Assessment of tillage systems in organic farming: influence of soil structure on microbial biomass. First results

Soil tillage modifies environmental conditions of soil microorganisms and their ability to release nitrogen. We compare the influence of reduced tillage (RT) and mouldboard ploughing (MP) on the soil microbial functioning in organic farming. In order to connect soil structure generated by these tillage systems on the soil microbial biomass we adopt a particular sampling scheme based on the morphological characterisation of the soil structure by the description of the soil profile. This method reveals the influence of soil structure on soil microbial biomass and allows a more precise assessment of the impact of tillage managements on the soil microbial functioning

Co-designing innovative cropping systems to improve soil functioning in organic farming

Organic agriculture is called upon to raise production to meet growing demand all the while ensuring the respect of the environment. In this context, improving the soil biological activity is crucial. Farmers are taking great interest in agroecological practices, such as conservation tillage associated with soil cover crops. The inclusion of these practices into current organic crop management systems calls for profound changes in the whole system.In this paper, we present aeight steps method to help farmers designing innovative prototypes of cropping systems. The method involves three design workshops, starting with a given decontextualized situation, before progressively integrating farmers‟ constraints. The method was run with two groups of six and seven farmers respectively in two different regions of France.Of the 28 completed prototypes designed, we present here only the seven most detailed. They differ greatly from current cropping systems in their increased use of cover crops (four times more frequent) and greatly decreased reliance on deep soil tillage (mouldboard plowing was eight times less frequent). Farmers initiated the adoption of these innovations by anticipating technical and pedoclimatic constraints. The method, involving researchers and farmers, produced conditions thatencouraged the famers to act creatively. Further studies in the form of ex post trials are necessary to accurately assess the consequences of such innovative cropping systems on soil functioning and crop performance

Spatial variability of microbial indicators and assessment of tillage systems on the soil microbiological functioning on organic farming.

Reduction tillage, in modifying the soil microorganisms’ environment, modifies their potential to supply plants nutrients. This is of primary importance in organic farming as the nutrients availability is mainly dependent on the organic matter degradation by microorganisms. To study the effect of tillage on soil physical and microbiological properties, we compare 4 tillage practises (deep and shallow ploughing, chisel and no tillage) in an experimental field near Lyon. Our objective is to link a structural statement with a microbiological functioning in order to study the microorganisms’ abilities to supply nitrogen and phosphorus. For such studies, it is of primary importance to use a convenient sampling design as the microbiological properties are highly variable in space and time. So, we first studied, before the treatments differentiation, the spatial variability of some microbiological properties. We first present this study briefly and its utilities for the future assessment of the tillage practises on the soil microbiological functioning

Effect of seeders and tillage equipment on vertical distribution of oilseed rape stubble

International audienceWhen the spreading of a disease depends on the proportion of infected residues remaining at soil surface it is of crucial importance to analyse the effects of tillage practices on the vertical distribution of stubble. This is the case with phoma stem canker (blackleg), whose epidemics are initiated in autumn, by air-borne ascospores released from stubble located at the soil surface. We compared initial vertical distribution of oilseed rape residues to those observed after sowing and various tillage operations (rotary harrowing, stubble disking, chiselling and mouldboard ploughing). Almost 20% of the initially buried residue was brought back to soil surface with seeding. Rotary harrow brought 40% of the residue buried in the 0-10 cm layer up to the surface and left unburied about 70% of surface residue. Stubble disking appeared to be more efficient for residue burial than chiselling. Mouldboard plough was the only tool that buried all residues. A simple model was developed that predicted burial and return to the soil surface of potentially infected residues as a function of tillage practices used after harvest. Simulation of different tillage sequences showed that the order in which tools were used also affected location of residues. Our results highlighted the importance of tillage in the cultural control of phoma stem canker and will contribute to the definition of integrated pest management strategies for oilseed rape

Agriculture et biodiversité. Valoriser les synergies

Que sait-on aujourd'hui des impacts, positifs et négatifs, de l’agriculture sur la biodiversité ? Quels services la biodiversité peut-elle apporter à l’agriculture, et à quelle hauteur de performance ? Comment favoriser au champ les synergies entre agriculture et biodiversité ? Quels instruments de politiques publics, économiques et juridiques, faut-il mettre en place pour promouvoir ces interactions ? Ces questions ont mobilisé un groupe pluridisciplinaire d’experts (écologues, agronomes, microbiologistes, spécialistes de santé végétale, économistes, juristes, sociologues), de différentes institutions (Inra, CNRS, IRD, Universités, Ecoles supérieures agronomiques) en France et à l’étrange

Lokalmeteorologiska förhållanden i Västra Ängby, Knivsta : förstudie /

<p>Variation of pollen beetle abundance along within-field (A) and between-field (B) transects as a function of distance (km) to woodland edges. (A) Number of pollen beetles per sampling point within two different OSR fields (fields in complex site, C). (B) Mean number of pollen beetles per field in three transects (in zones S, for simple landscape, and HC, for highly complex landscape). Abundance were measured on 10 OSR plants at each sampling point during three (A) or four (B) consecutive weeks (dates 1 to 4). Trans: Transect.</p

Crop establishment practices are a driver of the plant microbiota in winter Oilseed Rape (Brassica napus)

Gaining a greater understanding of the plant microbiota and its interactions with its host plant heralds a new era of scientific discovery in agriculture. Different agricultural management practices influence soil microbial populations by changing a soil’s physical, chemical and biological properties. However, the impact of these practices on the microbiota associated with economically important crops such as oilseed rape, are still understudied. In this work we investigated the impact of two contrasting crop establishment practices, conventional (plow based) and conservation (strip–tillage) systems, on the microbiota inhabiting different plant microhabitats, namely rhizosphere, root and shoot, of winter oilseed rape under Irish agronomic conditions. Illumina 16S rRNA gene sequence profiling showed that the plant associated microhabitats (root and shoot), are dominated by members of the bacterial phyla Proteobacteria, Actinobacteria and Bacteroidetes. The root and shoot associated bacterial communities displayed markedly distinct profiles as a result of tillage practices. We observed a very limited ‘rhizosphere effect’ in the root zone of WOSR, i.e., there was little or no increase in bacterial community richness and abundance in the WOSR rhizosphere compared to the bulk soil. The two tillage systems investigated did not appear to lead to any major long term differences on the bulk soil or rhizosphere bacterial communities. Our data suggests that the WOSR root and shoot microbiota can be impacted by management practices and is an important mechanism that could allow us to understand how plants respond to different management practices and environments

Agroecosystem management and biotic interactions: a review

Increasing the use of synthetic fertilisers and pesticides in agroecosystems has led to higher crop yields, accompanied by a decline in biodiversity at the levels of field, cropping system and farm. Biodiversity decline has been favoured by changes at landscape level such as regional farm specialisation, increases in field size, and the removal of hedgerows and woodlots. The loss of biodiversity in agroecosystems has increased the need for external inputs because beneficial functions are no longer provided by beneficial species as natural enemies of crop pests and ecosystem engineers. This trend has led to a strong reliance on petrochemicals in agroecosystems. However, many scientists have been arguing for more than two decades that this reliance on petrochemicals could be considerably reduced by a better use of biotic interactions. This article reviewsoptions to increase beneficial biotic interactions in agroecosystems and to improve pest management and crop nutrition whilst decreasing petrochemical use. Four agronomic options are presented. First, it has been shown that the choice of cultivar, the sowing date and nitrogen fertilisation practices can be manipulated to prevent interactions between pests and crop, in either time or space. Nevertheless, the efficacy of these manipulations may be limited by pest adaptation. Second, beneficial biotic interactions may result from appropriate changes to the habitats of natural enemies and ecosystem engineers, mediated by soil and weed management. Here, knowledge is scarce, and indirect and complex effects are poorly understood. Third, changes achieved by crop diversification and, fourth, by landscape adaptation are promising. However, these practices also present drawbacks that may not necessarily be outweighed by beneficial effects. Overall, these four management approaches provide a powerful framework to develop sustainable agronomic practices