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The Limits to Growthwas published 50 years ago. Ordered by the Club of Rome, the study was a milestone in the analysis of the economic, demographic, technical and ecological effects of the existing economic system. In industrialised Western countries in particular, the critical examination of the development model of continuous economic growth led to a broad discussion about the far-reaching implications of a global economy focusing on growth, on a planet with finite natural resources.

Knowledge gaps regarding system perspecitive. Examples with focus on 1) Climate change adaptation; 2) Biodiversity conservation; 3) Soil fertility; 4) Transformation and transition

Foto of field trial, statistical output

Jahrbuch der Braunschweigischen Wissenschaftlichen Gesellschaft, vol. 2021Jahrbuch 2021 der Braunschweigischen Wissenschaftlichen Gesellschaft, vol. 2021, p. 133

For several decades, farmers have been mixing rock powders with livestock slurry to reduce its NH3 emissions and increase its nutrient content. However, mixing rock powders with slurry is controversial, and there is currently no scientific evidence for its effects on NH3 and greenhouse gas (GHG) emissions or on changes in its nutrient content due to element release from rock powders. The major aim of this study was therefore to analyse the effects of mixing two commercially established rock powders with cattle slurry on NH3, CO2, N2O and CH4 emissions, and on nutrient release over a course of 46 days. We found that rock powders did not significantly affect CO2 emission rates. NH3 and N2O emission rates did not differ significantly up until the end of the trial, when the emission rates of the rock powder treatments significantly increased for NH3 and significantly decreased for N2O, respectively, which coincided with a reduction of the slurry crust. Cumulative NH3 emissions did not, however, differ significantly between treatments. Unexpected and significant increases in CH4 emission rates occurred for the rock powder treatments. Rock powders increased the macro- and micronutrient content of the slurry. The conflicting results are discussed and future research directions are proposed.

While intercropping is known to have positive effects on crop productivity, it is unclear whether the effects of mixing species start at the early plant stage, that is, during germination. We tested whether the germination of two legume species, alsike clover and black medic, characterized by a contrasting response to water availability and temperature is affected by mixing. We set up four experiments in each of which we compared a 1:1 mixture against the two monocultures, and combined this with various other experimental factors. These additional factors were (i) varied seed densities (50%, 100% and 150% of a reference density) in two field trials in 2016 and 2017, (ii) varied seed densities (high and low) and water availability (six levels, between 25% and 100% of water holding capacity (WHC)) in a greenhouse pot trial, (iii) varied seed spacing in a climate chamber, and (iv) varied temperatures (12 °C, 20 °C and 28 °C) and water availability (four levels between 25% and 100% of WHC) in a climate chamber. Across all experiments, the absolute mixture effects (AME) on germination ranged between −9% and +11%, with a median of +1.3%. Within experiments, significant mixture effects were observed, but the direction of these effects was inconsistent. In the field, AME on germination was significantly negative at some of the tested seed densities. A positive AME was observed in the climate chamber at 12 °C, and the mean AME decreased with increasing temperature. Higher density was associated with decreased germination in the field, indicating negative interaction through competition or allelopathy, among seedlings. Our findings indicate that interaction among seeds in species mixtures may be ongoing during germination, but that the direction of the mixture effect is affected by complex interactions with abiotic and biotic factors.

Yield stability is important for food security and a sustainable crop production, especially under changing climatic conditions. It is well known that the variability of yields is linked to changes in meteorological conditions. However, little is known about the long-term effects of agronomic management strategies, such as the supply of important nutrients. We analysed the stability of four major European crops grown between 1955 and 2008 at a long-term fertilization experiment located in Germany. Six fertilizer treatments ranged from no fertilization over the omission of individual macronutrients to complete mineral fertilization with all major macronutrients (nitrogen, phosphorus, potassium and calcium). Yield stability was estimated for each crop × treatment combination using the relative yield deviation in each year from the corresponding (nonlinear) trend value (relative yield anomalies (RYA)). Stability was lowest for potato, followed by sugar beet and winter wheat and highest for winter rye. Stability was highest when soils had received all nutrients with the standard deviation of RYA being two to three times lower than for unfertilized plots. The omission of nitrogen and potassium was associated with a decrease in yield stability and a decrease in the number of simultaneous positive and negative yield anomalies among treatments. Especially in root crops nutrient supply strongly influenced both annual yield anomalies and changes in anomalies over time. During the second half of the observation period yield stability decreased for sugar beet and increased for winter wheat. Potato yields were more stable during the second period, but only under complete nutrient supply. The critical role of potassium supply for yield stability suggests potential links to changes in the water balance during the last decades. Results demonstrate the need to explicitly consider the response of crops to long-term nutrient supply for understanding and predicting changes in yield stability., Environmental Research Letters, 16 (1), ISSN:1748-9326, ISSN:1748-9318

Roots of cover crops are important for nutrient uptake and prevention of nitrogen leaching. Root length density (RLD) and rooting depth of eight cover crop species were determined with the profile wall method before and after winter. High RLD was found for winter rye and crimson clover. A gain in RLD during winter was detected for winter rye and crimson clover, whereas bristle oat, oil radish, oil radish ‘deeptill’ and phacelia reduced RLD during winter. Great rooting depth before winter were found for oil radish and winter turnip rape. Mixtures of cover crops with a high RLD and a deep-rooting cover crops might be an approach to enlarge nitrogen uptake from the soil by cover crops’ roots.

Städte, Gemeinden und Landkreise haben in der COVID-19-Pandemie einen entscheidenden Beitrag zur Bewältigung der Krise geleistet. Zugleich wurde noch einmal offensichtlich, wie krisenanfällig und wenig resilient die kommunalen Finanzen und damit wie abhängig die Kommunen von Zuweisungen von Bund und Ländern sind, um ihre Aufgaben vor Ort verantwortlich zu erfüllen. Dabei wurden auch die durch Corona forcierten fiskalisch aufwendigen Herausforderungen für die Sanierung der Innenstädte/Ortskerne und bei der Digitalisierung der Kommunalverwaltungen einbezogen. Das vorliegende Positionspapier eines Anfang 2021 eingesetzten Ad-hoc-Arbeitskreises der ARL setzt sich mit den durch die Pandemie offenbarten strukturellen Defiziten der kommunalen Finanzausstattung auseinander und legt Reformvorschläge vor, wie eine für die kommunalen Aufgaben auskömmliche, die Selbstverantwortung stärkende und krisenfeste(re) Finanzierung der kommunalen Haushalte gestaltet werden sollte. Cities, municipalities and rural districts have made a decisive contribution to tackling the crisis caused by the COVID-19 pandemic. At the same time, the lack of resilience and vulnerability of municipal finances has again become obvious. In order to responsibly carry out their local tasks, the municipalities are thus dependent on allocations from the federal and state governments. This is also relevant to the fiscally costly challenges related to the redevelopment of inner cities/town centres and the digitalisation of local administrations, requirements that have been heightened by the Covid-19 pandemic. This Position Paper of an ad-hoc ARL Working Group, which was set up at the beginning of 2021, examines the structural deficits of municipal financial resources as revealed by the pandemic. The discussion includes reform proposals concerning the design of adequate and crisis-proof financing for municipal budgets that would strengthen the autonomy of municipal tasks. This also includes, in particular, making the municipalities more autonomous in terms of taxation and their right to set tax rates, compensating municipalities for their additional responsibilities with a higher share of VAT, objective criteria for determining municipal financial needs in the municipal financial compensation scheme, and an end to the condoning of regular financing via short-term loans.

A field trial with different cover crops was carried out in 2018 in Hennef, Germany, to clarify the fate of plant nitrogen over winter. High amounts of nitrogen (up to 100 kg ha-1) were taken up by aboveground plant biomass before winter. Nitrate leaching was avoided in a large scale compared to the untreated control. After winter 10 to 55 % of shoot nitrogen were lost with the highest decline in legumes and the lowest in crucifers. If mulched, losses raised up to 90 %, e.g. for narrow-leaved lupin. Nitrogen losses were slightly lower, when mulch was incorporated by rotary tilling. The CN ratio in stems became wider after winter. Only in leaves the CN ratio was narrow enough to cause an effect on nitrogen supply to the succeeding crop. A trend to higher soil mineral N in spring was only noted in treatments with frost hardy cover crops.

Um die individuelle Akzeptanz und gesellschaftliche Verbreitung technologischer Neuerungen in Form von Elektrofahrzeugen angemessen einschätzen zu können, muss die Perspektive eines potenziellen Nutzers und seines Entscheidungsverhaltens berücksichtigt werden. In Anbetracht dessen liefert der Beitrag einen Einblick in die vorliegenden Erkenntnisse zu den Bestimmungsfaktoren der subjektiven Substitutionsbereitschaft zwischen konventionellen Antriebssystemen und Elektrofahrzeugen im Bereich des motorisierten Individualverkehrs. Auf dieser Grundlage werden zudem einige sich daraus ergebende Implikationen für den Verkehrsbereich, die Umwelt sowie die mögliche Verbreitung von Elektrofahrzeugen im urbanen und ländlichen Raum abgeleitet. For the individual acceptance and social dissemination of technological innovations like electric vehicles in an appropriate manner the decision behavior of potential users should be taken into account. In consideration of this the paper provides an overview concerning relevant determinants of individual willingness to substitute between conventional propulsion technologies and electrical drive engineering in the field of individual motor car traffic. Based on these insights some significant implications of electric vehicles regarding future trends in traffic, important environmental effects as well as the spread of electric vehicles in urban and rural areas will be derived.

Weed suppression is a potential benefit of cover crop mixtures, as species diversity may allow for combining early and late-season competition with weeds. Here, we studied if this is possible for only-legume mixtures containing species with different growth rates, by testing two legumes, alsike clover (AC; Trifolium hybridum L.) and black medic (BM; Medicago lupulina L.) in two field trials sown in 2016 and 2017. Five AC:BM ratios (100:0, 67:33, 50:50, 33:67, and 0:100) were grown at three densities (50%, 100%, and 150% of recommended seed density). Cover crop and weed aboveground biomass (CCB and WB, respectively) were harvested three times, after establishment in spring (H1), in summer (H2), and in autumn after mulching (H3). Compared to fallow plots, all monocultures and mixtures showed early-season weed suppression in terms of biomass production and more efficiency over time with an average reduction of 42%, 52%, and 96% in 2016, and 39%, 55%, and 89% in 2017 at H1, H2, and H3, respectively. Out of 54 mixture treatments, only eight mixtures showed stronger weed suppression than monocultures. Mixtures reduced WB by 28%, as an average value, in 2017 compared to the respective monocultures, but not significantly in 2016, indicating that the crop diversity effect on weeds was dependent on the growing environment. Weed suppression was significantly higher at 100% and 150% seed density than 50%, but no significant differences were determined between 100% and 150% seed density. After mulching, no density effect was observed on CCB and WB. In conclusion, AC and BM can be used as a keystone species on weed suppression for sustainable agriculture as they possess plasticity to suppress weeds when higher biomass productivity is limited by environmental conditions. However, their diversity effects are time and condition dependent. Appropriate seed density and mulching can successfully be employed in weed management, but seed density may not have an effect after mulching.