Context Rising atmospheric carbon-dioxide (CO2) concentrations are expected to influence sugar beet development, yield, and quality, yet most existing evidence are from greenhouse experiments with limited validation under field conditions. Methods This study evaluated the effects of elevated CO2 (eCO2, 600 ppm) on sugar beet development, yield, and quality under free-air carbon-dioxide enrichment (FACE) conditions. Field experiments were conducted in 2023 and 2024 using two modern sugar beet varieties grown under ambient CO2 and eCO2. Leaf area index (LAI), taproot diameter, leaf and taproot biomass, white sugar yield, and taproot quality parameters were assessed, including an intermediate harvest. Results Under eCO2, LAI and taproot diameter were generally higher across both varieties and years. Taproot biomass was consistently higher under eCO2 at both intermediate and final harvests. The white sugar yield was 1.2–1.3 times higher than ambient CO2 across both varieties and years. The taproot-to-leaf ratio of both varieties generally increased under eCO2. Sugar content under eCO2 showed a slight increase in 2023 and a slight decrease in 2024 across both varieties, with no consistent response of other taproot quality parameters across years. Conclusions The results demonstrated that under field conditions, the primary effect of eCO2 on sugar beet is enhanced taproot biomass rather than consistent changes in sugar content. This field-based evidence highlighted that future increases in atmospheric CO2 could increase white sugar yield primarily through higher taproot biomass production, providing valuable insights for breeding strategies aimed at optimizing biomass allocation.

Sustainable land management can play an important role in climate change mitigation by reducing soil organic carbon (SOC) losses or even by sequestering C in soils. This can be achieved through practices that increase C inputs to the soil and/or improve the quality of these inputs, thereby facilitating the removal of atmospheric carbon dioxide (CO2) and storing it in the soil as SOC. In this study, we investigated the potential of an increased share of legumes in crop rotations to enhance SOC accrual-defined as the increase in SOC stocks at a given land unit compared to the baseline scenario-using data from 30 mid-term (MTEs, 5-20 years) and long-term (LTEs, 20+ years) field experiments across Europe. Our findings indicate that increasing the proportion of forage legumes in rotations (based on 21 experiments and 39 paired comparisons) led to SOC accrual of up to 13.25 Mg ha(-1) (0.44 Mg ha(-1) year(-1)), while grain legumes (based on nine experiments and 28 paired comparisons) resulted in a decrease in SOC stocks of up to 14.37 Mg ha(-1) (-0.48 Mg ha(-1) year(-1)) compared to the reference treatment. For forage legumes, the largest SOC gains were achieved at sites with the smallest reference SOC stocks and greater share of forage legumes in the rotation. Our observations suggested that the duration of crop growth of the forage legumes (annual vs. perennial) did not exert a significant impact on SOC stock increase, while pedoclimatic zone did. Positive effects on SOC stocks were more pronounced in the Atlantic climatic zone in contrast to the Mediterranean climatic zone. For grain legumes, larger SOC losses were observed with a greater share of grain legumes in the rotation. Overall, integrating forage legumes in cropping systems can enhance their sustainability and present a viable option for climate change mitigation. Finally, we present a regression equation to derive emission factors (EFs) for estimating SOC changes due to the increase of the share of forage legumes in a rotation, and another due to the increase of the share of grain legumes in the rotation. The first can be used to support the assessment of management impacts for the purpose of rewarding carbon farming and the estimation of a national-scale SOC accrual potential, while the second can be used for estimating national-scale SOC losses.

Sugar beet is generally seen as detrimental to soil organic carbon (SOC) stocks for multiple reasons although actual data verifying this claim are scarce. In this study, two approaches were combined to examine the effect of sugar beet on SOC from field data in Germany. First, SOC data of the German Agricultural Soil Inventory were used to compare sugar beet sites with similar sites without sugar beet cultivation. Second, a long-term crop rotation trial in Central Germany was evaluated for differences in SOC among crop rotations with and without sugar beet. Further, carbon input into soil from sugar beet residues was compared with wheat as a reference. In the nationwide dataset, lower SOC stocks (-4.6%) were found for sugar beet sites compared with those without. However, a re-sampling of the sites 10 years later showed no (further) SOC loss. In the long-term trial, no negative impact of sugar beet cultivation on SOC was found. From both databases, carbon input from sugar beet crop residues (2 and 2.7 Mg ha-1 year-1, respectively) was much lower than from wheat (3.6 and 5.8 Mg ha-1 year-1, respectively) because of evident differences in the amount of belowground residues. However, this may be counteracted by growing cover crops before sugar beet, as done in the long-term field trial studied. We conclude that sugar beet might have had a negative impact on SOC stocks in the past, yet that this does not necessarily continue in the present on long-term sugar beet fields, possibly because of a current steady SOC state. When growing cover crops, sugar beet cultivation might have no negative effect on SOC at all. In any case, a general loss of SOC because of sugar beet cultivation cannot be assumed.

For quite a while, there was no scientific discussion on the sustainable development of sugar beet production. The multiplicity of definitions and strategies appear as a misleading ball-of-wool. This paper summarizes theoretical aspects, such as wordings, principles, aims, and challenges of assessment schemes, on sustainable development of crop production in general. The aim is to enable a common understanding for harmonized and strategic decision making and certification. Further, we show the potential for the sustainable development of crop cultivation systems and point out specific options for the sustainable development of sugar beet cultivation. Nine of the 17 Sustainable Development Goals of the United Nations (2015) provide a guideline for the sustainable development of crop cultivation. We identified four general fields of action: (i) enhancement of yield stability, (ii) tackling of ecological challenges, (iii) enablement of risk assessment and forecast, (iv) development of certification schemes. We further identified eight major ecological challenges which can be addressed by nine crop cultivation activities. These were compared to Germany-wide information on current sugar beet cultivation. Therein, we identified the following activities that need to be in place: (i) establishment of forecast and risk assessment systems for decision support and for precision farming in irrigation, pest and disease management, fertilizer application, harvest timing; (ii) protection and increase of soil organic matter and soil structure by permanent soil cover, strip tillage and direct sowing, and reduction of heavy loads during harvest; (iii) increase of aboveground biodiversity, especially by integration of (semi-)permanent elements such as grassland, flower strips, hedges, and by crop rotation diversification especially using legumes and plants for permanent soil cover; (iv) reduction of greenhouse gas emissions by removing the leaves after harvest and by reducing diesel usage wherever possible.

Soils are the foundation of agricultural production, ecosystem functioning and human well-being. Bridging soil knowledge gaps and improving the knowledge system is crucial to meet the growing EU soil policy ambitions in the face of climate change and the ongoing trend in soil degradation. The objective of this article is to assess the current state of knowledge, knowledge use and knowledge gaps concerning sustainable soil management in Europe. This study is based on interviews with 791 stakeholders and 254 researchers and on a comprehensive review of >1800 documents carried out under the European Joint Programme on agricultural soils. Despite differences in stakeholder groups, the conclusions are rather consistent and complementary. We identified major knowledge gaps with respect to (1) soil carbon stocks, (2) soil degradation and fertility and (3) strategies for improved soil management. Transcending these three areas, particularly the loss of soil organic carbon, peatland degradation and soil compaction, are most critical, thus, we stress the urgency of developing more models and monitoring programmes on soils. Stakeholders further report that insufficient transfer of existing soil research findings to practitioners is a hindrance to the adoption of sustainable soil management practices. In addition to knowledge production, soil knowledge gaps may be addressed by considering seven recommendations from the stakeholders: (1) raising awareness, (2) strengthening knowledge brokers, (3) improving relevance of research activities and resource allocation for land users, (4) peer-to-peer communication, (5) targeting advice and information, (6) improving knowledge access, and (7) providing incentives. We argue that filling and bridging knowledge gaps should be a priority for policymakers and the insights provided in the article may help prioritise research and dissemination needs enabling a transition to more sustainable soil management in Europe.

The European Commission has set targets for a reduction in nutrient losses by at least 50% and a reduction in fertiliser use by at least 20% by 2030 while ensuring no deterioration in soil fertility. Within the mandate of the European Joint Programme EJP Soil 'Towards climate-smart sustainable management of agricultural soils', the objective of this study was to assess current fertilisation practices across Europe and discuss the potential for harmonisation of fertilisation methodologies as a strategy to reduce nutrient loss and overall fertiliser use. A stocktake study of current methods of delivering fertilisation advice took place across 23 European countries. The stocktake was in the form of a questionnaire, comprising 46 questions. Information was gathered on a large range of factors, including soil analysis methods, along with soil, crop and climatic factors taken into consideration within fertilisation calculations. The questionnaire was completed by experts, who are involved in compiling fertilisation recommendations within their country. Substantial differences exist in the content, format and delivery of fertilisation guidelines across Europe. The barriers, constraints and potential benefits of a harmonised approach to fertilisation across Europe are discussed. The general consensus from all participating countries was that harmonisation of fertilisation guidelines should be increased, but it was unclear in what format this could be achieved. Shared learning in the delivery and format of fertilisation guidelines and mechanisms to adhere to environmental legislation were viewed as being beneficial. However, it would be very difficult, if not impossible, to harmonise all soil test data and fertilisation methodologies at EU level due to diverse soil types and agro-ecosystem influences. Nevertheless, increased future collaboration, especially between neighbouring countries within the same environmental zone, was seen as potentially very beneficial. This study is unique in providing current detail on fertilisation practices across European countries in a side-by-side comparison. The gathered data can provide a baseline for the development of scientifically based EU policy targets for nutrient loss and soil fertility evaluation.

A stocktake study took place across 23 European countries to formulate recommendations for harmonising methodologies for delivering fertilisation guidelines. The stocktake revealed substantial differences in the content, format and delivery of current fertilisation guidelines across Europe. Substantial differences exist in soil test methods and how crop nutrient requirements are calculated; even between neighbouring countries, with similar soil types, cropping systems and within the same environmental zone. The general consensus from all participating countries was that harmonisation of fertilisation guidelines should be increased, in terms of shared learning in the delivery and format of fertilisation guidelines and mechanisms to adhere to environmental legislation. Some recent publications have assessed conversion equations that would enable data sets derived by different methods to be combined, but much research is still required. It was recognised in this study that it would be very difficult, if not impossible, to harmonise soil test data and agronomic requirements at EU-level due to soil types and agro-ecosystem influences. Nevertheless, increased future collaboration especially between neighbouring countries within the same environmental zone was seen as potentially very beneficial, and would contribute to the European Green Deal Vision. National guidelines for fertilisation planning and awareness of farm-gate N and P balances could help farmers optimise nutrient use, improve farm efficiencies and provide an overview of potential environmental risks on their farms. Additionally, advancement of precision agriculture technology, enabling greatly increased nutrient use efficiency at farm and field level through site-specific and precise fertiliser placement, and improved rate and timing of nutrient application, would be beneficial. Harmonisation or standardisation should not be an end in itself, but the main goal should be to increase nutrient use efficiency and minimise environmental impact.

Intensive field traffic and high axle loads can lead to soil compaction, with ecological and economic consequences. However, the relevance of this issue among practitioners is largely unknown. Therefore, the aim of this study was to determine the relevance of this issue for farmers in Germany, whether and which mitigation measures are applied to avoid it, and what a (non-) application might depend on. We conducted an online survey among farmers in Germany in winter 2017/2018. For the majority of the respondents, soil compaction is a relevant issue on their own farm, and even at higher share rates, this issue is important for Germany as a whole. To prevent or avoid soil compaction, 85% of the participants apply agronomic, 78% tyre/chassis, and 59% planning/management measures. The farm size, tractor power, working in full- or part-time, estimated relevance of soil compaction for Germany, and the estimated yield loss were positively associated with the application of management measures. The insights gained suggested that more effort is needed to encourage farmers’ perceptions regarding soil compaction in order to generate demand-oriented and practice-oriented recommendations for action for various target groups and thus promote the application of soil-conserving measures on a broad scale.

The interdisciplinary BonaRes collaborative project SOILAssist serves the 'Sustainable protection and improvement of soil functions with intelligent land management strategies' by developing a practical on-the-fly assistance system for farmers (grant number 031A563A). In its first phase, the SOILAssist sub-project 'Acceptance and Implementation' consisted of a literature and media analysis (Project Deliverable D11), a survey and a compilation (`Yellow Pages' Soil Compaction) and this analysis with Official recommendations for the prevention of soil compaction on arable land (Deliverable D12). The aim was an analysis of legal regulations on the state and federal levels, including performance assessments as well as interconnections to the EU level. Also completed were a detailed analysis of brochures, flyers and other recommendation tools. This analysis (closing date: February 22, 2018) is based on an internet search and therefore does not claim completeness. The opic 'soil compaction' is addressed in most governmental information material on the state and federal levels. Nevertheless, the quality of the content and the practicability vary in value. This analysis shows that prevention of soil compaction is only referred to explicitly in four federal states. Thus, it becomes clear that the application of the laws (German Federal Soil Protection Act (BBodSchG), German Federal Soil Protection and Contaminated Sites Ordinance (BBodSchV)) is regulated heterogeneously due to the complex federal structure in Germany. Overall, the implementation of the BBodSchG and the BBodSchV is seen as very difficult and - with some exceptions - lacking in exactness, comprehensibility, availability and timeliness of the materials. One federal state initiated a stakeholder-oriented discussion series and has used the consensus principle to successfully reach agreement on prevention of soil compaction. Results derived here are to be set in the context of the Sustainable Development Goals (SDGs), the Agenda 2030, EU-soil policies and the 7th Environmental Action Programme until 2020 (7th EAP). A stakeholder agreement on prevention of soil compaction seems to be - given the potential for improvement of the regulatory law and its performance - an adequate bottom-up solution or a suitable 'vehicle of change' for reaching a location-specific soil management. Launched in 2015, the funding initiative BonaRes of the Federal Ministry of Education and Research (BMBF) is headquartered at the Helmholtz Centre for Environmental Research (UFZ) and the Leibniz Centre for Agricultural Landscape Research (ZALF). It will serve to deliver a scientific basis to strengthen sustainable soil use within the bioeconomy (Soil as a sustainable resource for the bioeconomy - BonaRes). The funding initiative is part of the German National Research Strategy BioEconomy 2030 which focuses on a systemic approach. The SOILAssist sub-project 'Acceptance and Implementation' has already brought some results into public debate (in the period since 08/2015).

Background:There is considerable uncertainty about the actual size of the global soil organic carbon (SOC) pool and its spatial distribution due to insufficient and heterogeneous data coverage. Aims:We aimed to assess the size of the German agricultural SOC stock and develop a stratification approach that could be used in national greenhouse gas reporting. Methods:Soils from a total of 3104 sites, comprising 2234 croplands, 820 permanent grasslands and 50 sites with permanent crops (vineyards, orchards) were sampled in a grid of 8 x 8 km to a depth of 100 cm in fixed depth increments. In addition, a decade of management data was recorded in a questionnaire completed by farmers. Two different approaches were used to stratify cropland and grassland mineral soils and derive homogeneous groups: stratificationviasoil type (pedogenesis) andviaSOC-relevant soil properties. Results:A total of 146 soils were identified as organic soils, which stored by far the highest average SOC stock of 528 +/- 201 Mg ha(-1)in 0-100 cm depth. Of the mineral soils, croplands and permanent crops stored on average 61 +/- 25 and 62 +/- 25 Mg ha(-1)in 0-30 cm (topsoil) and 35 +/- 30 and 44 +/- 28 Mg ha(-1)in 30-100 cm (subsoil), while permanent grasslands stored significantly more SOC (88 +/- 32 and 47 +/- 50 Mg ha(-1)in topsoil and subsoil). Overall, topsoils stored 67 +/- 14% and subsoils 33 +/- 14% of total SOC stocks. Soil C:N ratio, clay content and groundwater level were major factors that explained the spatial variability of SOC stocks in mineral soils. Accordingly, Podzols, Gleysols and Vertisols were found to have the highest SOC stocks. Conclusions:Stratificationviasoil properties yielded the most comparable cropland and grassland strata and is thus preferable for estimating land-use change effects,e.g., for greenhouse gas inventories. In total, 2.5 Pg C are stored in the upper 100 cm of German agricultural soils, making them the largest organic carbon pool in terrestrial ecosystems of Germany. This bares a large responsibility for the agricultural sector and society as a whole to maintain and, if possible, enhance this pool.

Climate-smart use of soils for arable crop production encompasses all efforts leading to adaptation to climate change and to mitigation of greenhouse gas (GHG) emissions from soils and land use. Increasing soil organic carbon (SOC) using agricultural measures, as reviewed by Merante et al. (2017) and Wiesmeier et al. (2020), is regarded as a negative emission technology (Lal, 2019; Smith, 2016; 4 per Mille, 2020). It is also relevant for ensuring sustainable soil fertility and for saving mineral N-fertilisers and related emissions. Thus, upcoming benchmarking systems, such as ‘C-footprint’ and ‘C-neutral production’, of arable products (Stoessel et al., 2012), for farms and businesses are gaining interest as part of agro-ecological concepts (Saj and Torquebiau, 2018). A number of ini tiatives were developed world-wide in recent years (CarboCert, 2020; Carbon Farmers of Australia, 2020; ÖkoregionKaindorf, 2020; Zero Foodprint, 2020; Wesseler, 2020) acting as agencies for private and, so far, regional trade in SOCcertificates sold on the private market for offsetting individual or business GHG-emissions. However, questions remain about their consideration in country-level GHG-accounting in relation to mitigation targets. Governments are obliged to report SOC-changes within the sector ‘Land Use and Land Use Change’ (LULUCF) under the United Nations Framework Conven tion on Climate Change (UNFCCC) and the European Union (EU) climate change mitigation policy (European Parliament and the Council of the European Union, 2018 5). Moreover, all emissions (CO2-C losses from C-sinks) and removals (increases in C-sinks) in arable land, grassland and forestry count towards the ‘no-debit’ target of the LULUCF-Regulation from 2021 onwards (i.e. no increase in GHG-net-emissions, including C-removals in the LULUCF sector). In their national reporting duties, many countries claim that the SOC-stock in arable soils is stable. National soil monitoring programmes, e.g. ‘National Soil Inventory’ (Thünen Institute 2020a, 2020b) in Germany, are improving current methodologies by re placing stable SOC-stocks as sumptions with values measured at regular intervals and/or estimat ed by dynamic modelling. Farmers play an important part in reducing GHG-emissions from the agriculture and LULUCF sectors. Recently, in a German publication, Wiesmeier et al. (2020) proposed minimum sampling schemes and analytical standards to evaluate long term SOC changes and discussed op por tu nities and challenges arising from possible measures to increase SOC. Further, the authors elaborated

global warming potential (GWP) of crop cultivation (carbon dioxide equivalents (CO(2)eq) associated with the production and use of agronomic inputs + nitrous oxide emissions) should be minimized since a 'climate smart' label will become economically valuable in future. The choice and succession of crops in a cultivation system are rarely included in the comparison of methods for reducing GWP. This study elucidated the effects of different preceding crops (grain pea, silage maize, winter wheat) on GWP by agronomic inputs in sugar beet cultivation. In addition, the relation of the GPW to the energy yield was assessed as the global warming intensity (GWI). The study was done based on a field trial in Germany (Lower Saxony). The GWP of sugar beet cultivation as well as the GWI differed due to preceding crops (2.1-3.1 Mg CO(2)eq ha(-1) and 6.9-10.8 kg CO(2)eq GJ(-1), respectively). Values were significantly different between treatments with grain pea and silage maize as preceding crops. The cumulative GWP differed between the two years of crop successions (4.9-7.2 Mg CO(2)eq ha(-1)) with significant differences between the treatments with grain pea and winter wheat. The GWI as the average of the two years of each crop succession was in the range of 9.8-17.3 kg CO(2)eq GJ(-1) and differed significantly between the treatments with silage maize and winter wheat. Thus, the choice of the preceding crop can contribute to a climate smart cultivation of sugar beet. Moreover, this study offers a set of values which can serve as defaults for estimating the GWP of different sequences of crop rotations including catch crops, grain pea, silage maize, sugar beet, and winter wheat under Central European conditions.

Die Bundesrepublik Deutschland hat sich als Unterzeichnerstaat mehrerer internationaler Vereinbarungen zum Klimaschutz verpflichtet, anthropogene Quellen und Senken von Treibhausgasen jahrlich auf nationaler Skalenebene zu berichten. Dazu zahlen auch CO2-Emissionen aus Veranderungen des Vorrates an organischem Kohlenstoff (Corg) im Boden - denn ein Verlust von Corg ist verbunden mit Emissionen des Treibhausgases CO2 aus Boden, ein Aufbau des Corg-Vorrates entspricht einer Festlegung von CO2-Kohlenstoff in Boden. Veranderungen des Corg-Vorrates von Boden sind somit klimawirksam und entsprechend im Rahmen der Treibhausgas-Emissionsberichterstattung zu bilanzieren. Das Bundesministerium fur Ernahrung und Landwirtschaft (BMEL) beauftragte das Thunen-Institut fur Agrarklimaschutz mit der Planung und Durchfuhrung der ersten Bodenzustandserhebung Landwirtschaft (BZE-LW), um eine bundesweit konsistente und vergleichbare Datenbasis bezuglich des Corg-Vorrates in den landwirtschaftlich genutzten Boden Deutschlands zu erhalten. Die BZE-LW dient in erster Linie der Absicherung, Verbesserung und Weiterentwicklung der Treibhausgas-Emissionsberichterstattung der Bundesrepublik Deutschland in den Bereichen Landnutzung und Landnutzungsanderungen. Die Ergebnisse fliesen direkt in die Treibhausgas-Emissionsberichterstattung Deutschlands ein und bilden eine transparente Ausgangsbasis fur den Nachweis von Veranderungen des Corg-Vorrates in landwirtschaftlich genutzten Boden. Eine zentrale Voraussetzung fur die Bewertung der klimawirksamen Veranderungen des Corg-Vorrates in Boden ist die Kenntnis uber die aktuelle Hohe sowie das Verstandnis daruber, wie dieser Vorrat durch Klima-, Boden- und Nutzungsfaktoren beeinflusst wird. Neben der Erfassung des Corg-Vorrates in landwirtschaftlich genutzten Boden auf der Skalenebene Deutschlands sollte daher bewertet werden, welche Standort- und Nutzungsfaktoren diesen beeinflussen. Ein weiteres Ziel war die modellgestutzte Bewertung, ob bei der aktuellen Bodenbewirtschaftung Veranderungen des Corg-Vorrates in landwirtschaftlich genutzten Boden zu erwarten sind. Mit dieser ersten bundesweiten BZE-LW wird auch die methodische und strukturelle Basis fur eine regelmasige Wiederholungsinventur geschaffen werden. Fur spezifische Fragen zur Wirkung der landwirtschaftlichen Bodennutzung auf den Corg-Vorrat im Boden wurden parallel zur BZE-LW Untersuchungen an gezielt ausgewahlten Dauer- und Exaktversuchen sowie an Praxisflachen durchgefuhrt. Die BZE-LW basierte auf einer Beprobung landwirtschaftlich genutzter Boden in einem deutschlandweiten Raster von 8 × 8 Kilometern - insgesamt 3104 Beprobungspunkte. Sie wurde mit aktiver Unterstutzung der Landwirte, die die beprobten Flachen bewirtschafteten und Informationen zur Bodennutzung und ihrem landwirtschaftlichen Betrieb bereitstellten, durchgefuhrt. Die bodenkundliche Standortaufnahme erfolgte nach Bodenkundlicher Kartieranleitung KA5. Die Probenahme erfolgte einheitlich in den Tiefenstufen 0-10, 10-30, 30-50, 50-70 und 70-100 cm. Bei Moorboden wurden auch tiefer liegende Torfhorizonte beprobt. Die Bodenaufbereitung und -analysen erfolgten zentral im Labor des Thunen-Instituts. In den Bodenproben aller Standorte und Tiefenstufen wurden folgende Bodenkenngrosen gemessen: Gehalt an Corg sowie anorganischem Kohlenstoff und Gesamtstickstoff, pH-Wert, Feinbodenanteil (< 2 mm), Grobbodenanteil (= 2 mm), Wurzelanteil, Trockenrohdichte des Feinbodens, Bodentextur. Ein Archiv mit getrockneten Ruckstellproben von allen Beprobungspunkten und Tiefenstufen wurde am Thunen-Institut eingerichtet. [ ...]

Corrigendum Im Artikel „Intensität und Risiko des chemischen Pflanzenschutzes beim Anbau von Zuckerrüben, Silomais und Winterweizen in Fruchtfolgen“ von Brauer-Siebrecht, W., Jacobs, A., Koch H.-J., Strassemeyer, J. und Märländer, B., der auf den Seiten 184-195, Ausgabe 70, Nr. 6 erschien, wurden Korrekturen in Abb. 3 vorgenommen. In Abb. 3 wurde eine vertikale Strich-Punkt-Linie ergänzt, die eine Abgrenzung zwischen den Umweltkompartimenten Feld und Saumbiotop bzw. Boden ermöglicht. Weiterhin wurde im oberen und unteren Teil der Abbildung die Risikotoleranzgrenze als horizontale gepunktete (nicht gestrichelte) Linie dargestellt. Zuletzt wurde innerhalb der Boxplots neben dem Median auch der Mittelwert – dargestellt durch eine gestrichelte Linie – ergänzt. Die Änderungen beeinträchtigen nicht die Schlussfolgerungen des Artikels. Zusammenfassung Der Einsatz chemischer Pflanzenschutzmittel dient zum einen der Sicherstellung des Ertrages, steht jedoch auch aufgrund von möglichen ökologischen Risiken in der Kritik. Der Nationale Aktionsplan zur nachhaltigen Anwen­dung von Pflanzenschutzmitteln zielt auf die Redu­zierung dieser Risiken ab. In der vorliegenden Studie wurden chemische Pflanzenschutzmaßnahmen in Feldversuchen in den Jahren 2011–2014 in den Fruchtfolgen Zuckerrüben-Winterweizen-Winterweizen, Silo­mais-Win­ter­weizen-Winterweizen, Silomais-Zuckerrüben-Winterweizen und Silomais im Daueranbau an zwei Standorten untersucht. Als Indikator der Intensität diente der „Behandlungsindex“, das Umweltrisiko wurde mit dem Simulationsmodell „SYNOPS“ für Stellvertreterorganismen in den Nichtziel-Kompartimenten „Oberflächengewässer“, „Saumbiotope“ und „Boden“ kalkuliert. Der Behandlungsindex variierte zwischen den Fruchtfolgen von 5,1 bis 20,6 und das Umweltrisiko wurde überwiegend als sehr niedrig bis mittel kalkuliert. Es existierte keine Korrelation zwischen der Intensität und dem Umwelt­risiko über die Fruchtfolgen. Silomais im Daueranbau hatte die geringste Intensität, jedoch war das Umwelt­risiko höher. Für Silomais und Winterweizen existierten herbizide und fungizide Wirkstoffe, für die ein nicht tolerables Umweltrisiko kalkuliert wurde. Konsequenzen für den Integrierten Pflanzenschutz ergeben sich unter anderem aus der Wahl weniger toxischer Wirkstoffe, einer Reduktion der Gesamtaufwandmenge und nicht-chemischer Maßnahmen, wie mechanische Unkraut­­regulierung oder resistente Sorten.

The choice of the crop succession influences the agronomic efficiency (yield per unit agronomic input) and is relevant for the sustainable intensification of crop cultivation. However, such effects are often ignored in assessments of agronomic efficiency. The aim of the study was to propose a concept for the assessment of and to publish data on (i) the effect of the preceding crop on the amount of agronomic inputs used and the yield in sugar beet cultivation and (ii) the agronomic efficiency of the 2-year sum of preceding crop – sugar beet successions. As preceding crop (including catch crop) – sugar beet successions, we investigated (i) mustard – silage maize – sugar beet, (ii) phacelia – grain pea – mustard – sugar beet, and (iii) winter wheat – mustard – sugar beet in a field trial (Harste, Germany; 2011–2014). We found that fertilizer requirement of sugar beet was highest (108 kg nitrogen ha −1 ; 125 kg phosphate ha −1 ) when mustard – silage maize was the preceding crop and lowest (30 kg nitrogen ha −1 ; 96 kg phosphate ha −1 ) when phacelia – grain pea – mustard was the preceding crop. The efficiency of the agronomic inputs used for the cultivation of the 2-year sum of preceding crop – sugar beet successions was generally highest for the succession with silage maize with the exception of nitrogen-efficiency which was highest for the succession with grain pea. The main effect of the preceding crop on fertilizer requirement was driven by the amount of harvest residues. Results of 2-year agronomic efficiency were affected by the high energy yield of the succession with silage maize (670 GJ ha −1 ) and the low N-fertilization in the succession with grain pea (130 kg N ha −1 ). We show for the first time a methodological approach to assess preceding crop’s effects on agronomic efficiency and to illustrate results for decision making towards a sustainable intensification of crop cultivation.

Atmospheric carbon dioxide levels can be mitigated by sequestering carbon in the soil. Sequestration can be facilitated by agricultural management, but its influence is not the same on all soil carbon pools, as labile pools with a high turnover may be accumulated much faster but are also more vulnerable to losses. The aims of this study were to (1) assess how soil organic carbon (SOC) is distributed among SOC fractions on a national scale in Germany, (2) identify factors influencing this distribution and (3) identify regions with high vulnerability to SOC losses. The SOC content and proportion of two different SOC fractions were estimated for more than 2500 mineral topsoils (< 87 g kg−1 SOC) covering Germany, using near-infrared reflectance spectroscopy. Drivers of the spatial variability in SOC fractions were determined using the machine learning algorithm cforest. The SOC content and proportions of fractions were predicted with good accuracy (SOC content: R2 = 0.87–0.90; SOC proportions: R2 = 0.83; ratio of performance to deviation (RPD): 2.4–3.2). The main explanatory variables for the distribution of SOC among the fractions were soil texture, bulk soil C ∕ N ratio, total SOC content and pH. For some regions, the drivers were linked to the land-use history of the sites. Arable topsoils in central and southern Germany were found to contain the highest proportions and contents of stable SOC fractions, and therefore have the lowest vulnerability to SOC losses. North-western Germany contains an area of sandy soils with unusually high SOC contents and high proportions of light SOC fractions, which are commonly regarded as representing a labile carbon pool. This is true for the former peat soils in this area, which have already lost and are at high risk of losing high proportions of their SOC stocks. Those “black sands” can, however, also contain high amounts of stable SOC due to former heathland vegetation and need to be treated and discussed separately from non-black sand agricultural soils. Overall, it was estimated that, in large areas all over Germany, over 30 % of SOC is stored in easily mineralisable forms. Thus, SOC-conserving management of arable soils in these regions is of great importance.

In Europe, the framework for sugar beet (Beta vulgaris L.) production was subject to considerable changes and for the future it is expected that sugar beet cultivation might concentrate around the sugar factories for economic reasons. Based on data from a national sugar beet farmers’ survey and multi-year crop rotation trials, the effects of cropping interval (number of years in between two subsequent sugar beet crops) and of preceding crops on sugar yield were elucidated under current Central European management conditions. The dominating sugar beet cropping interval was ≥4 years in the farm survey with pronounced differences between regions. However, the cropping intervals 2, 3, and ≥4 years did not affect the sugar yield. Therefore, significant differences in sugar yield between regions were assumed to be caused by multiple interactions between year, site, and farmers’ skills. Throughout Germany, the dominating preceding crops in sugar beet cultivation were winter wheat (Triticum aestivum L.) and winter barley (Hordeum vulgare L.). In the field trials, the sugar yield was 5% higher after pea (Pisum sativum L.) compared to maize (Zea mays L.) as preceding crop, while differences between the preceding crops pea and winter wheat, and wheat and maize were not significant. Repeated measurements of canopy development and leaf color during the growing season revealed a higher N-availability after pea as preceding crop. However, decreased growth after maize was not completely compensated for by high N-fertilizer doses. Overall, the causes for the differences in sugar yield between the preceding crops remained open. The results do not support concerns about substantial yield losses in sugar beet production due to a reduction in the cropping interval from 3 to 2 years. Nevertheless, short rotations with maize and sugar beet might increase the risk of Rhizoctonia solani crown and root rot infestation. Leguminous crops such as pea offer the potential for higher sugar beet yield with lower N-fertilizer doses.

The study delivers values on greenhouse gas (GHG)-emission via cultivation of silage maize and sugar beet and of GHG-saving potential of electricity produced from biogas out of both biomass crops. Data are based on three rainfed crop rotation field trials in Germany (2011-2014) representative for Central Europe and can serve as default values. It was found that GHG-emission via crop cultivation was driven mainly by nitrous oxide emission from soil and mineral N-fertilizer use and was 2575-3390 kg carbon dioxide equivalents (CO(2)eq) per hectare for silage maize and 2551-2852 kg CO(2)eq ha(-1) for sugar beet (without biogas digestate application). Integrating a GHG-credit for surplus N in the biogas digestate reduced total GHG-emission via crop cultivation to 65-69% for silage maize but only to 84-97% for sugar beet. The GHG-saving potential of electricity production from biogas was calculated for three biogas plants differing in technical characteristics. The GHG-saving potentials were generally > 70% (silage maize: 78-80%, sugar beet: 72-76%) and the authors concluded that the technical setting of the biogas plant had a slight impact only. Overall, the authors assumed that the major potential for GHG-emission's reduction along the bioenergy production chain were N-management during crop cultivation and methane losses at the biogas plant. Finally, sugar beet, if cultivated in crop rotation, was shown to be an efficient alternative to silage maize as a biomass crop in order to achieve a higher diversity in biomass crop cultivation. (C) 2017 Elsevier Ltd. All rights reserved.