Legume crops, the production of which is related to their use in animal nutrition (referred to in this study as “legumes for livestock—LL” and include species such as bean, lupin, pea, vetch and clover), have positive effects on the economic performance of farms and environmental outcomes, although their relation to sustainable weed management practices (SWMP) has received limited attention. The expansion of LL in Europe is limited due to market constraints, despite important policy incentives. This study was designed to investigate whether a policy-oriented Scenario (S1) or a market-based Scenario (S2) could induce the expansion of the cultivation of LL as well as to examine the possible impact on the economic performance of farming systems, including cost savings related to pest management. A farm typology was developed according to the level of expenses of farms for crop protection and their implemented SWMP. Using technical and economic data from 45 farms that cultivate annual arable crops in Greece, with special emphasis on LL, a Linear Programming model was constructed to examine the potential role of each one of the three identified farm types in the expansion of LL in Central Greece (Baseline Solution—BS). Following the BS, the effects of the two Scenarios were examined through a Price Parametric Programming approach. The solutions revealed that the valorization of LL had a significant economic potential for all farm types. In addition, it was found that a substantial policy incentive of increasing the coupled payments of LL by 128% (S1) can have an equivalent impact on the expansion of LL as modest levels of market interventions—through the achievement of higher yields or/and higher selling prices—to increase the revenues of LL by 59% (S2). Farms that relied more on chemical pesticides could play a more decisive role in expanding LL. The novel aspect is related to the investigation of the economic performance of different farm types cultivating LL with a specific focus on potentially higher profitability related to SWMP. Furthermore, this study contributed to the “policy versus market solutions” debate toward the expansion of LL.

Plant identity control on soil food web structure and C transfers under perennial bioenergy plantations

Recent studies have shown dramatic decline in the abundance and diversity of insects over the last decades, including pollinators, lepidopterans, flying insects, parasitoids or epigeal predators, such as carabid and staphylinid beetles. Many of these studies are based on regional data, therefore it is hard to draw a conclusion about the generality of the reported effects across multiple groups and regions. In this paper we focus on testing the hypothesis of insect decline in annual arable crops over a wide geographical range, using meta-analysis of data on carabid beetles as a model group. We extracted pitfall trap catches and observed species richness from 105 independent publications originating from Europe and North America. Data were from a variety of arable annual crops in 22 countries, and spanned a period of 42 years. As sampling effort varied notably across studies, we standardized catches by trapping effort, and explored different options for calculating trapping effort from data. The data over time did not show any evidence of a decline in carabid numbers nor species caught over the 42 years covered by the dataset. A possible explanation for this finding is that carabid beetles living in these habitats are adapted to periodical disturbance by either withstanding these disturbances on site or by periodically re-colonizing fields from adjacent habitats. Although local decreases in carabid populations are documented in the literature as a result of agricultural intensification or landscape simplification, at the broader geographical scale, such a decline is not supported by the data.

Growing mixtures of annual arable crop species or genotypes is a promising way to improve crop production without increasing agricultural inputs. To design optimal crop mixtures, choices of species, genotypes, sowing proportion, plant arrangement, and sowing date need to be made but field experiments alone are not sufficient to explore such a large range of factors. Crop modeling allows to study, understand and ultimately design cropping systems and is an established method for sole crops. Recently, modeling started to be applied to annual crop mixtures as well. Here, we review to what extent crop simulation models and individual-based models are suitable to capture and predict the specificities of annual crop mixtures. We argued that: 1) The crop mixture spatio-temporal heterogeneity (influencing the occurrence of ecological processes) determines the choice of the modeling approach (plant or crop centered). 2) Only few crop models (adapted from sole crop models) and individual-based models currently exist to simulate annual crop mixtures. 3) Crop models are mainly used to address issues related to crop mixtures management and to the integration of crop mixtures into larger scales such as the rotation, whereas individual-based models are mainly used to identify plant traits involved in crop mixture performance and to quantify the relative contribution of the different ecological processes (niche complementarity, facilitation, competition, plasticity) to crop mixture functioning. This review highlights that modeling of annual crop mixtures is in its infancy and gives to model users some important keys to choose the model based on the questions they want to answer, with awareness of the strengths and weaknesses of each of the modeling approaches.

Crop diversification has been proposed as farm management tool that could mitigate the externalities of conventional farming while reducing productivity-biodiversity trade-offs. Yet evidence for the acclaimed biodiversity benefits of landscape-level crop diversity is ambiguous. Effects may strongly depend on spatial scale and the level of landscape heterogeneity (e.g. overall habitat diversity). At the same time, contrasting within-taxon responses obscure benefits to specific functional groups (i.e. species with shared characteristics or requirements) if studied at the community level. The objectives of this study were to 1) disentangle the relative effects of crop diversity and landscape heterogeneity on avian species richness across five spatial scales ranging from 250 to 3000 m radii around focal winter wheat fields; and 2) assess whether functional groups (feeding guild, conservation status, habitat preference, nesting behaviour) determine the strength and direction of responses to crop diversity and landscape heterogeneity. In central Germany, 14 landscapes were selected along independent gradients of crop diversity (annual arable crops) and landscape heterogeneity. Bird species richness in each landscape was estimated using four point counts throughout the breeding season. We found no effects of landscape-level crop diversity on bird richness and functional groups. Instead, landscape heterogeneity was strongly associated with increased total bird richness across all spatial scales. In particular, insect-feeding and non-farmland birds were favoured in heterogeneous landscapes, as were species not classified as endangered or vulnerable on the regional Red List. Crop-nesting farmland birds, however, were less species-rich in these landscapes. Accordingly, crop diversification may be less suitable for conserving avian diversity and associated ecosystem services (e.g. biological pest control), although confounding interactions with management intensity need yet to be confirmed. In contrast, enhancement of landscape heterogeneity by increasing perennial habitat diversity, reducing field sizes and the amount of cropland has the potential to benefit overall bird richness. Specialist farmland birds, however, may require more targeted management approaches.

Identifying crop rotation practice by the typification of crop sequence patterns for arable farming systems – A case study from Central Europe

Ecosystem service delivery of agri-environment measures: A synthesis for hedgerows and grass strips on arable land

Replacing fossil fuel with biofuel is environmentally viable from a climate change perspective only if the net greenhouse gas (GHG) footprint of the system is reduced. The effects of replacing annual arable crops with perennial bioenergy feedstocks on net GHG production and soil carbon (C) stock are critical to the system-level balance. Here, we compared GHG flux, crop yield, root biomass, and soil C stock under two potential tropical, perennial grass biofuel feedstocks: conventional sugarcane and ratoon-harvested, zero-tillage napiergrass. Evaluations were conducted at two irrigation levels, 100% of plantation application and at a 50% deficit. Peaks and troughs of GHG emission followed agronomic events such as ratoon harvest of napiergrass and fertilization. Yet, net GHG flux was dominated by carbon dioxide (CO2), as methane was oxidized and nitrous oxide (N2O) emission was very low even following fertilization. High N2O fluxes that frequently negate other greenhouse gas benefits that come from replacing fossil fuels with agronomic forms of bioenergy were mitigated by efficient water and fertilizer management, including direct injection of fertilizer into buried irrigation lines. From soil intensively cultivated for a century in sugarcane, soil C stock and root biomass increased rapidly following cultivation in grasses selected for robust root systems and drought tolerance. The net soil C increase over the two-year crop cycle was three-fold greater than the annualized soil surface CO2 flux. Deficit irrigation reduced yield, but increased soil C accumulation as proportionately more photosynthetic resources were allocated belowground. In the first two years of cultivation napiergrass did not increase net greenhouse warming potential (GWP) compared to sugarcane, and has the advantage of multiple ratoon harvests per year and less negative effects of deficit irrigation to yield.

Understanding the legacy effect of previous forage crop and tillage management on soil biology, after conversion to an arable crop rotation

Suggestions that novel, non‐food, dedicated biomass crops used to produce bioenergy may provide opportunities to diversify and reinstate biodiversity in intensively managed farmland have not yet been fully tested at the landscape scale. Using two of the largest, currently available landscape‐scale biodiversity data sets from arable and biomass bioenergy crops, we take a taxonomic and functional trait approach to quantify and contrast the consequences for biodiversity indicators of adopting dedicated biomass crops on land previously cultivated under annual, rotational arable cropping. The abundance and community compositions of biodiversity indicators in fields of break and cereal crops changed when planted with the dedicated biomass crops, miscanthus and short rotation coppiced (SRC) willow. Weed biomass was consistently greater in the two dedicated biomass crops than in cereals, and invertebrate abundance was similarly consistently higher than in break crops. Using canonical variates analysis, we identified distinct plant and invertebrate taxa and trait‐based communities in miscanthus and SRC willows, whereas break and cereal crops tended to form a single, composite community. Seedbanks were shown to reflect the longer term effects of crop management. Our study suggests that miscanthus and SRC willows, and the management associated with perennial cropping, would support significant amounts of biodiversity when compared with annual arable crops. We recommend the strategic planting of these perennial, dedicated biomass crops in arable farmland to increase landscape heterogeneity and enhance ecosystem function, and simultaneously work towards striking a balance between energy and food security.

Abstract Biogenic volatile organic compounds (BVOC) emissions from bioenergy crops may differ from those of conventional crops. We compared emission rates of isoprene and a number of monoterpenes from the lignocellulosic bioenergy crops short‐rotation coppice (SRC) willow and Miscanthus, with the conventional crops wheat and oilseed rape. BVOC emission rates were measured via dynamic vegetation enclosure and GC‐MS analysis approximately monthly between April 2010 and August 2012 at a location in England and from SRC willow at two locations in Scotland. The largest BVOC emission rates were measured from willow in England and varied between years. Isoprene emission rates varied between <lod and 1960 μg g−1 h−1. Of the monoterpenes detected from willow, α‐pinene emission rates were highest (<lod to 803 μg g−1 h−1), followed by <lod to 268 μg g−1 h−1 for δ‐3‐carene, <lod to 125 μg g−1 h−1 for β‐pinene and <lod to 80.4 μg g−1 h−1 for limonene. BVOC emission rates measured in Scotland were much lower. Low emission rates of isoprene and α‐pinene were measured from Miscanthus in 2010 (<lod to 6.42 μg g−1 h−1 and <lod to 20.8 μg g−1 h−1, respectively) but were not detected in subsequent years. Emission rates from wheat of isoprene were negligible but relatively high for monoterpenes (<lod to 422 μg g−1 h−1 and <lod to 104 μg g−1 h−1 for α‐pinene and limonene, respectively). No significant emission rates of BVOCs were measured from oilseed rape. The measured emission rates followed a clear seasonal trend. Crude extrapolations based solely on data gathered here indicate that isoprene emissions from willow could correspond to 0.004–0.03% (UK) and 0.76–5.5% (Europe) of current global isoprene if 50% of all land potentially available for bioenergy crops is planted with willow.

Abstract The removal of perennial bioenergy crops, such as Miscanthus, has rarely been studied although it is an important form of land use change. Miscanthus is a C4 plant, and the carbon (C) it deposits during its growth has a different isotopic signature (12/13C) compared to a C3 plant. Identifying the proportion of C stored and released to the atmosphere is important information for ecosystem models and life cycle analyses. During a removal experiment in June 2011 of a 20‐year old Miscanthus field (Grignon, France), vegetation was removed mechanically and chemically. Two replicate plots were converted into a rotation of annual crops, two plots had Miscanthus removed with no soil disturbance, followed by bare soil (set‐aside), one control plot was left with continued Miscanthus cultivation, and an adjacent field was used as annual arable crops control. There was a significant difference in the isotopic composition of the total soil C under Miscanthus compared with adjacent annual arable crops in all three measured soil layers (0–5, 5–10 and 10–20 cm). Before Miscanthus removal, total C in the soil under Miscanthus ranged from 4.9% in the top layer to 3.9% in the lower layers with δ13C values of −16.3 to −17.8 while soil C under the adjacent arable crop was significantly lower and ranged from 1.6 to 2% with δ13C values of −23.2. This did not change much in 2012, suggesting the accumulation of soil C under Miscanthus persists for at least the first year. In contrast, the isotopic signals of soil respiration 1 year after Miscanthus removal from recultivated and set‐aside plots were similar to that of the annual arable control, while just after removal the signals were similar to that of the Miscanthus control. This suggests a rapid change in the form of soil C pools that are respired.

Effects of a 20-year old Miscanthus × giganteus stand and its removal on soil characteristics and greenhouse gas emissions

SummaryIn Europe, glyphosate‐resistant weeds have so far only been reported in perennial crops. Following farmers' complaints of poor herbicide efficacy, resistance to glyphosate as well as to ACCase and ALS inhibitors was investigated in 11 populations of Lolium spp. collected from annual arable cropping systems in central Italy. Field histories highlighted that farmers had relied heavily on glyphosate, often at low rates, as well as in a non‐registered crop. The research aimed at elucidating the resistance status, including multiple resistance, of Lolium spp. populations through glasshouse screenings and an outdoor dose–response experiment. Target‐site resistance mechanism was also investigated for the substitutions already reported for EPSPs, ALS and ACCase genes. Three different resistant patterns were identified: glyphosate resistant only, multiple resistant to glyphosate and ACCase inhibitors and multiple resistant to glyphosate and ALS inhibitors. Amino acid substitutions were found at position 106 of the EPSPs gene, at position 1781, 2088 and 2096 of the ACCase gene and at position 197 and 574 of the ALS gene. Not all populations displayed amino acid substitutions, suggesting the presence of non‐target‐site‐mediated resistance mechanisms. After 39 years of commercial availability of glyphosate, this is the first report of multiple resistance involving glyphosate selected in annual arable crops in Europe. Management implications and options are discussed.

Despite many studies on the impact of arable land conversion to Short Rotation Coppice (SRC), few studies have been carried out on soil biota. This study aims at assessing biological and physico-chemical soil properties that are affected by SRC compared to forestry, grassland and an agrosystem. All samples were collected in the Aisne valley (France), from the same type of soil, with four land uses, i.e. willow SRC, agrosystem, grassland and alluvial forest, 3 years after SRC was planted. We studied fertility, the biological community (earthworm diversity, density and biomass, bacterial and fungal density and community structures) and biochemical parameters (enzyme activities, basal respiration and nitrification). After 3 years’ growth, soil biological parameters (fungal abundance, laccase activity, anecic earthworm proportion and earthworm diversity) and CEC were higher in the SRC than in the agrosystem soil. In parallel, fungal abundance was higher in SRC than in forest and grassland soils. Compared to annual arable crops, SRC promoted biological properties. However, in the short term, the parameters we measured were lower than in the forest and grassland soils. The use of certain parameters as indicators of soil functioning/quality assessment to discriminate the four land uses is discussed.

Abstract. Hydrologic climate change modelling is hampered by climate-dependent model parameterizations. To reduce this dependency, we extended the regional hydrologic modelling framework SIMGRO to host a two-way coupling between the soil moisture model MetaSWAP and the crop growth simulation model WOFOST, accounting for ecohydrologic feedbacks in terms of radiation fraction that reaches the soil, crop coefficient, interception fraction of rainfall, interception storage capacity, and root zone depth. Except for the last, these feedbacks are dependent on the leaf area index (LAI). The influence of regional groundwater on crop growth is included via a coupling to MODFLOW. Two versions of the MetaSWAP-WOFOST coupling were set up: one with exogenous vegetation parameters, the "static" model, and one with endogenous crop growth simulation, the "dynamic" model. Parameterization of the static and dynamic models ensured that for the current climate the simulated long-term averages of actual evapotranspiration are the same for both models. Simulations were made for two climate scenarios and two crops: grass and potato. In the dynamic model, higher temperatures in a warm year under the current climate resulted in accelerated crop development, and in the case of potato a shorter growing season, thus partly avoiding the late summer heat. The static model has a higher potential transpiration; depending on the available soil moisture, this translates to a higher actual transpiration. This difference between static and dynamic models is enlarged by climate change in combination with higher CO2 concentrations. Including the dynamic crop simulation gives for potato (and other annual arable land crops) systematically higher effects on the predicted recharge change due to climate change. Crop yields from soils with poor water retention capacities strongly depend on capillary rise if moisture supply from other sources is limited. Thus, including a crop simulation model in an integrated hydrologic simulation provides a valuable addition for hydrologic modelling as well as for crop modelling.

Abstract It is important to demonstrate that replacing fossil fuel with bioenergy crops can reduce the national greenhouse gas (GHG) footprint. We compared field emissions of nitrous oxide (N2O), methane (CH4) and soil respiration rates from the C4 grass Miscanthus × giganteus and willow (salix) with emissions from annual arable crops grown for food production. The study was carried out in NE England on adjacent fields of willow, Miscanthus, wheat (Triticum aetivum) and oilseed rape (Brassica napus). N2O, CH4 fluxes and soil respiration rates were measured monthly using static chambers from June 2008 to November 2010. Net ecosystem exchange (NEE) of carbon dioxide (CO2) was measured by eddy covariance on Miscanthus from May 2008 and on willow from October 2009 until November 2010. The N2O fluxes were significantly smaller from the bioenergy crops than that of the annual crops. Average fluxes were 8 and 32 μg m−2 h−1 N2O‐N from wheat and oilseed rape, and 4 and 0.2 μg m−2 h−1 N2O‐N from Miscanthus and willow, respectively. Soil CH4 fluxes were negligible for all crops and soil respiration rates were similar for all crops. NEE of CO2 was larger for Miscanthus (−770 g C m−2 h−1) than willow (−602 g C m−2 h−1) in the growing season of 2010. N2O emissions from Miscanthus and willow were lower than for the wheat and oilseed rape which is most likely a result of regular fertilizer application and tillage in the annual arable cropping systems. Application of 15N‐labelled fertilizer to Miscanthus and oil seed rape resulted in a fertilizer‐induced increase in N2O emission in both crops. Denitrification rates (N2O + N2) were similar for soil under Miscanthus and oilseed rape. Thus, perennial bioenergy crops only emit less GHGs than annual crops when they receive no or very low rates of N fertilizer.

Sensitivity of early indicators for evaluating quality changes in soil organic matter

Summary Biofuels offer one method for decreasing emissions of carbon dioxide (CO2) from fossil fuels, thus helping to meet UK and EU targets for mitigating climate change. They also provide a rational option for land use within the EU that could be economically viable, provided that an appropriate financial and policy environment is developed. If 80% of current set-aside land in the UK were used for production of biomass crops for electricity generation, about 3% of current UK electricity demand could be met from this source. Considering possibilities for increasing yields and land area devoted to such crops over the coming decades, this could possibly rise to 12%. These estimates exclude consideration of developments in electricity generation which should increase the efficiency of conversion. Also, the use of combined heat and power units at local level (e.g. on farms or in rural communities) gives additional energy saving. Dedicated biomass crops such as willow, poplar, miscanthus, switchgrass or reed canary grass are perennials: in comparison with annual arable crops they would be expected to deliver additional environmental benefits. The elimination of annual cultivation should give a more stable environment, beneficial for farmland biodiversity. Some increase in soil organic matter content is likely, leading to some sequestration of carbon in soil and long-term improvements in soil quality. The impact on water quality may be positive as nitrate losses are small and a similar trend is expected for phosphate and pesticides. However, these crops may well use more water than arable crops so their impact on water resources could be negative – an issue for further research. Agricultural land can also be used to produce liquid fuels for use in transport. At present biodiesel can be produced from oilseed rape and ethanol from either sucrose in sugar beet or cellulose from virtually any plant material. In the short-term, liquid biofuels are an easy option as they require little change to either agriculture or transport infrastructure. However, their benefits for CO2 emissions are much less than for biomass used for generating electricity. It is therefore necessary to debate the priorities for land use in this context.

When considering renewable energy from plants, corn ethanol and reforestation have been widely promoted. Herbaceous perennials, which produce an annual crop of above ground shoots, may have some important advantages over both of these systems. Herbaceous perennials require far fewer energy and financial inputs than annual arable crops. They can be higher yielding than forestry crops and utilize existing farm equipment. Perennial energy crops can sequester carbon into soil previously under annual arable crops, providing potential additional income in carbon credits. The advantages and disadvantages of different plant types are explained to show herbaceous perennials hold special promise as bioenergy crops. C4 photosynthesis allows greater efficiencies in the con- version of sunlight energy to biomass energy, and of nitrogen and water use. However, few plants in temperate climates use this more efficient process. One exception is the rhizomatous perennial grass Miscanthus ,w hich is aC 4 plant and exceptionally cold tolerant. Miscanthus is now being grown commercially in the European Union (EU) for direct combustion in local-area power stations. It may also have longer-term potential as a feedstock for other bio-based industry. The lessons learned from trials of this crop in the EU are summarized, potential yields in Illinois predicted and a tentative comparison of the economics of growing Miscanthus versus traditional row crops developed. Overall, the results suggest that Miscanthus could yield an average of 33 t of dry matter per hectare in Illinois. At current energy prices the crop would be profitable, if grown for 4 or more years, even without subsidy.