Juglans Cinerea: The American White Walnut

The American white walnut Juglans cinerea L. is a native North American tree in the Juglandaceae, or walnut family. It prefers rich, moist, rather neutral to slightly basic lowland soils. This is an in depth study of its taxonomy, morphology, anatomy, age, size, growth habit, distribution, ecology, propagation, economic importance, medicinal uses, toxicity, folklore, diseases and pests, and chemical constituents. J. cinerea L. is monoecious and confined in its distribution to the eastern and central parts of North America. It can be easily identified by its large, pinnately compound leaves and ashy-gray bark with broad, flat plates and deep furrows. It is a rather small to medium sized tree rarely attaining a height of more than 21.3 m or a trunk diameter of more than 91 cm. It is considered to be rather short-lived, rarely surviving more than 80 years. The fruits, referred to commonly as nuts, but more technically dry drupes, can be used for a variety of purposes. The most important of these are as food for man and other animals, as well as a source of a yellowish-brown dye. They are very rich in oil, which probably accounts for the common name butternut. Their caloric value is 3370 calories per pound, the highest for any nut species. The wood of this tree is very attractive and has a soft texture, light weight, and is easily workable. Because of these qualities it has been employed rather extensively in the past for interior finish and cabinet work, even though it is less durable and lower in strength than its close relative the black walnut. Despite these desirable qualities, the tree at present has little economic importance outside of local uses, such as in the New England states where maple butternut candy is made. The reason for this lack of interest is not actually known but it could be due to a variety of factors such as those mentioned above, as well as difficulty in cracking the nuts of wild trees and more importantly its susceptability to disease. The ravages of disease, combined with the great demand of this tree for cabinet work has resulted in this tree becoming very rare and scattered in native stands. A fact not known by many people is that many easily cracking, disease resistant varieties are now available through nurserymen. Probably the most important disease of this tree, which has resulted in its widespread decline over most of its range, is a canker disease caused by the fungus Sirococcus clavigignenti-juglandacearum Nair, Kostichka and Kuntz. Another important disease is a branch canker or dieback caused by the fungus Melanconis junglandis (Ell. and Ev.) Graves. Butternut twigs are most successfully grafted on 2-3 year old black walnut seedlings via a girdle graft or splice graft several feet from the ground just as growth begins in the spring. Grafts sometimes bear nuts after only two years from time of grafting. Trees are easily transplanted, and should be supplied with nitrogen and phosphorus fertilizer to stimulate growth and help fill out the nuts

Detrimental adsorbate fields in experiments with cold Rydberg gases near surfaces

We observe the shift of Rydberg levels of rubidium close to a copper surface when atomic clouds are repeatedly deposited on it. We measure transition frequencies of rubidium to S and D Rydberg states with principal quantum numbers n between 31 and 48 using the technique of electromagnetically induced transparency. The spectroscopic measurement shows a strong increase of electric fields towards the surface that evolves with the deposition of atoms. Starting with a clean surface, we measure the evolution of electrostatic fields in the range between 30 and 300 \mum from the surface. We find that after the deposition of a few hundred atomic clouds, each containing ~10^6 atoms, the field of adsorbates reaches 1 V/cm for a distance of 30 \mum from the surface. This evolution of the electrostatic field sets serious limitations on cavity QED experiments proposed for Rydberg atoms on atom chips.Comment: 4 pages, 3 figures Submitted to Phys. Rev.

Integrated analysis of water quality in a mesoscale lowland basin

This article describes a modelling study on nitrogen transport from diffuse sources in the Nuthe catchment, representing a typical lowland region in the north-eastern Germany. Building on a hydrological validation performed in advance using the ecohydrological model SWIM, the nitrogen flows were simulated over a 20-year period (1981-2000). The relatively good quality of the input data, particularly for the years from 1993 to 2000, enabled the nitrogen flows to be reproduced sufficiently well, although modelling nutrient flows is always associated with a great deal of uncertainty. Subsequently, scenario calculations were carried out in order to investigate how nitrogen transport from the catchment could be further reduced. The selected scenario results with the greatest reduction of nitrogen washoff will briefly be presented in the paper

Yield Gap Analysis for Tanzania – The Impacts of Climate, Management, and Socio-economic Impacts on Maize Yields

AbstractFood security will be the biggest challenge for Tanzania in the next decades. Besides, Tanzania has a multifarious ecosystem, which is endangered through not adapted agronomic practices. Current innovation strategies focus mostly either on the issue of food security or on environmental damages, but rarely on both issues. However, both issues are very crucial. With crop models, a wide range of agricultural practices can be investigated to show possibilities to optimize the application of these practices. Model assessments allow to separate the effects of agronomic and climatic conditions. The process-based model SWIM (Soil and Water Integrated Model) can compute the impacts of agronomic practices and thus develop strategies to decrease the yield gap between actual (farm) yields (Ya) and potential yields (Yp). The Yp are limited through the nutrient (Yn) and water supply and reduced by pests, diseases, and weeds. Furthermore, socio-economic impacts are also relevant (knowledge, tradition, or culture). These impacts can be captured by statistical crop models. Due to regional-adapted, integrated agronomic practices, Ya can be increased and thus the yield gap between Ya and Yp can be decreased. However, enhanced yields due to sufficient nutrient supply are more sensitive on climate (higher yield volatility). In particular, for innovative farmers increase the production risk of climate change impacts. These endangered adaptation from farmers and therefore both food security and the environment. However, not all influences between Ya and Yn can be explained by agronomic (fertilizer application, harvest time, tillage, and plant protection) and climatic conditions. Additionally, the Ya are affected by a broad range of non- biophysical, socio economic constraints. To decrease the yield gap on regional level, agricultural practices and knowledge are required, which consider regional-specific the issue of food security and environmental protection in a balanced ratio