‐contents below the value of 3%oin spite of high gypsum contents and optimum K‐supply of the soils (compared to soils with low salt contents). The content of nutrient elements can be improved by an increased nutrient supply up to the optimum range, and the content of detrimental elements in plants can be reduced below toxic limits. The specific toxicity of Mg‐salts (believed to be especially high) could be prevented by optimum nutrition of the plants until general salt effects became dominant factors of damage.At optimum nutrient supply 6–7%oMg in the tops of corn plants were toxic in greenhouse experiments. In the field even at high Mg‐supply of the soils no more than 2,5%oMg were found in cereals. At optimum K‐supply more than 1–2%oNa in wheat plants reduced the yield.The salt tolerance of plants, therefore, can be increased by p

ISSN:0044-3263    

DOI:10.1002/jpln.19761390303

出版商:WILEY‐VCH Verlag    

年代:1976

数据来源: WILEY

摘要:

Stabilitätskonstanten von Fe‐, Mn‐ und Zn‐Komplexen mit Humin‐ und Fulvosäuren, die aus mit organischer Substanz angereicherten ägyptischen Böden isoliert wurdenHumin‐ und Fulvosäuren wurden isoliert von Alluvial‐ und Kalkbodenproben, welche vorher mit verschiedenen anorganischen Rückständen angereichert waren. Die Verhältnisse von Metall zu Fulvo‐ und Huminsäuren und die Werte der Stabilitätskonstante der Metallkomplexe dieser Verbindungen mit Fe, Mn und Zn wurden bei pH 7 durch die Anwendung der Ionenaustauscherharz‐Methode bestimmt.Die durchschnittlichen Mengen der organischen Liganden, welche sich mit einem Mol von Fe, Zn und Mn verbanden, waren 2,1, 1,4 und 1,1 für Huminsäuren, und entsprechend 1,4, 0,9 und 0,6 für Fulvosäuren. Die Log K‐Werte der untersuchten Elemente waren verhältnismäßig höher mit Humin‐ als mit Fulvosäuren. Die Werte der Stabilitätskonstanten von Fe, Zn und Mn waren 7,05, 5,45 und 4,01 mit Huminsäuren und 5,15, 4,01 und 2,70 mit Fulvosäuren.Die Bodentypen hatten keinen Einfluß auf die organo‐metallischen Verhältnisse bzw. die log K‐Werte, dagegen spielt der Ursprung der organischen Rückstände anscheinend eine Rolle. Die Größe der log K‐Werte der verschiedenen Präparate standen in Beziehung zu den Mengen de

ISSN:0044-3263    

DOI:10.1002/jpln.19761390304

出版商:WILEY‐VCH Verlag    

年代:1976

数据来源: WILEY

摘要:

Extraktionsfähigkeit von natürlichen Huminstoffen und synthetischen Chelatbildnern bei der Extraktion von Fe, Mn, Zn und Ca aus BödenEs wurden die Fähigkeiten von Humin‐ und Fulvosäuren aus mit Rückständen angereicherten Bodenproben im Vergleich zu den synthetischen Chelatbildnern Na2EDTA bzw. Na2EDTA, zur Extraktion von Fe, Mn, Zn und Ca aus zwei verschiedenen Böden, studiert. Alle organischen Substanzen extrahierten Ca in der Reihenfolge F.A.>Na2EDTA>H.A.>Na2EDTA.Die natürlichen Chelate, besonders Fulvosäuren, waren ähnlich oder mehr effektiv im Herauslösen von Fe als die synthetischen Chelate, während das Gegenteil bei Mn und Zn eintrat.Mit Ausnahme von Na2EDTA brachten die untersuchten Verbindungen die nachstehenden Elemente in der Reihenfolge Fe>Mn>Zn in Lösung. Na2EDTA erhöhte die löslichen Mengen dieser Elemente in der Reihenfolge Mn>Zn>Fe. Das synthetische Chelat Na2EDDHA war mehr effektiv als Na2EDTA, während Fulvosäure mehr von diesen Elementen in Lösung brachte als Huminsäure. Das Verhalten von synthetischen und natürlichen Chelaten war von der Aktivität

ISSN:0044-3263    

DOI:10.1002/jpln.19761390305

出版商:WILEY‐VCH Verlag    

年代:1976

数据来源: WILEY

摘要:

Influence of Ancymidol and Ethrel on the synthesis of gibberellic acid (GA3) in cereal plants.In pot experiments with oat, barley and rye both growth regulators Ancymidol and Ethrel considerably reduced the GA3content in the 3 plant species. Ancymidol was approximately 10 times more effective than Ethrel. This higher effectivity of Ancymidol on the GA3content and the different structure of the Ancymidol molecule compared to Ethrel makes it probable that Ancymidol inhibits the GA synthesis in a different way than Ethrel (or CCC).Although Ethrel was less effective in reducing the GA content it decreased the stalk length more than Ancymidol. It is concluded that Ethrel not only influences the GA induced growth but also other processes which regulate the length growth of plants.

ISSN:0044-3263    

DOI:10.1002/jpln.19761390306

出版商:WILEY‐VCH Verlag    

年代:1976

数据来源: WILEY

摘要:

The Turnover of Plant Roots during the Growth Period and its Influence on “Soll Respiration”Mustard and wheat plants were grown under14CO2, 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 this14CO2‐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 proc

ISSN:0044-3263    

DOI:10.1002/jpln.19761390307

出版商:WILEY‐VCH Verlag    

年代:1976

数据来源: WILEY

摘要:

Determination of hydraulic parameters to estimate water movement and water storage in undisturbed soil. A comparison of field and laboratory methods.The soil moisture characteristics and the unsaturated conductivity were measured under field and laboratory conditions. In an undisturbed soil monolith in continous connection with the underlying loess‐soil‐layer 60 tensiometer and a neutronprobe‐accestube were used respectively to determine the matric potential and water content changes during a transient drainage experiment. Within the matric potential range of 0 to approximately −50 to −100 mbar the soil moisture characteristics determined in the laboratory and in the field are substantially different. When the matric potential is more negative than −100 mbar the slope of these curves and hence the specific moisture capacities are relatively well comparable.The field‐measured conductivity functions differ considerably from those values which were either measured under lab‐conditions or computed from the soil moisture characteristics data. The conductivities are expressed as a function of the matric potential which is possibly the major reason for these remarkable differences. However, the changes in water content in this dense silty clay loam are too small to express the unsaturated conductivity as a function of the absolute water content. The most serious problems in extrapolating the results of the less time consuming laborcalculation methods to field conditions arise in that range of matric potentials where water movement

ISSN:0044-3263    

DOI:10.1002/jpln.19761390308

出版商:WILEY‐VCH Verlag    

年代:1976

数据来源: WILEY

摘要:

Influences of some peat soil features on the capillary water supplyIn the Weiße Moor near Gifhorn the grassland suffered in summer 1972 from extreme drought (Fig. 2), on peat soil profiles with a thin top layer of medium decomposed high bog over layers of only slightly decomposed transition forms from bog to fen (Fig. 1). This transition peat form was marked by the nature of its pores (Fig. 1). It is supposed that this led to the considerable reduction of the unsaturated water flow (Fig. 3). By this the capillary water supply of the grassland from still largly saturated deeper peat layers (>30 cm) was limited

ISSN:0044-3263    

DOI:10.1002/jpln.19761390309

出版商:WILEY‐VCH Verlag    

年代:1976

数据来源: WILEY

摘要:

Einfluß von Stroh und Ammoniumnitrat auf Wachstum, Stickstoffixierung und Ertrag von SojabohnenIn einem Gefäßversuch mit sandigem Lehmboden wurde dem Einfluß von Stroh und Ammoniumnitrat auf Wachstum, symbiotische N2‐Bindung und Ertrag vonGlycine max(L) Merr. cult. Caloria nachgegangen.Die Versuchsglieder waren: Kontrolle, 9 und 18 g Stroh/Gefäß und 0,9 und 1,8 g N/Gefäß in Form von NH4NO3. Die Verabreichung von Stroh bei der Aussaat erhöhte die N2‐Bindung gegenüber der Kontrolle. Weiter erhöhte die Strohdüngung, besonders bei hoher Gabe, Blattzahl, Blattgewicht, Trockenmasse und den Samenertrag. Düngung mit 0,9 g N/Gefäß ergab einen

ISSN:0044-3263    

DOI:10.1002/jpln.19761390310

出版商:WILEY‐VCH Verlag    

年代:1976

数据来源: WILEY

摘要:

Soil hydrological methods for investigations on undisturbed samples of skeleton‐rich soilsNew methods are proposed, which allow the determination of moisture transmission properties of stony soils. A soil sampling technique is discussed whereby small monoliths are isolated from the surrounding soil and covered with polyester‐soaked glassfiber sheets. With use of such irregularly shaped columns the soil moisture characteristic and the unsaturated hydraulic conductivity are determined by laboratory procedures. Starting with a saturated column, suction is applied and the resulting outflow is measured. At the same time the suction in the sample is registered and also the hydraulic gradient within the sample is determined.Also discussed is a procedure to install tensiometers in stony soils. The installation provides reliable data and the maintenance is easy. By building in a heating system in the tensiometers, these can be operated all year ro

ISSN:0044-3263    

DOI:10.1002/jpln.19761390311

出版商:WILEY‐VCH Verlag    

年代:1976

数据来源: WILEY