Increased crop diversity in cereal-dominated rotations can enhance crop protection, nutrient use efficiency and climate change adaptation. Nevertheless, it is argued that replacing cereals in rotations diminishes food production, threatening food security. Here we compared outputs of calories and macronutrients (carbohydrates, proteins, fats) for human consumption from cereal monocultures, cereal-only rotations and rotations including two or three functionally distinct crop types (cereals plus root and oil crops, legumes or ley) in 16 long-term experiments across Europe. Rotations with three functional types produced more calories and macronutrients than cereal monocultures and cereal-only rotations with forage crops used to produce milk. Carbohydrate gains depended on growing conditions and crop choice. Advantages increased over time but were lost with forage crops used for beef or biofuel. Functionally rich rotations provided macronutrient proportions closer to recommended human diets. Our analysis shows no trade-off between functionally rich rotations and food production or agricultural land expansion.

Studies across multiple soils find increasing pH decreases water repellency. In this study, water repellency and a range of other soil physical properties of bulk soils, aggregates and intact specimens were measured on a long-term pH field experiment on a single sandy loam soil under a ley-arable crop rotation, with soil pH adjustments occurring annually by adding FeSO4 or CaCO3, to lower or raise the pH, respectively. Crop impacts were investigated by comparing 3rd year grass-white clover to spring oats, at the beginning (May) and end (September) of the growing season to allow soil structure comparisons. As in previous research, increased CO2 microbial respiration (p<0.05) was found with increasing pH along the gradient, but in this study, we found only the aggregate and soil bulk density affected by soil pH. Soil-water contact angles differed between crops (p<0.05), as well as the repellency index of soil aggregates, however, there was no soil pH effect. Overall, differences in data were found to be a result of the various crops in the rotation rather than by soil pH, indicating only minor impacts on soil physical characteristics after > 55 years of chemical additions to amend soil pH.

Diversified crop rotations have been suggested to reduce grain yield losses from the adverse climatic conditions increasingly common under climate change. Nevertheless, the potential for climate change adaptation of different crop rotational diversity (CRD) remains undetermined. We quantified how climatic conditions affect small grain and maize yields under different CRDs in 32 long-term (10-63 years) field experiments across Europe and North America. Species-diverse and functionally rich rotations more than compensated yield losses from anomalous warm conditions, long and warm dry spells, as well as from anomalous wet (for small grains) or dry (for maize) conditions. Adding a single functional group or crop species to monocultures counteracted yield losses from substantial changes in climatic conditions. The benefits of a further increase in CRD are comparable with those of improved climatic conditions. For instance, the maize yield benefits of adding three crop species to monocultures under detrimental climatic conditions exceeded the average yield of monocultures by up to 553 kg/ha under non-detrimental climatic conditions. Increased crop functional richness improved yields under high temperature, irrespective of precipitation. Conversely, yield benefits peaked at between two and four crop species in the rotation, depending on climatic conditions and crop, and declined at higher species diversity. Thus, crop species diversity could be adjusted to maximize yield benefits. Diversifying rotations with functionally distinct crops is an adaptation of cropping systems to global warming and changes in precipitation. Industrial agriculture often relies on one or few crop species grown in monocultures or short crop rotations, making them vulnerable to changes in climatic conditions. Using data from several agricultural experiments in Europe and North America, we show that including more crop species or crop types in rotation can mitigate cereal yield losses caused by increasingly common shifts in climatic conditions, such as increasing temperatures and decreasing precipitation. Hence, increasing crop rotational diversity can support the climate adaptation of the way we produce our food.image

BackgroundLiming agricultural land is essential to optimise crop yield and soil nutrients. Despite the importance of pH management in agricultural soils, liming applications have been decreasing in the United Kingdom for decades. There is no comparison of contemporary and historical liming requirement (LR) methods for Northern European, temperate climate mineral soils high in organic matter (OM). AimsThe aims of this research were to thoroughly comparatively analyse current methodologies and to ascertain which soil characteristics contribute to LR reactions. MethodsAnalysis compared methods for determining liming values common in the United Kingdom (Scottish Agricultural College [SAC] look-up chart, RothLime model), Europe and the United States (Shoemaker-McLean-Pratt, Sikora, Modified Mehlich buffers), and the 30-min calcium hydroxide titration developed by the University of Georgia. ResultsRothLime and SAC highly underestimated the LR value in acidic soils. The buffers highly over or underestimated LRs. The UGA titration method is a cheap, easy and accurate method which could be utilised for high OM soils but requires further calculation development. The characteristics most associated with soil-lime reactions in this experiment were measures of exchangeability (cation exchange capacity and loss on ignition, and by proxy, lime buffering capacity). ConclusionsThere is an opportunity to create buffer calculators and titration equations adapted to high OM soils. These are suggested for further development, through a larger diversity of UK soil types grouped by buffering capacity ranges. Including soil exchangeability factors in lime management calculations may contribute to more accurate values and therefore better resource management. Increasing LR accuracy for site-specific soil pH management, used in precision agriculture technologies, is a necessary tool for the conservation of natural resources like limestone, managing resource use efficiency, and for optimising yields.

New forms of field experimentation are currently emerging to support transitions towards sustainable agriculture, including "multi-actor experimental networks" (MAENs). Both in public policy and in academic research, such networks are increasingly presented as a promising approach for fostering sustainable farming system design. Many studies have inventoried, categorized and compared experimental processes to discuss them in relation to contemporary issues. However, to our knowledge, these studies have not considered how MAENs can be implemented, nor their various contributions to sustainable farming systems design. The present work therefore explores the mechanisms whereby MAENs, depending on the way they are managed, support participatory design processes. Drawing on concepts from the design sciences, we studied 11 MAENs established across Europe to support intercrop (IC) design for field crops. Data on the characteristics of these 11 MAENs and their contributions to IC design were collected through individual and group interviews with the network pilots, and the study of individual MAEN documents. The analysis provides three types of results. First, we identify nine generative functions, that is, various processes through which experiments contribute to IC design, including: (i) finding one best option or highlighting contrasts between different ICs; (ii) highlighting the conditions that must be met for an IC to achieve certain effects; (iii) discovering new ICs or properties of ICs; and (iv) supporting the emergence/continuation of collective action for IC design. Second, we highlight different ways to manage MAENs, in other words ways to manage several experiments (in space and time) with a view to supporting participatory IC design. We show that this involves (i) coordinating several objects under design within a network of experiments, (ii) managing the coexistence of experiments guided by different logics in the same geographical area, and (iii) developing interactions between the experiments at a given point in time and over time to support IC design. Third, based on the previous results, we show consistency between the various contributions of MAENs to IC design and the different ways in which the pilots managed them, and we highlight three strategies for managing MAENs to support IC design: MAENs supporting (i) R&D-led design; (ii) farmer-led design; and (iii) distributed design. All these results provide mechanisms, points of reference, MAEN types and characteristics to inspire and foster the reflexivity of R&D actors interested in developing such participatory networks in the future.

Diversifying agriculture by rotating a greater number of crop species in sequence is a promising practice to reduce negative impacts of crop production on the environment and maintain yields. However, it is unclear to what extent cereal yields change with crop rotation diversity and external nitrogen fertilization level over time, and which functional groups of crops provide the most yield benefit. Here, using grain yield data of small grain cereals and maize from 32 long-term (10–63 years) experiments across Europe and North America, we show that crop rotational diversity, measured as crop species diversity and functional richness, enhanced grain yields. This yield benefit increased over time. Only the yields of winter-sown small grain cereals showed a decline at the highest level of species diversity. Diversification was beneficial to all cereals with a low external nitrogen input, particularly maize, enabling a lower dependence on nitrogen fertilisers and ultimately reducing greenhouse gas emissions and nitrogen pollution. The results suggest that increasing crop functional richness rather than species diversity can be a strategy for supporting grain yields across many environments.

Abstract Agricultural lime is an important natural resource for changing soil pH values. Annual lime applications in the UK have fallen for decades. Estimating soil factors that contribute to the retention and losses of lime would be useful for farmers making resource decisions. The aim of this research was to analyse the soil factors contributing to leaching loss and retention of agricultural lime in Scottish grassland soils. This research also tested the applicability of a large centrifuge method for measuring leached solutions from soil, suggested as an alternative to leaching columns. The soils studied in this research were highly variable in their response to lime. Measures of soil exchange capacity (cation exchange capacity, lime buffering capacity and organic matter) and clay content were highly associated factors to calcium loss and retention within a soil. Suggestions to farmers include consideration of soil clay content, organic matter content (as expressed through C) and cation exchange capacity as factors in lime decision making. Higher exchange capacity soils lost more calcium, likely due to the greater liming requirement of these soils and potential increased excess calcium applied. It is suggested that methods for improving calcium exchange and soil uptake be explored for improving lime retention after liming events.

Soil health metrics with strong links to ecological function and agricultural productivity are needed to ensure that future management of agricultural systems meets sustainability goals. While ecological metrics and crop yields are often considered separately from one another, our work sought to assess the links between the two in an agricultural context where productivity is a key consideration. Here, we investigated the value of soil health tests in terms of their relevance to agricultural management practices and crop yields at contrasting long term cropping systems experiments. One site was on a sandy loam Leptic Podzol and the other on a sandy clay loam Endostagnic Luvisol. Furthermore, the experiments had different management systems. One contained legume-supported rotations with different grass-clover ley durations and organic amendment usage, while the other compared a range of nutrient input options through fertiliser and organic amendments on the same rotation without ley periods. Metrics included field tests (earthworm counts and visual evaluation of soil structure scores) with laboratory analysis of soil structure, chemistry and biology. This analysis included bulk density, macroporosity, pH, available phosphorus, exchangeable potassium, soil organic matter and potentially mineralizable nitrogen. Using a novel combination of long-term experiments, management systems and distinctive soil types, we demonstrated that as well as providing nutrients, agricultural management which resulted in better soil organic matter, pH, potassium and bulk density was correlated with higher crop yields. The importance of ley duration and potentially mineralizable nitrogen to yield in legume-supported systems showed the impact of agricultural management on soil biology. In systems with applications of synthetic fertiliser, earthworm counts and visual evaluation of soil structure scores were correlated with higher yields. We concluded that agricultural management altered yields not just through direct supply of nutrients to crops, but also through the changes in soil health measured by simple metrics.

Insect-pollinated legumes are rich in plant-based proteins making them a vital constituent of sustainable healthy diets for people and livestock. Furthermore, they deliver or support a range of ecosystem services that underpin agricultural production and their prevalence in agricultural landscapes is likely to increase. Under typical implementation and management, the value of legumes to pollinators has, however, been questioned. Through exploring a range of legume crops, grown as monocultures and mixtures, this study aims to identify multifunctional legume cropping systems that optimise forage availability for a diversity of wild pollinators whilst delivering a wide range of agronomic and environmental benefits. This study innovatively explores legume mixtures concurrently with monocultures of the component species using replicated small-plot field trials established in two geographical locations. Observational plots assessed the richness and abundance of floral resources, and wild pollinators (i.e. bumblebees and hoverflies) throughout the peak flowering period. Densely flowering, highly profitable legumes (e.g. Trifolium incarnatum and Trifolium mixes) supported abundant and rich pollinator assemblages. The functional makeup of floral visitors was strongly influenced by flower structure and hoverflies, with their shorter proboscises, were largely constrained to legumes with shallower corolla and open weed species. Floral richness was not a key driver of pollinator assemblages; however, clear intra-specific differences were observed in flowering phenology. Combining functionally distinct legumes with respect to flower structure and phenology, will support a wider suite of pollinating insects and help stabilise the temporal availability of forage. For highly competitive legumes (e.g. Vicia faba and Vicia sativa), planting in discrete patches is recommended to reduce the risk of less competitive species failing in mixtures. Legumes can provide valuable forage for pollinators; however, they fail to meet all resource requirements. They should therefore be used in combination with agri-environmental measures targeted to promote early-season forage (e.g. hedgerows and farm woodlands), open flowers for hoverflies, saprophytic hoverfly larval resources (e.g. ditches and ponds) and nesting habitats (e.g. undisturbed field margins).

CONTEXT: Although cereal-legume intercropping is a recognized approach to improve crop production sus-tainability, its uptake on European commercial farms remains slow, due to numerous questions raised by the introduction of intercrops in a cropping system. Co-design workshops allow multiple scenarios to be explored without risks. They favor identification of consistent answers to complex problems, considering local conditions and constraints. OBJECTIVE: We present Interplay, the serious game we created to support players' exploration of intercrops by designing a wide-range of cereal-legume intercropping scenarios in given cropping system contexts and assessing eight ecosystem services provided by intercrops, i.e., intercropped cereal and legume yields, cereal protein content, nitrogen supply to the following crop, impact on soil structure and weed, insect and disease control.METHODS: Interplay aims at being used with groups of farmers and their advisor or students and their agronomy teacher. The game includes a game board and cards to design intercropping scenarios defined by: (i) the cropping system and field context; (ii) the farmers' objectives when introducing an intercrop; (iii) the species to associate and (iv) the crop management. A computer model assesses the ecosystem services provided by the intercropping scenario designed on the game board. The players compare these results to their objectives and to sole crop performances and, if necessary, adjust the scenarios. The players are guided through the design process by a facilitator.RESULTS AND CONCLUSIONS: In the context of the Covid-19 pandemic, we used the game with 70 French agriculture students divided into six groups to design intercropping scenarios improving nitrogen supply to the following crop in a rotation. Students designed scenarios that improved nitrogen supply compared to the initial sole crop, yet cereal yield decreased more than the farmer desired. Guided by the facilitator, students reconsidered the cropping system to improve nitrogen supply at the crop rotation level. Interplay is an interactive tool used to stimulate players' creativity by exploring intercropping scenarios and providing salient, credible and legitimate assessment of the ecosystem services provided. It also promotes knowledge sharing on intercropping and allows redesigning the cropping system completely. Students and teachers who used it declared that it helped enhance their knowledge on intercrops.SIGNIFICANCE: Interplay is the first serious game suited to develop the practice of intercropping. It is currently available for cereal-grain legume intercrops sown simultaneously in a random pattern under French soil-climate conditions, but could be adapted to other countries and intercrops.

Abstract Sustainable farming systems provide food for humans while balancing nutrient management. Inclusion or exclusion of livestock has nutrient management implications, as livestock produce food from otherwise inedible crops and their manure is a valuable soil conditioner. However, plant‐based diets are becoming more widespread due to perceived environmental benefits. We measure both food production in terms of nourishment to humans (in this study measured by protein, fat, starch and sugar production) and nutrient sustainability in terms of fertiliser use of six rotational farming systems with differences in nutrient management approaches. The arable practices included were the application of synthetic fertilisers, a range of organic amendments, incorporation of crop residues and legume cultivation. Livestock and associated products were included in some systems but excluded in others. The production of protein, fat, starch and sugar was combined with the balance of nitrogen (N), phosphorus (P) and potassium (K) into an overall measure of nutrient use efficiency of human macronutrient production. Across all systems considered, N use efficiency (5–13 kg protein/kg applied N) was lower than P (84–772 kg protein/kg applied P) or K (63–2060 kg protein/kg applied K), and combining synthetic fertiliser use with organic amendment applications raised production significantly while balancing P and K management, regardless of which organic amendment was used. Legume‐supported rotations without livestock produced more protein, starch and sugar per unit area than those with livestock. Nutrient balances and nutrient use efficiencies were more sensitive to management changes than purely food production. Using this approach allowed us to identify areas for improvement in food production based on the specific nutritional value of offtakes as opposed to yield overall.

New forms of field experimentation are currently emerging, including “multi-actor experimental networks” (MAENs). Both in public policy and in academic research, such networks are increasingly presented as a promising approach for fostering innovation towards sustainable farming systems. Many studies have inventoried, categorized and compared experimental processes to discuss them in relation to contemporary issues. However, to our knowledge, these studies didn’t consider MAENs’ various contributions to innovation processes supporting sustainable farming. The present work therefore explores the mechanisms whereby MAENs, depending on the way they are deployed, support these processes. Drawing on concepts from the design sciences, we studied 11 MAENs established across Europe to support intercrop (IC) design for field crops. The data on the characteristics of these 11 MAENs and their contributions to IC design were collected through individual and group interviews with network pilots, and the study of individual MAEN documents. The analysis provides three types of results. First, we identify nine generative functions, that is, processes through which experiments contribute to IC design, including: (i) finding one best option or highlighting contrasts between different ICs; (ii) highlighting the conditions that must be met for an IC to achieve certain effects; (iii) discovering new ICs or properties of ICs; and (iv) supporting the emergence/continuation of collective action for IC design. Second, we show that piloting a MAEN involves coordinating several experiments to support IC design, and in particular: (i) simultaneously coordinating experiments with several intercrops under design, (ii) managing their coexistence despite different logics within the same geographical area, and (iii) developing interactions between the experiments at a given point in time to support IC design. Third, we highlight three strategies for managing MAEN to support IC design: MAENs (i) supporting R&D-led design; (ii) supporting farmer-led design; and (iii) supporting distributed design. All these results provide heuristic markers to inspire other researchers and field actors interested in deploying such MAEN in the future, and they offer new perspectives for fostering their development in support of innovation towards sustainable agriculture.

The influence of biotic and abiotic factors on viral communities across environmental gradients in soil is relatively unknown. While soil pH strongly influences microbial community structure, it is unclear whether there is a similar influence on soil viruses. In this study, prokaryotic and viral communities were characterized in soils from a long-term pH-manipulated soil gradient (pH 4.5 and 7.5), and viral populations also compared to those of other soils ranging in pH (4.0–7.5). Viral communities were significantly influenced by pH at the local scale with 99% of viral operational taxonomic units restricted to pH 4.5 or 7.5 soil only. Analysis of viromes from six other European and North American soil systems demonstrated that a selection of viral clusters from acidic and neutral pH soils were more associated with those from the local gradient pH 4.5 or 7.5 soils, respectively. While direct pH effects on virion integrity and indirect selection via host composition were not distinguished, the results reveal that soil pH is a factor in structuring viral communities at local and global scales.

Ecological intensification (EI) could help return agriculture into a 'safe operating space' for humanity. Using a novel application of meta-analysis to data from 30 long-term experiments from Europe and Africa (comprising 25,565 yield records), we investigated how field-scale EI practices interact with each other, and with N fertilizer and tillage, in their effects on long-term crop yields. Here we confirmed that EI practices (specifically, increasing crop diversity and adding fertility crops and organic matter) have generally positive effects on the yield of staple crops. However, we show that EI practices have a largely substitutive interaction with N fertilizer, so that EI practices substantially increase yield at low N fertilizer doses but have minimal or no effect on yield at high N fertilizer doses. EI practices had comparable effects across different tillage intensities, and reducing tillage did not strongly affect yields. Intensifying food production sustainably is critical given growing demand and agriculture's environmental footprint. This meta-analysis finds that practices such as adding organic matter and increasing crop diversity can partly substitute for nitrogen fertilizer to sustain or increase yields.

Viruses shape microbial community structures, impacting metabolic pathways and influencing biogeochemical cycles. Despite their importance, the influence of biotic and abiotic factors on viral community structures across environmental gradients in soil is relatively unknown compared to their prokaryotic hosts. While soil pH strongly influences microbial community structure, it is unclear whether there is a similar influence on soil virus communities. In this study, prokaryotic and viral communities were characterized in soils sampled from the extremes of a long-term pH-manipulated soil gradient (pH 4.5 and 7.5), and viral populations were compared to those in a variety of soil ecosystems ranging in pH (4.0 – 7.5). Prokaryotic and viral community structure were significantly influenced by soil pH at the local scale. Of 1,910 viral operational taxonomic units (vOTUs), 99% were restricted to pH 4.5 or 7.5 soil only. These were compared in gene sharing networks of populations from six other European and North American soil systems. A selection of viral clusters from acidic and neutral pH soils were more associated with those from the local gradient pH 4.5 or 7.5 soils, respectively. Results indicate that as with prokaryotes, soil pH is a factor structuring viral communities at the local and global scale.

Apios americana Medik, a native American plant has potential as a commercially viable Northern European-grown motcrop, mainly due to its resistance to extreme climate and nutritional quality. Analysis of A. americana sourced from two UK sites; South (51.4690 degrees N, 1.1150 degrees W) and North (55.9661 degrees N, 3.2063 degrees W) showed that the tubers were a complete source of amino acids (UPLC-TUV analysis), were rich in protein (15.0 +/- 0.0160 and 17.3 +/- 0.0779%; Vario Max CN analysis), fibre (total non-starch polysaccharides, 10.4 +/- 0.570 and 10.6 +/- 0.280%; GC analysis) and micronutrients (calcium, manganese, iron, zinc, molybdenum, potassium and phosphorus; ICP-MS analysis). Apios americana tubers were also rich in bioactive phytochemicals. From the 156 plant metabolites measured using LC-MS/MS analysis, genistein was the major phytophenol in both the Southern- and Northern UK tubers (259 +/- 12.2 mg Kg(-1) and 356 +/- 29.9 mg Kg(-1) respectively); the peel having similar phytochemical profiles. The protein and fibre content of the leaves (17.3 +/- 0.0434% and 11.7 0.0445%) and rhizomes (18.4 +/- 0.0152% and 13.5 +/- 0.590%) were significantly higher (p < 0.05) than the tubers. The leaves were also a good source of anthocyanins; delphinidin and cyanidin (840 +/- 137 and 3934 +/- 176 mg Kg(-1) respectively). Cultivation of A. americana as a high-protein staple-crop has enormous potential in Northern European countries for human nutrition, diet diversification, and use in livestock diets.