Determination of potassium and magnesium status of soils using different soil extraction procedures in the upper part of Mesopotamia (in the Harran Plain)

It is a common belief that most of the Turkish soils are rich in potassium (K) and magnesium (Mg) for crop production and that there is no crop response to fertilization of these nutrients. However, it is currently a common agricultural practice by farmers to use an excess amount of K and, in some instances, Mg fertilizers especially for horticultural cash crops. Two biological (pot and Neubauer experiments) and four chemical extraction methods (0.3 N HCl, 0.5 N HCl, 1 N NH4OAc, and 0.5 N NaHCO3) were employed to measure the amounts of extractable K and Mg in the selected ten soil series of Harran Plain (Fertile Crescent) in the upper part of the Mesopotamia area. Italian grass (Lolium italicum) and barley (Hordeum vulgare L.) were used as test plants in the pot and Neubauer experiments, respectively. The amount of slowly available K extracted using four chemical extraction methods were much higher in two soil series (Ekinyazi and Akcakale) than that of the other soil series. The Akcakale series had more slowly available Mg than the other soil series. Total amounts of slowly available K extracted with both of the biological, and 0.3 N HCl and 1 N NH4OAc chemical extraction methods were found statistically significant at 1% level. Correlation coefficients between the biological and chemical methods were calculated. As the number of grass harvests increased, percentage of K content decreased and Mg content increased in plant dry matter. At the last harvest, K content of the soils depleted, whereas Mg content nearly did not change. According to index grouping, Italian grass grown in the pots did not need K and Mg fertilization

Implications of cereal-based crop rotations, nitrogen fertilization, and stubble grazing on soil organic matter in a mediterranean-type environment

Soil organic matter (SOM) is essential to all soil processes that have an impact on crop production and the environment. Soils of the semi-arid Mediterranean region are low in SOM due to environmental conditions (temperature, moisture) and centuries of cultivation. Hence, as SOM has a major influence on soil aggregation, nutrient supply, and soil moisture, as well as the relationships between them, there is a need to assess the impact of cropping systems on this critical soil parameter. During a 14-year rotation trial of durum wheat with alternate crops in northern Syria (mean annual rainfall: 340 mm), we examined the effects of common rotations, fertilizer nitrogen (N), and variable grazing of cereal stubble on SOM by measuring organic C in soil samples (depth: 0-20 cm) during October-November, before planting. The rotations significantly influenced mean SOM level, the order being fallow (lowest), continuous wheat, lentil, chickpea, vetch, and medic (highest). The mean effect of N was to increase SOM, but grazing intensity tended to decrease SOM. While results from different aspects of the trial published elsewhere demonstrated the value of legume-based rotations as biologically and economically viable alternatives to fallow or continuous cropping, this soil sampling SOM study showed that crop production can be compatible with the goal of improving soil quality, with potential environmental benefits. Thus, soil and crop management practices involving appropriate rotations (legumes/cereals), adequate N fertilization of the cereal crop, and retention of crop residues can combine sustainable and economic cropping while reversing soil degradation. © TÜBİTAK

Displacement analysis of robotic frames for reliable and versatile use as external fixator

Centre for Robotics and Automation (CRA);Chiba Institute of Technology;City University of Hong Kong;IEEE Future Directions;Shenyang Institute of Automation Chinese Academy of Sciences4th Annual IEEE International Conference on Cyber Technology in Automation, Control and Intelligent Systems, IEEE-CYBER 2014 --4 June 2014 through 7 June 2014 -- --External fixators are widely used in the area of orthopedics to manage deformities and fractures. The historical trend in obtaining a mechanical infrastructure has shifted from simple devices like pins, rods, and hinges to more sophisticated frames involving parallel manipulators. Despite advantages of such robotic frames especially in removing stiffness issues, there are still problems associated with the reliable deployment of these modern devices. Problems like singularity, possibilities of guiding fragments along many different trajectories have been handled in this paper. A method has been shown how to detect singularity in displaced, aligned, and intermediate positions of the fragments. How the robotic system could be actuated according to different functions have been investigated, in addition to their effects on trajectories of distal fragment end. These considerations have been demonstrated on numerical examples. © 2014 IEEE