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Aim: Balanced crop nutrition is key to improve nutrient use efficiency and reduce environmental impact of farming systems. We developed and tested a dynamic model to predict the uptake of P and K in long-term experiments to better understand how changes in soil nutrient pools affect nutrient availability in crop rotations. Methods: Our RC-KP model includes labile and stable pools for P and K, with separate labile pools for placed P and organic fertilizers including farm yard manure (FYM). Pool sizes and crop-specific relative uptake rates determined potential uptake. Actual crop uptake from labile pools was based on concepts developed by Janssen et al. (Geoderma 46:299-318, 1990). The model was calibrated on three long-term experiments from Kenia (Siaya), Germany (Hanninghof) and the United Kingdom (Broadbalk) to estimate parameter values for crop-specific relative uptake rates and site-specific relative transfer rates. Results: The model described N, P and K uptake accurately with a Nash-Sutcliff modelling efficiency of 0.6–0.9 and root mean squared errors of 2.6–3.4 kg P ha−1 and 14–20 kg K ha−1. Excluding organic labile pools did not affect model accuracy in Broadbalk in contrast to Hanninghof where Mg deficiencies affected crop uptakes in treatments without Mg or FYM. Conclusions: This relatively simple model provides a novel approach to accurately estimate N, P and K uptake and explore short- and long-term effects of fertilizers in crop rotations. Interactions between limiting nutrients affecting actual nutrient uptake were captured well, providing new options to include N, P and K limitations in crop growth models. [ABSTRACT FROM AUTHOR]

Perennial energy grasses have gained attention in recent years as a promising resource for the bioeconomy because of their benign environmental profile, high stress tolerance, high biomass yields and low input requirements. Currently, strong breeding efforts are being made to extend the range of commercially available miscanthus and switchgrass genotypes. In order to foster farmers' acceptance of these crops, and especially of novel hybrids, more information is required about how they can be efficiently integrated into cropping rotations, how they can be removed at the end of their productive lifespan, and what effect they have on subsequently grown crops. Farmers in Europe are meanwhile increasingly constrained in the methods available to them to remove these crops, and there is a risk that the herbicide glyphosate, which has been used in many studies to remove them, will be banned in coming years. This study looks at the removal of seven‐year‐old stands of miscanthus and switchgrass over 1 year at an experimental site in Southern‐Germany. Three novel miscanthus genotypes were studied, alongside one variety of switchgrass, and the impact of each crop's removal on the yield of maize grown as a follow‐on crop was examined. A combination of soil tillage and grass herbicides for maize cultivation was successful in controlling miscanthus regrowth, such that yields of maize grown after miscanthus did not differ significantly from yields of maize grown in monoculture rotation (18.1 t dry biomass ha−1). Yields of maize grown after switchgrass (14.4 t dry biomass ha−1) were significantly lower than maize in monoculture rotation caused by insufficient control of switchgrass regrowth by the applied maize herbicide. Although some regrowth of miscanthus and switchgrass was observed in the follow‐on crop maize, complete eradication of both crops was achieved by subsequent winter wheat cultivation. [ABSTRACT FROM AUTHOR]

The development of resistance in Alopecurus myosuroides populations to different herbicide active ingredients in Europe exacerbates efforts toward its chemical control. In Europe, cinmethylin provides an additional mode of action for the control of A. myosuroides. The objective of this study was to evaluate three resistance weed management (RWM) strategies, including cinmethylin and other pre‐emergence herbicides, for the control of multiple herbicide–resistant A. myosuroides. The RWM strategies used in this study differed in the extent of preventive cultural practices (tillage, crop rotation, sowing date and stale seedbed). Two field trials were conducted at sites with ACCase‐ and ALS‐resistant A. myosuroides biotypes in Germany between 2017 and 2020. Cinmethylin was included in the herbicide regime for A. myosuroides control. The combination of initial inversion tillage, delayed sowing, crop rotation diversification, and stale seedbed reduced the density of A. myosuroides bup to 90% compared to a strategy with pre‐emergence herbicides used as main components in control. At both sites, the amount of viable A. myosuroides seeds in the soil seed bank was reduced by over 90% after a 3‐year trial period in plots with initial inversion tillage. Molecular analyses revealed that the omission of ACCase and ALS inhibitors did not reduce the proportion of resistant A. myosuroides biotypes. Long‐term control of resistant A. myosuroides must be based on a combination of cultural practices that reduce the soil seed bank and suppress the occurrence of A. myosuroides and the use of still‐effective active ingredients for preventing the renewed entry of seeds into the soil. [ABSTRACT FROM AUTHOR]

Satellite and sensor-based systems of site-specific fertilization have been developed almost exclusively in conventional farming. Agronomic and ecological advantages can also be expected from these digital methods in organic farming. However, it has not yet been investigated whether the algorithms and models are also applicable under organic farming conditions. In this study, the digital data and systems tested in the years 2021 and 2022 in southern Germany were (a) reflectance measurements with a tractor-mounted multispectral sensor, calculation of the vegetation index REIP, and application of algorithms; (b) satellite data in combination with the plant growth model PROMET; and (c) determination of the vegetation index NDVI based on satellite data. They were used to determine plant parameters (crop yield, biomass potential) and to calculate nitrogen balances at a high spatial resolution (10 × 10 m). The digital systems were tested at two sites with different organic farming systems (arable farming and dairy farming). Validation of the digital methods was carried out with ground-truth data from manual biomass sampling and combine harvester yield measurement. The nitrate leaching risk from the crop rotations of the farms was analyzed via site-specific N balancing using multi-year satellite data. The N balances were validated by measuring nitrate concentrations in leakage water. Additionally, soil properties, such as soil organic carbon (SOC) and total nitrogen (TN), were measured at the sub-field level. Using geostatistics, plant data, soil properties, and nitrate measurements were transferred into grids of the same resolution to enable correlation analyses. The correlations between yield determined with digital systems and the validation data were up to r = 0.77. Site-specific N balancing showed moderately positive correlations with nitrate concentrations in leakage water (r = 0.50–0.66). The strongly positive influence of the soil properties SOC and TN on crop yields underlines the importance of soil organic matter on soil fertility and site-specific yield potentials. The results show that digital methods allow the spatially high-resolution determination of yields and nitrogen balances in organic farming. This can be the basis for new management strategies in organic farming, e.g., the targeted use of limited nutrients to increase yields. Further validations under differentiated soil, climate, and management conditions are required to develop remote and proximal sensing applications in organic farming. [ABSTRACT FROM AUTHOR]

Global warming can increase insect pest pressure by enhancing reproductive rates. Whether this translates into yield losses depends on phenological synchronisation of pests with their host plants and natural enemies. Simultaneously, landscape composition may mitigate climate effects by shaping the resource availability for pests and their antagonists. Here, we study the combined effects of temperature and landscape composition on pest abundances, larval parasitism, crop damage and yield, while also considering crop phenology, to identify strategies for sustainable management of oilseed rape (OSR) pests under warming climates.In all, 29 winter OSR crop fields were investigated in different climates (defined by multi‐annual mean temperature, MAT) and landscape contexts in Bavaria, Germany. We measured abundances of adult pollen beetles and stem weevil larvae, pollen beetle larval parasitism, bud loss, stem damage and seed yield, and calculated the flowering date from growth stage observations. Landscape parameters (proportion of non‐crop and OSR area, change in OSR area relative to the previous year) were calculated at six spatial scales (0.6–5 km).Pollen beetle abundance increased with MAT but to different degrees depending on the landscape context, that is, increased less strongly when OSR proportions were high (1‐km scale), interannually constant (5‐km scale) or both. In contrast, stem weevil abundance and stem damage did not respond to landscape composition nor MAT. Pollen beetle larval parasitism was overall low, but occasionally exceeded 30% under both low and high MAT and with reduced OSR area (0.6‐km scale).Despite high pollen beetle abundance in warm climates, yields were high when OSR flowered early. Thereby, higher temperatures favoured early flowering. Only among late‐flowering OSR crop fields yield was higher in cooler than warmer climates. Bud loss responded analogously. Landscape composition did not substantially affect bud loss and yield.Synthesis and applications: Earlier flowering of winter OSR compensates for higher pollen beetle abundance in warmer climates, while interannual continuity of OSR area prevents high pollen beetle abundance in the first place. Thus, regional coordination of crop rotation and crop management promoting early flowering may contribute to sustainable pest management in OSR under current and future climatic conditions. [ABSTRACT FROM AUTHOR]

Monoculture croplands are a major source of global anthropogenic emissions of nitrous oxide (N2O), a potent greenhouse gas that contributes to ozone depletion. Agroforestry has the potential to reduce N2O emissions. Presently, there is no systematic comparison of soil N2O emissions between cropland agroforestry and monoculture systems in Central Europe. We investigated the effects of converting the monoculture cropland system into the alley cropping agroforestry system on soil N2O fluxes at three sites (each site has paired agroforestry and monoculture) in Germany, where agroforestry combined crop rows and poplar short‐rotation coppice (SRC). We measured soil N2O fluxes monthly over 2 years (March 2018–January 2020) using static vented chambers. Annual soil N2O emissions from agroforestry ranged from 0.21 to 2.73 kg N ha−1 year−1, whereas monoculture N2O emissions ranged from 0.34 to 3.00 kg N ha−1 year−1. During the rotation of corn crop, with high fertilization rates, agroforestry reduced soil N2O emissions by 9% to 56% compared to monocultures. This was mainly caused by low soil N2O emissions from the unfertilized agroforestry tree rows. Soil N2O fluxes were predominantly controlled by soil mineral N in both agroforestry and monoculture systems. Our findings suggest that optimized fertilizer input will further enhance the potential of agroforestry for mitigating N2O emissions. [ABSTRACT FROM AUTHOR]

Two major global challenges related to agriculture are climate change and the unbalanced nitrogen cycle. For both, national and international reduction targets have been defined to catalyse policy support for more sustainable farming systems. Miscanthus cultivation in water protection areas has been proposed as a contribution to achieving these targets. However, a thorough understanding of the underlying system dynamics at various spatial levels is required before recommendations for policy development can be provided. In this study, a model framework was established to provide economic and environmental indicator results at regional and sub-regional levels. It presents a consequential Life Cycle Assessment coupled with an agro-economic supply model (Economic Farm Emission Model) that simulates crop and livestock production, and an agricultural hydrology model (DAISY) that assesses effects on the nitrogen cycle. The framework is applied to Baden-Württemberg, a federal state in southwest Germany with eight agro-ecological regions. Scenarios investigating the differences between mandatory and voluntary miscanthus cultivation were also explored. While the results show the high potential of miscanthus cultivation for the reduction of greenhouse gas emissions (-16% to -724%), the potential to reduce nitrate leaching (-4% to -44%) is compromised in some sub-regions and scenarios (+4% to +13%) by substantial effects on the crop rotation. Furthermore, the cultivation of miscanthus reduces gross margins in most sub regions (-0.1% to -9.6%) and decreases domestic food production (-1% to -50%). However, in regions with low livestock density and high yields, miscanthus cultivation can maintain or increase farmers' income (0.1%-5.8%) and improve environmental protection. The study shows that the heterogeneity of arable land requires a flexible promotion programme for miscanthus. Voluntary cultivation schemes were identified as most suitable to capture sub-regional differences. Policies should address the demand for miscanthus, for example, support the development of regional value chains, including farmers, water suppliers and the biobased industry. [ABSTRACT FROM AUTHOR]

• The net ecosystem carbon balance was extended for harvest residues (HR). • The balance term related to HR can be in the range of other cumulative carbon terms. • Therefore, it is imperative to consider HR in the carbon balance of croplands. • Soil carbon loss/gain are mostly controlled by the fast-decomposing carbon pools. Over the past two decades, major efforts have been made to quantify the extent to which and under what conditions croplands are sources or sinks for carbon. For this purpose, the net carbon stock change of the study site is typically quantified based on net CO 2 fluxes monitored with an eddy covariance or chamber system, on measured C import by organic fertilizer and C export by harvest. While in cropland studies this balance is usually referred to as net biome productivity (NBP), we prefer to use the term net ecosystem carbon balance (NECB) here. NECB is basically the sum of the stock change of plant carbon (ΔPC) and soil organic carbon (ΔSOC). In the standard approach, the assumption is that at an annual cropland site the bulk of plant biomass is typically removed at harvest, and that ΔPC can therefore be neglected. In this case, ΔSOC equals NECB. In this paper we show that this assumption is problematic, particularly if in crop rotation systems the budget is determined over a single cropping period. The present contribution extends the concept of NECB to include harvest residues (HR) and applies it to a case study over a maize - winter wheat - winter wheat rotation at a cropland site in southwest Germany. In all three cropping periods, the sign of NECB was opposite that of ΔSOC. Accordingly, neglecting HR led to an incorrect result concerning the question whether the site is a sink or a source for soil carbon. Our findings demonstrate that for croplands HR must be included to obtain an accurate and meaningful carbon balance. [ABSTRACT FROM AUTHOR]

• Suberin contributed more to bulk SOC stocks than cutin in topsoil and subsoil. • Of all monomers, suberin monomers were affected most by deep-ploughing. • Effects of deep-ploughing on suberin SOC stocks were not uniform for sandy and silty sites. • Changes in SOC stocks in topsoil and subsoil after deep-ploughing affected input of root-derived C. Roots can add significant amounts of carbon (C) to the subsoil, which improves soil physical properties and can mitigate climate change. About 5% of croplands in Germany have been deep-ploughed (30–120 cm) at least once. This can provide better root access to the subsoil and may increase yields, but little is known on the fate of root-derived C in the subsoil (at depth greater than 30 cm) after deep-ploughing. We hypothesized that five decades after deep-ploughing, root-derived C stocks were higher than conventionally ploughed treatments due to better root development. We analysed suberin and cutin monomers as tracers for root- and shoot-derived C at three former deep-ploughed sites in Northern Germany with different soil textures and deep-ploughing depths. Concentrations of suberin monomers in the soil positively correlated with root biomass; this was most pronounced at one sandy site, but had higher variability at the other two sites due to crops with different root systems in the crop rotation, lower root development, and more favourable conditions for C decomposition. Suberin contributed more to the bulk soil organic carbon (SOC) stocks than cutin throughout the soil profile at all sites. The contribution of suberin monomers to the bulk SOC stock at silty site Banteln and the sandy site Essemühle was 38% higher in the deep-ploughed plots than at the reference plot, respectively, these differences were most visible in the subsoil of Essemühle. We conclude that as C stocks and root development increase, suberin SOC stocks also increase, especially in sandy subsoils with low pH. [ABSTRACT FROM AUTHOR]

The cultivation of perennial wild plant mixtures (WPMs) is becoming increasingly important in Germany for providing sustainably produced bioenergy. However, perennial energy cropping systems always raise the question of how to reclaim the land for arable crops. This study examined this issue by looking at how a former WPM area was returned to arable cropping for an organic farm. From 2013 to 2018, the WPM area was harvested annually in the autumn. From 2019 to 2020, it was co-managed with the surrounding land as a semi-intensive grassland under a three-cut regime. The area was then ploughed in the spring of 2021 to grow silage maize. Weeds were controlled mechanically once. Nevertheless, the perennial wild plant species grew vigorously, with common tansy (Tanacetum vulgare L.) standing out with a total fresh matter share of 29.0%. This maize–WPM mixture achieved a dry matter yield of 15.5 ± 5.5 Mg ha−1, which was notably but not significantly (p < 0.05) lower than that of silage maize growing next to the former WPM area (23.4 ± 5.5 Mg ha−1). After silage maize, winter wheat was sown in the autumn of 2021 and further regrowth of common tansy was observed in the spring of 2022. Yield and quality effects must therefore be given special consideration in the first arable crop following WPM cultivation. [ABSTRACT FROM AUTHOR]

To investigate the effects of management practices on the dynamics of soil temperature, during 2014–2017, a field experiment was carried out in Bad Lauchstaedt, Germany. In this study, four management systems are compared for determining management-induced changes in soil temperature at different depths: (i) conventional tillage (TC) with the standard rate of N fertilizer (P1N1), (ii) conventional tillage with the half-standard rate of N fertilizer (P1N0), (iii) reduced tillage (TR) with the standard rate of N fertilizer (P0N1), and iv) reduced tillage with the half-standard rate of N fertilizer (P0N0). Temporal analysis of soil temperature is assessed to examine data observed at a specific time to achieve a better understanding of the soil temperature dynamic that occurs at different time scales. The results showed that the soil temperature has decreasing amplitudes and increasing phase shifts with increasing soil depth, i.e., the deeper the measurement depth, the smoother the soil temperature changes cycle and the smaller the variability. Results showed that the diurnal temperature variation is found up to 45 cm depth of soil whereas annual temperature variation is up to a depth of 180 cm. The results, moreover, revealed that soil temperature dynamic was affected by tillage systems and fertilization and a time lag is observed between the temperature fluctuations at the surface and deeper layers, due to induced management effects on plant cover, residues, and soil properties. Although higher soil temperature at the sowing stage under TR is contributed to higher amounts of surface crop residues in crop rotations, the effect of residues on soil temperature variation reduces with an increase in percent plant cover and shading of soil, which happens in the last stage of plant growth. At the last stage of crop development regardless of tillage systems, applying more N fertilization increased crop yield, resulting in cooling soil temperature. [ABSTRACT FROM AUTHOR]

Tree strips on agricultural production sites offer many economic, ecological and social advantages. However, the introduction of trees creates a transition zone between tree strips and crop land. Here, trees and crop plants compete for resources such as space, nutrients, water and light, which causes stress in the low‐competitive system. On the other hand, facilitation such as additional nutrient input through tree leaf litter and fine roots are possible. This study aims to provide indications for competition and benefits that can arise for plants growing in the transition zone of a temperate short rotation alley cropping agroforestry system (SRACS). Various climatic and plant‐growth parameters were investigated between 2013 and 2019 at different positions of an SRACS with fast‐growing poplars in northern Germany. Reduced yield of wheat, oilseed rape and silage maize close to the tree strip was associated with greater soil water tension in 30 and 60 cm soil depth due to the presence of poplar roots, reduced solar radiation due to tree shading and leaf litter coverage. In contrast, poplars growing in the outer rows produced more biomass than those in the inner rows due to the additional availability of space, light and nutrients taken from the crop field. Trees in the transition zone seem to be competitive with arable crops, but without effect on the average long‐term yield of arable crops. [ABSTRACT FROM AUTHOR]

Long-term experiments are an important tool to investigate the effects of crop rotation and fertilization measures under climate change conditions. However, there are few studies on nitrogen use efficiency (NUE) of crops in long-term cropping systems in Europe, but no consolidate studies in Germany. We analyzed a long-term experiment established in 1982 to observe the role of legumes on total nitrogen uptake, NUE, agronomic efficiency, nitrogen response index and N recovery efficiency compared to fallow land and cereals in a crop rotation over the long-term. The experiment included five different precrops (fallow land, maize, oat, field bean and clover mulch) in combination with four levels of fertilization (control, PK, PK+N with reduced dosage, and PK+N with full dosage followed by three years of cereal cultivation (winter wheat, winter rye, summer barley) in all treatments. The field trial was conducted as a fully factorial split plot design, with spatially randomized field repetitions in four blocks. Long-term mineral NPK fertilization improved the N uptake of winter wheat (185.7 kg N ha−1), winter rye (152.2 kg N ha−1) and summer barley (92.2 kg N ha−1) when the higher level of fertilization (NPK 100%) was implemented. A year-round application of clover mulch as green manure in the rotational system resulted in higher NUE (up to 37%) compared to fallow land after 40 years. Crop rotation with oat and maize (100% cereals) led to lower NUE (up to 30%) compared to fallow land. Clover mulch (198%), field bean (155%), fallow land (148%) and maize (119%) significantly increased the N uptake of wheat compared to oat in 2015. Over time, the agronomic efficiency was increased. This increase was 4 or 5 times higher in the 9th and 10th crop rotation compared to the beginning of the experiment (in 1983). Nitrogen response index of clover mulch was approximately 33–37% lower than fallow land at the beginning of the experiment in 1983 and 45–50% lower over the 40 years. N recovery efficiency values of winter wheat (94%), winter rye (66%) and summer barley (46%) increased within the 10th crop rotation compared to the beginning of the long-term experiment. Combining clover mulch as a green manure with mineral fertilizer has greater potential to improve NUE and crop productivity by increasing soil N availability. Our study highlights the importance of evaluating agronomic management practices in long-term field experiments to understand their sustainable effects. • Soil nutrition is regulated by the quality & quantity of plant residues incorporated into the soil. • Long-term application of green mulch and mineral fertilizer improves NUE and crop productivity. • After 40 years, agronomic efficiency was about 4 or 5 times higher than at the beginning of the experiment in 1983. • Nitrogen response index of clover mulch was about 33–37% lower than fallow at onset of the experiment. [ABSTRACT FROM AUTHOR]

Agrivoltaic (AV) systems integrate the production of agricultural crops and electric power on the same land area through the installation of solar panels several meters above the soil surface. It has been demonstrated that AV can increase land productivity and contribute to the expansion of renewable energy production. Its utilization is expected to affect crop production by altering microclimatic conditions but has so far hardly been investigated. The present study aimed to determine for the first time how changes in microclimatic conditions through AV affect selected agricultural crops within an organic crop rotation. For this purpose, an AV research plant was installed near Lake Constance in south-west Germany in 2016. A field experiment was established with four crops (celeriac, winter wheat, potato and grass-clover) cultivated both underneath the AV system and on an adjacent reference site without solar panels. Microclimatic parameters, crop development and harvestable yields were monitored in 2017 and 2018. Overall, an alteration in microclimatic conditions and crop production under AV was confirmed. Photosynthetic active radiation was on average reduced by about 30% under AV. During summertime, soil temperature was decreased under AV in both years. Furthermore, reduced soil moisture and air temperatures as well as an altered rain distribution have been found under AV. In both years, plant height of all crops was increased under AV. In 2017 and 2018, yield ranges of the crops cultivated under AV compared to the reference site were −19 to +3% for winter wheat, −20 to +11% for potato and −8 to −5% for grass-clover. In the hot, dry summer 2018, crop yields of winter wheat and potato were increased by AV by 2.7% and 11%, respectively. These findings show that yield reductions under AV are likely, but under hot and dry weather conditions, growing conditions can become favorable. [ABSTRACT FROM AUTHOR]

High productivity and yield stability over time in combination with a reduction in the crop failure risk are the principal goals of both conventional and organic agriculture. These goals are achieved in organic agriculture through the maintenance of soil fertility and soil functions through agronomic practices such as balanced crop rotations and the application of organic amendments. Reduced tillage constitutes an important practice that limits the disturbance to the soil structure and biota, but deep ploughing is frequently used in organic farming for weed control and aeration of heavy soils. This study aimed to assess the impact of mixed organic farms and farms without livestock, so called stockless farms, with their respective crop rotations and fertilization management, and the effect of reduced tillage on yield dynamics. We compared yield dynamics i.e., crop yield, yield stability and the production risk, of three organic farming systems involving four levels of tillage intensity each at the Organic Arable Farming Experiment Gladbacherhof (OAFEG), Germany, based on a long-term (24 year) dataset. The six-year crop-rotation of a mixed farm was compared to stockless farming with rotational alfalfa ley and stockless farming with cash crops. The levels of tillage intensity ranged from deep inversion ploughing to non-inversion tillage. The yield data from the OAFEG trial were evaluated with respect to the mean yield data from all cropland systems at Gladbacherhof research farm. We calculated the yield dynamics of the complete crop rotation as well as three crops within the rotations i.e., winter wheat, winter rye and potato. The most promising combination of high yield and yield stability was mixed farming with deep (30 cm) and shallow (15 cm) ploughing, in contrast to stockless farming (with ley) with non-inversion tillage. Similar results were recorded for cereals, but not for potatoes. Stockless farming with cash crops and non-inversion tillage had the highest production risk, i.e., the highest probability of falling below the defined critical yield level. Under the predominant heavy soil conditions in central Germany, non-inversion tillage can't keep up with inversion tillage regarding a stable organic production. Mixed farming with livestock which is representative of traditional organic farming system was found to produce high yields, but also stockless farming with rotational alfalfa ley was competitive. Stockless or "vegan" organic farming can be an alternative production system to organic mixed farming with stable yields provided that rotational alfalfa ley is part of the crop rotation. Ploughing depth can be reduced without affecting productivity. [Display omitted] • Stockless farming with ley and inversion ploughing shows high and stable yield. • Shallow ploughing is a promising alternative to deep ploughing in respect to yields. • Worst yield dynamics with non-inversion tillage in all farming systems. • Farming system and tillage affect yield of winter cereals wheat and rye in a comparable way. • Potato yield dynamics were independent from long-term tillage effects. [ABSTRACT FROM AUTHOR]

Grain legume cultivation has multifaceted benefits in farmland and its on-going expansion in Europe contributes to the targeted self-sufficiency in protein production for human and livestock nutrition. However, there is limited information on key environmental processes such as the nitrogen (N) cycle. To address this knowledge gap, N input and output pathways were investigated among six grain legumes across two experimental farms (Gladbacherhof and Oberfeld) in central Germany, between 2020 and 2022. Percentage of N derived from atmospheric fixation (%Ndfa), was estimated at peak biomass production stage through the ¹⁵N natural abundance method, and ranged from 8.9% to 93.9%. Grain legumes at Oberfeld were found to have a higher %Ndfa (median 75.4%) than at Gladbacherhof (54.5%) with winter varieties i.e., winter pea (Pisum sativum) and winter faba (Vicia faba), found to be more efficient at acquiring Ndfa in comparison to soya (Glycine max). At Gladbacherhof, the N export in the form of harvested grain was higher than the N input resulting from biological N fixation while at Oberfeld, an opposite trend was observed. The potential of winter legumes to reduce nitrate leaching compared to plots which were left fallow over winter and then cropped with spring legumes, was measured. Nitrate leaching was found to be low at both sites, ranging from 1.1 to 3.4 kg N ha⁻¹ at Gladbacherhof, and from 1.0 to 1.5 kg N ha⁻¹ at Oberfeld, with no significant differences across treatments. N₂O emissions were measured from November 2020 to October 2021. Daily emissions averaged 0.033 mg N₂O-N m⁻¹ h⁻¹ whereas the cumulative emissions ranged from 0.8 to 1.6 kg N₂O-N ha⁻¹ (November 2020 – April 2021), and from 0.7 to 2.1 kg N₂O-N ha⁻¹ (April 2021 – October 2021). Selecting for grain legume varieties that can fix considerable amounts of atmospheric N₂ can be an important criterion for inclusion in crop rotations. However, the drawbacks of N losses through nitrate leaching and nitrous oxide emissions, as well as N exports through grains, should be accounted for, to ensure efficient field-scale N management. • Nitrogen (N) dynamics of six grain legumes were evaluated across sites and years. • Legumes obtained 8.9–93.9% of N from BNF, or 48.1–196.6 kg N ha⁻¹. • Legume cultivation time (10 vs. 4 months) had no effect on nitrate leaching. • Nitrous oxide (N 2 O) emissions during winter represented 30.1–51.4% of emissions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Manure increases topsoil carbon stocks in organic farming. • Reduced tillage increases topsoil carbon stocks. • Crop rotation with alfalfa tends to increase POM in subsoils. • No effect of crop rotation with alfalfa on subsoil microstructure. • Highest biopore length by conventional farming. An asset of organic farming systems with diversified crop rotations, next to a cut in pesticide and mineral fertilizer application, is the built-up of organic carbon stocks in the long-term. In addition, the inclusion of deep-rooting legumes like alfalfa is known to improve soil structure and increase particulate organic matter contents in the subsoil. These views have been challenged recently ascribing limited potential for legume-based crop rotations to increase carbon stocks in Chernozems (Mollisols) due to limited accrual of mineral-associated organic carbon. Likewise, the direct impact of these legumes on soil structure and associated soil properties like water retention and transport has been questioned and linked to indirect effects instead. The objective of this study was to investigate the impact of legume-based crop rotations on carbon stocks and soil structure properties in the Flurweg II long-term farming systems trial (26 years) established on a Chernozem soil in Germany. We compared one conventional (INT) and two organic farming systems, with (O + M) and without (O - M) integrated livestock management. The three farming systems differ in biomass return via plant residues or farmyard manure as well as share and type of legumes in the eight-year crop rotation (INT: pea, O - M: faba bean and pea, O + M: biannual alfalfa). The comparison included yields, carbon stocks, soil physical properties and microstructure properties based on X-ray computed tomography of soil within and beneath the plow horizon. All farming systems underwent conventional plowing. In addition, we compared carbon stocks and microstructure properties with those from the nearby Westerfeld tillage trial with conventional and reduced tillage in a legume-free crop rotation. The carbon stocks in the plowed topsoil of the Flurweg II systems trial increased significantly with organic farming including livestock (INT: 53 ± 2 vs. O + M: 61 ± 2 t ha−1), but not without (O - M: 53 ± 4 t ha−1), likely because of farmyard manure application in the O + M system. This increase in topsoil carbon stocks is only moderate compared to the increase in topsoil carbon stocks in the Westerfeld tillage trial by switching from conventional to reduced tillage (53 vs. 70 t ha−1). The carbon stocks of the whole soil profile (down to 48 cm) in the Flurweg II systems trial tended to increase with organic farming irrespective of livestock integration (INT: 72 ± 5 t ha−1 vs. O ± M: 82–83 ± 7 t ha−1). Particulate organic matter (POM) contents and biopore diameter below the plow layer tended to increase with alfalfa in the crop rotation of the O + M farming system. However, the legacy effect four years after the presence or absence of alfalfa was only in the range of natural, spatial variability. As a result of similar soil microstructure there was also hardly any difference in hydraulic conductivity and no difference in soil mechanical properties between farming systems. This study shows that Chernozems in this region still have the capacity to increase POM contents and carbon stocks with climate-smart, regenerative agricultural management, but also demonstrate that this has limited effects on structural properties. [ABSTRACT FROM AUTHOR]

Summary: The development of acetolactate synthase (ALS) tolerant sugar beet provides new opportunities for weed control in sugar beet cultivation. The system consists of an ALS−inhibiting herbicide (foramsulfuron + thiencarbazone‐methyl) and a herbicide‐tolerant sugar beet variety. Previously, the use of ALS‐inhibitors in sugar beet was limited due to the susceptibility of the crop to active ingredients from this mode of action. The postulated benefits of cultivation of the ALS‐tolerant sugar beet are associated with potential risks. Up to now, with no relevant proportion of herbicide‐tolerant crops in Germany, ALS‐inhibitors are used in many different crops. An additional use in sugar beet cultivation could increase the selection pressure for ALS‐resistant weeds. To evaluate the impact of varying intensity of ALS‐inhibitor use on two weed species (Alopecurus myosuroides and Tripleurospermum perforatum) in a crop rotation, field trials were conducted in Germany in two locations from 2014 to 2017. Weed densities, genetic resistance background and crop yields were annually assessed. The results indicate that it is possible to control ALS‐resistant weeds with an adapted herbicide strategy in a crop rotation including herbicide‐tolerant sugar beet. According to the weed density and species, the herbicide strategy must be extended to graminicide treatment in sugar beet, and a residual herbicide must be used in winter wheat. The spread of resistant biotypes in our experiments could not be attributed to the integration of herbicide‐tolerant cultivars, although the application of ALS‐inhibitors promoted the development of resistant weed populations. Annual use of ALS‐inhibitors resulted in significant high weed densities and caused seriously yield losses. Genetic analysis of surviving weed plants confirmed the selection of ALS‐resistant biotypes. [ABSTRACT FROM AUTHOR]

Agricultural landscapes are globally dominated by monocultures under intensive management. This is one of the main reasons for biodiversity loss and insect population decline in many regions all over the world. Agroecosystem biodiversity in these areas can be enhanced by cropping system diversification, such as crop rotations. Yet, long‐term studies on effects of crop rotations on aboveground agrobiodiversity are lacking. We set up a 10‐year long‐term crop rotation experiment in Central Germany and monitored the temporal dynamics of aboveground arthropods over a full cultivation period to investigate influence of current and preceding crop identity and cropping system diversification on activity density, species richness, and community structure. We found that species composition was strongly influenced by currently grown crop although effect on arthropods varied between species groups. Especially, winter oilseed rape strongly affects arthropod community structure. Interestingly, we were also able to show an influence of the preceding crops, indicating an ecological memory effect in the aboveground arthropod community. Our results show that crop identity of both currently and previously grown crops in crop rotations may lead to an increase in arthropod activity density and changes in species composition. Diversified crop rotations including appropriate crops can be an easily implemented tool to increase arthropod biodiversity and biomass at large spatial and temporal scales, particularly in areas dominated by a single crop (e.g., wheat, maize). Our results may help to design optimized crop rotations for large‐scale enhancement of insect biodiversity in agroecosystems. [ABSTRACT FROM AUTHOR]

Highlights • High C losses from intensive crop rotations in southwest Germany. • C removals via harvest trigger SOC losses. • The recent increase in silage maize cropping threatens SOC stocks. • Growing bioenergy maize for CO 2 mitigation seems questionable. • A re-diversification of crop rotations is needed to protect soil C stocks. Abstract The carbon (C) sequestration potential of croplands has recently become a subject of debate because it may contribute significantly to global climate change mitigation. By contrast, carbon dioxide (CO 2) emissions from German croplands have continuously increased over the past decades as a result of soil organic carbon (SOC) losses. Contrasting results, however, have been obtained on the C sink or source function of European croplands based on long-term experiments and rather recent eddy covariance (EC) measurements. Over a period of eight years (2010–2017), we measured the net ecosystem exchange (NEE) of CO 2 on six intensively managed cropland sites in two climatically different regions of southwest Germany (Kraichgau (KR) and Swabian Jura (SJ)) using the EC technique. Additionally, we measured aboveground crop biomass at three development stages and estimated management-related C inputs and exports. The inter-annual on-site variability of cumulated annual NEE was large, and neither the region nor the different sites significantly affected NEE budgets. Winter rapeseed showed the lowest CO 2 uptake capacity among the observed crops, and the mean annual NEE in the years with winter rapeseed harvest was significantly lower compared to winter wheat, silage maize and winter barley. On average over 46 site-years, annual NEE showed a distinct CO 2 uptake of −2580 kg CO 2 -C ha−1 yr−1. Considering management-related C fluxes, the resulting net biome productivity (NBP) indicated a C source function of the study sites with mean annual losses of 1190 kg C ha−1 yr−1. Due to high C removals after whole plant harvests, silage maize cropping resulted in significantly higher C losses of 4280 kg C ha−1 yr−1 compared to winter rapeseed, winter wheat and winter barley, with mean annual NBPs of 1430, −188 and −1340 kg C ha−1 yr−1, respectively. Consequently, a higher share of exported C in annual NBP resulted in higher C losses. We conclude that the recently increased importance of silage maize in crop rotations destabilizes SOC stocks, threatening the efforts in enhancing soil C sequestration. This calls for further investigations on the C sequestration potentials of more diverse crop rotations including perennial phases. [ABSTRACT FROM AUTHOR]

During the last years, a demand for regionally produced biogas feedstocks was created by government subsidies to biogas production in Germany—contrary to the trend of specialization of agricultural production towards global commodity markets. The question arose whether this trend could contribute to an increased cultivation of uncommon crops and diversification of cropping patterns, owing to comparably different and less restricted feedstock requirements. In the cooperative research project "EVA," a multi-site experimental crop rotation field trial was conducted over 8 years at eight sites, representing the variety of soil-climatic conditions in Germany. The aim of the trial was to assess a variety of established and novel crops for anaerobic digestion. This paper presents the key findings of the trial. Special emphasis is given to biomass productivity and profitability. The chances for the approach "diversification of cropping patterns via energy cropping" are discussed. Results show that maize (average 4-year dry matter yield varied site-specific between 14.22 and 25.12 t ha−1) is clearly the most efficient crop for biogas production in Central Europe. Some cropping options for biogas feedstock production, such as winter triticale (whole crop, average yield of 6.71 to 15.17 t ha−1) or perennial fodder mixtures (average yield of 7.51 to 19.44 t ha−1) are feasible choices for farmers in some regions, which could contribute to diverse cropping systems. [ABSTRACT FROM AUTHOR]

Perennial energy crop production methods such as short rotation coppice (SRC) have gained interest among farmers and policy makers. SRC is characterised by rapid biomass production, low inputs, and high managerial flexibility. SRC plantations also provide environmental advantages relative to annual crop production and contribute to the transition towards renewable energy. Yet, the combination of high sunk costs and high uncertainty hampers SRC adoption among farmers. Policy instruments currently implemented to foster SRC adoption exhibit limited success. In this paper we assess the performance of different policy measures intended to stimulate SRC adoption in terms of efficiency and farm-level effects, taking into account related uncertainty. We use a combination of stochastic programming and the real options approach in our model featuring SRC poplar cultivation in Germany. We analyse four policy measures intended to foster SRC adoption: an establishment subsidy, a price floor, a guaranteed price, and increasing the “Ecological Focus Area” (EFA) value for SRC systems within the European Union Common Agricultural Policy. Our results indicate that a guaranteed price can stimulate immediate SRC adoption; however, it is inferior to the other instruments in other dimensions. An establishment subsidy as recently implemented in the study area might incentivise farmers to adopt SRC by contributing substantially to farm income, but should be modified because it may encourage postponement of SRC adoption. Increasing the EFA coefficient and a price floor are more efficient measures in terms of governmental expenditures, while having limited positive effects on bioenergy produced. [ABSTRACT FROM AUTHOR]

The concept of sustainable intensification in crop production has become more and more important over the last years. Calls for an efficient production demand an increase in yield without extending the agricultural area or increasing the amount of agricultural inputs. Thus, our study aimed to identify which variables influence the efficiency in crop cultivation in Central Europe and how we can explain the variances between fields. The data base for the present study was a survey among sugar beet farmers in all parts of Germany in the years 2010–2014. In order to structure the fields, variables representing environment, management and farm characteristics were extracted. The performed analysis according to components (principal component analysis) did not result in a nationwide structure of the data. Thus, fields were grouped according to similar preconditions such as regions and crop rotations. Sugar yield ranged from 12.5 t ha −1 in 2010 to 15.4 t ha −1 in 2014 on nationwide average. The median value for N fertilization over all fields and years was 137.4 kg ha −1 , the median treatment index (TI) reached 3.7, the median field evaluation index (Ackerzahl) was 70 and the median field size 8 ha. We found that over 50% of the variance among the data was explained by environment, management and farm characteristics. The comparison of fields on a regional basis was more sensible than on a nationwide basis as the variance of farms and fields was too broad for a useful clustering. It was concluded that the adaption of the farmer’s management to regional specific conditions is an opportunity to reduce yield gaps and to increase efficiency in terms of a sustainable intensification in sugar beet production. [ABSTRACT FROM AUTHOR]

Spatial land use information is one of the key input parameters for regional agro-ecosystem modeling. Furthermore, to assess the crop-specific management in a spatio-temporal context accurately, parcel-related crop rotation information is additionally needed. Such data is scarcely available for a regional scale, so that only modeled crop rotations can be incorporated instead. However, the spectrum of the occurring multiannual land use patterns on arable land remains unknown. Thus, this contribution focuses on the mapping of the actually practiced crop rotations in the Rur catchment, located in the western part of Germany. We addressed this by combining multitemporal multispectral remote sensing data, ancillary information and expert-knowledge on crop phenology in a GIS-based Multi-Data Approach (MDA). At first, a methodology for the enhanced differentiation of the major crop types on an annual basis was developed. Key aspects are (i) the usage of physical block data to separate arable land from other land use types, (ii) the classification of remote sensing scenes of specific time periods, which are most favorable for the differentiation of certain crop types, and (iii) the combination of the multitemporal classification results in a sequential analysis strategy. Annual crop maps of eight consecutive years (2008–2015) were combined to a crop sequence dataset to have a profound data basis for the mapping of crop rotations. In most years, the remote sensing data basis was highly fragmented. Nevertheless, our method enabled satisfying crop mapping results. As an example for the annual crop mapping workflow, the procedure and the result of 2015 are illustrated. For the generation of the crop sequence dataset, the eight annual crop maps were geometrically smoothened and integrated into a single vector data layer. The resulting dataset informs about the occurring crop sequence for individual areas on arable land, so that crop rotation schemes can be derived. The resulting dataset reveals that the spectrum of the practiced crop rotations is extremely heterogeneous and contains a large amount of crop sequences, which strongly diverge from model crop rotations. Consequently, the integration of remote sensing-based crop rotation data can considerably reduce uncertainties regarding the management in regional agro-ecosystem modeling. Finally, the developed methods and the results are discussed in detail. [ABSTRACT FROM AUTHOR]

Winter rapeseed is one of the most important field crops in Germany. In comparison to other crops, nitrogen (N) surplus of rapeseed is usually high and increased values of mineral nitrogen are observed in soil after harvest. N losses via nitrate leaching or emissions of nitrous oxide (N 2 O) have a negative impact on the greenhouse gas (GHG) balance of biodiesel produced from rapeseed. So far, the effects of different post-harvest management options on these losses after rapeseed cultivation have not been assessed. The aim of this study was to investigate agronomic measures, such as different following main crops (wheat and barley) as well as different catch crops (mustard respectively ryegrass) and varied tillage intensity for their effectiveness in reducing high soil nitrate contents and the associated N 2 O emissions after rapeseed harvest. A field trial was conducted in Southern Germany at a site characterized by a silty loam soil, temperate climate and high precipitation. N 2 O fluxes were measured twice a week with the closed chamber method. In 2013/14 and 2014/15 the calculated N-balance (N input – N output) showed a surplus after rapeseed harvest of 61 kg N ha −1 and 117 kg N ha −1 , respectively. N 2 O-N emissions were relatively low from August to March in both years, remaining within a range of 0.3 and 2.0 kg ha −1 . The biomass N uptake of the succeeding crops increased significantly in both years and all treatments over winter with the exception of the mustard treatment which lost N due to freezing off. No clear relationship between N 2 O emissions and the course of soil mineral nitrogen (SMN) dynamics was observed. In both years, there were no significant differences in N 2 O emissions between all treatments. Our results indicate that as far as N 2 O emissions under well-managed soils in southern Germany are concerned, there is no need to change the established crop sequence of rapeseed – winter wheat. [ABSTRACT FROM AUTHOR]

Long-Term Field Experiments (LTEs) were implemented to study the long-term effects of different management practices, including tillage, fertilization and crop rotation under otherwise constant conditions. Climate change is expected to change these conditions, challenging interpretation of LTE data with regard to the distinction between climate change and management effects. The objective of the study was to quantify the expected, spatially differentiated changes of agroclimatic conditions for the German LTE sites as a precondition for modelling and LTE data interpretation. We developed a framework combining spatially distributed climate data and LTE metadata to identify the possible climatic changes at 247 LTE sites with experiments running for 20 years or more. The LTEs were classified using the following categories: fertilization, tillage, crop rotation, field crops or grassland, conventional or organic. We utilized climate variables (temperature, precipitation) and agroclimatic indicators (aridity, growing degree days, etc.) to compare a baseline (1971–2000) with future periods (2021−2100) under the IPCC's Shared Socio-economic Pathways (SSP). A comprehensive LTE risk assessment was conducted, based on changes in climate variables and agroclimatic indicators between baseline and future scenarios. Under the most extreme scenario (SSP585), 150 LTEs are expected to shift from humid and dry sub-humid to semi-arid conditions. Frost days in LTE areas are expected to decline by 81%, and the growing season to lengthen by up to 92%. The spatial differentiation of expected climate change also facilitates the identification of suitable sites for future agricultural practices and may inform the design of new LTEs. Our results may guide the interpretation of LTE data regarding the effect of climate change, facilitating future soil crop modelling studies with LTE data and providing information for planning new LTE sites to support future agricultural research and/or adapting management on existing LTE sites. The framework we developed can easily be transferred to LTE sites in agricultural regions worldwide to support LTE research on climate change impacts and adaptation. [Display omitted] • The effects of climate change on Long-Term Field Experiments (LTE) sites were assessed using Germany as a case study. • 150 LTEs were estimated to shift from humid and dry sub-humid to semi-arid conditions. • Frost days in LTE areas are expected to decline by 81%, and the growing season to lengthen by up to 92%. • No considerable correlation between soil quality and agroclimatic indicators were found on the LTE sites. [ABSTRACT FROM AUTHOR]

Agriculture is a major contributor to nitrate groundwater contamination. Hence, farmers are demanded to reduce the environmental impact but simultaneously must provide sufficient food products. One important building block for this "sustainable intensification" are appropriate cropping strategies. The potential of modified crop rotations was evaluated in a high-yielding environment in Northern Germany. Therefore, in five consecutive growing seasons (2016/2017 – 2020/2021) three crop rotations were grown in a field trial and compared with respect to agronomic (cereal unit), economic (gross margin) and environmental (N surplus) parameters. A standard crop rotation, typical for the region of the study, was compared with rearranged and augmented crop rotations. Therefore, crops with a high autumnal N uptake (winter oilseed rape and catch crops) were grown after crops with typically high soil mineral N (SMN) amounts after harvest (faba bean and winter oilseed rape). Due to the change of preceding and subsequent crops, an increased N transfer was supposed to prevent N from leaching and a lower N fertilizer demand of the subsequent crop was expected. On average, the modified crop rotations achieved significantly higher cereal units (9.3 and 10.8 t · ha−1) compared to the local crop rotation (8.5 t · ha−1). The gross margin of the local crop rotation was 1474 € · ha−1 and the other crop rotations maintained (1443 € · ha−1) or significantly increased (1572 € · ha−1) this value, respectively. The local crop rotation had a N surplus of 47 kg N · ha−1. In contrast, the N surplus of the modified crop rotations was significantly lower (10 and 28 kg N · ha−1). In summary, the results showed that a thoughtful rearrangement of crop rotations is an appropriate measure to simultaneously improve yields and gross margins with less unfavorable environmental impacts. • Field trial in five seasons fulfilling the principles of crop rotation experiments. • Modified crop rotations improve cereal units, gross margins, and nitrogen surpluses. • Thoughtful rearranged crop rotations can contribute to a sustainable intensification. [ABSTRACT FROM AUTHOR]

Avoiding soil compaction caused by agricultural management is a key aim of sustainable land management, and the soil compaction risk should be considered when assessing the environmental impacts of land use systems. Therefore this project compares different crop rotations in terms of soil structure and the soil compaction risk. It is based on a field trial in Germany, in which the crop rotations (i) silage maize (SM) monoculture, (ii) catch crop mustard (Mu)_sugar beet (SB)-winter wheat (WW)-WW, (iii) Mu_SM-WW-WW and (iv) SB-WW-Mu_SM are established since 2010. Based on the cultivation dates, the operation specific soil compaction risks and the soil compaction risk of the entire crop rotations are modelled at two soil depths (20 and 35 cm). To this end, based on assumptions of the equipment currently used in practice by a model farm, two scenarios are modelled (100 and 50% hopper load for SB and WW harvest). In addition, after one complete rotation, in 2013 and in 2014, the physical soil parameters saturated hydraulic conductivity (k S ) and air capacity (AC) were determined at soil depths 2–8, 12–18, 22–28 and 32–38 cm in order to quantify the soil structure. At both soil depths, the modelled soil compaction risks for the crop rotations including SB (Mu_SB-WW-WW, SB-WW-Mu_SM) are higher (20 cm: medium to very high risks; 35 cm: no to medium risks) than for those without SB (SM monoculture, Mu_SM-WW-WW; 20 cm: medium risks; 35 cm: no to low risks). This increased soil compaction risk is largely influenced by the SB harvest in years where soil water content is high. Halving the hopper load and adjusting the tyre inflation pressure reduces the soil compaction risk for the crop rotation as a whole. Under these conditions, there are no to low soil compaction risks for all variants in the subsoil (soil depth 35 cm). Soil structure is mainly influenced in the topsoil (2–8 cm) related to the cultivation of Mu as a catch crop and WW as a preceding crop. Concerning k S , Mu_SB-WW-WW (240 cm d −1 ) and Mu_SM-WW-WW (196 cm d −1 ) displayed significantly higher values than the SM monoculture (67 cm d −1 ), indicating better structural stability and infiltration capacity. At other soil depths, and for the parameter AC, there are no systematic differences in soil structure between the variants. Under the circumstances described, all crop rotations investigated are not associated with environmental impacts caused by soil compaction. [ABSTRACT FROM AUTHOR]

Empirical data on energy performance (net-energy yield, energy efficiency, land demand) of biomass crop cultivation are needed for policy and agronomic decision making. Energy input and energy performance of the cultivation of silage maize (SM), sugar beet (SB), and winter wheat (WW) in crop rotations and continuous cultivation were evaluated on the basis of three field experiments on highly productive sites in Germany. Silage maize and SB root were considered as crops for biogas production and WW as a food crop. Even if SM cultivation needed the largest energy input across sites and years (19–22 GJ ha −1 a −1 ), the energy output compensated for it and largest net-energy yield (212–317 GJ ha −1 a −1 ), energy efficiency (11.4–17.1 GJ GJ −1 ), and smallest land demand (33–48 m 2 GJ −1 ) were observed. For SB cultivation, energy input (15–19 GJ ha −1 a −1 ) and energy performance were lower (119–266 GJ ha −1 a −1 , 9.1–14.7 GJ GJ −1 , 38–279 m 2 GJ −1 , respectively). Differences between both crops were significant (p ≤ 0.05), but not in all cases. Winter wheat cultivation required an energy input of 13–18 GJ ha −1 a −1 and showed the lowest energy performance (103–119 GJ ha −1 a −1 , 6.6–8.6 GJ GJ −1 , 84–102 m 2 GJ −1 , respectively). The net-energy yield and land demand values presented are among the largest and the lowest, respectively, for rainfed Central European conditions. As the preceding crops, SB induced a higher energy performance of the subsequent WW than SM. When taking such crop rotation effects into account for the overall evaluation, we concluded that SB root as a biomass crop is a suitable alternative to SM. [ABSTRACT FROM AUTHOR]

The reduction of pesticide use intensity is a societal and political ambition. Crop rotation is one important method to control pests and diseases in arable farming. We investigated the contribution of crop rotation to the variability of herbicide and fungicide use of 60 farms in four regions of Northern Germany. Our study aimed at answering the question: do diverse crop sequences lead to reduced herbicide and fungicide use in arable farming? Ten-year data on chemical plant protection measures and field management were examined for six field crops. We classified crop sequences (triplets of three succeeding crops) according to their susceptibility for weeds and diseases (= ’riskiness’). The Treatment Frequency Index (TFI) of the last crop in the triplet was set in relation to the crop triplet riskiness, additionally also in combination with tillage. In general, herbicide and fungicide use intensities were smaller in more diverse crop sequences. Diversified cereal sequences, involving roots and tubers, maize or spring cereals were less dependent on herbicides. Cultivation of maize in three subsequent years increased herbicide use. Crop sequences including high proportion of winter cereals increased fungicide use in cereals, while roots and tubers, winter oilseed rape and set-aside in the crop sequence decreased it. In winter oilseed rape, sequences with roots and tubers also increased fungicide use. In sugar beets, sequences with maize or a high concentration of sugar beets led to increasing fungicide use. If farmers chose riskier crop sequences tillage by plough decreased the need for herbicide and fungicide use. To reduce herbicide and fungicide use intensities we recommend increasing the diversity of crop rotations, including a higher number of crops per rotation together with ploughing. Simplifying both crop sequence diversity and tillage intensity implies higher use of herbicides and fungicides. Results will be useful for convincing farmers to diversify crop sequences. [ABSTRACT FROM AUTHOR]

Crop cultivation intensifies globally, which can jeopardize biodiversity and the resilience of cropping systems. We investigate changes in crop rotations as one intensification metric for half of the croplands in Germany with annual field-level land-use data from 2005 to 2018. We proxy crop rotations with crop sequences and compare how these sequences changed among three seven-year periods. The results reveal an overall high diversity of crop sequences in Germany. Half of the cropland has crop sequences with four or more crops within a seven-year period, while continuous cultivation of the same crop is present on only 2% of the cropland. Larger farms tend to have more diverse crop sequences and organic farms have lower shares of cereal crops. In three federal states, crop rotations became less structurally diverse over time, i.e. the number of crops and the number of changes between crops decreased. In one state, structural diversity increased and the proportion of monocropping decreased. The functional diversity of the crop sequences, which measures the share of winter and spring crops as well as the share of leaf and cereal crops per sequence, remained largely stable. Trends towards cereal- or leaf-crop dominated sequences varied between the states, and no clear overall dynamic could be observed. However, the share of winter crops per sequence decreased in all four federal states. Quantifying the dynamics of crop sequences at the field level is an important metric of land-use intensity and can reveal the patterns of land-use intensification. [Display omitted] • First analysis of temporal trends in crop sequences on half of the German cropland. • Declining number of crops per sequence in three federal states. • Functional diversity of crop sequences remains stable. • High numbers of livestock often occur with less diverse crop sequences. • Organic farms use less cereal crops in their crop sequences. [ABSTRACT FROM AUTHOR]

The cultivation of short rotation coppices (SRC) on agricultural land represents an economically and environmentally promising option for sustainable provision of bioenergy. Not only the further development of efficient harvesting machinery, but also the development of harvest-optimised storage systems are necessary to implement cost-efficient cultivation and use strategies for SRC in practice. The storage of fine wood chips from poplar harvest with a forage harvester results in high dry matter losses of up to 25%. Tractor-mounted mower-chippers can harvest coarse wood chips that might possess more favourable storage and drying properties. The main objective of the current research project was to develop and perform a storage experiment in which the storage behaviour of fine and coarse wood chips could be examined and compared in detail over a period of nine months. In this experiment two covered storage piles (height 3.5 m), with over 500 m 3 fine and coarse wood chips respectively, were examined under practice scale conditions in Germany. After nine months of storage the fine chips in the core of the storage pile had dried to a moisture content of 34% with dry matter losses of 22%. Coarse chips, on the other hand, achieved a moisture content of 29% and dry matter losses of 21% in the same period. The maximum moisture content of 40% required by heating plants in practice is achieved by fine chips after 6.5 months and by the coarse chips already after 3.5 months. [ABSTRACT FROM AUTHOR]

Wheat is an important crop to meet the increasing demand for food and fodder. In Germany, it is the most common cereal crop, but only small area is cultivated with spring wheat. However, within the system of organic agriculture this acreage share is considerably higher. Diversified crop rotations with balanced proportions of summer and winter crops are an essential part of organic production systems. Thus, there is a need for varieties with potential under less intensive conditions. In a field trial, breeding progress among 7 European spring wheat varieties with different ages of approval (1949-2011) was investigated at two study sites in Germany and Russia. Newer varieties showed at both sites significant better yields (2 to 4 times higher) than the oldest one. Better lodging resistance as well as lower vulnerability to powdery mildew was observed at significant level for varieties released in the 2000er compared to 1949. Furthermore, individual yield-forming components like 1000-kernel weight, grains/ear and ears/m² were significantly higher among the newer than at the oldest variety. Overall, these results confirm breeding progress for the observed varieties over the entire period for their region of origin (Germany) and under other climatic conditions in Siberia, respectively. [ABSTRACT FROM AUTHOR]

Biomass provides two thirds of the total energy produced from renewables in Europe. The share of bioenergy from energy crops is growing rapidly. Given the environmental pressures arising from pesticide pollution from current agricultural food production, a substantial increase in energy crop cultivation might put additional pressure on biodiversity and soil and water resources. In the present study, we examine the potential of energy crops for pesticide contamination and develop general conclusions and recommendations for the future large-scale expansion of agricultural bioenergy. We base our analysis on the development of energy crop cultivation in Germany, the European country with the largest share of energy crops. Our findings reveal that there will not necessarily be an increase or decrease in the amounts of pesticides released into the environment. Due to the great variety of energy crops, the potential effects will depend rather on the future design of the agricultural systems. Possible risks are associated with the increased cultivation of pesticide-intensive energy crops, such as rapeseed, especially when grown in monocultures or on formerly set-aside land or converted grassland. Instead, energy crops should be integrated into the existing food production systems. Financial incentives and further education are needed to encourage the use of sustainable crop rotations, innovative cropping systems and perennial energy crops, which may add to crop diversity and generate lower pesticide demands than intensive food farming systems. Optimised cultivation systems with diverse crop rotations could help to improve monotonous agricultural landscapes, increase biodiversity and minimise pesticide exposure. [ABSTRACT FROM AUTHOR]

Integrating leys, cover crops, and animal manures constitute promising avenues to reach annual soil organic carbon changes (ΔSOC) >0.4% in forage and grain-based crop rotations, rates required to offset the increasing C emissions from fossil fuels ("4 per mille" initiative). How these practices and rotations perform in reaching this aim was object of analysis in this paper. Five cropping systems (CS), including three three-year forage and grain-based crop rotations containing annual grass-clover leys (FR and MR) or cover crops (GR), and two contrasting controls (continuous silage maize (CM), and permanent grassland (PG)) were compared for their impact on SOC stocks over eight years (2010–2018). The CS were unfertilized (N0) or fertilized using cattle slurry (N1) at a rate of 240 kg N ha−1 yr−1 applied in the non-leguminous crops. The ΔSOC of the top 30 cm soil layer and the annual carbon inputs (Cin) from slurry applications and plant residues were estimated, their relationship established, and the slurry-induced C retention coefficient was determined. The FR and MR SOC stocks remained stable at N1, while the GR and CM SOC decreased over time by tendency even at N1. Only the PG reached ΔSOC >0.4%. Differences in ΔSOC between CS and N rates were highly associated with the system-specific increase in belowground Cin, induced by slurry applications. Slurry-induced C retention coefficients differed strongly between CS: CM (3%) followed by GR (12%), and by FR and MR (20–15%), and lastly by PG (24%). Promoting belowground carbon inputs was identified as an efficient way to reach significant increases in ΔSOC. We conclude that a ley in only one out of three years is not sufficient to significantly increase SOC stocks in arable crop rotations of the study region. [ABSTRACT FROM AUTHOR]

Monitoring agricultural systems becomes increasingly important in the context of global challenges like climate change, biodiversity loss, population growth, and the rising demand for agricultural products. High-resolution, national-scale maps of agricultural land are needed to develop strategies for future sustainable agriculture. However, the characterization of agricultural land cover over large areas and for multiple years remains challenging due to the locally diverse and temporally variable characteristics of cultivated land. We here propose a workflow for generating national agricultural land cover maps on a yearly basis that accounts for varying environmental conditions. We tested the approach by mapping 24 agricultural land cover classes in Germany for the three years 2017, 2018, and 2019, in which the meteorological conditions strongly differed. We used a random forest classifier and dense time series data from Sentinel-2 and Landsat 8 in combination with monthly Sentinel-1 composites and environmental data and evaluated the relative importance of optical, radar, and environmental data. Our results show high overall accuracy and plausible class accuracies for the most dominant crop types across different years despite the strong inter-annual meteorological variability and the presence of drought and non-drought years. The maps show high spatial consistency and good delineation of field parcels. Combining optical, SAR, and environmental data increased overall accuracies by 6% to 10% compared to single sensor approaches, in which optical data outperformed SAR. Overall accuracy ranged between 78% and 80%, and the mapped areas aligned well with agricultural statistics at the regional and national level. Based on the multi-year dataset we mapped major crop sequences of cereals and leaf crops. Most crop sequences were dominated by winter cereals followed by summer cereals. Monocultures of summer cereals were mainly revealed in the Northwest of Germany. We showcased that high spatial and thematic detail in combination with annual mapping will stimulate research on crop cycles and studies to assess the impact of environmental policies on management decisions. Our results demonstrate the capabilities of integrated optical time series and SAR data in combination with variables describing local and seasonal environmental conditions for annual large-area crop type mapping. • Large-area crop type mapping without region−/class-specific feature selection. • Integration of data describing local and seasonal environmental conditions. • 24 agricultural land cover classes at national scale and for multiple years. • High accuracy despite strong inter-annual meteorological variability. • Combined crop type maps enable crop sequence analysis at national scale. [ABSTRACT FROM AUTHOR]

Abstract: Although there is a need for biomass and a potential for short rotation coppice (SRC), farmers hesitate to establish SRC, even on marginal agricultural land on which annual crops show low productivity. Probably the most important factor explaining this reluctance might be the uncertain economic prospects of the cultivation of SRC. Therefore, the aim of this study is to analyse the economy of a typical SRC supply chain by calculating the annuities which can be expected by German farmers who establish SRC on their marginal land. The result shows that the yearly annuity of a 20-year SRC cultivation is about 70 € y−1 ha−1 when poplar SRC is harvested every 4 years with a forage harvester (one-step system). The result includes the establishment, cultivation and transport of the fresh wood chips to a plant 50 km away. However, this result is not competitive with the result of annual crops (226–462 € y−1 ha−1) and is also lower than the CAP subsidy payments that farmers receive from the EU (300 € y−1 ha−1). To achieve higher annuities, four options were analysed possibly leading either to higher biomass yields or to higher market prices (extension of rotation cycle, implementation of irrigation, technical drying of fresh wood chips, using a two-step harvesting system). The implementation of drip irrigation to increase biomass yield turned out to be uneconomic. An extension of the rotation cycle from 4 to 5 years can be recommended as it leads to an annuity of 255 € y−1 ha−1 (instead of 69 € y−1 ha−1). Results also show that the technical drying of chips using (cheap) surplus heat can be very profitable if the added value is reflected in higher market prices. Furthermore, it is shown that the use of an alternative two-step harvesting system with natural interim drying of the rods can be an attractive option for farmers to increase the annuity of their SRC. [Copyright &y& Elsevier]

Legume catch crops can enhance soil fertility and promote the N and P supply of the subsequent main crop, especially with low mineral fertilizer use. However, the specific impact of catch crops on arbuscular mycorrhiza formation of the following main crop is unknown. Therefore, the impact of serradella (Ornithopus sativus) vs. bare fallow was tested on mycorrhiza formation, potential soil enzyme activities and plant-available P under subsequently grown barley (Hordeum vulgare) and different fertilization treatments (P-unfertilized—P0; triple superphosphate—TSP; compost—COM; combined—COM + TSP) in a long-term field experiment in northeastern Germany. Catch cropping significantly increased mycorrhiza formation of barley up to 14% compared to bare fallow. The impact of serradella on mycorrhiza formation exceeded that of the fertilization treatment. Serradella led to increased phosphodiesterase activities and decreased ß-glucosidase activities in soil. Plant availability of P was not significantly affected by serradella. These findings provide initial evidence that even serradella as a non-host crop of mycorrhizal fungi can promote the mycorrhiza formation of the subsequent crop and P mobilization in soil. We conclude that the prolonged vegetation cover of arable soils by the use of catch crops can promote P mobilization and transfer from P pools to the following main crops. [ABSTRACT FROM AUTHOR]

Nitrogen fertilizers are the major source of nitrous oxide (N 2 O) emissions from arable land. The addition of nitrification inhibitors to fertilizers may improve the nitrogen (N) use efficiency and reduce N 2 O emissions. However, it is still unclear how crop rotations affect nitrification and urease inhibitors to reduce N 2 O emissions. We conducted a field experiment with two-year winter wheat and one-year oilseed rape cultivation in Germany from 2016 to 2017. We applied five different fertilizer treatments: (1) a control treatment without fertilization (N0); (2) calcium ammonium nitrate (CAN); (3) ammonium sulfate nitrate with the nitrification inhibitor 3,4-dimethylepyrazole phosphate (ENTEC); (4) urea; and (5) urea with the urease inhibitor N -(n -butyl) thiophosphoric triamide (UTEC). Crop yield, grain and straw N content, and N 2 O fluxes were measured to assess yield-scaled N 2 O emissions under different treatments. We found that in all fertilized treatments, the aboveground N uptake of wheat after wheat was 199–203 kg N ha−1, which was much lower than that of wheat after oilseed rape (252–271 kg N ha−1). The apparent N recovery of oilseed rape (13–23%) was much lower than in wheat after wheat (63–66%). The enhanced-efficiency fertilizers increased aboveground N uptake by 0–5% compared to fertilizers without inhibitors. The oilseed rape field had the highest yield-scaled N 2 O emissions (18.0, 15.1, 16.7 and 15.6 g N 2 O-N kg−1 aboveground N uptake in CAN, ENTEC, urea and UTEC, respectively). These results indicate that urease and nitrification inhibitors hold the potential to increase crop yield and reduce N 2 O emissions. Oilseed rape straw should be carefully managed to avoid high N 2 O emissions. Future research should be focused on different fertilizer level and optimized N application strategy to increase the efficiency of urease and nitrification inhibitors, for instance, by increasing the N application rate in wheat after wheat, but reducing it in oilseed rape. • Effect of NBPT and DMPP on grain yield is minor. • NBPT and DMPP hold the potential to reduce N 2 O emissions in winter wheat and oilseed rape fields. • In oilseed rape, N fertilization induced high post-harvest N 2 O emissions. [ABSTRACT FROM AUTHOR]

The demand for wood from short rotation coppice ( SRC) plantations as a renewable energy source is currently increasing and could affect biodiversity in agricultural areas. The objective was to evaluate the contribution of SRC plantations to phytodiversity in agricultural landscapes assessed as species richness, species-area relationships, Shannon indices, detrended correspondence analysis on species composition, Sørensen similarities, habitat preference proportions, and species proportions found in only one land use. Vegetation surveys were conducted on 12 willow ( Salix spp.) and three poplar ( Populus spp.) coppice sites as well as on surrounding arable lands, grasslands and forests in central Sweden and northern Germany. SRC plantations were richer in plant species (mean: 30 species per 100 m²) than arable land (10), coniferous forests (13) and mixed forests in Germany (12). Comparing SRC plantations with other land uses, we found lowest similarities in species composition with arable lands, coniferous forests and German mixed forests and highest similarities with marginal grassland strips, grasslands and Swedish mixed forests. Similarity depended on the SRC tree cover: at increased tree cover, SRC plantations became less similar to grasslands but more similar to forests. The SRC plantations were composed of a mixture of grassland (33%), ruderal (24%) and woodland (15%) species. Species abundance in SRC plantations was more heterogeneous than in arable lands. We conclude that SRC plantations form novel habitats leading to different plant species composition compared to conventional land uses. Their landscape-scale value for phytodiversity changes depending on harvest cycles and over time. As a structural landscape element, SRC plantations contribute positively to phytodiversity in rural areas, especially in land use mosaics where these plantations are admixed to other land uses with dissimilar plant species composition such as arable land, coniferous forest and, at the German sites, also mixed forest. [ABSTRACT FROM AUTHOR]

Abstract: Power based on biomass, in particular biogas, is increasing, with a concomitant increase in the need for energy crop production. The objective of this study was to determine the profitability of biogas substrate production on a marginal site in southwestern Germany. The effects of crop rotation and nitrogen fertilization level were evaluated in a three-year filed experiment. Production costs for supply of biogas substrates and sales of produced electricity were assessed using five crop rotations (CR1: annual monoculture maize; CR2: perennial monoculture perennial ryegrass; CR3: perennial monoculture Jerusalem artichoke; CR4: three-course crop rotation of sorghum – winter triticale – clover grass; CR5: four-course crop rotation of catch crop – maize – winter wheat – winter triticale) and three nitrogen fertilization levels (zero, middle and high levels of nitrogen). The variables were production costs, dry matter yield, substrate costs, energy output, biomass energy supply price, biomass energy sales price and sale/supply ratio. Production costs increased in the order CR4 (1252 € ha−1 a−1) < CR2 (1256 € ha−1 a−1) < CR5 (1404 € ha−1 a−1) < CR3 (1462 € ha−1 a−1) < CR1 (1649 € ha−1 a−1) due to differing mechanical cultivation needs. Dry matter yields ranged from 10.8 t ha−1 a−1 (CR3) to 4.0 t ha−1 a−1 (CR2) and showed significantly higher yields with increasing fertilization levels. Accounting for all variables, the lowest biomass energy supply price was achieved with CR3 (6.6 ct kWh−1), and increased in the order CR1 < CR5 < CR4 < CR2 (12.4 ct kWh−1). It was determined that only CR3 and CR1 were effective for the production of biogas substrates on marginal sites. The biogas substrate costs of the remaining crop rotations were not compensated for by the sale of electricity. [Copyright &y& Elsevier]

Abstract: The study provides information to more reliably estimate the value of conservation tillage in a temperate climate. Tillage effects on yield and weeds were evaluated in field experiments at two sites in SW Germany between 1999 and 2010. Tillage varied at site Ihinger Hof from mouldboard plough (P), chisel plough (CP), rototiller (RTT), varying P and CP (VAR), to no tillage (NT), partially combined with stubble tillage (S). Tillage at site Meiereihof was S/P, S/CP, and NT. Crop rotations included winter wheat (WW, Triticum aestivum), triticale (TR, Triticosecale), oat (OA, Avena sativa), silage maize (SM, Zea mays) and oilseed rape (OSR, Brassica napus) at Ihinger Hof, and winter wheat, spring barley (SB, Hordeum vulgare), silage maize, sugar beets (SBE, Beta vulgaris) and faba bean (FB, Vicia faba) at Meiereihof. At Ihinger Hof, tillage had an effect on yield (P > F =0.0049), but no effects were found on crop emergence and crop density. Tillage effects on yield were consistent across crops though differences between crops appeared to exist. The yield of S/P, the standard tillage, was 8.5 (WW), 7.7 (TR), 4.7 (OA), 18.3 (SM) and 4.1 (OSR)tDMha−1 at Ihinger Hof, with yield under NT always significantly lower than S/P by 7.3% on average for all crops. At Meiereihof, yields ranged from 7.2 to 8.0 (WW), 3.3 to 4.2 (SB), 19.8 to 21.5 (SM) and 3.1 to 3.2 (FB)tDMha−1, and 61.3 to 67.6 FM ha−1 for SBE. Yield was reduced by 4.5% from S/P to S/CP (P > F =0.0516), and by about 10% from S/P to NT (P > F =0.0009). Weed density ranged between 0.5 and 44plantsm−2 at Ihinger Hof and was higher in treatments without stubble tillage and under non-inversion tillage, though significance differed for the different classes of weeds. NT led to weed infestation about 2–20 times higher than S/P. The interaction crop×treatment indicated that factors other than tillage influenced weed infestation. It is unlikely that weed infestation and reduced yield will be problems in temperate climates if soil disturbance through tillage is reduced. Non-inversion tillage can easily replace inversion tillage, and stubble tillage can be added to primary tillage if needed to reduce weeds. Since no specific tillage method was unequivocally superior to another one, any method well suited to specific regional and farm conditions can be adopted successfully. [Copyright &y& Elsevier]

Abstract: Ten years of a long-term field experiment using different strategies of conventional and conservation tillage in SW Germany were evaluated for soil mineral nitrogen (SMN) and soil moisture content. Treatments analysed were combinations of stubble tillage (S) or no stubble tillage with primary tillage P: mouldboard plough, CP: chisel plough, RTT: rototiller, NT: no-till, and VAR: alternating S/P or S/CP. Best management practices were used for crop rotation, fertilisation and plant protection. CP, VAR and NT resulted in 18.7–19.0% gravimetric water content in spring. Partially significantly lower water content was observed in spring under S/P and CP with 18.2%; P and S/RTT resulted in 18.5%. Autumn soil moisture ranged from 15.3 to 15.8% and did not significantly differ between the treatments. Interactions between treatment and depth were not significant. There was no clear trend for spring soil moisture. No treatment showed a particular response to dry or wet season. Total SMN ranged between 8 and 49kgha−1 in spring and 5–26kgha−1 in autumn; significant effects of the treatments or interactions of treatment×depth did not occur. The effect of the season was most relevant for the amount of SMN, probably as a result of different conditions for mineralisation. Downward movement of nitrogen in spring was low in all treatments if catch crops were grown in the previous autumn. Overall, different soil tillage methods had little effect on soil moisture and soil SMN under temperate conditions. Seriously adverse effects of any tillage treatment in terms of nitrate leaching or reduced mineralisation seem unlikely. Similarly, the tillage systems did not exhibit obvious advantages or disadvantages in terms of soil water content. An exception may have been the higher water content in autumn in 0–30cm under high soil disturbance which provided more suitable conditions for germination of the following crop. The decision of whether or not to adopt conservation tillage in temperate climates seems not to be primarily dependent on soil moisture and nitrogen mineralisation or on nitrogen leaching. [Copyright &y& Elsevier]

Abstract: This study provides a risk analysis of long-term field experiments in Germany (Bavaria) on various field crops (potato, wheat and corn), grown in rotation, under a variety of different tillage and nitrogen management systems. The field experiment provided yield and input data for the analysis, and was combined with market data relevant to the case-study region. The emphasis of the analysis is on the interaction between risk and tillage and nitrogen strategies. Over the whole rotation (corn–wheat–potato–wheat), conventional tillage combined with conventional nitrogen rates is optimal, both for risk-neutral and risk-averse farmers. Although less intensive management practices involve lower risk, the decrease in risk premium is not sufficient to alter the ranking of strategies, even for farmers with higher levels of risk aversion. Reducing nitrogen rates would be costly to farmers, especially under reduced or shallow tillage. Decoupled farm subsidies within the expected utility model show that even for a scenario with no subsidies our conclusions do not change. [Copyright &y& Elsevier]

The effect of various rotations and fallow periods on development of sugar beet, product quality and nematode infestation as well as soil physical parameters have been studied in the sugar beet rotation experiment Etzdorf, which had been started in 1970 on a Haplic Chernozem in the state Saxony-Anhalt, Germany. In 2006, for the first time various soil physical parameters have been analysed. The different rotations did not affect the parameters significantly. This does also apply to the total organic carbon content, which was 2.08 vol. % in sugar beet monoculture and thus only 0.16 vol. % in a rotation with only 20% sugar beet. Serious yield effects were measured if the proportion of sugar beet in the rotation was increased to 25% and more. The break in the rotation affected the yield and quality parameters. In situations with a substantial nematode infestation breaks of a minimum of three years are recommended. If this recommendation is exceeded a critical infestation with 500 eggs and larvae in 100 g soil causes yield decreases of a minimum of 5% on average, which might be higher in single years. This affects yield stability depending on seasonal weather conditions. In dem Fruchtfolgeversuch auf Loss-Schwarzerde in Etzdorf (Sachsen-Anhalt), angelegt 1970, wurden die Auswirkungen unterschiedlicher Anbaukonzentrationen und Anbaupausen bei Zuckerruben auf die Pflanzenentwicklung, Produktqualitat und den Nematodenbesatz als auch auf bodenphysikalische Parameter untersucht. Bei den 2006 erstmalig in Krume und Unterboden unter Zuckerruben ermittelten bodenphysikalischen Eigenschaften (Trockenrohdichte, Grobporenvolumen und Wasserleitfahigkeit) wurden zwischen den Anbaukonzentrationen nur geringe Differenzierungen festgestellt. Das trifft auch fur den TOC-Gehalt zu, der bei Rubendaueranbau (2,08 M.-%) gegenuber 20% Anteil in der Fruchtfolge nur um 0,16 M.-% abnahm. Deutliche Ertragseinbussen treten bei Zuckerrubenanteilen von mehr als 25% in der Fruchtfolge auf. Die Anbaupausen wirken sich auf den Korper- und Zuckerertrag stark differenzierend aus, besonders wenn mehrere Zuckerrubenfelder in die Rotation einbezogen werden. Auf den nematodenverseuchten Standorten sind deshalb Anbaupausen von mindestens 3 Jahren einzuhalten. Bei Uberschreitung dieser Empfehlung werden in Abhangigkeit vom Ausgangszustand die kritischen Nematoden-Verseuchungswerte von 500 Eier und Larven je 100 g Boden, die zu gesicherten Ertragsausfallen von mehr als 5% fuhren, in den Einzeljahren haufiger erreicht und teilweise auch wesentlich ubertroffen. Unter diesen Bedingungen wird in Abhangigkeit von jahresspezifischen Einflussen die Ertragssicherheit ungunstig beeinflusst. [ABSTRACT FROM AUTHOR]

Abstract: Nitrogen inputs into surface waters from diffuse sources are still unduly high and the assessment of mitigation measures is associated with large uncertainties. The objective of this paper is to investigate selected agricultural management scenarios on nitrogen loads and to assess the impact of differing catchment characteristics in central Germany. A new modelling approach, which simulates spatially distributed N-transport and transformation processes in soil and groundwater, was applied to three meso scale catchments with strongly deviating climate, soil and topography conditions. The approach uses the integrated modelling framework JAMS to link an agro-ecosystem, a rainfall-runoff and a groundwater nitrogen transport model. Different agricultural management measures with deviating levels of acceptance were analysed in the three study catchments. N-leaching rates in all three catchments varied with soil type, the lowest leaching rates being obtained for loess soil catchment (18.5 kg nitrate N ha−1 yr−1) and the highest for the sandy soils catchment (41.2 kg nitrate N ha−1 yr−1). The simulated baseflow nitrogen concentrations varied between the catchments from 1 to 6 mg N l−1, reflecting the nitrogen reduction capacity of the subsurfaces. The management scenarios showed that the highest N leaching reduction could be achieved by good site-adapted agricultural management options. Nitrogen retention in the subsurface did not alter the ranking of the management scenarios calculated as losses from the soil zone. The reduction effect depended strongly on site specific conditions, especially climate, soil variety and the regional formation of the crop rotations. [Copyright &y& Elsevier]

Rhizoctonia solani (AG 2-2IIIB), causing root and crown rot in sugar beet, poses an increasing problem in Europe. Agronomic measures have to be optimized to control disease and minimize yield and quality loss, because no fungicides can be applied. Resistant sugar beet cultivars have been introduced to reduce disease occurrence. Furthermore, crop rotation can influence R. solani occurrence. In contrast to other cereals, maize serves as a host of the fungus. In order to study the combined effect of these factors, a series of four field trials was established with crop rotations varying in the proportion of maize and comparing a resistant with a susceptible sugar beet cultivar in 2001-02 in southern Germany. Within crop rotations, cultivation methods were varied in the form of soil tillage, intercrops, or both. Sugar beet cultivar and crop rotation had the main impact on disease severity and sugar yield. With increasing proportion of maize, sugar yield decreased, whereas cultivation method had only a minor impact. Plowing directly before sugar beet increased sugar yield only within the unfavorable maize-maize-sugar beet rotation compared with mulching. These results give strong evidence that crop rotation of sugar beet with nonhost plants and cultivation of resistant sugar beet cultivars are adequate means for integrated R. solani control. [ABSTRACT FROM AUTHOR]

[Display omitted] • We propose summable C factors to enable easy assessment of water erosion. • Summable C factors were calculated for 57 crops instead of defined crop rotations. • Results for Central Europe also include estimation functions for additional crops. • Summable C factors have changed due to climate change. • Row crop C decreased and small grain C increased. Crop cultivation, crop stages and the seasonal distribution of rainfall erosivity are continuously changing in response to changes in climate and socio-economic conditions. Therefore, the crop and cover factor (C factor) of the (Revised) Universal Soil Loss Equation should also be adjusted continuously. Within the framework of the (R)USLE, C factors can only be calculated for crop rotations. However, for large-scale and regional modeling of soil erosion on arable land and targeted subsidy schemes for the implementation of soil protection measures, C factors are required that quantify the effect of individual crops and management options on the risk of soil erosion. We therefore develop a method for deriving summable C factors that can easily be combined to derive C factors for crop rotations. These summable C factors also account for carry-over effects that influence the risk of soil erosion in subsequent crops. Using the latest data on the temporal distribution of rain erosivity and approximately 3.5 million observations of crop stages, summable C factors were derived for 57 crops and crop management options, including double cropping, which is currently becoming more prevalent in temperate areas. These C factors apply for Germany. However, the regional variation of summable C factors within Germany was small and comparison with Swiss data indicated that our summable C factors will also apply in neighboring countries in Central Europe. Changes in the seasonal distribution of rain erosivity and in crop development due to climate change caused some convergence of the summable C factors for different crops, i.e. the C factors for crops where the risk of soil erosion potential had previously been low increased, while for those crops where the risk of erosion had previously been high the C factors decreased. Of the arable crops, potatoes had by far the highest summable C factor, whereas sod-forming crops had negative summable C factors, leading to low C factors for crop rotations. The sod crops seem to be largely responsible for the low level of soil erosion found on many organic farms and in Switzerland, where sod crops account for a large share of arable land. [ABSTRACT FROM AUTHOR]

The advantages of using multispectral remotely sensed data instead of CORINE Land Cover for the modelling of nitrate concentrations in the leachate of the Rur catchment are presented and discussed in this paper. In this context it has been shown that the identification of main crops and annual crop rotation in the Rur catchment by SPOT, LANDSAT and ASTER imagery provides the key for a spatial and thematic enhancement of the model results. The spatial resolution of the nitrogen surplus data set which denotes the linkage between RAUMIS and GROWA is enhanced from district level to field/pixel level. In parallel, the empirical water balance model GROWA is enhanced to differentiate between agricultural crops in the real evapotranspiration calculation. It is calibrated by runoff data measured at gauging stations. Results indicate, e.g., an average nitrate concentration in the leachate of 42mg NO3/L in the relatively wet year of 2002 and almost 62mg NO3/L in the dry year of 2003. There is a 20mg NO3/L weather-induced difference which can be modelled in a more detailed way using self-processed remotely sensed data. The model results were compared to nitrate concentrations observed in the top parts of multi-level wells. In this way the related coefficient of determination has been improved from a value (R) of −0.50 using CORINE to 0.59 by using self-processed remotely sensed data, thus demonstrating the potential of the enhanced model system. [Copyright &y& Elsevier]

Combining agriculture and photovoltaics on the same land area gains in attention and political support in a growing number of countries accompanied by notable research activities in France, USA and Korea, amongst others. This study assesses the technical feasibility of agrivoltaic (APV), while it gives insights on how to design an APV system. Furthermore, it analyses the electrical yield and the behavior and productivity of four crops grown in Germany's largest agrivoltaic research facility installed in 2016 near Lake Constance within the research project APV-RESOLA by Fraunhofer Institute for Solar Energy Systems ISE. The German design differs from most other agrivoltaic approaches by allowing for a wide range of machine employment, facilitated by a vertical clearance of 5 m and a width clearance of up to 19 m. Crops cultivated under the APV system and on the reference field under a crop rotation scheme include potato, celeriac, clover grass and winter wheat. The land use efficiency measured by the Land Equivalent Ratio (LER) indicated a rise between 56% and 70% in 2017 while the dry and hot summer in 2018 demonstrated that the agrivoltaic system could increase land productivity by nearly 90%. Radiation simulations showed that deviating from full south by around 30° resulted in equal distribution of radiation on ground level, representing the basis for the agrivoltaic design. Considering climate change and increasing land scarcity, our overall results suggest a high potential of agrivoltaics as a viable and efficient technology to address major challenges of the 21rst century. • Light distribution under the APV system simulated by Radiance software tool. • Assessment of different system orientations on the light availability. • The effect of different row distance on the biomass and electrical yield. • The technical feasibility and the design of APV in arable farming. • Promising results of Land Equivalent Ratios for the first two operational years. [ABSTRACT FROM AUTHOR]