Crop residue displacement by soil inversion: Annelid responses and their impact on carbon and nitrogen dynamics in a lab-based mesocosm study

In the context of sustainable agriculture, a deeper knowledge of the effects of soil management on soil annelids is needed, as they play an important role in many soil processes. In a laboratory mesocosm experiment, we compared the simulated effect of ploughing by inverting the top soil (crop residues at 15 cm depth) to a noninversion treatment (crop residues on the soil surface) using the soil type Haplic Luvisol. We investigated the response of earthworms and enchytraeids and the consequences for microbial and chemical soil parameters. Four treatments with soil fauna were established by adding: (i) endogeic earthworms (Octolasion cyaneum), (ii) anecic earthworms (Lumbricus terrestris), (iii) a combination of two enchytraeid species (Enchytraeus crypticus and Enchytraeus christenseni) and (iv) having control columns (without annelids). Feeding behaviour of annelids was investigated using isotopic analysis (delta C-13, delta N-15), and chemical and microbial soil properties were measured. Carbon and nitrogen losses in the form of gas emissions (CO2, N2O) and leachate were recorded during the time of incubation.We found no interactions of soil inversion and annelid addition on chemical and microbial soil properties; these properties were closely related to crop residue placement, indicated by the effect of soil inversion between 0 and 20 cm. Below 20 cm, this effect disappeared. Here, the presence of enchytraeids enhanced soil microbial properties, regardless of soil inversion. Stimulating microbial activity and increasing soil aeration seem to be the most important factors that increase CO2-C emissions in the presence of anecic earthworms. N2O-N emissions were consistently higher (+188%) in the inverted columns. Our results show that regardless of the placement of crop residues, anecic earthworms and enchytraeids fed more on crop residue derived carbon than endogeic earthworms, while endogeic earthworms appeared to avoid feeding at the soil surface. Moreover, it was found that the inversion and the annelid effects did not interact in an experimental setting where soil inversion is carried out in a form without detracting or impairing the annelids directly

Auswirkungen eines Pflugereignisses auf die Verteilung von Aggregaten und organischem Material in Grünlandböden.

Die Auswirkungen sporadischen Pflügens sind noch nicht vollständig verstanden. Ziel dieser Arbeit war die Effekte sporadischen Pflügens (mit Ackerzwischennutzung) auf Kohlenstoff- Vorräte sowie die Erträge und Verteilung der Aggregate und leichten Fraktionen zu untersuchen. Zwei Jahre nach einem Pflugereignis sind noch deutliche Unterschiede, vor allem in der obersten Bodenschicht, vorhanden. So wurde in dieser Bodenschicht eine signifikante (p<0,05) Abnahme der Vorräte an organischem Kohlenstoff, großer Makroaggregate und der freien leichten Fraktion festgestellt. Fünf Jahre nach dem Pflugereignis sind diese Effekte zwar noch sichtbar, jedoch wesentlich schwächer ausgeprägt und nicht mehr signifikant

Tillage and land use management effects on soil organic matter and soil microbial biomass in a field network of practical farms in France, Romania, and Sweden

Gefördert im Rahmen des Projekts DEA

The Effects of Conservation Tillage on Chemical and Microbial Soil Parameters at Four Sites across Europe

Conservation tillage is often discussed as an effective tool to improve the soil quality in agriculture. Four sites across Europe (in Germany, Romania, Spain, and Sweden) were investigated as case studies for country-specific reductions in tillage intensity. Conventional tillage (CT) by mouldboard ploughing was compared with shallow and deep non-inversion minimum tillage (MT) and/or no-tillage (NT). In Sweden, NT and MT had positive effects on the concentrations of soil organic carbon (SOC), total nitrogen (N), and microbial biomass carbon (MBC) in the upper 20 cm compared with CT. At the German site, MT increased SOC, N, and MBC concentrations in the top 10 cm. In contrast, CT increased MBC contents and bulk density between 20 and 30 cm soil depth. At the Romanian site, soil parameters showed no differences between inverse tillage (CT) and non-inverse tillage (MT), both with a working depth of 25 to 30 cm. At the Spanish site, the use of NT significantly increased the concentrations as well as the stocks of C, N, and MBC compared to CT. In conclusion, reduced tillage improved soil microbial properties in most cases. However, the effectiveness of reduced tillage appears to be highly dependent on site conditions such as pH, soil texture, and climatic conditions

Reduced tillage intensity does not increase arbuscular mycorrhizal fungal diversity in European long‐term experiments

Abstract Mechanical soil disturbance is one among the key factors influencing soil biodiversity in agriculture. Although many soil organisms are sensitive to soil disturbance, fungi could be highly impacted due to their sessile lifestyle, relatively slow growth and filamentous body structure. Arbuscular mycorrhizal (AM) fungi are of particular interest in arable lands, providing crop plants with numerous vital services such as nutrient acquisition and protection against abiotic and biotic stressors. Considering this, tillage practices that aim to reduce soil disturbance are often seen as a fungal‐friendly alternative to conventional inversion tillage. Although local studies exist on the impacts of minimal tillage practices on AM fungi, the universality of this approach has been debated. Our objective was to assess the effects of reduced tillage intensity on AM fungi in comparison with conventional tillage. Using high‐throughput sequencing techniques in long‐term field experiments in five European countries, we show that the effects of reduced tillage intensity may not necessarily be positive on soil AM fungal diversity. Plots which were tilled using reduced tillage techniques had lower AM fungal richness in three countries, whereas in one of them, no significant differences were found. We also observed a shift in AM fungal communities where prevalence of taxa preferring root colonisation rather than soil exploration increased under reduced tillage regimes. Here, we argue that more detailed and long‐term studies are needed to understand the factors that could make the reduction of soil disturbance more beneficial to AM fungi if agricultural sustainability goals are to be met

Legacy effects of temporary grassland in annual crop rotation on soil ecosystem services

The introduction of temporary grassland into an annual crop rotation is recognized to improve soil ecosystem services, and resulting legacies can be beneficial for the following crops. In this context, the aim of the present study was to evaluate legacy effects of introducing temporary grassland into an annual crop rotation on five ecosystem services (i) soil structure maintenance (aggregate stability), (ii) water regulation (saturated hydraulic conductivity), (iii) biodiversity conservation (microbial biomass and microbial metabolic activity, as well as microorganism, enchytraeid, springtail and earthworm communities), (iv) pathogen regulation (soil suppressiveness to Verticillium dahliae), and (v) forage production and quality. Three crop rotation schemes, maintained for twelve years, were compared in four random blocks, one being an annual crop rotation without grassland (0%), another with a medium percentage of grassland (50%, corresponding to 3 years of continuous grassland in the crop rotation), and a third one with a high percentage of grassland in the crop rotation (75%, corresponding to 6 years of continuous grassland in the crop rotation). The results showed that the grassland introduction into an annual crop rotation improved, whatever the duration of the grassland, soil structure maintenance and biodiversity conservation, while it decreased pathogen regulation and did not modify water regulation. Comparing the two crop rotations that included grassland, indicated a stronger beneficial grassland legacy effect for the higher proportion of grassland concerning soil structure maintenance and biodiversity conservation. By contrast, water regulation, pathogen regulation and forage production were not affected by the legacy of the 75% grassland during the rotation. Overall, our findings demonstrated the extent to which grassland legacies are affecting the current state of soil properties and possible ecosystem services provided. To improve ecosystem services, soil management should take legacy effects into account and consider longer timeframes to apply beneficial practices.This work was supported by the EU SoilMan project (grant number 01LC1620) funded through the 2015–2016 BiodivERsA COFUND call for research proposals, with national funders the Federal Ministry of Education and Research (BMBF), the French National Research Agency (ANR), the Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning (FORMAS), the Spanish Ministry of Economy and Competitiveness (MINECO), the Executive Agency for Higher Education, Research, Development and Innovation Funding (UEFISCDI), the European Regional Development Fund (Centre of Excellence EcolChange). We would like to thank the National Research Infrastructure “Agro-écosystèmes, Cycles Biogéochimique et Biodiversité” (ACBB) http://www.soere-acbb for providing access to an excellent field experiment and the “the AnaEE France (ANR-11-INBS-0001)”, “AllEnvi” and “CNRS-INSU” which support it. We thank Météo France for meteorological data