Changes in the macro-pore structure of restored soil caused by compaction beneath heavy agricultural machinery: a morphometric study

Compaction can seriously degrade soil in modern agriculture. Soil that has been temporarily removed and stored is particularly sensitive to compaction when restored, although little is known about the structural changes in such soils under mechanical loads. We investigated the structural changes in a restored soil that had been gently cultivated for several years and then was trafficked by a heavy combine harvester, analysing the macro‐pore structure by quantitative morphometry of three‐dimensional microcomputed tomography images. Increased trafficking caused decreases in both the porosity and connectivity of the macro‐pores. The fraction of spherical pores (and thus the convexity of the pore space) and the mean pore separation were increased. Trafficking had no clear effect on the orientation of pores. While the mean pore diameter tended to decrease, biopores were more stable than interaggregate pores originating from the packing of soil aggregates. This is relevant for the development of structural stability in restored soils, as the macro‐pores consist mainly of interaggregate pores initially, whereas biopores develop and increase in proportion only gradually over time. Quantitative morphometry provides valuable morphological indices for the objective assessment of the macro‐pore structure and changes induced by compaction.     

Acrylamide in roasted almonds and hazelnuts

The influences of composition and roasting conditions on acrylamide formation in almonds and hazelnuts were investigated. Eighteen samples of almonds originating from the U.S. and Europe were analyzed for sugars and free amino acids, and acrylamide formed during roasting was determined. Asparagine was the main free amino acid in raw almonds and correlated with the acrylamide content of dark roasted almonds. Roasting temperature was another key factor and had a very strong influence on acrylamide formation. Almonds of European origin contained significantly less free asparagine and formed significantly less acrylamide during roasting as compared to the almonds from the U.S. Roasted hazelnuts contained very little acrylamide because of the low content of free asparagine in the raw nut. Reducing sugars, although being consumed much faster than free amino acids in both types of nuts, were not decisive for the extent of acrylamide formation during roasting.     

The contribution of<Emphasis Type="Italic"> Phragmites australis</Emphasis> litter to methane (CH<Subscript>4</Subscript>) emission in planted and non-planted fen microcosms

The contribution of Phragmites australis (Cav.) Trin. ex Steud. (common reed) litter as an origin of CH ₄-C was studied in a microcosm experiment. ¹⁴C-labelled, dried and ground P. australis root and shoot litter was buried in waterlogged, planted or non-planted fen microcosms. The evolution of ¹⁴CO ₂ and ¹⁴CH ₄ from the pots was monitored during the 35-day experiment. The ¹⁴C activity in the shoots and roots of the plants, soil, and inundation water was also analysed at the end of the experiment. Up to 40% of the released CH ₄-C originated from the added litter, whereas the rest originated from old soil organic matter. The comparison of planted and non-planted pots suggested that the contribution of recent plant-derived C (i.e. root exudates) to CH ₄ emission was negligible. The proportion of litter-derived CH ₄-C was significantly higher in the planted pots, suggesting that the presence of plants enhanced the formation of CH ₄ from litter. The major part of the initial ¹⁴C activity was recovered from the soil. About 3% was recovered from the inundation water, about 10% was emitted as CO ₂, and only <0.01% as CH ₄. However, these results demonstrated that plant litter and old soil organic matter are the major sources of CH ₄-C in fens during the early growth stage of P. australis.     

Rheological‐stiffness analysis of K+‐treated and CaCO3‐rich soils

Rheological methods are applied whenever flow behavior of substances needs to be investigated on a particle‐to‐particle scale executed by a parallel‐plate rheometer. Under oscillation, mechanical effects due to trafficking or vibrations caused by agricultural and forest machinery can be simulated by conducting amplitude‐sweep tests. Hooke's law of elasticity, Newton's law for ideal fluids (viscosity), Mohr‐Coulomb's equation, and, finally, Bingham's yielding are well‐known relationships and parameters in the field of rheology. This paper aims to introduce rheometry as a suitable method to determine the mechanical behavior of salt‐affected soils when subjected to external stresses. Potassium‐treated loamy sand from Halle and loamy silt from Kassel, both sites located in Germany, as well as loess from Israel, saturated with NaCl solutions in several concentrations were analyzed. From the stress‐strain–relationship parameters like the storage modulus G′ and the loss modulus G″, yield stress τ_y and the linear viscoelastic (LVE)–deformation range including the deformation limit γ_L, i.e., the transition from an elastic to a viscous state, were determined and calculated, respectively. With respect to salt effects, amplitude‐sweep tests on originally CaCO₃‐rich Avdat Loess show an increasing stability if saturated with higher NaCl concentrations. Comparable tests with K⁺‐rich substrates from Halle and Kassel evinced similar tendencies including the phenomenon of a critical K⁺ content, which becomes more obvious in case of the drained (–60h Pa) loamy‐silt samples from Kassel. Nevertheless, a higher microstructural stability is given in both substrates from Halle and Kassel, affected by different water contents, in general, which influence the exchange and availability of cations. The results verify that oscillatory tests are applicable for retracing salt‐induced effects, beside those ones, which are influenced by texture, current water content, and/or further chemical parameters.     

Räumliche Spannungsmessungen mit dem Stress State Transducer (SST) in ungesättigten aggregierten Böden - theoretische Betrachtungen und erste Ergebnisse

Stress measurements in undisturbed unsaturated soils with a Stress State Transducer (SST) - theory and first results A method to quantify the spatial stress distribution will be introduced and first results will be discussed. This method allows the detailed analysis of principal and shear stresses as well as the determination of the direction angle of principal stresses and the octahedral shear stress angle. The described Stress State Transducer (SST) is composed of six single strain gage sensors that enable the accurate and reproducable recording of stresses in six directions in a wide load range. Their data form the base for calculation of spatial stress distribution. Some first results show that in a luvisol derived from loess wheeling at a wheel load of 4.0 Mg induces high shear stresses in a depth of 30 cm. This probably causes plastic soil deformation.     

Experimental repetitive quantum error correction

The computational potential of a quantum processor can only be unleashed if errors during a quantum computation can be controlled and corrected for. Quantum error correction works if imperfections of quantum gate operations and measurements are below a certain threshold and corrections can be applied repeatedly. We implement multiple quantum error correction cycles for phase-flip errors on qubits encoded with trapped ions. Errors are corrected by a quantum-feedback algorithm using high-fidelity gate operations and a reset technique for the auxiliary qubits. Up to three consecutive correction cycles are realized, and the behavior of the algorithm for different noise environments is analyzed.     

Mutations in dynein link motor neuron degeneration to defects in retrograde transport

Degenerative disorders of motor neurons include a range of progressive fatal diseases such as amyotrophic lateral sclerosis (ALS), spinal-bulbar muscular atrophy (SBMA), and spinal muscular atrophy (SMA). Although the causative genetic alterations are known for some cases, the molecular basis of many SMA and SBMA-like syndromes and most ALS cases is unknown. Here we show that missense point mutations in the cytoplasmic dynein heavy chain result in progressive motor neuron degeneration in heterozygous mice, and in homozygotes this is accompanied by the formation of Lewy-like inclusion bodies, thus resembling key features of human pathology. These mutations exclusively perturb neuron-specific functions of dynein.     

Biotechnische Regulierung der Kohlmottenschildlaus in Kohlgem��se �C Sachstand und Perspektiven

The cabbage whitefly,Aleyrodes proletella, has developed to a key pest in brassica vegetable crops throughout Germany. In a 3-year project we investigated a biotechnical approach employing netting (0.8?×?0.8 mm meshsize) in combination with the native parasitoidEncarsia tricolor in an inoculative-inundative approach in organic Brussels sprouts under field conditions. In small scale plot experiments continuous netting from transplanting in May till October alone reduced whitefly larval densities by 77 % at peak infestation in all years. Remaining whitefly infestation under net was associated with the necessity of temporary net removal for the purpose of mechanical weeding, which caused primary whitefly infestation. Release of mass rearedE. tricolour under net at the first signs of larval infestation significantly increasedA. proletella-parasitation and reduced infestation compared to netted controls without release. Furthermore, at highest dosage in 2009,E. tricolor had a significant enhancing effect on raw yield and the quality level of marketable yield. Additional on-farm experiments without netting in 2008 and 2009 confirmed the control potential ofE. tricolor. Although the most important project mile stones have been achieved, namely (a)E. tricolour-establishment under net and in the open field, (b) enhanced parasitation corresponding with pest density decline and (c) a positive impact on yield and quality parameters, further research will be necessary. The focus should be on the initial infestation period, optimizing the timing, frequency and required dosage.