The Economic Impact of Site-Specific Weed Control

In order to evaluate economic and ecological benefits, site-specific weed control was realised in a 4-year experiment on five fields with a GPS-guided sprayer. An average of 54% of the herbicides could be saved. Savings were strongly dependent on crop and year. For grass weed herbicides, the savings were 90% in winter cereals, 78% in maize, and 36% in sugar beet. For herbicides against broadleaf weeds, 60% were saved in winter cereals, 11% in maize, and 41% in sugar beet. The monetary savings resulting from the reduction in herbicide use varied between the crops, depending on the amount of herbicides saved and the price of the herbicides. In maize, savings of 42euro/ha were realised, in winter wheat of 32euro/ha, in winter barley of 27euro/ha and in sugar beet of 20euro/ha. Large sections of the fields needed herbicide treatment significantly less frequently. In those areas where weed density remained below the weed control threshold, flora and fauna were allowed to establish largely without disturbance.     

Southern Hemisphere and deep-sea warming led deglacial atmospheric CO2 rise and tropical warming

Establishing what caused Earth's largest climatic changes in the past requires a precise knowledge of both the forcing and the regional responses. We determined the chronology of high- and low-latitude climate change at the last glacial termination by radiocarbon dating benthic and planktonic foraminiferal stable isotope and magnesium/calcium records from a marine core collected in the western tropical Pacific. Deep-sea temperatures warmed by approximately 2 degrees C between 19 and 17 thousand years before the present (ky B.P.), leading the rise in atmospheric CO2 and tropical-surface-ocean warming by approximately 1000 years. The cause of this deglacial deep-water warming does not lie within the tropics, nor can its early onset between 19 and 17 ky B.P. be attributed to CO2 forcing. Increasing austral-spring insolation combined with sea-ice albedo feedbacks appear to be the key factors responsible for this warming.     

Analyse der Ertrags- und Unkrautverteilung in Ackerschlägen mit einem Geo-Informations-System (GIS)

Analysis of the yield and weed distribution in arable fields in a Geo Information System (GIS)
The variation in yield was assessed and mapped in cereals, maize, sunflower and faba beans at Dikopshof Research Station of the University of Bonn from 1998 to 2000 using a CERES 2 yield sensor (RDS^® Company, Minchin-hampton, UK). The calculated yields differed on average by 4–12 % from weighed grain yields depending on the crop and the grain moisture. The yield maps were georeferenced with a Geo Information System and compared to soil and aerial maps, field data and maps of the weed, nutrient and organic matter distributions to identify reasons for the yield variation. In two of the three fields studied, a strong correlation amongst grain yield, soil quality and relief map was found. In another field that was originally separated into two sections with different crop rotations, the distributions of grain yield, phosphorus, potassium and organic matter were still influenced by the former cropping system. On the basis of the results of this study, recommendations were made for site-specific crop management. In addition, the results of this study contribute to elucidation of the complex influences of soil and management on the grain yield.     

Site-Specific Weed Control in Maize,Sugar Beet,Winter Wheat,and Winter Barley

A four-year study of site-specific weed control is presented in this paper. Weed seedling distribution was sampled and mapped prior to and after post-emergence herbicide application in four fields planted with maize, sugar beets, winter wheat and winter barley, rotating on one site. Herbicides and other weed control strategies were applied site-specifically according to the spatial variation of weed populations. Different decision algorithms were used for chemical weed control methods in each crop. A weed treatment map was created to direct location and dosage of herbicide application. The sprayer was coupled with a differential Global Positioning System (DGPS). The solenoid valves of the sprayer were opened automatically when the tractor entered a weed patch characterized in the weed treatment map. For site specific herbicide application, a patch sprayer was developed that allowed variable rate application and the selective control of each section of the spray boom.     

The use of shellfish for eutrophication control

Effects of excess loading of nutrients to the marine environment can be mitigated by mussel cultures, basically through nutrient removal from the marine environment when shellfish are harvested. Shellfish farming also provide other goods and services to the marine environment primarily through the impact on water transparency caused by shellfish filtration. There is an increasing awareness of the mitigation potential in mussel culture in relation to eutrophication, but so far practical examples of culture on full scale devoted to mitigation are few. Further, impact of mussel farming on nutrient cycling, e.g. in the sediments below the culture units, has raised concerns. In this review, we clarify concepts in relation to nutrient mitigation and discuss goods and services delivered by mussel mitigation cultures and their impact on an ecosystem scale based primarily on results from studies in heavily eutrofied estuaries. A multi-criteria approach for site selection is presented based on experiences from Danish waters, and economic aspects of mitigation cultures are analysed in relation to use of the produced mitigation mussels. Future perspectives for extractive cultures are discussed in relation to source of excess nutrients.     

Nährstoffverlagerung und Wasserbilanz einer Braunerde aus Löß-Kolluvium unter Ackernutzuug

Nutrient displacement and water balance under oat crop on a Cambisol from loess colluvium Field experiments with oat on a loess soil were carried out from January until December 1978 on a since 6 years cultivated small plot area to study the water budget and the influence of different nitrogen fertilization on nutrient leaching. Ceramic cups were used to obtain soil water samples at a depth of 100 cm at two-week intervals, two years after application of a compost and after the application of artificial nitrogen fertilizers. Main components of the water balance were calculated with the use of a computer simulation (CSMP) program, the performance of which was controlled by tensiometer measurements. It was calculated that 214 mm of the total 608 mm rainfall in 1978 drained out of the profile, and that the cumulative evapotranspiration was 448 mm. This study included 70 stress days during which evapotranspiration was reduced. Chemical analyses of the soil solution samples showed that an intensive nitrogen fertilization surrendered to a significant increase in the nitrate displacement, whereas the average yearly losses of other nutrient elements, including potassium, phosphorus, calcium and magnesium were unchanged. The use of the compost fertilizer resulted in a significant increase in the sodium concentration of the soil solution samples.     

Ash dieback: pathogen spread and diurnal patterns of ascospore dispersal,with special emphasis on Norway*

Dieback of European ash (Fraxinus excelsior), caused by the ascomycete Hymenoscyphus pseudoalbidus (anamorph Chalara fraxinea), started around 1992 in Poland and has since then spread over large geographical areas. By November 2010, the disease had been recorded in 22 European countries. The gradual expansion and high intensity of the ash dieback epidemic in Europe may suggest that H. pseudoalbidus is an invasive alien organism. In Norway, ash dieback was first reported in spring 2008, and a survey in early summer of the same year revealed that the disease had spread over large parts of the southern and eastern regions of the country. The distance from the southernmost to the northernmost infected stands was, at that time, about 400 km. Some old necrotic lesions were also observed, indicating that the ash dieback pathogen is likely to have been present in Norway since at least 2006. In 2009, a spore sampler was installed in a diseased ash stand at Ås, South‐Eastern Norway. Sampling started in late July and continued until late September. Large numbers of ascospores resembling those of H. pseudoalbidus were observed, with the maximum number of spores occurring from the end of July to mid‐August. The deposition of ascospores occurred mainly between 6 and 8 a.m. Ascospores are most likely to be the primary source initiating host infections and responsible for the rapid recent spread of H. pseudoalbidus in Europe.     

Reduced interannual rainfall variability in East Africa during the last ice age

Interannual rainfall variations in equatorial East Africa are tightly linked to the El Ni?o Southern Oscillation (ENSO), with more rain and flooding during El Ni?o and droughts in La Ni?a years, both having severe impacts on human habitation and food security. Here we report evidence from an annually laminated lake sediment record from southeastern Kenya for interannual to centennial-scale changes in ENSO-related rainfall variability during the last three millennia and for reductions in both the mean rate and the variability of rainfall in East Africa during the Last Glacial period. Climate model simulations support forward extrapolation from these lake sediment data that future warming will intensify the interannual variability of East Africa's rainfall.