Soil functions such as water regulation, resistance to degradation (i.e., erosion) and habitat provision for soil biota are essential for climate-resilient cropping systems. While soil functions are largely governed by pedo-climatic conditions, the relative importance of agricultural management remains unclear. Because these functions are governed by soil physical properties, we quantified the relative influence of pedo-climatic conditions and soil management on key soil physical properties across ten long-term field experiments in Europe. The sites spanned a 2500 km climatic gradient from Spain to Sweden and included contrasting tillage or organic matter management practices. Measurements included bulk density (BD), water storage, aeration, hydraulic conductivity, soil organic carbon (SOC), aggregate stability, and earthworm abundance in topsoil (similar to 10 cm) and subsoil (similar to 30 cm) across 92 plots and 23 management treatments. Management intensities (carbon inputs, tillage, mineral nitrogen fertilisation) were quantified over the preceding decade. We applied mixed-effects models, variance partitioning and structural equation modelling to identify direct and indirect effects. Pedo-climatic conditions explained more variability in soil physical properties than management (threefold in the topsoil and eightfold in the subsoil). Mean annual temperature and clay content controlled topsoil SOC content, which in turn mediated most soil physical properties. Management effects, although smaller, significantly influenced topsoil properties. Higher C inputs increased SOC, aggregate stability and earthworm abundance. These effects indirectly reduced BD and penetration resistance while increasing water storage, air capacity and hydraulic conductivity. Higher tillage intensity reduced BD directly but was also associated with lower aggregate stability and reduced saturated hydraulic conductivity in the topsoil. Overall, pedo-climatic conditions dominated soil physical properties, particularly in the subsoil, whereas management mainly affected topsoil properties relevant for climate resilience, highlighting limited subsoil responsiveness and the need for management strategies targeting subsoils.

Agricultural management is critical in shaping soil carbon (C) stocks, pools and fluxes. The soil priming effect (PE) is known as a key component of the global C cycle that reflects alterations in soil organic carbon (SOC) mineralization induced by fresh C inputs. Here, we show that priming can help to predict soil C content across European Long-Term Experiments (LTEs), a result which was maintained at continental and global scales. Results reveal that lower-intensity management significantly enhances PE in soils from European croplands. Conversely, high-intensity management led to lower or even negative PE. Management intensity influences PE directly through alterations in SOC and indirectly by modifying aggregates stability and microbial biomass. Both fertilization and tillage affect PE, with soils under organic fertilization and no-tillage showing higher values of PE. These findings advance our understanding of the long-term impacts of agricultural management on the C cycle at the continental scale.

No-till may have the potential to improve the resilience of agricultural systems to climate change by enhancing soil structure and soil health. However, the experimental evidence for this is inconclusive because few field trials have been established long enough for the soil to reach a new (quasi-) equilibrium state upon adopting no-till practices. Soil-crop models should be useful tools to fill this knowledge gap, but most neglect the dynamics of soil properties and so cannot predict long-term changes in soil health. One exception is Uppsala model of Soil Structure and Function (USSF), which accounts for soil structure dynamics due to physical (e.g., swell-shrink, tillage) and biological (e.g., faunal activity, aggregation) processes. In this study, we used the USSF model to evaluate the potential long-term impacts of no-till systems on soil structure, soil organic matter (SOM), water balance, and yields of winter wheat based on data obtained from a long-term farming systems trial near Z & uuml;rich, Switzerland. The model was first calibrated against field measurements during one growing season of soil water contents, leaf area index, and grain yield and aboveground biomass of winter wheat. The calibrated model was then used to simulate a baseline period (1985-2015) and 18 transient future climate scenarios for the period 2020 to 2090 for continuous winter wheat in conventionally cultivated and no-till systems. In the simulations driven by future climate projections, SOM stocks decreased by 3%-15% in the tilled soil, whereas they were maintained under no-till despite rising temperatures. Enhanced physical protection associated with soil aggregation and improved thermal regulation from the surface residue cover were identified as mechanisms contributing to the maintenance of SOM stocks under no-till. Wheat yields increased slightly and were similar for tilled and no-tilled treatments, as simulated drought stress rarely occurred at the site, which has a wet climate, despite reductions in summer rainfall. The no-till system also showed an improved water balance, with smaller losses by surface runoff and soil evaporation, suggesting that conservation agriculture should be a promising strategy for sustaining soil health and soil functions in the face of a warming climate.

Understanding the effects of agricultural soil management on the soil system and its functions is crucial to ensure the sustainable use of soil. Due to the countless ways in which soil can be managed, it is not an easy task to compare soil management practices across different locations and over time. One approach to making soil management comparable is the use of numerical soil management indicators. However, due to the lack of standardisation of soil management data and indicators, the comparability of results across studies remains limited. To address these shortcomings, we developed SoilManageR, an accessible R package. The first version of SoilManageR calculates numerical soil management indicators for carbon (C) input, tillage intensity, soil cover duration, nitrogen (N) fertilisation, equivalent livestock units per area, and plant diversity. In this paper, we present the functionality of SoilManageR and demonstrate its capabilities with three case studies. The cases were selected to compare soil management across space, time and context, as well as to relate soil management to soil quality. For this, we calculated soil management indicators for 16 experimental treatments from six agricultural long-term experiments and for 18 farmers' fields in Switzerland. We found that experimental treatments were representative of the management of the farmers' fields in terms of tillage intensity and soil cover, but that farmers' fields tended to exhibit higher livestock integration, leading to higher C and N inputs through organic amendments. We related soil management indicators to selected soil quality indicators in experimental treatments and showed that tillage intensity is the most important management driver of earthworm biomass, whereas C and N inputs were the best predictors of the organic carbon content of the topsoil. Finally, we applied SoilManageR to three sites of the Swiss Soil Monitoring Network and identified significant reductions of N inputs across time in two sites. We demonstrate that SoilManageR is a versatile tool for quantifying multiple aspects of soil management intensity, which can be useful to analyse how policy changes affect soil management. Additionally, SoilManageR can be used to assess soil management impacts on soil quality and provide guidance based on these insights.

Investigating plant responses to climate change is key to develop suitable adaptation strategies. However, whether changes in land management can alleviate increasing drought threats to crops in the future is still unclear. We conducted a management × drought experiment with winter wheat (Triticum aestivum L.) to study plant water and vegetative traits in response to drought and management (conventional vs organic farming, with intensive vs conservation tillage). Water traits (root water uptake pattern, stem metaxylem area, leaf water potential, stomatal conductance) and vegetative traits (plant height, leaf area, leaf Chl content) were considered simultaneously to characterise the variability of multiple traits in a trait space, using principal component analysis. Management could not alleviate the drought impacts on plant water traits as it mainly affected vegetative traits, with yields ultimately being affected by both management and drought. Trait spaces were clearly separated between organic and conventional management as well as between drought and control conditions. Moreover, changes in trait space triggered by management and drought were independent from each other. Neither organic management nor conservation tillage eased drought impacts on winter wheat. Thus, our study raised concerns about the effectiveness of these management options as adaptation strategies to climate change.

Soil structure is important for plant growth and ecosystem functioning, and provides habitat for a wide range of soil biota. So far, very few studies directly compared the effects of three main farming practices (conventional, organic and conservation agriculture) on soil structure and soil physical properties. Here, we collected undisturbed soil cores from the FArming System and Tillage long-term field experiment (FAST) near Zurich (Switzerland). This trial compares the effects of conventional tillage, conventional no-tillage, organic tillage and non-inversion reduced tillage under organic farming since 2009. We assessed 28 soil chemical and physical properties and related them to root and microbial biomass as well as to the diversity of bacteria and fungi. Tillage decreased bulk density (−14 %) and penetration resistance (−40 %) compared to no/reduce-tillage, potentially promoting a facilitative environment for plant root growth. Water holding capacity varied among systems, being the lowest in conventional tillage and highest (+10 %) in organic reduced tillage. We observed that microbial biomass and rhizosphere microbial diversity was positively associated with water holding capacity and the occurrence of mesopores. The presence of mesopores could provide additional niche space for microbes possibly explaining its positive effect on microbial diversity. Soil microbial biomass and rhizosphere microbial diversity were higher in plots subjected to soil conservation practices, indicating that tillage has a detrimental effect on soil microbes. Our work demonstrates that organic, conventional and conservation agriculture create contrasting soil physical environments. This work highlights the trade-off between creating a facilitative environment for root growth by tillage and maintaining complex and diverse soil microhabitats for microbes under conservation agriculture.

CONTEXT: Climate change increasingly threatens food security, particularly through prolonged phases of drought. It is therefore important to evaluate and develop arable cropping systems with an enhanced capability to withstand severe drought events to ensure food production. However, it is still poorly understood whether specific management strategies, in particular organic farming and conservation tillage that are thought to be more resilient to drought, can enhance the ability of agroecosystem to withstand drought. OBJECTIVE: The main objective of this study was, therefore, to test the ability of organic farming and conservation tillage practices to withstand drought within expected boundaries of climate scenarios for the end of the century. METHODS: This study summarizes the effects of drought (both natural and experimental) on the productivity of three arable crops (maize, pea-barley mixture and winter wheat) assessed in three consecutive years in a long-term cropping system field experiment. We tested whether four relevant cropping systems (i.e., conventional and organic with and without soil conservation tillage) differ in their ability to reduce the impact of drought on plant yield and crop performance. We studied conditions of moderate natural drought (summer 2018) and severe experimental droughts using rainout shelters (3 years) after 8 years of contrasting field management. RESULTS AND CONCLUSIONS: We found pronounced and consistent yield reductions due to experimental drought events for all cropping systems (34% for maize, 23% for pea-barley, and 17% for winter wheat). Drought induced yield reductions were largely similar across the four cropping systems, suggesting very limited capacity of any cropping system to buffer severe drought. Yet, there was an obvious but insignificant trend in maize in 2018 where under moderate and experimental drought conservation tillage resulted in a higher on-average yield compared to the plowed systems. Furthermore, drought resulted in lower nitrogen (N) uptake by the crops and a positive N budget, which could result in higher N losses after a drought period. SIGNIFICANCE: This study demonstrates that drought has consistent and adverse effects on crop productivity under conventional, organic and soil conservation arable cropping. It further demonstrates that it is difficult to find effective adaptation strategies for arable systems under realistic future scenarios and underlines the need to combine all available practices, from soil management to crop and cultivar choice, to mitigate drought impacts on crop productivity.

For decades, conservation tillage has been promoted as a measure to increase carbon stocks in arable soils. Since organic farming improves soil quality and soil carbon storage, reduced tillage under organic farming conditions may further enhance this potential. Therefore, we assessed soil organic carbon (SOC) stocks of reduced tillage compared with mouldboard ploughing in nine organic farming field trials in France, Germany, the Netherlands, and Switzerland with the same sampling and analytical protocol. We sampled soil cores until a depth of 100 cm to determine soil carbon stocks that are relevant for climate change mitigation but are often overlooked in tillage studies with shallow sampling depths. The studied field experiments were between 8 and 21 years old and comprised different soil types with clay contents ranging from 10% to 50%. SOC stocks increased with increasing clay-to-silt ratio, precipitation and organic fertiliser input. Across sites, reduced tillage in comparison with ploughing increased SOC stocks in the surface layer (0-10/15 cm) by 20.8% or 3.8 Mg ha- 1, depleted SOC stocks in the intermediate soil layers to 50 cm soil depth with a maximum depletion of 6.6% or 1.6 Mg ha- 1 in 15/ 20-30 cm and increased SOC stocks in the deepest (70-100 cm) soil layer by 14.4% or 2.5 Mg ha- 1. The subsoil SOC stock increase may be linked to the inherent soil heterogeneity. Cumulative SOC stocks increased by 1.7% or 1.5 Mg ha- 1 (0-50 cm, n = 9) and 3.6% or 4.0 Mg ha- 1 (0-100 cm, n = 7) by reduced tillage compared with ploughing with estimated mean C sequestration rates of 0.09 and 0.27 Mg ha- 1 yr- 1, respectively. There was no effect of field trial duration on tillage induced cumulative SOC stocks differences. Under reduced tillage, biomass production was 8% lower resulting in a decrease of crop C input by 6%. However, this reduction may have been outbalanced by increased C inputs from weed biomass resulting from a higher weed incidence in reduced tillage, which warrants further research. Thus, reduced tillage in organic farming has the potential to increase total SOC stocks, while crop management has to be improved to increase productivity.

Litter decomposition is a fundamental process in soil carbon dynamics and nutrient turnover. However, litter decomposition in arable systems remains poorly explored, and it is unclear whether different management practices, such as organic farming, conservation agriculture can mitigate drought effects on litter decomposition. Thus, we examined the effects of a severe experimental drought on litter decomposition in four cropping systems, i.e., organic vs. conventional farming, each with two levels of tillage (intensive vs. conservation tillage) in Switzerland. We incubated two types of standard litter (tea bags), i.e., high-quality green tea with a low C:N ratio and low-quality rooibos tea with a high C:N ratio. We assessed litter decomposition during the simulated drought and in the post-drought period during three years in three different crops, i.e., pea-barley, maize, and winter wheat. Subsequently, we assessed whether decomposition in the four cropping systems differed in its resistance and resilience to drought. Drought had a major impact on litter decomposition and suppressed decomposition to a similar extent in all cropping systems. Both drought resistance and resilience of decomposition were largely independent of cropping systems. Drought more strongly reduced decomposition of the high-quality litter compared to the low-quality litter during drought conditions regarding the absolute change in mass remaining (12.3% vs. 6.5 %, respectively). However, the decomposition of high-quality litter showed a higher resilience, i.e., high-quality approached undisturbed decomposition levels faster than low-quality litter after drought. Soil nitrate availability was also strongly reduced by drought (by 32-86 %), indicating the strong reduction in nutrient availability and, most likely, microbial activity due to water shortage. In summary, our study suggests that severe drought has a much stronger impact on decomposition than cropping system indicating that it might not be possible to maintain decomposition under drought by the cropping system approaches we studied. Nevertheless, management options that improve litter quality, such as the use of legume crops with high N concentrations, may help to enhance the resilience of litter decomposition in drought-stressed crop fields.

Agricultural production is under threat of water scarcity due to increasingly frequent and severe drought events under climate change. Whether a change in cropping systems can be used as an effective adaptation strategy against drought is still unclear. We investigated how plant water uptake patterns of a field-grown pea–barley (Pisum sativum L. and Hordeum vulgare L.) mixture, an important fodder intercrop, responded to experimental drought under four cropping systems, i.e. organic intensive tillage, conventional intensive tillage, conventional no tillage, and organic reduced tillage. Drought was simulated after crop establishment using rain shelters. Proportional contributions to plant water uptake from different soil layers were estimated based on stable water isotopes using Bayesian mixing models. Pea plants always took up proportionally more water from shallower depths than barley plants. Water uptake patterns of neither species were affected by cropping systems. Both species showed similar responses to the drought simulation and increased their proportional water uptake from the shallow soil layer (0–20 cm) in all cropping systems. Our results highlight the impact of drought on plant water uptake patterns for two important crop species and suggest that cropping systems might not be as successful as adaptation strategies against drought as previously thought.

Conservation tillage is suggested to sequester carbon although a stratification of soil organic carbon rather than a total increase is mostly observed. It is not clear whether conservation tillage in combination with organic farming practices has a higher potential. Beyond, many datasets are biased in terms of sampling depth. A joint sampling campaign in nine European long-term trials considered soil organic carbon stocks until 100 cm soil depth comparing reduced tillage with ploughing under organic farming conditions. First results show a significant increase of carbon stocks in 0-30 cm and also in 0-100 cm depth with the conversion to reduced tillage.

CONTEXT: Crop phenology integrates information of how environmental drivers and management practices affect plant performance and crop yield. However, little is known about the impact of cropping systems (CS) on crop phenology and how this relates to differences in yield. OBJECTIVES: We assessed the applicability of PhenoCams to track crop phenology, how four CS, i.e., organic vs. conventional farming with either intensive or conservation (no/reduced) tillage affect the phenology of a pea-barley mixture and winter wheat, how crop phenology is related to harvest characteristics, e.g., grain yield and total N uptake, and explains CS effects on these characteristics. METHODS: We used time-lapse cameras (PhenoCams) to track vegetation changes in the two crops and extracted the green chromatic coordinate (GCC) to estimate different phenological metrics, i.e., dates with major changes in GCC (PhenoTimePoints), the duration between those (PhenoPhases), and the rate of increasing or decreasing GCC (PhenoSlopes). We assessed how phenological metrics were affected by different CS, and related pheno-logical metrics to harvest characteristics. RESULTS AND CONCLUSIONS: CS significantly affected phenological metrics of both crops, with less pronounced effects in the unfertilized pea-barley mixture compared to the fertilized winter wheat, and stronger effects for early-season than for late-season PhenoTimePoints. For winter wheat, organic compared to conventional farming caused an initial growth lag (up to 7 days) and a shorter duration (approximately 10 days) of the period of stable GCC. Winter wheat in reduced/no-tillage systems showed a tendency of delayed phenology (up to 5 days) compared to intensive tillage. While phenological metrics explained harvest characteristics of winter wheat well, they were almost unrelated to those of pea-barley, most likely because pea-barley yields were similar among CS. For winter wheat, effects of CS on harvest characteristics could be well explained by phenological metrics (max. R2 = 0.9). Thus, we demonstrated that delayed phenology acted as an important factor causing lower yield in organic compared to conventional farming. SIGNIFICANCE: PhenoCams are valuable tool for high-resolution temporal monitoring of crop phenology. As different CS have been proposed as a tool for climate change adaptation, we suggest that the effects of CS on crop phenology need to be considered as they may impact yield via changes in crop phenology, particularly in organic agriculture.

In recent years there has been an upsurge of studies on ecosystem multifunctionality (EMF), or the ability of ecosystems to simultaneously provide multiple functions and/or services. The concept of EMF itself, the analytical approaches used to calculate it, and its implications depending on the spatial scale and field of study have been discussed in detail. However, to date there has been little dialogue concerning the basis of EMF studies: what should or should not be considered appropriate measures for ecosystem functions. To begin this discussion, we performed an in-depth review of EMF studies across four major terrestrial ecosystems (agroecosystems, drylands, forests and grasslands) by analysing 82 studies, which together have assessed 775 ecosystem functions from a variety of field and greenhouse experiments across the globe. The number of ecosystem functions analysed varied from two to 82 per study and we found large differences in the distribution of functions across ecosystem types and ecosystem service categories. Furthermore, there was little explanation of why certain variables were included in the EMF calculation or how they relate to ecosystem functioning. Synthesis. Based on the literature analysis, it is clear that there is no general agreement regarding which measurements should or should not be considered functions in the field of ecology. To address this issue, we propose a general guideline for determining and measuring appropriate functions.

Ecosystems provide multiple services to humans. However, agricultural systems are usually evaluated on their productivity and economic performance, and a systematic and quantitative assessment of the multifunctionality of agroecosystems including environmental services is missing. Using a long-term farming system experiment, we evaluated and compared the agronomic, economic, and ecological performance of the most widespread arable cropping systems in Europe: organic, conservation, and conventional agriculture. We analyzed 43 agroecosystem properties and determined overall agroecosystem multifunctionality. We show that organic and conservation agriculture promoted ecosystem multifunctionality, especially by enhancing regulating and supporting services, including biodiversity preservation, soil and water quality, and climate mitigation. In contrast, conventional cropping showed reduced multifunctionality but delivered highest yield. Organic production resulted in higher economic performance, thanks to higher product prices and additional support payments. Our results demonstrate that different cropping systems provide opposing services, enforcing the productivity-environmental protection dilemma for agroecosystem functioning.

Cover crops are often recommended as a valuable practice to develop more sustainable cropping systems but, despite many benefits, their adoption in practice is still limited mainly because the effects on productivity and economic return are variable. Furthermore, it is still unclear under which combinations with other management practices (e.g. tillage, fertilization, weed control) cover crops can provide the highest paybacks. Here we tested whether cover crops are a suitable management tool to reduce fertilizer input, tillage intensity and herbicide use in Swiss arable cropping systems. We compared the effects of four different cover crop treatments (fallow, radish, subterranean clover and hairy vetch) on maize at two fertilization levels combined with three levels of tillage intensity. To unravel the effects of cover crops on maize growth, we assessed vegetation dynamics using the Normalized Differential Vegetation Index (NDVI) from aerial spectral imagery. Cover crops on average increased yields by 12 % (+ 7 % to + 20 %) and cover crop effects depended on tillage intensity, fertilization level and cover crop treatment for most of the assessed maize parameters. Best results were obtained with hairy vetch, which increased maize N uptake by 79 kg ha(-1) on average. As a consequence, at least combinations of two of the three targeted inputs (tillage, fertilization and herbicides) could be successfully reduced, e.g. tillage and fertilization under no tillage or tillage and herbicides under reduced tillage. Even under intensive tillage, both legume cover crops allowed a reduction of fertilization without compromising yield. Spectral imagery analysis showed that legume cover crops compensated for delayed N availability in reduced and no tillage systems and cover crops contributed to enhanced N uptake and crop growth later in the season. We provide evidence that cover crop based cropping systems can be used to reduce synthetic inputs and tillage without compromising yield, thus presenting an example of ecological engineering. We highlight the importance of considering the whole set of management practices when adopting cover cropping in order to maintain or increase productivity with reduced anthropogenic inputs under conventional cropping.

An amendment to this paper has been published and can be accessed via the original article.

The impact of organic and conventional crop management together with two variations of conservation tillage was evaluated on N supply and losses at the end of a 4-year Swiss crop rotation. Soil samples were taken from four cropping systems: conventional intensive tillage (C-IT), conventional no tillage (C-NT), organic intensive tillage (O-IT) and organic reduced tillage (O-RT). Laboratory incubations were used to estimate rates of net mineralization, gross nitrification and potential denitrification, while quantitative PCR was used to determine copy numbers of genes of relevant enzymes in these processes. N supply via mineralization and nitrification was unaffected by cropping system. Significant decrease in bacterial ammonia oxidizer (AOB) abundance at the end of the gross nitrification incubation indicated greater responsiveness of this group for activity, in particular under conventional management. C-NT produced the highest potential denitrification, although only significantly different than C-IT. O-RT was similar to C-IT and C-NT in terms of soil N supply and N gaseous losses, meaning that added benefits through its use does not compromise plant N availability or increase N2O losses compared to conventional practices.

We aimed to understand how crop practices such as tillage, crop management and cover crop use affect aggregate microhabitats for nitrogen (N)-cycling microorganisms. We quantified the abundance of five N-cycling functional genes: two genes related to ammonia oxygenation (amoA from archaea and bacteria), two nitrite reducers (nirS and nirK) and one for nitrous oxide reduction (nosZ) as well as total eubacteria (16S) in two soil aggregate fractions. These fractions were total (occluded and non-occluded) microaggregates (tMi) and total silt and clay (tS + C) from a field trial under conventional and organic crop management combined with intensive or conservation tillage and four different cover crops. Although we found no clear associations between abundances of different functional genes in aggregate fractions, abundance of nosZ and amoA AOA changed almost exclusively in the tMi, suggesting that this fraction may mediate soil microbial response to crop management practices. Terminal restriction fragment length polymorphism (T-RFLP) analysis of the nosZ gene indicated that aggregate fractions host different microbial communities, therefore providing distinct microhabitats.