•Low earthworm taxonomic diversity was observed under Mediterranean conditions.•Organic fertilization significantly increased earthworm populations.•Endogeic earthworm species can benefit from soil ...inversion tillage.•Combining reduced tillage and green manure cropping did not show positive effects on earthworms.
Earthworms are one of the most important soil macrofaunal groups, and they play a major role in agricultural ecosystems. Agricultural practices, such as reduced tillage, the use of green manures and organic fertilization, can be beneficial for earthworm populations in agricultural systems. However, under a Mediterranean climate, not much is known regarding their response to agricultural management. The aim of this study was to analyse the effects of tillage type, organic fertilization, and green manures on the density and biomass of earthworms in organic arable dryland. The trial was conducted in a four-year crop rotation with a complete factorial design that combined tillage system (mouldboard ploughing vs. chisel), fertilization (composted farmyard manure vs. no fertilizer) and green manures (green manures vs. no green manures). Earthworms were assessed in each plot by the extraction of all individuals in three soil areas of 33cm×33cm that were excavated to a depth of 25cm. Only five earthworm species were found in this trial, and the earthworm community was dominated by such endogeic ecotypes as Aporrectodea rosea and Allolobophora georgii, and the anecic ecotype Aporrectodea trapezoides. Endogeic species can benefit from soil inversion because of the incorporation of organic matter, but the anecic ones can be negatively affected by it. The results show that plots with farmyard manure had higher density and biomass of earthworms. We observed that the type of tillage significantly affected earthworm populations: plots that had been ploughed with mouldboard ploughing (soil inversion) the year prior to sampling presented more juveniles. The biomass of earthworms was significantly lower in plots with green manures and chiselling. Our results indicated that the combination of chiselling and green manures were not optimal for earthworm populations, but organic fertilization played a considerably more important role and enhanced their abundances.
► Profil cultural method is a visual soil profile observation method to assess topsoil and subsoil structure. ► Assessment of the transition layer between top and subsoil is necessary to better ...understand subsoil rooting. ► Cracking and biological activity are closely related to root density in subsoil.
In France, agronomists have studied the effects of cropping systems on soil structure using a field method based on a morphological description of soil structure. In this method, called “profil cultural” or soil profile in English, the soil structure of the tilled layer is observed on a vertical face of a pit. Subsoil and more especially the transition layer between topsoil and subsoil have not always been given specific consideration. However, these layers undergo the effect of cropping systems through soil compaction or smoothing/smearing. A more accurate quantification of earthworm macropores and cracks in the transition layer would enable a more precise evaluation of the agronomical potential of the soil, manifest in root development or water retention. Thus, the aim of this paper is to present the profil cultural method in detail, along with the improvements we have made to quantify the ability of roots to penetrate compacted zones in the transition layer. We propose two indicators: (i) number of earthworm burrows per m2 counted on a horizontal surface at the bottom of the transition layer in the soil pit (ii) cracking quantified by taking a 50-mm×50-mm×100-mm sample of soil from the transition layer and examining the number of cracks. Results from experiments on different tillage treatments are used to demonstrate why it is worthwhile to take into account cracks and earthworm activity. Soil profiles were examined in mouldboard ploughed and no tillage fields, and described using the profil cultural method and the new indicators. Root maps were also traced to observe the effect of soil structure on root growth. Preliminary results show that the classification of cracking and the quantification of the number of earthworm burrows per m2 can explain observed root development in subsoil. This first approach towards a better observation of subsoil structure and the effect it has on roots needs to be confirmed through further research, and especially via quantification and scoring of soil structure impact on roots.
•The “profil cultural” method has been adapted to no-till.•The improved “profil cultural” method takes better account of natural processes.•Improvements to the “profil cultural” method allows a more ...accurate diagnosis in no-till.
In France, agronomists have studied the effects of cropping systems on soil structure using a field method that is based on a visual description of the soil structure. This “profil cultural” method was designed as a field diagnostic tool to identify the effects of tillage and compaction on soil structure dynamics. It is of great benefit to agronomists seeking to improve crop management and preserve soil structure and fertility.
However, the “profil cultural” method was developed and has mainly been used in conventional tillage systems with regular ploughing. As there has been an increase in the use of various forms of reduced, minimum and no-tillage systems in many parts of the world, it is necessary to re-evaluate this method’s ability to describe and interpret soil structure dynamics in no-till or reduced tillage. In these situations, changes in soil structure over time are mainly driven by compaction and by regeneration through natural agents (climatic conditions, root growth and macrofauna), therefore it is important to evaluate the effects of these natural processes on soil structure dynamics.
These concerns have led to adaptations and amendments to the initial method based on field observations and experimental work in different cropping systems, soil types and climatic conditions. The description of crack types has been improved and a criterion of biological activity based on the visual examination of clods has been introduced.
To test this modified method, a comparison with the initial method was undertaken and its ability to make diagnoses tested in five experiments in France, Brazil and Argentina. The adapted method allowed an improved assessment of the impact of cropping systems on soil functioning when natural processes were integrated into the description.
The interest of organic farmers in adopting conservation agriculture principles, including minimal soil disturbance, permanent soil cover and crop rotation has been growing since the early 2000s. ...However, currently there is no network for organic farmers practicing conservation agriculture, and a lack of knowledge on how organic farmers implement conservation agriculture in practice. Consequently, few technical references are available for organic farmers when they start applying conservation agriculture practices, in particular on controlling weeds without the use of herbicides. The main objectives of this study were: (1) to explore the diversity of conservation agriculture techniques (i.e., reduced tillage, no-tillage and green manures) practiced among European farmers, and (2) to identify farmers’ main strategies for implementing conservation agriculture and the agronomic and environmental factors that determine these strategies. Strategies were identified by analyzing survey results on: (1) the type and degree of use of conservation agriculture practices by farmers, and (2) the effects it produces in terms of soil disturbance and soil cover (low, medium and high). We carried out a survey of 159 European organic farmers and collected 125 data sets on management of winter-sown crops. Among the conservation agriculture practices, reduced tillage was used by 89%, no-tillage by 27% and green manure by 74% of the 159 interviewed farmers. Green manures were more frequently used in northern Europe than in the south (below 45°N). Most of the farmers used crop rotations, with a mean duration of 6 years. A wide diversity of conservation agriculture practices were used, with farmers rarely using all three techniques (no-till, reduced till and green manures) within one system. The range of practices was grouped into five strategies ranging from intensive non-inversion tillage without soil cover to very innovative techniques with no-tillage and intercrops. The five strategies for conservation agriculture could be grouped into two larger categories based on weed control approach: (1) intensification of the mechanical work without soil inversion or (2) biological regulation of weeds with cover crops. The diversity of strategies identified in this study shows that organic farmers use innovative approaches to implement conservation agriculture without herbicides. This study's findings will help organic farmers to experiment with innovative practices based on conservation agriculture principles and also benefit conventional farmers who use conservation agriculture practices and would like to reduce or eliminate the use of herbicides.
Organic farmers aim at improving cropping systems to preserve soil fertility. To this end, researchers and organic farmers in two French regions have co- designed 14 cropping systems (prototypes) ...integrating the principles of conservation agriculture. The objective of this article is to show the contribution of prototype multi-criteria evaluation in the codesign process. Several indicators of the MASC 2.01 model are mobilized to evaluate the objectives farmers assigned to their prototypes. The evaluation proves useful at the individual level: it highlights the strengths and weaknesses of each prototype, allowing each farmer to improve his prototype while considering these different aspects during the redesigning process. It also gives farmers confidence before testing the prototype on farm, as they have a clearer idea of the key points to watch during the experimentation. At the collective level, highlighting strengths or weaknesses shared by several prototypes reinforces farmers in choices made to improve their cropping systems, and encouragesthem to find collective solutions when weaknesses are shared. While it was already for researchers that evaluation is a key step in such work, the fact that farmers also have a positive perception of this method is a sign of its success. Multi-criteria evaluation is also apowerful tool to show the tradeoffs between empirical and scientific knowledge in the design of new cropping systems.
Les acteurs de l'agriculture biologique réfléchissent à leurs systèmes de culture afin de préserver la fertilité des sols, socle de ce mode de production. À cette fin, dans deux régions françaises, des agriculteurs ont conçu, avec des chercheurs, 14 prototypes de systèmes de culture intégrant les principes de l'agriculture de conservation. L'objectif de cet article est de montrer les apports de l'évaluation ex ante de prototypes de systèmes de culture dans un processus de co-conception. Pour ce faire, 11 indicateurs provenant du modèle d'évaluation de la durabilité MASC 2.0® ont été mobilisés pour évaluer les objectifs fixés par les agriculteurs à leurs prototypes. Cet outil permet d'évaluer des innovations à l'échelle du système de culture et sur les trois piliers de la durabilité. L'évaluation présente des apports à l'échelle individuelle pour les agriculteurs : elle met en évidence les forces et faiblesses des prototypes afin de les améliorer. Ainsi, l'agriculteur est mis en confiance avant de tester le système de culture et peut identifier les points de vigilance à surveiller lors de l'expérimentation. À l'échelle collective, la mise en évidence de points forts partagés par les prototypes conforte les agriculteurs pour changer de systèmes de culture. Par ailleurs, l'identification de points faibles les incite à trouver collectivement une solution. Pour les chercheurs, l'évaluation est une étape clé : la perception positive qu'en ont les agriculteurs est un signe de la réussite du travail. Elle permet aussi de mettre en évidence les combinaisons entre savoirs empiriques et scientifiques, ces derniers étant mobilisés et discutés lors de l'utilisation des indicateurs de MASC 2.0®
Microbial indicators exhibit a high spatial heterogeneity which often masks comparison of the effects of different soil management treatments. It is therefore desirable to use a proper sampling ...design which integrates spatial heterogeneity at field level. Thus, the objectives were: (1) to study the spatial heterogeneity of biological and chemical soil variables, and (2) with obtained maps of spatial variability to test different sampling strategies to assess the usefulness of this ‘new’ soil map unit. 63 soil samples were collected according to a 10 m × 10 m grid on a 0.48 ha plot. On each of these samples, 10 variables were measured: soil water content, cation exchange capacity (CEC), organic carbon (OC) and total nitrogen (N), C/N, soil microbial biomass (SMB), labile soil organic matter (LOM), mineralisable C (C
min) and N (N
min), inverse of specific respiratory activity (1/SRA = SBM/C
min). The spatial heterogeneity of each variable was charted with geostatistics. The biological variables exhibited spatial variability of the same order of magnitude as physicochemical parameters. From the maps, zones with different levels of organic matter, microbial biomass and specific respiratory activity were identified. The spatial patterns of SMB and SRA were related to CEC (positively for SMB and negatively for SRA), pointing out the effects of soil protection on microbial biomass and availability of organic substrates. The definition of these zones for a pool of variables (OC, N, SMB, LOM, CEC) is useful at 3 levels: (1) to record the initial values of the measured variables for each plot, (2) to integrate these zones as blocks in experimental design for future experiments, and (3) to focus analysis of specific biological mechanisms such as activity of micro-organisms.
Reduced tillage is increasingly promoted to improve sustainability and productivity of agricultural systems. Nonetheless, adoption of reduced tillage by organic farmers has been slow due to concerns ...about nutrient supply, soil structure, and weeds that may limit yields. Here, we compiled the results from both published and unpublished research comparing deep or shallow inversion tillage, with various categories of reduced tillage under organic management. Shallow refers to less than 25 cm. We found that (1) division of reduced tillage practices into different classes with varying degrees of intensity allowed us to assess the trade-offs between reductions in tillage intensity, crop yields, weed incidence, and soil C stocks. (2) Reducing tillage intensity in organic systems reduced crop yields by an average of 7.6 % relative to deep inversion tillage with no significant reduction in yield relative to shallow inversion tillage. (3) Among the different classes of reduced tillage practice, shallow non-inversion tillage resulted in non-significant reductions in yield relative to deep inversion; whereas deep non-inversion tillage resulted in the largest yield reduction, of 11.6 %. (4) Using inversion tillage to only a shallow depth resulted in minimal reductions in yield, of 5.5 %, but significantly higher soil C stocks and better weed control. This finding suggests that this is a good option for organic farmers wanting to improve soil quality while minimizing impacts on yields. (5) Weeds were consistently higher, by about 50 %, when tillage intensity was reduced, although this did not always result in reduced yields.
An agro-ecological indicator
I
N
losses
was introduced in order to estimate the risks of air and water pollution through nitrogen management on grasslands. The
I
N
losses
score in this study ...corresponded to the lowest score of four sub-indicators (
I
N
H
3
,
I
N
2
O
,
I
NO
and
I
N
O
3
) which, respectively, provide information on volatilisation, nitrous and nitric oxide emissions in the air and nitrate leaching in groundwater. The score of each sub-indicator was obtained by comparing nitrogen losses to a threshold which corresponded to the maximal level acceptable for the environment (e.g. 50
mg NO
3 L
−1 for the leaching sub-indicator
I
N
O
3
). The losses in air of NH
3, N
2O, NO were calculated by means of emission coefficients. Nitrate leaching was estimated from the residual mineral nitrogen in grassland soil found at the beginning of the drainage period. A validation of the indicator by comparing calculated data with measurements of nitrate leaching by ceramic cups was carried out on grazed and hay grasslands. A discrepancy between observed and calculated data was observed when using data from ceramic cups to validate the indicator. Nevertheless, the indicator gave realistic results and is valid for use in order to indicate the degree of pollution risk in agricultural management.
Conservation agriculture and organic farming are considered as promising sustainable agricultural system for producing food, while minimizing environmental impacts. Despite an increasing number of ...experimental data on organic conservation practices and various studies dealing with the adoption of conservation agriculture by farmers, none of those studies have specifically addressed conservation agriculture adoption under organic conditions in Europe. We carried out a survey with 159 farmers located in 10 European countries. These farmers had applied at least two of the following conservation practices: (i) no-tillage, (ii) reduced tillage and (iii) green manures. Each farmer assessed socio-economic, agronomic and environmental motivations and problems for each conservation practice, using a Likert scale. For each conservation practice, we ranked motivations and problems and carried out a principal component analysis, followed by clustering to identify groups of farmers. Independent of the conservation practices, the most important motivations were related to soil fertility preservation and challenges were mainly linked to crop management, machinery and yield performances. For all conservation practices, we identify three groups of farmers that shared the same type of motivations and challenges across Europe: “soil conservationists,” “agro-technically challenged farmers,” and “indifferent farmers.” Soil conservationist farmers were strongly motivated by soil preservation and minimizing environmental impacts. Agro-technically challenged farmers mainly expressed agronomic problems and challenges. There were no clear effects of location or farm characteristics explaining these attitudes, but they depended on farmers’ environmental concerns and beliefs. The study demonstrated that research priorities should address agronomic problems caused by the adoption of conservation practices in organic farming, weed control in particular.
PDF
