Agroecosystem management and biotic interactions: a review

Abstract

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 reviews options 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. (Résumé d'auteur

How to implement biodiversity-based agriculture to enhance ecosystem services: a review

“…Many pest-management studies have highlighted that adapted management strategies at multiple levels are needed to greatly reduce pesticide use (Médiène et al 2011;Rusch et al 2010;Scherr and McNeely 2008). This has been widely reported for integrated pest management (IPM, Médiène et al 2011;Shea et al 2002).…”

“…In this way, plant-soil interactions (Eviner 2008), especially in conservation agriculture (Koohafkan et al 2011), plant nutrition and soil fertility (Doltra and Olesen 2013;Drinkwater 2009), pest management (Rusch et al 2010;Médiène et al 2011), and biological regulations (e.g., Malézieux 2011; Shennan 2008) greatly depend on the site, i.e., the field and its environment.…”

Spatial diversification of agroecosystems to enhance biological control and other regulating services: An agroecological perspective

“…For example in their review, Lopes et al (2016) showed that diversifying crop habitat solely through intercropping allows significantly reducing pests while not necessarily enhancing natural enemies in wheat (Triticum aestivum)-based systems. Such a bottom-up control of pests was also analysed for cover cropping (Médiène et al, 2011). The success of this bottom-up approach (inter-and cover-cropping management) on pest reduction can be explained by the creation of chemical and physical barriers by the non-host plants complicating the search for host plants by pests (Poveda et al, 2008).…”

“…Cover cropping leads to substituting unwanted weeds by a manageable plant species (Médiène et al, 2011). The cover crop must be sown to develop earlier than weeds, hence competing for resources and reducing the ability of weeds to grow.…”

Conservation Agriculture and Soil Quality– An Overview

“…It has been estimated that 1 gram of soil contain millions of living organism (bacteria, fungi, mycorrhiza, protozoa, nematodes, earthworms, mites, enchytraeidsants, termites, beetles and spiders etc) (Hawksworth, 1991;Hawksworth and Mound, 1991). Improvement in ecosystem function and services of arable soils through enhancement of microorganism diversity is well known thus the microbial biomass and their functional diversity is used as sensitive indicator to access the soil quality (Médiène et al, 2011). Since, due to exponential increase in global population, the demands for food are likely to increase substantially, the major challenge for present population is to enhance the food production with the use of soil management practices that can maintain soil biodiversity.…”