A meta‐analysis of the differences in environmental impacts between organic and conventional farming

Abstract

Purpose -This paper aims to perform a meta-analysis of the literature comparing the environmental impacts of organic and conventional farming and linking these to differences in management practises. The studied environmental impacts are related to land use efficiency, organic matter content in the soil, nitrate and phosphate leaching to the water system, greenhouse gas emissions and biodiversity. Design/methodology/approach -The theoretic framework uses the driver-state-response framework and literature data were analysed using meta-analysis methodology. Meta-analysis is the statistical analysis of multiple study results. Data were obtained by screening peer reviewed literature. Findings -From the paper's meta-analysis it can conclude that soils in organic farming systems have on average a higher content of organic matter. It can also conclude that organic farming contributes positively to agro-biodiversity (breeds used by the farmers) and natural biodiversity (wild life). Concerning the impact of the organic farming system on nitrate and phosphorous leaching and greenhouse gas emissions the result of the analysis is not that straightforward. When expressed per production area organic farming scores better than conventional farming for these items. However, given the lower land use efficiency of organic farming in developed countries, this positive effect expressed per unit product is less pronounced or not present at all. Original value -Given the recent growth of organic farming and the general perception that organic farming is more environment friendly than its conventional counterpart, it is interesting to explore whether it meets the alleged benefits. By combining several studies in one analysis, the technique of meta-analysis is powerful and may allow the generation of more nuanced findings and the generalisation of those findings.

Enhanced top soil carbon stocks under organic farming

“…Although there is some evidence that soil carbon concentrations are higher in soils managed organically than in those from integrated or conventional (nonorganic) farming (6,(8)(9)(10), other studies have not found such differences (11,12). Because of these inconsistent findings, advantages and disadvantages of the organic farming system vs. integrated or conventional production are hotly debated (11,13).…”

Importance of health and environment as quality traits in the buying decision of organic products

“…As documented by Mondelaers et al (2009), nitrate leaching levels on organic and conventional farms varied between 0 and 152 mg N/l, the latter being an outlier. The EU directive 1991 prescribes a maximum nitrate leaching level of 50 mg N/l.…”

“…For each of the two quality traits (health or environment), two attributes were included in the choice experiment, of which one triggers desirable (positive) expectations and the other undesirable (negative). The choice of the attributes (and their levels) was the result of careful deliberation between the choice experiment preconditions and objective scientific boundaries, the latter based upon an extensive literature review (Hoefkens et al, 2009 andMondelaers et al, 2009). …”

Why Might Organic Labels Fail to Influence Consumer Choices? Marginal Labelling and Brand Equity Effects

“…If the meaning was clearer, labels could add complementary, focused information to brand information. One perspective is suggested by Mondelaers et al (2009b) highlighting the contribution to the natural biodiversity as an advantage of organic products.…”

“…For example, policy makers could explore how to transform greater agro-biodiversity and natural biodiversity (Mondelaers et al 2009b) into consumer benefits.…”