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Digestate, a by‐product of biogas production, is widely recognized as a promising renewable nitrogen (N) source with high potential to replace synthetic fertilizers. Yet, inefficient digestate use can lead to pollutant N losses as ammonia (NH3) volatilization, nitrous oxide (N2O) emissions and nitrate (NO3−) leaching. Cover crops (CCs) may reduce some of these losses and recycle the N back into the soil after incorporation, but the effect on the N balance depends on the CC species. In a one‐year field study, we tested two application methods (i.e., surface broadcasting, BDC; and shallow injection, INJ) of the liquid fraction of separated co‐digested cattle slurry (digestate liquid fraction [DLF]), combined with different winter cover crop (CC) options (i.e., rye, white mustard or bare fallow), as starter fertilizer for maize. Later, side‐dressing with urea was required to fulfil maize N‐requirements. We tested treatment effects on yield, N‐uptake, N‐use efficiency parameters, and N‐losses in the form of N2O emissions and NO3− leaching. CC development and biomass production were strongly affected by their contrasting frost tolerance, with spring‐regrowth for rye, while mustard was winter killed. After the CCs, injection of DLF increased N2O emissions significantly compared with BDC (emission factor of 2.69% vs. 1.66%). Nitrous oxide emissions accounted for a small part (11%–13%) of the overall yield‐scaled N losses (0.46–0.97 kg N Mg grain−1). The adoption of CCs reduced fall NO3− leaching, being 51% and 64% lower for mustard and rye than under bare soil. In addition, rye reduced NO3− leaching during spring and summer after termination by promoting N immobilization, thus leading to −57% lower annual leaching losses compared with mustard. DLF application method modified N‐loss pathways, but not the cumulative yield‐scaled N losses. Overall, these insights contribute to inform an evidence‐based design of cropping systems in which nutrients are recycled more efficiently. [ABSTRACT FROM AUTHOR]

• Timing and method of slurry application modified N loss. • Winter slurry injection led to the highest N 2 O emissions. • Slurry injection may reduce NH 3 volatilization, but increase N 2 O emissions. • Autumn application increased NO 3 − leaching by 65 % compared with winter and spring. • Autumn slurry injection had the lowest yield and N uptake. Livestock manure is a major source of nitrogen (N) for plants, but also of ammonia (NH 3) and nitrous oxide (N 2 O) emissions to the atmosphere, and nitrate (NO 3 −) leaching to groundwater. Slurry application practices targeted at reducing each of these N losses individually are relatively well known. Yet, our understanding of the potential relationships between N loss pathways is far from being complete. In this field study on grassland, we tested the effect of slurry application timing (autumn vs. winter vs. spring) and method (injection vs. broadcasting) and their interactions on N 2 O emissions, NH 3 volatilization and NO 3 − leaching, as well as on plant N uptake. We found that autumn application increased NO 3 − leaching by 65 % compared with winter and spring due to 63 % higher rainfall following application. On average, autumn application reduced plant N uptake by 26 %. N 2 O emissions after winter slurry application were 43 % higher that after either spring or autumn applications. Slurry application method had no effect on NO 3 − leaching. Slurry injection led to 32 % higher N 2 O emissions compared with broadcast application. Slurry injection decreased NH 3 volatilization only in autumn when the soil was relatively dry before application, but not in winter or spring when the soil was wet. Changes in slurry application timing led to variations in total N losses of up to 146 %, and application method of up to 19 %, highlighting the great potential of slurry application practices to steer an efficient N management. Overall, autumn application should be avoided to promote more sustainable grassland production; however, if slurry must be applied in autumn, injection should be recommended to reduce NH 3 volatilization. [ABSTRACT FROM AUTHOR]

Introducing smart and sustainable tools for climate change adaptation and mitigation is a major need to support agriculture's productivity potential. We assessed the effects of the processed gypsum seed dressing SOP® COCUS MAIZE+ (SCM), combined with a gradient of N fertilization rates (i.e., 0%, 70% equal to 160 kg N ha−1, and 100% equal to 230 kg N ha−1) in maize (Zea mays L.), on: (i) grain yield, (ii) root length density (RLD) and diameter class length (DCL), (iii) biodiversity of soil bacteria and fungi, and (iv) Greenhouse Gases (GHGs, i.e., N2O, CO2, and CH4) emission. Grain yield increased with SCM by 1 Mg ha−1 (+8%). The same occurred for overall RLD (+12%) and DCL of very fine, fine, and medium root classes. At anthesis, soil microbial biodiversity was not affected by treatments, suggesting earlier plant-rhizosphere interactions. Soil GHGs showed that (i) the main driver of N losses as N2O is the N-fertilization level, and (ii) decreasing N-fertilization in maize from 100% to 70% decreased N2O emissions by 509 mg N-N2O m−2 y−1. Since maize grain yield under SCM with 70% N-fertilization was similar to that under Control with 100% N-fertilization, we concluded that under our experimental conditions SCM may be used for reducing N input (−30%) and N2O emissions (−23%), while contemporarily maintaining maize yield. Hence, SCM can be considered an available tool to improve agriculture's alignment to the United Nation Sustainable Development Goals (UN SDGs) and to comply with Europe's Farm to Fork strategy for reducing N-fertilizer inputs. [ABSTRACT FROM AUTHOR]

• No-till (NT) increases soil organic C (28%) and earthworm abundance (5 times) compared with conventional tillage (CT). • Using rye (Secale cereale L.) instead of vetch (Vicia villosa Roth.) cover crop under NT decreases N 2 O and increases yield. • NT reduces N 2 O emissions (51%) compared with CT in well-drained silty clay soils. • Replacing CT with NT in intensive agro-ecosystems can mitigate N 2 O emissions without reducing yield. No-till (NT) often increases soil carbon (C) sequestration compared with conventional tillage (CT), yet its net effect on N 2 O emissions is controversial. Cover crops (CCs) adoption is promoted in NT systems because CCs growth curbs nitrate losses via leaching. However, incorporating CC residues into the soil may have positive or negative effects on N 2 O emissions depending on CC species and agro-ecosystem management. A better understanding of how tillage practices and CC species affect N 2 O emissions is therefore needed for the development of productive agroecosystems that contribute to climate change mitigation. The objectives of this three-year (2015–2017) field experiment on a Udertic Haplustalf soil in the Po Valley were to compare N 2 O emissions and crop yield of soybean under NT and CT, and to examine how contrasting residues from two CCs (rye, Secale cereale L. vs hairy vetch, Vicia villosa Roth) affect N 2 O emissions in NT soybean and maize. We hypothesized that N 2 O emissions would be lower with NT than with CT and with rye residues than with vetch ones. Nitrous oxide was continuously sampled using automatic chambers during three periods (emergence, N-fixation and maturity) over the soybean-cropping season in 2015 and during the entire cropping maize season in 2017. The DNDC model was calibrated (2015 data) and validated (2017 data), and then used to estimate the annual cumulative N 2 O emissions in different treatments. Overall, N 2 O emissions in NT were 40–55% lower than in CT, for both in situ measurements (Period I) and modelled estimations. These differences could be ascribed to the higher water-filled pore space (WFPS) and soil nitrate availability in CT than in NT. No-till also increased SOC content (28%; 0–5 cm) and earthworm abundance (5 times) compared with CT. Within NT systems, N 2 O emissions were 20–36% lower with rye CC than with vetch CC (P < 0.05), which was a consequence of the lower availability of soil mineral N under rye than under vetch due to the high C/N ratio of rye residues. Yield of soybean and maize under NT was higher with rye CC than with vetch CC. The combination of NT and rye CC that led to the lowest N 2 O emissions and highest yields should be recommended in the Po Valley region. [ABSTRACT FROM AUTHOR]

Conventional agricultural practices (CAP) highly impacted soil functions involved in the provision of multiple ecosystem services. No-till (NT) has been repeatedly indicated as a key way to enhance soil fertility and biodiversity, while having a positive effect on the environment and climate change. However, experimental evidence to date shows contrasting effects of NT on physical parameters of soil fertility, as well as on soil organic carbon (SOC) storage and soil biodiversity especially if different soil types and cropping systems are considered. The objectives of the present 7-year field study were: (i) to unravel the effect of NT on SOC, soil bulk density, and water stability index (WSI) of soil aggregates across five different soil types (Silty Clay, Silty Clay Loam, Clay Loam, Silt Loam, and Sandy Loam) and cropping systems (silage vs grain production), (ii) to examine how soil fauna (i.e. microarthropods and earthworms) is affected by NT practices under those soil-crop conditions, and (iii) to assess relationships among responses of soil physical indicators (i.e. soil bulk density and WSI), SOC, and soil fauna. Our results showed that soil bulk density was generally not affected by 7-year NT across all soil types. At the same time, NT increased WSI. It follows that NT may increase stable rather than artificial tillage-derived porosity due to reduced soil disturbance, and increased SOC and biological activity. However, reduced importance for boosting aggregates stability should be attributed to NT where initial SOC is high, clay and silt are predominant soil fractions, and the rate of crop residue is low. Our findings suggest that NT may enhance SOC stock (on average 0.66 Mg C ha−1 year−1) in the 0–30 cm soil layer. However, we found (i) a tendency of NT to decrease SOC concentration in the 15–30 cm soil layer (on average −1.18 g C kg−1), and (ii) no SOC increase induced by NT if crop residues were not left onto the soil surface. Nevertheless, NT practices promoted (i) the microarthropods adaptation measured with the QBS-ar index (105.5 vs 64.7), and (ii) the increase of earthworm abundance (412 vs 123 individuals m−2), which are fundamental for enhancing nutrient cycling and soil porosity. Correlations among soil fauna (i.e. QBS-ar and earthworm density), soil physical parameters (i.e. soil bulk density and WSI), and SOC (i.e. concentration and stock) corroborates the hypothesis that soil fauna adaptation and proliferation are main detectors of soil quality and sensitive indicators of changes in soil tillage. • No-till enhances aggregates stability when (i) starting SOC is low, (ii) clay and silt are not predominant soil fractions. • No-till has a limited C sequestration potential if crop residues are not left onto the soil surface. • QBS-ar index and earthworms' abundance are highly enhanced under no-till soils (63% and 235%). • Soil fauna adaptation and proliferation are sensitive detectors of soil quality and indicators of changes in soil tillage. [ABSTRACT FROM AUTHOR]

• Minimum tillage (MT) increased grain yield (+7%) in an 8-year maize monoculture. • Maize yield was reduced by no-till (NT) during the initial 5 years, while increased afterwards. • NT and MT increased C sequestration by 1.45 and 1.52 Mg ha−1 yr−1 compared with CT. • C and N associated to microaggregates within macroaggregates accounted for 41–65 % of total soil C and N under NT and MT. Intensive management of agroecosystems has been widely indicated as major responsible for soil degradation, thus negatively impacting on relationships between agriculture and climate change. Conservation tillage (i.e. no-till and minimum tillage) has been recommended for enhancing soil organic carbon (SOC) and total nitrogen (STN) stocks while having a positive impact on food security, biodiversity, water quality and the environment. Nevertheless, positive responses were mainly reported in hot and semiarid climates, with rainfed crops and low N fertilization rates. Therefore, the main objective of this study was to test the adoption of conservation tillage in intensive maize cropping systems under temperate soil, with high N fertilization rate (> 200 kg N ha−1 yr−1) and organic matter input (i.e. manure distribution and high biomass return), and with permanent optimum water moisture due to irrigation. We conducted an 8-year field experiment on a maize (Zea mays L.) monoculture to assess: (i) the effect of no-till (NT) and minimum tillage (MT), on grain yield and biomass return as compared with conventional tillage (CT); (ii) how tillage systems affect the evolution of SOC and STN levels over time under these conditions; (iii) soil aggregation processes and mechanisms leading to SOC and STN changes in the long-term. Results showed that MT increased maize grain yield (+7 %) and total biomass (+10 %) compared with CT. Conversely, NT reduced maize grain and biomass production during the initial 5-year transition, but afterwards increased maize yield up to that of CT. At the end of the experiment, SOC sequestration was increased under NT and MT by 1.45 and 1.52 Mg C ha−1 yr−1 compared with CT, respectively. Also, STN accumulation was higher under NT and MT than under CT (+0.15 and +0.17 Mg N ha−1 yr−1, respectively). Most of such a SOC and STN increase was located into C- and N-rich macroaggregates. Within those macroaggregates (large macroaggregates, LM; small macroaggregates, sM), we found that C and N pools associated to mM accounted for between 41 and 65 % of total C and N content in NT and MT systems across the different soil layers, which is beneficial for long-term C and N stabilization in soils. Thus, introducing conservation tillage within intensive agricultural context devoted to maize monoculture as that of the Po Valley should be recommended to: (i) maintain (or even increase) maize yield, and (ii) enhance SOC and STN accumulation and stabilization. [ABSTRACT FROM AUTHOR]

Intensive irrigation and nitrogen (N) fertilization are often linked to low N-fertilizer efficiency, and to high emissions of the greenhouse gas nitrous oxide (N 2 O). Efficient irrigation systems (e.g. subsurface drip irrigation [SDI]) combined with N-fertigation in a no-till agroecosystem can promote N-use efficiency, thereby curbing N 2 O emissions without depressing crop yield. Yet, crop type and SDI plant settings (and management) such as dripline spacing may determine the agronomic and environmental performance of SDI. In this two-year field study on maize (Zea mays L.) - soybean (Glycine max [L.] Merr.) rotation with conservation agriculture management (no-till and cover crops), we investigated the effects of three different irrigation/fertilization systems (SDI with a narrow dripline spacing (70 cm) + fertigation with ammonium sulphate, SDI with a large dripline spacing (140 cm) + fertigation with ammonium sulphate, and sprinkler irrigation [SPR] + granular urea application) on yield, N-fertilizer efficiency, and N 2 O emissions in a fine-textured soil. We hypothesized that SDI systems (especially with narrow dripline distance) would increase yield and mitigate N 2 O compared with SPR, and particularly for maize due to its higher water and nutrient demand. We found that SDI increased maize yield (+31%) and N-fertilizer efficiency (+43–71%). These positive results were only observed during the drier year in which irrigation supplied ca. 80% of maize water requirements. The narrower dripline spacing mitigated N 2 O emissions compared with sprinkler irrigation (by 44%) and with the wider spacing (by 36%), due to a more homogeneous distribution of N in soil, and to a lower soil moisture content. Soybean yield and N-use efficiency were not affected by the irrigation systems. We also found that SPR enhanced cover crop residue decomposition, thus promoting the release of C and N into the soil and increasing N 2 O emissions. Overall, our study provides important insights on key management decisions that define the sustainability of novel irrigation systems; in particular SDI with a 70 cm dripline distance should be promoted for maize to increase productivity and decrease N 2 O emissions in fine-textured soils. • Benefits of SDI increases with high water and N demanding crops. • SDI increases maize yield and N-fertilizer efficiency during dry years. • Narrow dripline distance (0.70 m) mitigates N 2 O emissions. • N release from litter decomposition may play a major role in N 2 O emissions. [ABSTRACT FROM AUTHOR]

• No-till (NT) with cover crops (CCs) maintains yield of wheat, maize and soybean. • NT-CCs increased SOM from 20% to 30% compared to CT in the 0-30 cm soil layer. • NT-CCs increased STN from 21% to 28% compared to CT in the 0-30 cm soil layer. • Replacing CT with NT and winter CCs enhances soil fertility in the long-term. Introducing no-till and cover crops in arable agro-ecosystems leads to the restoration of soil fertility, through the increase of soil organic matter (SOM), soil total nitrogen (STN), and available phosphorus (P), therefore maintaining or enhancing crop yield and reducing costs. Although the effects of those practices have been widely examined, many studies show conflicting results and little is known about the combined effects of no-till (NT) and cover crops (CCs) under intensive arable cropland in the Po Valley (Northern Italy). The objectives of this study were: (i) to evaluate if NT management coupled with CCs negatively affects yields during the transition period and how yields evolve; (ii) to assess SOM, STN, and P dynamics in the 60-cm soil depth layer; and (iii) to evaluate the effects of different types of winter cover crops on yield and soil parameters. A six-year field experiment was established in Piacenza, on a silty-clay soil under temperate climate conditions. The crop sequence was: winter wheat, maize, maize, soybean, winter wheat, and maize. The four experimental treatments were: (1) conventional tillage (CT) as control; (2) NT with CC of rye (NT-R); (3) NT with CC of hairy vetch (NT-V); and (4) NT with a mixture of CCs (rye, hairy vetch, crimson clover, Italian rye-grass and radish) [NT-M]). Dry biomass yield of CCs ranged between 2.2 and 3.1 Mg ha−1 for rye; 1.9 and 3.0 Mg ha−1 for hairy vetch; and 1.9 and 3.2 Mg ha−1 for mixture. In the present study, yields of winter wheat, maize, and soybean were generally not reduced with NT-CCs since the first year after conversion. The different composition and thickness of cover crop mulch showed an opposite yield response to rainfall pattern: under NT-R, a negative correlation was observed between grain yield and rainfall, while under NT-V this correlation was positive. After six years, SOM and STN concentrations in the 0-30 cm soil layer increased in NT-CCs. SOM concentration was +30%, +23% and +20% higher than CT for NT-R, NT-M and NT-V, respectively. STN was +28% higher under NT-R and NT-V, and +21% higher under NT-M, than CT. Conversely, P concentration was not influenced by the NT-CCs system, although we observed a tendency to increase under NT-V. In the 30-60 cm soil, layer, the tillage systems did not affect SOM and STN. We concluded that introducing NT with winter CCs into intensive arable agricultural systems is an effective strategy for enhancing soil fertility in fine-textured soils under temperate climates, without penalizing yields. [ABSTRACT FROM AUTHOR]