Arable Cropping Systems Research Articles

Productivity in an arable and stockless organic cropping system may be enhanced by strategic recycling of biomass

AbstractRecirculation of nitrogen (N) from crop residue and green-manure biomass resources may reduce the need to add new reactive N to maintain crop yield and quality. The aim of this study was to determine how different strategies for recycling residual and green-manure biomass influence yield and N concentration of the edible parts of food crops in a stockless organic cropping system. For this purpose, three biomass distribution treatments were investigated in a field experiment, based on a cropping system designed to produce both high-quality food crops and biomass resources from crop residues, cover crops and a green-manure ley. The three treatments, applied at the cropping system level, were: (1) incorporating the aboveground biomass resources in situ (IS); (2) harvesting, ensiling and redistributing the same biomass resources to the non-legume crops (biomass redistribution, BR); and (3) harvesting, ensiling and using the biomass resources as substrate for production of bio-methane via anaerobic digestion (AD) followed by distribution of the digestate as bio-fertilizer to the non-legume crops. The redistribution of ensiled (BR) and digested (AD) biomass did not increase the yield of the edible parts in winter rye (Secale cereal L.), white cabbage (Brassica oleracea L.) or red beet (Beta vulgaris L.) compared with leaving the biomass on the ground at harvest (IS). The BR treatment increased the yield of lentil intercropped with oat, compared with IS treatment in one of the two studied years. The total biomass yield of the cover crop following winter rye was significantly higher in the BR treatment than in IS in both years. The legume proportion in the green-manure ley was significantly higher in the AD and BR treatments as compared with IS in one of the experimental years. This study showed that strategic biomass redistribution has the potential to enhance biomass productivity while maintaining food crop yields, thereby enhancing whole system productivity. Biomass redistribution systems both with and without biogas digestion offer a new strategy for the development of multifunctional arable cropping systems that rely on internal nutrient cycling.

Quantifying in situ and modeling net nitrogen mineralization from soil organic matter in arable cropping systems

Improved assessment and prediction of net nitrogen mineralization (NNM) from soil organic matter in field conditions are essential for a better management of nitrogen (N) in arable cropping systems and an accurate simulation of its seasonal dynamics. The first objective of this study was to quantify accurately NNM rates by combining measurements of soil water and mineral N contents in soil profile, daily weather data and the LIXIM calculation model (Mary et al., 1999). The second objective was to develop a predictive model of in situ NNM rates based on basic soil properties and to evaluate if additional factors related to cropping history, organic matter fractions or microbial biomass could improve the model performance.We selected a set of 65 field experiments representative of arable cropping systems in France which were carried out in bare fallow soils without recent addition of crop residue (minimal delay of 4 months) or organic amendment. In these experiments, soil water and mineral N contents were monitored over the soil profile (0–90 to 0–150 cm depth, 3 to 5 layers) during 100–555 days (median value of 272 days). LIXIM was able to satisfactorily simulate water (EF = 0.58) and mineral N contents (EF = 0.80) in the several layers, allowing to disentangle the two main processes involved in mineral N changes: NNM (occurring in the upper soil layer) and nitrate transfer (through the whole soil profile). The actual NNM rates varied widely between sites from 0.13 to 1.10 kg N ha−1 day−1. The potential NNM rates (Vp), calculated under standard conditions of water and temperature, varied between 0.17 and 1.67 kg N ha−1 nday−1 (nday = “normalized” day at 15 °C and field capacity).A novel model with a multiplicative structure and a sequential approach was developed by including functions explaining the relationship between mineralization rate Vp (predicted variable) and explanatory variables. Soil organic N (SON) was the most correlated variable with Vp (r = 0.51, p < 0.001) and the first variable introduced in the model as a linear function. Non-linear functions of soil clay content, pH, C/N ratio and CaCO3 content were successively introduced, leading to a “soil model” based on five basic soil parameters that allowed explaining 61% of the variance in Vp. Two functions relative to the frequency of rapeseed and legumes in rotations were found to further improve the predictive quality of the soil model, explaining finally 72% of Vp variance (“soil-history model”). Organic matter fractions (particulate or extractible organic matter) did not explain significantly more variance of Vp due to their strong correlations with SON. Microbial biomass explained only 2% additional variance in Vp compared to the “soil-history model”. The predictive error of prediction (RMSEP) varied between 0.22, 0.19 and 0.17 kg N ha−1 nday−1 for the “soil” (n = 65), “soil-history” (n = 65) and “soil-history-biological” (n = 47) models. This multiplicative, non-linear approach performed better than a multiple linear regression approach which explained 10–15% less variance of Vp when using the same explanatory variables.The models based on soil properties and cropping history could be further implemented in multidisciplinary soil-crop models and decision support systems in order to enhance the prediction of N dynamics in soils and improve fertilizer recommendations.

Soil loss measure from Mediterranean arable cropping systems: Effects of rotation and tillage system on C-factor

Soil erosion is one of the most serious environmental problems, widespread globally, affecting the productivity of natural ecosystems as well as agricultural and forest ecosystems. Mediterranean regions are highly exposed to soil erosion due to soil features and rainfall distribution, characterized by high intensity and degree of erosivity, especially in autumn. Several cropping systems – differing for crop species and relative biological cycle – were established with the aim to assess their ability to limit soil erosion. An experimental device was placed to measure soil losses. Four experimental plots were cultivated with different cropping systems (CS) and levels of intensification, compared to standard plot (SP) maintained in bare conditions by up and down slope tillage operations, according to Universal Soil Loss Equation (USLE). The impact of four cropping systems, managed by conventional or conservation tillage, on soil erosion was estimated by the C-factor calculation. The relationship between crop intensification and erosion was also studied. The traditional conventional cropping system (CS2) emerged as the most susceptible to erosion risks with an average soil loss of 26.41tha−1 and a C-factor of 0.513. The cropping system CS4 characterized by reduced tillage, shredding of crop residues with mulch function and the introduction of fodder crops, showed the lowest C-factor value (0.089), highlighting the highest ability to protect the soil from erosion compared to the other systems. In conclusion, the C-factors calculated in this study can be used as a criterion to select a suitable crop rotation system to reduce erosion risk in marginal land of Mediterranean Basin. The different stakeholders will have useful information to guide them in their choices.

Lack of yield response in potato (Solanum tuberosum L.) to phosphate fertilizer under contrasting soil types varying in phosphate absorption coefficient and available phosphate

ABSTRACTThere is growing evidence of excessive use of phosphate fertilizer and high residual soil phosphate levels in arable cropping systems in Japan. However, there is a lack of regional-scale information on the current status of soil-available phosphate as well as its impacts on a potato (Solanum tuberosum L.) cropping system. Although phosphorus is an essential nutrient, there have been confounding reports about the effects of excessive soil-available phosphate on potato tuber yields. This study was conducted in Hokkaido, Japan, to determine the current status of phosphate fertilizer application rate and soil-available phosphate levels, and their effects on tuber yield. In two contrasting soil types varying in phosphate absorption coefficient (PAC), soil and potato tuber samples were collected from 90 and 80 grower fields in Tokachi and Kamikawa districts, respectively, in the 2013 and 2014 growing seasons. The soil samples were analyzed for PAC, available phosphate by the Truog method, and total phosphate along with total carbon and acid-oxalate extractable aluminum. The tuber samples were collected at the harvesting stage for the calculation of yields. This study revealed (1) ongoing excessive phosphate fertilization regardless of high soil-available phosphate levels in potato-producing fields of Hokkaido, (2) no positive impacts of excess soil-available phosphate on tuber yields, and (3) no yield response from the applied phosphate fertilizer in excess of the recommended rate in two contrasting soil types. In conclusion, excess phosphate fertilizer was an unnecessary cost to the growers and could also be a potential harm to the environment, and changes are urgently needed to optimize the input–output balance of phosphate in this agricultural system.

Cover crops support ecological intensification of arable cropping systems

A major challenge for agriculture is to enhance productivity with minimum impact on the environment. Several studies indicate that cover crops could replace anthropogenic inputs and enhance crop productivity. However, so far, it is unclear if cover crop effects vary between different cropping systems, and direct comparisons among major arable production systems are rare. Here we compared the short-term effects of various cover crops on crop yield, nitrogen uptake, and weed infestation in four arable production systems (conventional cropping with intensive tillage and no-tillage; organic cropping with intensive tillage and reduced tillage). We hypothesized that cover cropping effects increase with decreasing management intensity. Our study demonstrated that cover crop effects on crop yield were highest in the organic system with reduced tillage (+24%), intermediate in the organic system with tillage (+13%) and in the conventional system with no tillage (+8%) and lowest in the conventional system with tillage (+2%). Our results indicate that cover crops are essential to maintaining a certain yield level when soil tillage intensity is reduced (e.g. under conservation agriculture), or when production is converted to organic agriculture. Thus, the inclusion of cover crops provides additional opportunities to increase the yield of lower intensity production systems and contribute to ecological intensification.

IMPACT OF ENVIRONMENTAL CONDITIONS AND AGROTECHNICAL FACTORS ON GROUND BEETLE POPULATIONS IN ARABLE CROPS

Ground beetles (Coleoptera: Carabidae) are the largest family of adephagan beetles. Their role in natural pest control is important due to their predatory polyphagous nutrition and bioindicative value since they are sensitive to environmental and anthropogenic changes. Therefore, the main objectives were to understand how common arable cropping systems in Croatia affect ground beetles abundance in respect to the environmental conditions. We hypothesized that environmental specifics (soil type and structure, climatic conditions) together with cultivation measures (tillage, insecticide application) would affect ground beetle activity and abundance. The research was conducted in two locations Lukac, Virovitica – Podravina County and Tovarnik, Vukovar – Sirmium County. Ground beetles were collected weekly, from May to September 2015, by epigeic pitfall traps and endogeic perforated probes from fields sown with typical arable crops in these areas. In total, 2, 582 ground beetle individuals were collected using epigeic traps, and 323 ground beetles were collected using endogeic traps. Significantly lower ground beetle abundance has been recorded in Tovarnik than in Lukac. The crop and cropping history affect the abundance through modification of environmental conditions (soil characteristics, microclimate factors such as temperature and humidity), as well as trough disturbance factors such as tillage schedules and harvest/sowing schedules.

Crop residues as driver for N2O emissions from a sandy loam soil

Nitrogen (N) cycling within agriculture constitutes a source of direct and indirect emissions of the potent greenhouse gas nitrous oxide (N2O). We analysed relationships between N2O emissions and C and N balances of four arable cropping systems under conventional or organic management within a long-term experiment on a loamy sand soil at Foulum in Denmark. All cropping systems included winter wheat, a leguminous crop (faba bean or grass-clover), potato and spring barley grown in different 4-crop rotations varying in strategies for N supply (fertilizer/manure type and rate, use of catch crops and green manure). Crops in both organic and conventional systems received N at rates below the optimum for crop production. Soil N2O emissions were monitored in 2008–2009 in six selected crops which could be combined with data from other monitoring programs to calculate N2O emission factors for each of the 16 crops and four entire crop rotations. Accumulated annual N2O emissions were on average 0.8 to 0.9kgNha−1 y−1 and did not differ significantly between rotations. Soil N inputs in above- and belowground crop residues from main crops and catch crops were quantified by field measurements. Average nitrate-N leaching losses ranged from 39 to 56kgNha−1 y−1 and were lowest in rotations with catch crops; leaching was not correlated with N surplus or N input in fertilizer or manure. Crop yields of the organic rotations were 25 to 37% lower than in identical conventional rotations. As a consequence, yield-scaled N2O emissions were lower under conventional management compared with the organic alternatives. There was no significant correlation between N2O emissions and N input in fertilizer/manure, neither for annual emissions nor spring emissions. In contrast, N2O emissions were correlated with N input in residues from the previous main crop and catch crop (r=0.56, p<0.01). This indicates that, besides nitrogen, degradable carbon provides an important and estimable driver for N2O emissions in arable cropping systems.

Sustainability of European winter wheat- and maize-based cropping systems: Economic, environmental and social ex-post assessment of conventional and IPM-based systems

In order to ensure higher sustainability of winter wheat and maize production in Europe, cropping systems featuring different levels of Integrated Pest Management (IPM) need to be tested in the field and validated for their sustainability before being adopted by farmers. However, the sustainability evaluation of cropping systems is difficult to perform effectively due to the complex economic, social and environmental dimensions of sustainability. Within the EU research project PURE, nine long-term experiments were conducted in various European regions from 2011 to 2014, comparing two IPM levels against the conventional system (CS) in winter wheat- and maize-based cropping systems. IPM1 encompassed some pesticide use in semi-diverse crop rotations while IPM2 favoured reduced- and non-chemical methods in diverse rotations. The modified DEXiPM (DEXi Pest Management) model for arable cropping systems was used for ex-post assessments to compare the economic, environmental and social sustainability of these systems. The assessments showed that in six out of nine trials the CS was overall unsustainable because of low evaluation of the environmental sustainability that was mainly due to high pesticide use and simplified crop rotations where the choice of crops is primarily market-driven. In contrast, six IPM1 and five IPM2 systems could be classified as sustainable, achieving ‘medium’ or ‘high’ scores for all three sustainability dimensions. Differences in the socio-economic conditions across countries and/or climatic and soil conditions across experimental trials highlighted that IPM is based on general principles that must be adapted to address specific local conditions. Overall, IPM systems included more diverse crop rotations and practices compared to the CS, promoting IPM-based strategies with less pesticide use but also a reduced reliance on pesticides that could partially compensate for any yield reductions by the savings on pesticide and application costs. It is recommended that the results of the study should be disseminated to policy-makers, advisors and farmers and that their implementation should be considered on a regional level. Regional policies to encourage the adoption of more sustainable systems based on IPM principles, as well as better support by more closely involving the regional advisory services for the general implementation of IPM is further recommended. Ex-post analysis with DEXiPM also identified the constraints of the IPM1 and IPM2 systems evaluated as not sustainable. These were related to i) environmental issues for those IPM1 systems that still relied mainly on pesticide use and had less diverse crop rotations, and ii) economic issues for IPM2 systems, mainly due to the choice of less profitable crops in the rotation, as well as to yield penalties caused by the very low pesticide use or replacing pesticides with less effective non-chemical methods. The identification of these constraints is a valuable input to the local and regional discussion on how to adopt IPM and develop more sustainable cropping systems.

Diversity of methodologies to experiment Integrated Pest Management in arable cropping systems: Analysis and reflections based on a European network

Integrated Pest Management (IPM) aims to promote physical and biological regulation strategies that help farmers contain populations of pests (pathogens, animal pests and weeds) and to finally reduce the reliance on pesticides. It is based on the holistic combination of multiple management measures rather than on the sum of single methods, each of them having only small effects on pests reduction. Thus, to analyse the interactions between IPM measures and to evaluate the sustainability of their implementation, we require an approach considering the whole cropping system (CS), i.e. a functional entity whose complexity is more than the sum of its parts. A network of European experiments at the CS level was set up recently, and aimed at sharing data and expertise to enhance knowledge of IPM. Comparison of existing methodologies highlighted a diversity of CS designs and experimental layouts. We deduced that the concept of CS itself was viewed differently among scientists, and this affected experimental protocols. Other differences were related to the research context and objectives. Some experiments aimed to explore very innovative strategies and generated knowledge on both their effects on the agroecosystem and their ability to satisfy a set of performance targets, while others aimed to provide quickly adoptable solutions for local farmers in line with the current socio-economic constraints. In some research programmes, the experiment was part of the CS design process — and tested CS were regularly revised based on an continuous improvement loop — while in other cases CS were kept stable across years so as to enable the evaluation of their long-term cumulative effects. A critical aspect contributing to the diversity among CS experiments was the distinction between a factorial design of experimental CS and systemic approaches: factorial experiments allowed quantification of the effects of each IPM component regardless of the consistency between components defining the CS. In contrast, systemic approaches focused on the overall evaluation of CS designed with consideration of their consistency, hence maximising their ability to meet the objectives. Because CS experiments represent a huge investment in terms of economics and time, preliminary reflections of the relevance of the experimental strategy is of critical importance.

Alternative arable cropping systems: A key to increase soil organic carbon storage? Results from a 16 year field experiment

Alternative cropping systems such as conservation agriculture and organic farming are expected to decrease negative impacts of conventional systems through sequestration of organic carbon in soil and mitigation of greenhouse gas emissions. We studied soil organic carbon (SOC) dynamics in the long-term (16 years) field experiment ⿿La Cage⿿ (France) which compares four arable cropping systems, free from manure application, under conventional (CON), low input (LI), conservation agriculture (CA) and organic (ORG) management. Bulk densities and SOC concentrations were measured at different dates between 1998 and 2014. SOC stocks were calculated at equivalent soil mass taking into account bulk density variations and SOC redistribution across the different soil layers. We analyzed the evolution of SOC stocks and compared it with outputs of the simulation model AMG. The rate of change in SOC stocks in the old ploughed layer (ca. 0⿿30cm) during the 16 years was 0.08, 0.02, 0.63 and 0.28tha⿿1 yr⿿1 in the CON, LI, CA and ORG systems respectively and significantly differed from 0 in the CA and ORG treatments. The AMG model satisfactorily reproduced the observed evolution of SOC stocks in the old ploughed layer in all treatments. A Bayesian optimization procedure was used to assess the mean and the distribution of the most uncertain parameters: the SOC mineralization rate and the C inputs derived from belowground biomass of cover crops which were fescue (Festuca rubra) and alfalfa (Medicago sativa). The model thus parameterized was able to predict SOC evolution in each block and soil layer (0⿿10, 10⿿20 and 20⿿30cm). There was no significant difference in SOC mineralization rates between all cropping systems including CA under no-till. In particular, the increased SOC storage in CA was explained by higher carbon inputs compared to the other cropping systems (+1.72tCha⿿1 yr⿿1 on average). The CA and ORG systems were less productive than the CON and LI systems but the smaller C inputs derived from cash crop residues were compensated by the extra inputs from additional crops (fescue and alfalfa) specifically grown in CA and ORG, resulting in a positive carbon storage in soil. We conclude that alternative arable systems have potential to sequester organic carbon in temperate climate conditions, through higher carbon input rather than by the effect of reduced soil tillage.

Analysing reduced tillage practices within a bio-economic modelling framework

Sustainable intensification of agricultural production systems will require changes in farm practice. Within arable cropping systems, reducing the intensity of tillage practices (e.g. reduced tillage) potentially offers one such sustainable intensification approach. Previous researchers have tended to examine the impact of reduced tillage on specific factors such as yield or weed burden, whilst, by definition, sustainable intensification necessitates a system-based analysis approach. Drawing upon a bio-economic optimisation model, ‘MEETA’, we quantify trade-off implications between potential yield reductions, reduced cultivation costs and increased crop protection costs. We extend the MEETA model to quantify farm-level net margin, in addition to quantifying farm-level gross margin, net energy, and greenhouse gas emissions. For the lowest intensity tillage system, zero tillage, results demonstrate financial benefits over a conventional tillage system even when the zero tillage system includes yield penalties of 0–14.2% (across all crops). Average yield reductions from zero tillage literature range from 0 to 8.5%, demonstrating that reduced tillage offers a realistic and attainable sustainable intensification intervention, given the financial and environmental benefits, albeit that yield reductions will require more land to compensate for loss of calories produced, negating environmental benefits observed at farm-level. However, increasing uptake of reduced tillage from current levels will probably require policy intervention; an extension of the recent changes to the CAP (‘Greening’) provides an opportunity to do this.

Effect of soil texture and wheat plants on N2O fluxes: A lysimeter study

Agricultural soils are a major source of nitrous oxide (N2O) emissions and an understanding of factors regulating such emissions across contrasting soil types is critical for improved estimation through modelling and mitigation of N2O. In this study we investigated the role of soil texture and its interaction with plants in regulating the N2O fluxes in agricultural systems. A measurement system that combined weighing lysimeters with automated chambers was used to directly compare continuously measured surface N2O fluxes, leaching losses of water and nitrogen and evapotranspiration in three contrasting soils types of the Riverine Plain, NSW, Australia. The soils comprised a deep sand, a loam and a clay loam with and without the presence of wheat plants. All soils were under the same fertilizer management and irrigation was applied according to plant water requirements. In fallow soils, texture significantly affected N2O emissions in the order clay loam>loam>sand. However, when planted, the difference in N2O emissions among the three soils types became less pronounced. Nitrous oxide emissions were 6.2 and 2.4 times higher from fallow clay loam and loam cores, respectively, compared with cores planted with wheat. This is considered to be due to plant uptake of water and nitrogen which resulted in reduced amounts of soil water and available nitrogen, and therefore less favourable soil conditions for denitrification. The effect of plants on N2O emissions was not apparent in the coarse textured sandy soil probably because of aerobic soil conditions, likely caused by low water holding capacity and rapid drainage irrespective of plant presence resulting in reduced denitrification activity. More than 90% of N2O emissions were derived from denitrification in the fine-textured clay loam—determined for a two week period using K15NO3 fertilizer. The proportion of N2O that was not derived from K15NO3 was higher in the coarse-textured sand and loam, which may have been derived from soil N through nitrification or denitrification of mineralized N. Water filled pore space was a poorer predictor of N2O emissions compared with volumetric water content because of variable bulk density among soil types. The data may better inform the calibration of greenhouse gas prediction models as soil texture is one of the primary factors that explain spatial variation in N2O emissions by regulating soil oxygen. Defining the significance of N2O emissions between planted and fallow soils may enable improved yield scaled N2O emission assessment, water and nitrogen scheduling in the pre-watering phase during early crop establishment and within rotations of irrigated arable cropping systems.

Selection of focal earthworm species as non-target soil organisms for environmental risk assessment of genetically modified plants

By means of a literature survey, earthworm species of significant relevance for soil functions in different biogeographical regions of Europe (Atlantic, Boreal, Mediterranean) were identified. These focal earthworm species, defined here according to the EFSA Guidance Document on the environmental risk assessment (ERA) of genetically modified plants, are typical for arable soils under crop rotations with maize and/or potatoes within the three regions represented by Ireland, Sweden and Spain, respectively. Focal earthworm species were selected following a matrix of four steps: Identification of functional groups, categorization of non-target species, ranking species on ecological criteria, and final selection of focal species. They are recommended as appropriate non-target organisms to assess environmental risks of genetically modified (GM) crops; in this case maize and potatoes. In total, 44 literature sources on earthworms in arable cropping systems including maize or potato from Ireland, Sweden and Spain were collected, which present information on species diversity, individual density and specific relevance for soil functions. By means of condensed literature data, those species were identified which (i) play an important functional role in respective soil systems, (ii) are well adapted to the biogeographical regions, (iii) are expected to occur in high abundances under cultivation of maize or potato and (iv) fulfill the requirements for an ERA test system based on life-history traits. First, primary and secondary decomposers were identified as functional groups being exposed to the GM crops. In a second step, anecic and endogeic species were categorized as potential species. In step three, eight anecic and endogeic earthworm species belonging to the family Lumbricidae were ranked as relevant species: Aporrectodea caliginosa, Aporrectodea rosea, Aporrectodea longa, Allolobophora chlorotica, Lumbricus terrestris, Lumbricus friendi, Octodrilus complanatus and Octolasion cyaneum. Five out of these eight species are relevant for each biogeographical region with an overlap in the species. Finally, the earthworm species Ap. caliginosa (endogeic, secondary decomposer) and L. terrestris (anecic, primary decomposer) were selected as focal species. In the Mediterranean region L. terrestris may be substituted by the more relevant anecic species L. friendi. The selected focal species are recommended to be included in a standardized laboratory ERA test system based on life-history traits.

Crop residue management in arable cropping systems under a temperate climate. Part 2: Soil physical properties and crop production. A review

Introduction. Residues of previous crops provide a valuable amount of organic matter that can be used either to restore soil fertility or for external use. A better understanding of the impact of crop residue management on the soil-water-plant system is needed in order to manage agricultural land sustainably. This review focuses on soil physical aspects related to crop residue management, and specifically on the link between soil structure and hydraulic properties and its impact on crop production. Literature. Conservation practices, including crop residue retention and non-conventional tillage, can enhance soil health by improving aggregate stability. In this case, water infiltration is facilitated, resulting in an increase in plant water availability. Conservation practices, however, do not systematically lead to higher water availability for the plant. The influence of crop residue management on crop production is still unclear; in some cases, crop production is enhanced by residue retention, but in others crop residues can reduce crop yield. Conclusions. In this review we discuss the diverse and contrasting effects of crop residue management on soil physical properties and crop production under a temperate climate. The review highlights the importance of environmental factors such as soil type and local climatic conditions, highlighting the need to perform field studies on crop residue management and relate them to specific pedo-climatic contexts.

Crop residue management in arable cropping systems under temperate climate. Part 1: Soil biological and chemical (phosphorus and nitrogen) properties. A review

Introduction. Interacting soil organisms support biological processes that participate in soil functions, organic matter decomposition, and nutrient cycling. Earthworms and microorganisms play a range of beneficial roles in agricultural systems, including increased organic matter mineralization, nutrient cycling, and soil structure stabilization. Literature. The following aspects of crop residue management effects are examined in this paper: (i) earthworm composition and structure; (ii) soil microbial communities; and (iii) phosphorus (P) and nitrogen (N) element availability and distribution in the soil profile. Conventional tillage (ploughing) is often reported to generate decreased soil organism abundance and diversity, primarily earthworms and microorganisms, as well as a uniform distribution of the nutrients P and N within the ploughed soil horizon. Soil residue incorporation of mineral particles can maintain P and N levels, however returning soil also increases aeration and the activation of microbial activity. Hence, comparisons of tillage effects on soil biological functioning and nutrient cycling remain unclear. Conclusions. This review highlights the challenges in establishing definitive evidence regarding the effects of crop residue management on soil organisms and nutrient dynamics. The studies examined reported variability in soil and climate, and the complexity of soil processes contributed to the absence of clear findings. Further research is required under temperate climate conditions.

C and N models Intercomparison – benchmark and ensemble model estimates for grassland production

Much of the uncertainty in crop and grassland model predictions of how arable and grassland systems respond to changes in management and environmental drivers can be attributed to differences in the structure of these models. This has created an urgent need for international bench- marking of models, in which uncertainties are estimated by running several models that simulate the same physical and management conditions (ensemble modelling) to generate expanded envelopes of uncertainty in model predictions (Asseng et al. , 2013). Simulations of C and N fluxes, in particular, are inherently uncertain because they are driven by complex interactions (Sandor et al. , 2016) and complicated by considerable spatial and temporal variability in the measurements. In this context, the Integrative Research Group of the Global Research Alliance (GRA) on Agricultural Greenhouse Gases promotes a coordinated activity across multiple international projects (e.g. C and N Models Inter-comparison and Improvement to assess management options for GHG mitigation in agrosystems worldwide (C-N MIP) and Models4Pastures of the FACCE-JPI, https://www.faccejpi.com) to benchmark and compare simulation models that estimate C – N related outputs (including greenhouse gas emissions) from arable crop and grassland systems (http://globalresearchalliance.org/e/model- intercomparison-on-agricultural-ghg-emissions). This study presents some preliminary results on the uncertainty of outputs from 12 grassland models, whereas exploring differences in model response when increasing data resources are used for model calibration.

Yields and quality of Cynara cardunculus L. wild and cultivated cardoon genotypes. A case study from a marginal land in Central Italy

Abstract Cardoon yields and quality under low input conditions (reduced nitrogen fertilization and rainfed conditions) in a marginal land of Central Italy are presented. During 2011–2013, two cultivated and two wild cardoons were compared for the lignocellulosic biomass production, grain yield, and their chemical composition. The results showed a 3-year average aboveground biomass and grain yield in the range 8–18 and 1.2–2.8 t ha −1 dry matter respectively, significantly higher in the cultivated genotypes. The grain lipid contents were not significantly different as average, but the wild genotype Tolfa achieved the highest content (20.3%) in the last year of research. Average oil yields were 0.45 and 0.23 t ha −1 in cultivated and wild genotypes respectively. ANOVA showed a general prevalent influence of the genotype factor (G) on crop yields, and grain lipid and protein contents; on the other hand, the nitrogen factor (N) never showed significant effects on the different parameters. The chemical composition of the lignocellulosic biomass showed slight differences among the genotypes, but not always significant. Cardoon cultivation improved soil fertility parameters, even if differences were not always statistically different. Considering the results, dedicated production chains could be implemented in many Italian Regions taking advantage also from the availability of wild cardoon genotypes. The production costs and revenues analysis of cardoon in comparison with other herbaceous annual crops, demonstrated the low cultivation costs per hectare, the higher total revenues deriving from the yield outcomes, and its suitability for the inclusion in arable cropping systems in marginal lands.

Nitrous oxide emissions and nitrate leaching in an organic and a conventional cropping system (Seine basin, France)

Agricultural activities can lead to nitrogen losses in the environment, particularly nitrate (NO3−) leaching and nitrous oxide (N2O) emissions. This study aims to measure N losses from organic farming (OF) and conventional farming (CF) arable cropping systems, both adopted in a single farm, located on the same drained loamy soil in the Seine basin, in the North of France. Leaching was measured with ceramic cups and N2O emissions with automatic and manual chambers over the 2011–2014 period.Manual chambers showed the same trend as automatic chambers but underestimated small variations and overestimated peak emissions. On average, N2O emissions were lower in OF (0.65±0.64kgNha−1yr−1) than in CF fields (0.95±0.77kgNha−1yr−1). The mean amount of N leached was 13.3kgNha−1yr−1 in the OF system during the 8-crops rotation (alfalfa 1, alfalfa 2, wheat, green bean, wheat, faba bean, wheat, flax) and 18.4kgNha−1yr−1 in the CF system for a 3-crops CF rotation (legume, wheat, wheat), corresponding to 9 and 10% of total N inputs, respectively. Leached N and N2O emissions expressed per unit of protein-N harvested were slightly higher in CF (0.11kg NO3–Nkg−1Nyr−1 and 5.4 N2O–Nkg−1Nyr−1, respectively) than in OF systems (0.10kg NO3–Nkg−1Nyr−1 and 4.7g N2O–Nkg−1Nyr−1, respectively). These results show a relative lower environmental impact of OF practices compared to CF practices (−30% area-scaled and −12% yield-scaled for leaching and N2O emissions), with further margins of progress in both systems, including a better management of fertilisers, legumes and catch-crops.

Crop diversification for weed management in organic arable cropping systems

&lt;p&gt;Within the ERA-net CORE Organic Plus transnational programmes supported project PRODIVA producing of the information required for a better utilization of crop diversification for weed management in North European organic arable cropping systems was started. To fulfill the goal of this project- not to eradicate weed problems, which is unlikely to happen in any arable farming system, but to maintain a diversified and manageable weed flora that can support beneficial organisms- there were data from ongoing long-termed cropping system experiments from Latvia analyzed.&lt;/p&gt;&lt;p&gt;It is hypothesised that: a) perennial weeds can be suppressed in the post-harvest period by improved cover crop establishment and pertinent selection of cover crop species; b) on-farm practices of crop diversification are related to weed pressure and species composition.&lt;/p&gt;&lt;p class="R-MainText"&gt;On the bases on data from organic farm and ongoing long-termed cropping system experiment on weed dynamics in six-field crop rotations with cover crop was concluded that red clover as cover crop after the harvest period is effective to manage perennial weeds. In crop rotation with higher proportions of cereals weed infection growth in six-field rotation with 50% share of cereals up to 3.4, but with 33.3 % share-up to 2.1 times.&lt;/p&gt;

Grassland-Cropping Rotations: An Avenue for Agricultural Diversification to Reconcile High Production with Environmental Quality.

A need to increase agricultural production across the world to ensure continued food security appears to be at odds with the urgency to reduce the negative environmental impacts of intensive agriculture. Around the world, intensification has been associated with massive simplification and uniformity at all levels of organization, i.e., field, farm, landscape, and region. Therefore, we postulate that negative environmental impacts of modern agriculture are due more to production simplification than to inherent characteristics of agricultural productivity. Thus by enhancing diversity within agricultural systems, it should be possible to reconcile high quantity and quality of food production with environmental quality. Intensification of livestock and cropping systems separately within different specialized regions inevitably leads to unacceptable environmental impacts because of the overly uniform land use system in intensive cereal areas and excessive N-P loads in intensive animal areas. The capacity of grassland ecosystems to couple C and N cycles through microbial-soil-plant interactions as a way for mitigating the environmental impacts of intensive arable cropping system was analyzed in different management options: grazing, cutting, and ley duration, in order to minimize trade-offs between production and the environment. We suggest that integrated crop-livestock systems are an appropriate strategy to enhance diversity. Sod-based rotations can temporally and spatially capture the benefits of leys for minimizing environmental impacts, while still maintaining periods and areas of intensive cropping. Long-term experimental results illustrate the potential of such systems to sequester C in soil and to reduce and control N emissions to the atmosphere and hydrosphere.