Roots and earthworms under grass, clover and a grass-clover mixture

White clover has a lower root biomass and a higher abundance of earthworms than grass. This might have an impact on the ecosystem services soil structure maintenance and water regulation when white clover is introduced in a grass-clover mixture. We investigated the root biomass, the abundance of earthworms and a selection of soil physical parameters in white clover, grass-clover, and grass with and without inorganic N fertilizer. The treatment with clover-only had a lower root biomass, a lower C/N-ratio of the roots, a higher abundance of earthworms, a higher number of earthworm burrows, a lower penetration resistance at the 20-30 cm soil layer and a lower proportion of crumbs in the soil, than the other treatments. This confirms the literature that pure clover stimulates the ecosystem services of water regulation, but is less conducive to soil structure maintenance. However, the grass-clover mixture did not differ significantly from the grass treatments, but differed from pure clover in a higher percentage of soil crumbs. We infer that, when clover is introduced in grassland to reduce the reliance on inorganic fertilizer, the mixture of grass and clover maintains the positive impact of grass roots on soil structure but only may show a positive effect of clover - only on water regulation with a higher clover percentage in the dry matter than in our experiment

Effect of reduced tillage in organic farming on soil structure measured by non-destructive X-ray computed tomography in two long-term experimental field trials

Reduction of tillage intensity by non-inversion and very superficial tillage techniques is expected to have effects on soil structure such as soil porosity and soil structure stratification. Our hypothesis was that, mainly due to earthworms’ activity, soil macroporosity increases in the superficial soil layer with non-inversion and very superficial tillage compared to ploughing whereas, the opposite would be observable in the deeper soil layers. In the framework of the FERTILCROP project (http://www.fertilcrop.net/fc-home-news.html), we compared the effects of ploughing, non-inversion tillage and very superficial tillage techniques on soil structure in soil strata and more specifically on soil macropores using non-destructive X-ray computed tomography (CT) method. In 2016, after the growing season but before land preparation, we collected undisturbed soil columns (24 cm diameter to 30 cm soil depth) in two long-term experiments Thil (France) and Aesch (Switzerland). At each site a conventional tillage treatment (ploughing to 18-20 cm soil depth) was compared with reduced tillage intensity treatments (rotary and chisel tillage to 5-7 cm soil depth in Thil; chisel to 8 cm soil depth in Aesch). As a reference, we also sampled undisturbed grassland soil from a nearby area. Soil structure was analysed by X-ray CT with a resolution of 0.5 mm. The number of pores per m2, total pore volume (%), and total pore length (cm per m2) were determined per soil pore class and per soil layer (1-6 cm and 10-15cm soil depth). Reduction of the tillage intensity (i.e. reduced tillage depth and non-inversion) resulted in an increased total length of all pore diameter size classes in the uppermost soil layer compared to ploughing, but especially of the pore diameter size classes <4mm2. In general, pore diameters of <4mm2 diameter are too small to be directly associated with earthworm activity, suggesting a rejection of the hypothesis. In addition, reduced tillage intensity in the Thil trial resulted in larger contrasts in pore numbers and volume between the upper and lower soil layers. In the Aesch trial on loess the effect was not statistically significant. Results obtained with X-ray CT confirm soil structure stratification obtained by reduced tillage intensity, previously shown with visual soil observations and penetration resistance measures in the same fields (Peigné et al., 2018)

Organic matter composition and the protist and nematode communities around anecic earthworm burrows

By living in permanent burrows and incorporating organic detritus from the soil surface, anecic earthworms contribute to soil heterogeneity, but their impact is still under-studied in natural field conditions. We investigated the effects of the anecic earthworm Lumbricus centralis on fresh carbon (C) incorporation, soil organic matter composition, protists, and nematodes of a Cambisol under grassland. We used plant material labelled with stable isotope tracers to detect fresh C input around earthworm-occupied burrows or around burrows from which the earthworm had been removed. After 50 days, we sampled soil (0–10 cm depth) in concentric layers around the burrows, distinguishing between drilosphere (0–8 mm) and bulk soil (50–75 mm). L. centralis effectively incorporated fresh C into the drilosphere, and this shifted soil organic matter amount and chemistry: total soil sugar content was increased compared to unoccupied drilosphere and bulk soil, and the contribution of plant-derived sugars to soil organic matter was enhanced. Earthworms also shifted the spatial distribution of soil C towards the drilosphere. The total abundance of protists and nematodes was only slightly higher in earthworm-occupied drilosphere, but strong positive effects were found for some protist clades (e.g. Stenamoeba spp.). Additional data for the co-occurring anecic earthworm species Aporrectodea longa showed that it incorporated fresh C less than L. centralis, suggesting that the two species may have different effects on soil C distribution and organic matter quality

Sensitivity of labile carbon fractions to tillage and organic matter management and their potential as comprehensive soil quality indicators across pedoclimatic conditions in Europe

Soil quality is defined as the capacity of the soil to perform multiple functions, and can be assessed by measuring soil chemical, physical and biological parameters. Among soil parameters, labile organic carbon is considered to have a primary role in many soil functions related to productivity and environmental resilience. Our study aimed at assessing the suitability of different labile carbon fractions, namely dissolved organic carbon (DOC), hydrophilic DOC (Hy-DOC), permanganate oxidizable carbon (POXC, also referred to as Active Carbon), hot water extractable carbon (HWEC) and particulate organic matter carbon (POMC) as soil quality indicators in agricultural systems. To do so, we tested their sensitivity to two agricultural management factors (tillage and organic matter input) in 10 European long-term field experiments (LTEs), and we assessed the correlation of the different labile carbon fractions with physical, chemical and biological soil quality indicators linked to soil functions. We found that reduced tillage and high organic matter input increase concentrations of labile carbon fractions in soil compared to conventional tillage and low organic matter addition, respectively. POXC and POMC were the most sensitive fractions to both tillage and fertilization across the 10 European LTEs. In addition, POXC was the labile carbon fraction most positively correlated with soil chemical (total organic carbon, total nitrogen, and cation exchange capacity), physical (water stable aggregates, water holding capacity, bulk density) and biological soil quality indicators (microbial biomass carbon and nitrogen, and soil respiration). We conclude that POXC represents a labile carbon fraction sensitive to soil management and that is the most informative about total soil organic matter, nutrients, soil structure, and microbial pools and activity, parameters commonly used as indicators of various soil functions, such as C sequestration, nutrient cycling, soil structure formation and soil as a habitat for biodiversity. Moreover, POXC measurement is relatively cheap, fast and easy. Therefore, we suggest measuring POXC as the labile carbon fraction in soil quality assessment schemes in addition to other valuable soil quality indicators.</p

Responses of earthworm communities to crop residue management after inoculation of the earthworm Lumbricus terrestris (Linnaeus, 1758)

Earthworms are important for soil functioning in arable cropping systems and earthworm species differ in their response to soil tillage and crop residue management. Lumbricus terrestris (Linnaeus, 1758) are rare in intensively tilled arable fields. In two parallel field trials with either non-inversion (NIT) or conventional tillage (CT), we investigated the feasibility of inoculating L. terrestris under different crop residue management (amounts and placement). Simultaneously, we monitored the response of the existing earthworm communities to L. terrestris inoculation and to crop residue treatments in terms of earthworm density, species diversity and composition, ecological groups and functional diversity. L. terrestris densities were not affected by residue management. We were not able to infer effects of the inoculation on the existing earthworm communities since L. terrestris also colonized non-inoculated plots. In NIT and two years after trial establishment, the overall native earthworm density was 1.4 and 1.6 times higher, and the epigeic density 2.5 times higher, in treatments with highest residue application (S100) compared to 25% (S25) or no (S0) crop residues, respectively. Residue management did not affect earthworm species composition, nor the functional trait diversity and composition, except for an increase of the community weighted means of bifide typhlosolis in S0 compared to S100. In CT, however, crop residues did have a strong effect on species composition, ecological groups and functional traits. Without crop residues (S0), epigeic density was respectively 20 and 30% lower than with crop residues placed on the soil surface (S100) or incorporated (I100). Community composition was clearly affected by crop residues. Trait diversity was 2.6 to 3 times larger when crop residues were provided, irrespective of placement. Crop residues in CT also resulted in heavier earthworms and in a shift in the community towards species with a thicker epidermis and cuticle, a feather typhlosolis shape, and a higher average cocoon production rate. We conclude that earthworm communities under conventional tillage respond more strongly to the amount of crop residue than to its placement. Under non-inversion tillage, crop residue amounts affected earthworm communities, but to a smaller degree than under conventional tillage

Biodiversity and ecosystem services science for a sustainable planet: the DIVERSITAS vision for 2012–20

DIVERSITAS, the international programme on biodiversity science, is releasing a strategic vision presenting scientific challenges for the next decade of research on biodiversity and ecosystem services: “Biodiversity and Ecosystem Services Science for a Sustainable Planet”. This new vision is a response of the biodiversity and ecosystem services scientific community to the accelerating loss of the components of biodiversity, as well as to changes in the biodiversity science-policy landscape (establishment of a Biodiversity Observing Network — GEO BON, of an Intergovernmental science-policy Platform on Biodiversity and Ecosystem Services — IPBES, of the new Future Earth initiative; and release of the Strategic Plan for Biodiversity 2011–2020). This article presents the vision and its core scientific challenges.Fil: Larigauderie, Anne. DIVERSITAS. Muséum National d’Histoire Naturelle; FranciaFil: Prieur Richard, Anne Helene. DIVERSITAS. Muséum National d’Histoire Naturelle; FranciaFil: Mace, Georgina. Imperial College London. Center for Population Biology; Reino UnidoFil: Londsdale, Mark. CSIRO Ecosystem Sciences; AustraliaFil: Mooney, Harold A.. Stanford University. Department of Biological Sciences; Estados UnidosFil: Brussaard, Lijbert. Wageningen University, Soil Quality Department; Países BajosFil: Cooper, David. Secretariat of the Convention on Biological Diversity; CanadáFil: Wolfgang, Cramer. Institut Méditerranéen de Biodiversité et d’Ecologie marine et continentale; FranciaFil: Daszak, Peter. EcoHealth Alliance. Wildlife Trust; Estados UnidosFil: Diaz, Sandra Myrna. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Duraiappah, Anantha. International Human Dimensions Programme; AlemaniaFil: Elmqvist, Thomas. University of Stockholm. Department of Systems Ecology and Stockholm Resilience Center; SueciaFil: Faith, Daniel. The Australian Museum; AustraliaFil: Jackson, Louise. University of California; Estados UnidosFil: Krug, Cornelia. DIVERSITAS. Muséum National d’Histoire Naturelle; FranciaFil: Leadley, Paul. Université Paris. Laboratoire Ecologie Systématique Evolution, Ecologie des Populations et Communautés; FranciaFil: Le Prestre, Philippe. Laval University; CanadáFil: Matsuda, Hiroyuki. Yokohama National University; JapónFil: Palmer, Margaret. University of Maryland; Estados UnidosFil: Perrings, Charles. Arizona State University; Estados UnidosFil: Pulleman, Mirjam. Wageningen University; Países BajosFil: Reyers, Belinda. Natural Resources and Environment; SudáfricaFil: Rosa, Eugene A.. Washington State University; Estados UnidosFil: Scholes, Robert J.. Natural Resources and Environment; SudáfricaFil: Spehn, Eva. Universidad de Basilea; SuizaFil: Turner II, B. L.. Arizona State University; Estados UnidosFil: Yahara, Tetsukazu. Kyushu University; Japó

Effects of agricultural management practices on soil quality : A review of long-term experiments for Europe and China

In this paper we present effects of four paired agricultural management practices (organic matter (OM) addition versus no organic matter input, no-tillage (NT) versus conventional tillage, crop rotation versus monoculture, and organic agriculture versus conventional agriculture) on five key soil quality indicators, i.e., soil organic matter (SOM) content, pH, aggregate stability, earthworms (numbers) and crop yield. We have considered organic matter addition, no-tillage, crop rotation and organic agriculture as “promising practices”; no organic matter input, conventional tillage, monoculture and conventional farming were taken as the respective references or “standard practice” (baseline). Relative effects were analysed through indicator response ratio (RR) under each paired practice. For this we considered data of 30 long-term experiments collected from 13 case study sites in Europe and China as collated in the framework of the EU-China funded iSQAPER project. These were complemented with data from 42 long-term experiments across China and 402 observations of long-term trials published in the literature. Out of these, we only considered experiments covering at least five years. The results show that OM addition favourably affected all the indicators under consideration. The most favourable effect was reported on earthworm numbers, followed by yield, SOM content and soil aggregate stability. For pH, effects depended on soil type; OM input favourably affected the pH of acidic soils, whereas no clear trend was observed under NT. NT generally led to increased aggregate stability and greater SOM content in upper soil horizons. However, the magnitude of the relative effects varied, e.g. with soil texture. No-tillage practices enhanced earthworm populations, but not where herbicides or pesticides were applied to combat weeds and pests. Overall, in this review, yield slightly decreased under NT. Crop rotation had a positive effect on SOM content and yield; rotation with ley very positively influenced earthworms’ numbers. Overall, crop rotation had little impact on soil pH and aggregate stability − depending on the type of intercrop; alternatively, rotation of arable crops only resulted in adverse effects. A clear positive trend was observed for earthworm abundance under organic agriculture. Further, organic agriculture generally resulted in increased aggregate stability and greater SOM content. Overall, no clear trend was found for pH; a decrease in yield was observed under organic agriculture in this review

Biodiversity and ecosystem functioning in soil: The dark side of nature and the bright side of life : Behind the paper

This article belongs to Ambio’s 50th Anniversary Collection. Theme: Agricultural land us