Agroecological crop protection in organic farming: Relevance and limits

International audiencePlant protection is one of the major issues in organic farming. Organic crop protection (OCP) strategies often rely on a limited number of methods that provide only partial control of pests and that induce lower yields and economic performances. As a result, farmers hesitate to adopt these strategies and doubts are cast on the ability of organic agriculture to feed the world. This chapter questions how agroecological concepts may contribute to OCP, while taking the different alternative schemes already developed to manage, integrate and design crop protection strategies into account. As demonstrated by a bibliographic analysis, Integrated pest management (IPM) remains the leading paradigm in crop protection. It also provides its foundational basis, giving priority to bioecological processes and alternative techniques to reduce pesticide use. Beyond IPM, agroecology is characterised by a holistic approach and the importance given to the design of a “healthy” agroecosystem. In practice, all these concepts are subject to various interpretations, and organic farming includes a variety of practices, ranging from intensive input substitution to a comprehensive integrated approach. This paper provides key elements for crop protection in OF on the basis of the adaptation of the agroecological crop protection approach. Based on a successful case study of fruit fly management in OF in Reunion Island (France), we highlight three major pillars to design pest management strategies: sanitation, habitat manipulation and conservation biological control. Finally, in the field of crop protection, this paper shows that organic farming can be both a prototype for designing innovations and a source of practices to be extended to other types of agroecosystem

Stabilization of external filter cake by colloidal forces in a "well-reservoir" system

Growth of an external filter cake with its final stabilization has been widely reported for waterflooding in oilfields, well drilling, fresh water storage, and industrial waste disposal in aquifers. We derive the mechanical equilibrium equation for stabilized cake accounting for electrostatic force and for varying permeate force factor. The main empirical parameter of the model, highly affecting the stabilized cake prediction, is the lever arm ratio for the particle on the cake surface. The lever arm ratio was calculated from laboratory cross-flow filtration experiments and from well injectivity data. It was also determined from Hertz’s theory for the elastic particle deformation on the solid cake surface. Good agreement between the results validates the developed mechanical equilibrium model with the lever arm ratio determined from the elastic particle deformation theory.A. Kalantariasl and P. Bedrikovetsk