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A significant challenge in our time is to produce sufficient agricultural products on limited farmable land to meet the needs for food, feed, fiber, and industrial uses in the face of a changing climate. Conventional cropping systems mostly rely on inputs, such as fertilizers and pesticides, to boost crop yields. However, excessive inputs increase production costs and entail more direct and indirect emissions of greenhouse gases to the atmosphere that negatively impact the environment. Finding sustainable ways to increase crop productivity with little or no impact on the environment is the primary goal of modern agriculture. This review reveals that temporal-spatial diversification of crop rotations is critically needed to advance toward this goal sustainably. We find that (i) intensified crop rotations enhance carbon conversion from atmospheric CO2 into plant biomass and thus sequester more carbon into soil; (ii) diversified crop mixtures improve system resilience, i.e., increased resistance to pest/disease incidence and weed infestation, and faster recovery after removal of the abiotic or biotic stress; (iii) diversifying crop rotations increases crop yields at the system level with improved water and fertilizer use efficiencies; (iv) legume-based crop rotations reduce the need for synthetic nitrogen fertilizers thus lowering N2O and CO2 emissions to the atmosphere; (v) crop diversity leads to soil microbiome diversity that optimizes soil microenvironment, improving soil health. We believe that developing and adopting of diversified cropping systems are key factors for agricultural policy setting and a top priority for on-farm decision-making to increase crop productivity and enhance soil health, while reducing negative environmental impacts. [ABSTRACT FROM AUTHOR]

The reduction in crop diversity and specialization of cereal-based cropping systems have led to high dependence on synthetic nitrogen (N) fertilizer in many areas of the globe. This has exacerbated environmental degradation due to the uncoupling of carbon (C) and N cycles in agroecosystems. In this experiment, we assessed impacts of introducing grain legumes and cover crops to innovative cropping systems to reduce N fertilizer application while maintaining wheat yields and grain quality. Six cropping systems resulting from the combination of three 3-year rotations with 0, 1 and 2 grain legumes (GL0, GL1 and GL2, respectively) with (CC) or without (BF, bare fallow) cover crops were compared during six cropping seasons. Durum wheat was included as a common high-value cash crop in all the cropping systems to evaluate the carryover effects of rotation. For each cropping system, the water use efficiency for producing C in aerial biomass and yield were quantified at the crop and rotation scales. Several diagnostic indicators were analyzed for durum wheat, such as (i) grain yield and 1000-grain weight; (ii) aboveground biomass, grain N content and grain protein concentration; (iii) water- and N-use efficiencies for yield; and (iv) N harvest index. Compared to the GL0-BF cropping system, which is most similar to that traditionally used in southwestern France, N fertilizer application decreased by 58%, 49%, 61% and 56% for the GL1-BF, GL1-CC, GL2-BF and GL2-CC cropping systems, respectively. However, the cropping systems without grain legumes (GL0-BF and GL0-CC) had the highest water use efficiency for producing C in aerial biomass and yield. The insertion of cover crops in the cropping systems did not change wheat grain yield, N uptake, or grain protein concentration compared to those of without cover crops, demonstrating a satisfactory adaptation of the entire cropping system to the use of cover crops. Winter pea as a preceding crop for durum wheat increased wheat grain production by 8% (383 kg ha −1 ) compared to that with sunflower − the traditional preceding crop − with a mean reduction in fertilizer application of 40–49 kg N ha −1 during the six-year experiment. No differences in protein concentration of wheat grain were observed among preceding crops. Our experiment demonstrates that under temperate submediterranean conditions, properly designed cropping systems that simultaneously insert grain legumes and cover crops reduce N requirements and show similar wheat yield and grain quality attributes as those that are cereal-based. [ABSTRACT FROM AUTHOR]

• Crop intensification enhances soil macropores hydraulic conductivity compared to mono-cropping. • Long-term NT improves soil structure and water transport properties. • Soil water flux and pore continuity are greater within than between crop rows. • Intensive tillage creates non-persistent changes on soil hydro-dynamic properties. Soil hydraulic properties and pore continuity are important parameters of soil quality and may differ among tillage systems, crop rotations, and change over time. However, there are some contrasting results, depending on soil type, climate and cultivation history on the spatial and temporal variations. The objective of this study was to determine spatio-temporal dynamics of soil hydraulic properties and pore characteristics (i.e., pore volume, effective porosity, and continuity) on a silt loam long-term tillage field experiment, in Agramunt, NE Spain, during two cropping years. Undisturbed soil samples were used to determine soil water retention, θ(Ψ) , and soil hydraulic conductivity, K(Ψ) , curves in two different tillage systems (intensive tillage, IT vs no-tillage, NT), two crop sequences (short fallow-maize, FM vs legume-maize, LM) and two positions (within the row of crops, W-row vs between the rows of crops, B-row). The results revealed that LM had greater specific hydraulic conductivity, K pc in its macroporosity (>1000 µm) than FM due to greater number of effective pores, N pc and effective porosity, ε pc. Soil water content, θ was greater under IT than under NT at higher soil water matric potential, Ψ (≥-3 cm H 2 O), whilst the opposite was observed at lower Ψ (≤ − 50 cm H 2 O). Long-term NT showed greater hydraulic conductivity, K at higher Ψ (≥ − 10 cm H 2 O) than IT, and no difference at lower Ψ. Although IT had greater pore volume, ϕ pc than NT in the macroporosity and coarse mesoporosity (1000–60 µm) pore size classes, NT had two times greater K pc than IT due to increased N pc , ε pc , and pore continuity, C wpc. K(Ψ) and pore characteristics showed spatial variations (W-row vs B-row). W-row had significantly greater K at higher Ψ (≥ − 3 cm H 2 O) than B-row. Temporal dynamics of soil hydraulic properties and pore characteristics were not evident under IT during crop succession. This study shows that LM increases specific hydraulic conductivity of soil macroporosity by increasing the number of effective macropores and the effective porosity. In a Mediterranean climate, this may improve the hydrological functions of agricultural soil and associated crop yield. Further, long-term NT formed a stable number of effective macropores and coarse mesopores, and showed a greater pore continuity in coarse and fine mesopores, resulting in improved soil water flux. [ABSTRACT FROM AUTHOR]

Under Mediterranean rainfed areas, no-till cereal-based systems have been adopted to cope with water availability and increasing input costs. However, the increased risk of biotic stresses, high N-fertilizer dependence, and current EU policies warrant cropping systems re-design. Evaluate diversification and N fertilization as strategies to improve N use efficiency at the cropping system level and quantify its productivity. Four crop sequences combined with four levels of N fertilization were assessed in a three-year field experiment in semiarid rainfed north-eastern Spain. Crop sequences were continuous winter wheat (WCS) and three-year diversified rotations with pea (PCS), faba bean (FCS), or a multi-service cover crop (MSCS) and two years of cereals. Crop, pre-crop and cropping system levels were considered. Agronomic evaluation included crops above-ground biological N fixation (Ndfa), net N balance (Ndfa minus N removed by grain), soil N mineralisation productivity, energy to N tradeoff (ENT), and N use efficiency of protein (NUEp) production. Pea yields ranged from 0 to 766 kg ha−1 and Ndfa from 24% to 54%. Faba bean yield ranged from 1378 to 4251 kg ha−1 and Ndfa from 32% to 72%. Net N balance was close to neutral for pea while in faba bean it ranged from 41 to −21 kg N ha−1. Alternative pre-crops led to greater soil N mineralisation (51 kg N ha−1, on average) and higher wheat yield (564 kg ha−1, on average) compared to wheat as the pre-crop. N fertilization increased protein yields, with FCS presenting the highest yields at all N fertilizer rates. This effect led to a stable NUEp (1.69 kg protein kg N supply−1), as the protein yield increased proportionally to N supply. Diversification improved the succeeding wheat performance and grain legumes N fixation exceeded grain N removal. Introducing legumes into cropping systems led to a decrease in energy productivity compared to the cereal-based system. However, protein production in the FCS was higher than in any other cropping system regardless of the N fertilizer rate. Crop diversification adds challenges and risks in dry Mediterranean areas. However, the study shows that crop diversification with faba bean can decrease cropping system's N-fertilizer dependence and increase protein productivity, contributing to cropping systems' sustainability. • Effect of crop diversification and N fertilization to support N efficient cropping systems. • Multiscale assessment including crop, pre-crop and the cropping system level. • Pea and faba bean supported cropping systems N use efficiency through biological N fixation. • Faba bean cropping system showed the greatest protein yields regardless of the N fertilizer rate. [ABSTRACT FROM AUTHOR]

Mediterranean cropping systems, characterised by continuous cereal cropping, are largely dependent on synthetic inputs, such as N fertilisers. On the other hand, they face difficult pedoclimatic conditions, exacerbated by climate change. Diversification is seen as a way to increase cropping systems resilience. The aim of this study was to co-design diversified cropping systems based on the expertise of local stakeholders and co-assess their performance, using modelling data. Our case study is the Ebro valley in Spain, a Mediterranean area with great potential for diversification, particularly where irrigation is available. Two workshops were organized to i) define the reference system in the study area and its limitations ii) co-design diversified systems to overcome these limitations and iii) co-assess reference and diversified systems. Between the two workshops, the STICS soil-crop model was calibrated with local experimental data, enabling to simulate the inter-annual (2000–2021) agronomic and environmental performance of the reference and diversified systems. An economic analysis was conducted. Stakeholders evaluated all economic, agronomic and environmental aspects. The reference system was a continuous winter cereal crop based on synthetic N fertilisation and intensive tillage. The four diversified co-designed systems consisted in introducing pea and/or rapeseed every 2 or 4 years, reducing tillage and partially replacing synthetic N fertilisation with locally sourced livestock manure. Simulation results showed that wheat and barley grain yields remained stable with diversification. Pea and rapeseed yields were lower in rotations where both were introduced compared to when each was the only break crop over 4 years. At the system level, protein yield remained stable with diversification, however, energy yield decreased by 20 % when break crops were introduced twice and by 10 % when introduced once. Gross margins improved with diversification only when pea was introduced once (12 %), mainly due to reduced expenses (-31 %), while incomes remained stable compared to RCS. However, incomes decreased by 5 % when rapeseed was introduced once, and by 10 % when both break crops were introduced. Unexpectedly, environmental performance deteriorated with diversification, with increased N losses through ammonia volatilisation and nitrate leaching in the years following pea and rapeseed cropping, due to greater N availability in the soil. An increased use of pesticides was predicted by the stakeholders in diversified systems, where the environmental impacts were exacerbated with the higher presence of break crops. The reference system presented slightly lower N availability and increased soil organic carbon storage. Overall, the approach proved useful in identifying a diversification strategy that improved agronomic and economic performance, with the system including pea once every four years being the most efficient. However, the environmental trade-offs associated with the increased presence of pea and rapeseed in the crop rotation must be considered in order to mitigate the environmental risks. • Participatory workshops and modelling were combined to assess diversification. • Introducing pea and rapeseed maintain protein yield but decreased energy yield. • Continuous cereal was the most efficient in raising long-term soil organic carbon. • Gross margin increased only when introducing pea once in a 4-year rotation (+12 %). • Diversified cropping systems increased N availability and risk of losses. [ABSTRACT FROM AUTHOR]

Agriculture today faces opposing challenges: reducing its environmental impacts while feeding a growing population and adapting to climate change. Diversification of cropping systems has been proposed as a solution to address these issues and promote sustainable and resilient agricultural systems. While alternatives have been proposed by research and development, changing the agricultural systems remains a huge challenge. Engaging local actors when considering those changes is important for their successful implementation. While co-designing with stakeholders is gaining interest in the scientific community, approaches that consider varying local contexts remain uncommon. In this study, our aim was to co-design, during workshops with local stakeholders, diversification options in five case studies located in the Mediterranean countries of Algeria, France, Greece, and Spain. Prior to the co-design process, we conducted a SWOT/PESTLE analysis in each case study to analyze the local context of current and potential agricultural systems. Our hypothesis was that co-designed systems would differ between case studies, according to their environmental, social and political contexts leading to fine-tuned locally ad hoc systems. Options for intercropping and diversifying rotations were considered for both cereal-based systems and vine systems. Additionally, these options included adapted management practices for cereal-based systems and more innovative diversification, such as photovoltaic panels or agroforestry, for vine systems. While some of these options could serve as adaptations to climate change, they may not be sufficient to address future climate conditions. Interestingly, we did not observe significant differences among the system options designed for the various case studies, even though the local contexts were very different. Indeed, options only partially addressed the issues identified by stakeholders: primarily, economic and environmental threats. This study points to the advantage of participatory research in diverse contexts along with cross-case analyses, and to the need to consider the future of these Mediterranean regions, where crop diversification is limited by water deficit. To foster the transition next steps should consider assessing experimentally these systems with farmers to stimulate learning, while considering market possibilities. • We combined SWOT analysis and co-design workshops to study diversification options. • The approach was applied in five case studies in the Mediterranean basin. • Intercropping was seen as the most promising solution in most case studies. • New cereal-based rotations included legume species, or rapeseed. • New systems provided a partial solution to local environmental and economic threats. [ABSTRACT FROM AUTHOR]

Relay cropping (RC) is a multiple cropping system that consists in planting a second crop into a standing first crop prior to its harvest. RC has potential to address food security and environmental sustainability via spatio-temporal diversification of cropping systems. Key potential benefits of RC include increased crop productivity, net economic returns, land use efficiency, soil fertility, efficient nutrient cycling, and pest control (pests sensu lato that include animal pests, pathogens and weeds). Despite these potential benefits, RC is poorly adopted worldwide, especially in Europe, compared to other forms of innovative cropping systems including cover- and inter-cropping. Here we review the literature to assemble information on key factors affecting the performance of RC by focusing on field crops grown for grain harvest purpose across temperate regions. We found severe knowledge gaps on crop management issues affecting the RC performance including the crop species and genotypic traits to be efficiently combined; the RC configuration including row number and width; optimal sowing dates and densities; irrigation, fertilization, and pest management; and technical problems in the harvesting phase. We identified that while RC may represent "a very versatile system" for farmers in terms of crop management - via an efficient utilization of time, labor, and equipment - this cropping system also requires a lot of anticipation and organization even before the primary crop sowing. This increases crop management complexity for the farmers including the difficulty in managing " the competition phase " and the need for specific farming equipments. Finally, we propose three research priorities to fill the current knowledge gaps in RC research and implementation, worldwide, viz. varietal evaluation and selection, RC modelling and development of decision support systems, and technological innovation for an improved RC management. • Relay cropping may be practiced under conventional, organic and conservation agriculture. • Despite a lot of research on relay cropping, we found little evidence of relay cropping uptake by farmers. • Crop management complexities that increase labour costs and unfavorable climatic conditions are two plausible hypotheses affecting relay cropping adoption. • Technological innovation is required for an improved management of relay cropping. • Crop models developed so far are not adapted for effective modeling of relay cropping. [ABSTRACT FROM AUTHOR]

Soil-crop models are widely used as valuable tools to assess the combined effects of cropping practices, soil management and climate on the agro-environmental indicators. They provide a wide range of predictive information that are useful to design and evaluate innovative cropping systems. However, intercropping modeling is still under development, especially for grain legumes-based intercropping system. We performed here the first calibration of the STICS (v 9.2) model on chickpea grown under contrasting nitrogen (N) levels during two copping seasons (2018/2019 and 2019/2020). This calibration allowed us to simulate a wide range of agronomic scenarios (climate, N-fertilization and cropping system) to optimize intercrops (durum wheat-chickpea) management. 37 parameters were estimated by using a sequential optimization method. Our results showed that STICS performs well in predicting Leaf Area Index (LAI), above ground biomass (AGB) and N uptake (AGPN) for both intercropped and sole cropped species, with satisfactory model efficiency (EF ranged from 0.62 to 0.93). In addition, grain yield was correctly predicted by the model with small error (NRMSE≤13%) especially for wheat crop (EF≥0.50), while it was less correctly predicted for chickpea crop (EF≤0.24 and NRMSE≤21%). STICS predicted well root depth under the conditions of our field study (EF ≥ 0.65 and NRMSE ≤ 37%). For soil outputs variables, the model simulated adequately soil water content with a satisfactory model efficiency (EF ≥ 0.65) and low relative error (NRMSE ≤. 8.8%) especially for sole cropped and intercropped chickpea. The soil N stocks were less adequately predicted (EF ≤ 0.28) with high relative error (NRMSE ≥ 56%) in sole cropping system, while it was moderately adequately predicted (EF ≤ 0.44) in intercropping. Under the two contrasted years and N-application conditions of this study, the temporal dynamic was well reproduced by the model for both plant and soil outputs with low simulation errors. RMSE values were lesser than 0.6 m2m-2 (9%), 0.2 t ha-1 (14%) and 30 kg ha-1 (12%), respectively for LAI, grain yield and AGPN of sole cropped chickpea. The dynamic of soil water content was also well reproduced among all N-application rate and during the two cropping year, with RMSE equal to 27 mm (<10%). The present work provides the first calibration for chickpea sole crop and an evaluation for durum wheat-chickpea intercrops, which will allow to use the STICS model to simulate scenarios of innovative cropping practices based on crop diversification (i.e. grain legumes and cereals) and N-fertilization management. • We developed a new calibration able to simulate plant growth, N uptake and grain yield for chickpea crop. • Soil water and nitrogen stocks were accurately predicted in both cropping system under contrasted N-application levels. • The model simulate adequately root depth up to a 80 cm depth under contrasted climatic conditions. • Temporal dynamic was well reproduced in both contrasted cropping years and N-application conditions. [ABSTRACT FROM AUTHOR]