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A column experiment with five different pore densities (0, 1, 2, 3, and 4 pores column−1) and two varying moisture regimes (comparatively dry and comparatively moist regime) in the subsoil part of the columns was established. In each pore, Lumbricus terrestris was introduced for 28 days before sowing wheat plants. After 40 days of plant growth, watering was stopped to induce progressive topsoil drying. Parameters describing the shoot hydration, mineral uptake, and aboveground biomass were quantified. Root biomass and root length densities (RLD) were measured separately for six soil layers. Under dry subsoil conditions, plants grown under increasing biopore density showed an increase of the RLD and an improved shoot hydration but the aboveground biomass was unaffected. Since RLD but not root biomass was enhanced, it is assumed that roots were able to explore a larger volume of soil with the same amount of root biomass. Thereby, subsoil water likely was used more efficiently leading to an improved hydration. Under moist subsoil conditions, plants grown with increasing biopore density revealed enhanced shoot biomasses and nutrient uptake while the belowground biomass was unaffected. The improved nutrient uptake can be ascribed to, first, the higher subsoil water availability favoring mass flow driven nutrient uptake, and second, to direct and indirect effects of earthworms on the availability of soil nutrients. It is concluded that high biopore abundancies have the potential to improve not only the belowground but also the aboveground biomass. This, however, largely depends on subsoil moisture. Bundesministerium für Bildung, Wissenschaft, Forschung und Technologie http://dx.doi.org/10.13039/501100010571 Humboldt-Universität zu Berlin (1034)

Combining no-till and cover crops (NT + CC) as an alternative to conventional tillage (CT) is generating interest to build-up farming systems&rsquo, resilience while promoting climate change adaptation in agriculture. Our field study aimed to assess the impact of long-term NT + CC management and short-term water stress on soil microbial communities, enzymatic activities, and the distribution of C and N within soil aggregates. High-throughput sequencing (HTS) revealed the positive impact of NT + CC on microbial biodiversity, especially under water stress conditions, with the presence of important rhizobacteria (e.g., Bradyrhizobium spp.). An alteration index based on soil enzymes confirmed soil depletion under CT. C and N pools within aggregates showed an enrichment under NT + CC mostly due to C and N-rich large macroaggregates (LM), accounting for 44% and 33% of the total soil C and N. Within LM, C and N pools were associated to microaggregates within macroaggregates (mM), which are beneficial for long-term C and N stabilization in soils. Water stress had detrimental effects on aggregate formation and limited C and N inclusion within aggregates. The microbiological and physicochemical parameters correlation supported the hypothesis that long-term NT + CC is a promising alternative to CT, due to the contribution to soil C and N stabilization while enhancing the biodiversity and enzymes.

Lettuce (Lactuca sativa L.) is a leading greenhouse-grown vegetable. However, nitrate (NO3&minus, ) accumulation in leaves remains a major issue. The aims of this research were: (i) to test the modified intermittent Nutrient Film Technique (NFT) in the cultivation of soilless lettuce in which plants are grown on peat blocks in trays and supplied with an intermittent flow of nutrient solution, and (ii) to calibrate the fertilization scheme to increase yield performance, while keeping NO3&minus, concentration under control. Two greenhouse trials were performed between autumn 2013 and spring 2014. Results showed that a 30-day cycle is the optimum duration in terms of fresh biomass yield, both for autumn and spring cultivation. Reducing N fertilization in the last cropping days never affected NO3&minus, concentration in leaves during autumn trial, due to unfavourable growing conditions. Conversely, suspension of fertilization 2 days before harvest had a consistent effect during the spring trial, when NO3&minus, concentration in leaves was highly reduced (from 20 to 36%) without yield penalties. Thus, suspending fertilization 2&ndash, 4 days before harvesting in intermittent NFT may reduce, on average, NO3&minus, accumulation by 29&ndash, 58% and the fertilization rate by 7&ndash, 16%, respectively. Yet, growing conditions are crucial to make this system effective.

Italian journal of agronomy = Rivista di agronomia 16(3), 1807 (2020). doi:10.4081/ija.2021.1807 special issue: "Special issue on "Integrated weed management" / Guest Editors: Vittoria Giannini; Donato Loddo;", Published by Forum Editrice Univ. Udinese, Udine

No-till (NT) has repeatedly been reported to result in several environmental advantages, including the reduction of soil erosion, sequestration of carbon from the atmosphere and increase of water retention in soils. However, experimental evidences to date show negative effects of NT on soil physical parameters (i.e., increasing penetration resistance and soil bulk density) and root development of plants, thus reducing crop yield. A three-year field study (2014–2016) was conducted to assess the effects of NT vs conventional tillage (CT) on root growth in maize, soybean, and winter wheat, on a silty clay soil in the Northern Italy. Root length density (RLD), diameter class length (DCL), root dry weight (RDW) and roots composition (C and N) in the top 60 cm of soil were measured. The total amount of root C (TRC) was calculated by multiplying RDW by root C content. Relationships among root traits, soil bulk density (BD) and penetration resistance (PR) were investigated using the non-parametric Spearman rank coefficient. RLD was significantly increased under NT compared to CT in the topsoil (0–5 cm) in maize (6.37 vs. 2.03 mg cm−3) and winter wheat (5.38 vs. 2.90 cm cm−3), while it was lower in NT than in CT in the deeper soil (5–15 cm) only in maize (3.19 vs. 4.53 cm cm−3). RDW was increased under NT compared to CT in the 0–5 cm layer in maize (3.86 vs.0.50 mg cm−3), soybean (4.33 vs. 0.43 mg cm−3), and winter wheat (0.96 vs. 0.38 mg cm−3). NT significantly reduced root C:N ratio of maize (-9%), increased C:N ratio of soybean (+14%), and did not affect C:N ratio of winter wheat. This was mainly related to the effect of NT on coarse roots, which decreased average roots N content. A negative correlation between root traits (RLD, RDW) and soil physical parameters (BD, PR) was found in this study under NT while no correlation occurred for CT. This corroborates the hypothesis that when tillage is abandoned roots are major drivers and detectors of soil physical conditions, which in turn affects roots growth again. Moreover, these results showed that BD did not always represent the main factor affecting root development and the increase of soil strength and particle density under NT did not reduce downwards root growth, which suggests that stability of continuous biopores as induced by NT in well-structured soils is probably much more relevant than the total amount of pores to affect root traits.

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.

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.