Agriculture and greenhouse effect : Consumption of carbon dioxide (CO2) at different intensity of land management

Für den Landbau der Bundesrepublik Deutschland werden CO2-Freisetzungen für Vorleistungen und bei produktionstechnischen Maßnahmen sowie temporäre CO2-Senken in geernteter Biomasse bei traditionellem Landbau und bei ökonomisch-ökologisch begründet veränderter Bewirtschaftung (Brachlegung, Extensivierung, Anbau nachwachsender Rohstoffe) geschätzt. Beim traditionellen Landbau stehen einem maximalen temporären CO2-Sink von ca. 256 Megatonnen CO2-Emissionen im Vorleistungsbereich von ca. 2 0,5 Megatonnen entgegen. Mit jeder Maßnahme der Extensivierung wird der temporäre CO2-Senkeneffekt durch Landbau reduziert

Influence of lime on the Ni transfer into plants

In zweijährigen Gefäßversuchen mit einem sauren, podsoligen sandigen Lehm, der mit Nickel (Ni) kontaminiert und mit steigenden Kalkgaben behandelt war, wurde der Ni-Transfer vom Boden in die Pflanzen untersucht. Es konnte gezeigt werden, dass Kalkgaben die mobile Ni-Konzentration im Boden, die Ni-Konzentration in Pflanzen und folglich den Transferfaktor signifikant vermindern. Auf der Grundlage der sigmoidalen Bolzman Gleichung wurden die Veränderungen in den Ca/Ni-Interaktionen geschätzt. Sie wird als Schätzfunktion für die Beschreibung vergleichbarer Prozesse im System Boden-Pflanze vorgeschlagen.In a two years pot experiment with a sod-podzolic, acid sandy loam, contaminated with nickel (Ni) and treated with increased lime doses, the Ni transfer from soil to plants was studied. It was shown that lime addition significantly decreased mobile Ni concentration in soil, Ni concentration in plants and consequently its transfer factor. The sigmoidal Bolzman equation estimates the range of changes in parameters of Ca and Ni interaction. It is suggested as an estimation function for the description of related processes in the soil-plant system

Dry bulk density of Gezira Vertisol as determined by X-ray computed tomography

     Soil bulk density is an important parameter indicating the aeration of the soil, the extent of its compaction, its permeability and the state of ease of tillage. It is as well important for expression of gravimetric soil moisture values as volumetric. Current measurements of soil bulk density depend on methods that, to some extent, disturb the soil. In the case of cracking soils, sampling of soil by cylinders probably results in an imprecise determination of the bulk density considering the possible bias in placing the core samplers away from large cracks. The clod method also results in siY1ificant overestimation of the field bulk density of soils because of the small sample used and hence less number of cracks accounted for.      Under continuous cultivation and cropping as practiced in the Gezira for more than 80 years, it is quite possible that the repeated wetting and drying of the soil could cause an adverse effect on soil structure that is possibly envisaged in effects on soil bulk density. X- ray computed tomography is a non-destructive imaging technique to construct a 3-dimensional image of the scanned object (Crestana et al., 1985; Hopmans et al., 1994; Phogat et ale, 1991; Rogasik et al., 1994, 1999). The computed tomogaphy scan has shown so far a consi- derable improvement in quantification of soil morphological parame- ters (Rogasik et al., 1994, 1999).      The objective of this study is to demonstrate the usefulness of the X-ray computed tomography in determination of the narrow spaced differences in the bulk density of cracking soils and to use the results  btained   to   examine   the  effects  of   continuous   cropping   on  soi

Die Böden der Nusswälder in Süd-Kirgisien – schützenswerte Ökosysteme von besonderer Bedeutung

Die Nusswälder der Jalal-Abad-Region erstrecken sich vorrangig auf den Nordhängen des Fergana- und des Chatkal-Gebirges im Tien Shan. Die Funktion der historisch gewachsenen Waldökosysteme hat sich geändert: dienten sie früher vorrangig der Nahrungsbeschaffung, haben sie heute besondere Bedeutung als natürlicher Ursprung zahlreicher Obst- und Nusssorten, die in vielen Ländern der gemäßigten Klimazone kultiviert werden. Diese Waldökosysteme zeichnen sich durch Artenreichtum aus, die Vielfältigkeit der Pflanzenwelt trägt zur Bildung von sehr fruchtbaren Böden bei. Braunerden sind die vorherrschende Bodenart. An siebem Standorten wurden an Bodenprofilen bis zu einer Tiefe von 150 cm Nährstoffe, Humusgehalt und -zusammensetzung sowie die Lagerungsdichte bestimmt. Der Humusgehalt im Oberboden lag zwischen 2,4 bis 18,5 % (organische Bodensubstanz). An pflanzenverfügbaren Nährstoffen wurden bis zu 25,4 mg/100 g Stickstoff, 4,9 mg/100 g Phosphor und 54,6 mg/100 g Kalium gemessen. Die Böden waren gut basengesättigt, sehr hohe Kalzium (670 bis 6.239 mg/100 g) – und Magnesiumgehalte (bis zu 1.179 mg/100 g) wurden nachgewiesen. Beide Elemente sind an der Entstehung von stabilen organo-mineralischen Bodenaggregaten beteiligt und tragen damit zur Erosionsminderung bei. In den untersuchten Regionen sind zunehmend Bodenverluste durch menschliche Einflüsse zu beobachten, deshalb sind Maßnahmen zur nachhaltigen Verbesserung der Bodenfruchtbarkeit und deren nachfolgende Erhaltung von größter Bedeutung.The walnut forests of the Jalal-Abad region are located primarily in the northern slopes of the Fergana and Chatkal mountain ranges of the Tien Shan. The role of these organically evolved forest ecosystems changed from a pure food source to an important natural gene pool functioning as source of many domesticated fruit and nut trees that are widely cultivated in countries of the temperate zone. Natural walnut forests are characterised by an enormous biodiversity of the plant communities promoting the formation of highly fertile soils. The dominant soil type is brown soil. On seven different sites, several soil characteristics were investigated on soil profiles until 150 cm soil depth. The soil samples were investigated for macro and micro nutrient contents, humus content and its composition, as well as bulk density. The humus content of the top soils ranged from 2.4 to 18.5 % (soil organic matter). Up to 25.4 mg/100 g nitrogen, 4.9 mg/100 g phosphorus, and 54.6 mg/100 g potassium in plant available form were determined. Noticeable high contents of calcium (670 to 6,239 mg/100 g) and magnesium (up to 1,179 mg/100 g) were also determined indicating a good base saturation of these soils. Both nutrients are involved in the formation of stable mineral and organic-mineral soil aggregates which should maintain an increased water erosion resistance of these soils. Since an intensive progress of soil erosion by human impacts is to observe in the nut-fruit forest belt of Kyrgyzstan, in particular the enhancement of soil fertility and its subsequent maintenance are of utmost importance

Quantification of root water uptake in soil using X-ray Computed Tomography and image based modelling

Spatially averaged models of root-soil interactions are often used to calculate plant water uptake. Using a combination of X-ray Computed Tomography (CT) and image based modelling we tested the accuracy of this spatial averaging by directly calculating plant water uptake for young wheat plants in two soil types. The root system was imaged using X-ray CT at 2, 4, 6, 8 and 12 days after transplanting. The roots were segmented using semi-automated root tracking for speed and reproducibility. The segmented geometries were converted to a mesh suitable for the numerical solution of Richards’ equation. Richards’ equation was parameterised using existing pore scale studies of soil hydraulic properties in the rhizosphere of wheat plants. Image based modelling allows the spatial distribution of water around the root to be visualised and the fluxes into the root to be calculated. By comparing the results obtained through image based modelling to spatially averaged models, the impact of root architecture and geometry in water uptake was quantified. We observed that the spatially averaged models performed well in comparison to the image based models with <2% difference in uptake. However, the spatial averaging loses important information regarding the spatial distribution of water near the root system

Discrimination of soil phases by dual energy x-ray tomography

Numerous soil ecological functions are influenced by soil structure through its impact on spatial and temporal distributions of soil particles, water, and air within the soil profile. The nondestructive technique of x‐ray computed tomography (CT) was used for studying soil structure. X‐ray attenuation determined for two energy levels (80 kV and 120 kV) was used to calculate distributions of water, air, and solids, as well as the voxel dry bulk density for two silt loam subsoils. The spatial resolution during scanning was 0.25 mm in the horizontal and 1 mm in the vertical direction. For different voxel sizes, the weighted mean of the derived volumetric water, air, and solid contents, and the dry bulk densities agreed with the sample's phase composition and dry bulk density obtained by weighing. The use of dual energy scanning to study the heterogeneity of soil structure and the spatial distribution of water, air, and solids is discussed