Environmental impacts of organic agriculture in temperate regions.

Abstract

Can organic agriculture elaborate a scientifically based, resource-efficient and agroecological approach to low-input farm management? This review examines the literature from temperate regions, with a particular emphasis on Canadian and US studies that relate to environmental and ecological impacts of organic agriculture with respect to (i) soil organic matter storage, (ii) soil quality/soil health, (iii) nutrient loading and risks of off-farm nutrient and agrochemical losses, (iv) biodiversity and (v) energy use and global warming potential. The context and implications of semi-arid conditions and low soil P levels, common to many organic farms in North America, and widespread adoption of genetically engineered crops in conventional production, is also considered. The consensus of the data available to date indicates the distinctiveness of cropping, floral and habitat diversity, soil management regime, nutrient intensity and use efficiency, and energy, and pesticide use in organic farming confer important environmental and ecological benefits. These include maintenance of soil organic matter and added return of carbon to soil, improved soil health, reduced off-farm nitrogen and phosphorus losses, enhanced vegetative and wildlife (bird) biological diversity, extended sometimes to other taxa depending on landscape context, improved support for pollinators and pollination and reduced energy use and improved energy efficiency. The continued evolution of organic agriculture to a more outcomes-based, agroecological production system will require an expanded multi-disciplinary research effort, linked ideally to support from consumers and policy-makers on the basis of renewed understanding of its potential contribution to global environmental sustainability.

Impacts of Organic Zero Tillage Systems on Crops, Weeds, and Soil Quality

“…Syntheses of published research suggest soil responses to organic production practices are positive with respect to improving soil function through the enhancement of biophysical properties and processes [111,112]. Such soil biophysical improvements are attributed to the emphasis of organic farming on diverse crop rotations, including perennial forages, as well as application of carbon-rich soil amendments [113].…”

“…It is important to acknowledge reviewed studies focused on near-surface soil responses to applied treatments, and while certainly justified from the standpoint of inferring treatment effects on soil erosion, water infiltration, and nutrient conservation [150], the lack of characterization of subsoil conditions and an absence of soil bulk density data compromises our capacity to accurately resolve treatment effects on soil nutrient stocks [112,151]. Supplementing whole-profile assessments with soil bulk density measurements in future evaluations will strengthen conclusions regarding organic conservation tillage system effects on soil quality.…”

Using Digestate and Biochar as Fertilizers to Improve Processing Tomato Production Sustainability

“…Reviews and meta-analyses revealed that the OFS has greater soil carbon content and less soil erosion compared with conventional systems [4][5][6]. Different works also reported that the agrosystem biodiversity is improved in the OFS [5,7,8]. In addition, synthetic pesticides and fertilizers are not allowed, and there is a reduction of nitrate leaching and greenhouse gas emissions in comparison with the conventional farming system [3,8,9].…”

“…Different works also reported that the agrosystem biodiversity is improved in the OFS [5,7,8]. In addition, synthetic pesticides and fertilizers are not allowed, and there is a reduction of nitrate leaching and greenhouse gas emissions in comparison with the conventional farming system [3,8,9]. However, since the OFS has lower land-use efficiency than the conventional system, these positive effects are less pronounced and in sometime reversed when expressed per unit product [9,10].…”

Improvement of soil structure through organic crop management, conservation tillage and grass-clover ley

“…In arable systems, it includes organic management and conservation tillage practices (Hobbs et al, 2008). These improved variations of 2 tillage (no till, chisel, disk, sweep till types of reduced tillage ), alone or combined, have shown to be effective in adapting to environmental demands (Lal, 2009) by, for example reducing soil erosion (Lynch, 2012).…”