Thünen Institute Publishes Study on the Value of Organic Farming
Although the environmental and social benefits of organic farming have been increasingly recognized in science and politics, the potential for organic farming to solve the environmental and resource challenges of our time remains inconsistently assessed. With this in mind, the Thünen Institute, together with several research partners and funding from the German Federal Ministry of Food (BMEL), selected 528 scientific studies on organic and conventional farming for inclusion in a comprehensive literature review.
Released on 21 January 2019, the publication offers a comparative analysis and evaluation of these 528 studies and 33 parameters, which resulted in 2,816 individual comparative pairs. The study focused on the following topic areas: water protection, soil fertility, biodiversity, climate protection, climate adaptation, resource efficiency, and animal welfare. Across all areas, organic management was shown to be more advantageous than conventional management.
Studies selected for inclusion met the following criteria:
(a) publication period: January 1990 to March 2018
(b) region: temperate climates
(c) study design: one organic / conventional pair, and
(d) language: studies in German or English
Summarized Results for Individual Environmental Factors:
Water Protection: organic agriculture shows a high potential to protect ground- and surface water against the seepage of nitrate and pesticides. On average, the study indicates that organic farming reduces nitrogen inputs by 28% (median). Organic farming is also expected to lower veterinary burdens and phosphorus inputs into water sources, however there were not enough comparative studies on phosphorus erosion for a conclusive result. In 71% of comparative pairs, the organic variant performed better than its conventional counterpart for critical substance discharge (nitrogen, pesticides).
Soil Fertility: the study shows that soil fertility clearly benefits from organic farming. The abundance and biomass of earthworm populations are, respectively, 78% and 94% higher under organic management (median). In 62% of the comparative pairs, organic farming is associated with lower topsoil acidification (difference totaling 0.4 pH units). On average, the penetration resistance of soil is lower (median ‐22 %) in organic farming.
Biodiversity: the study clearly demonstrates that organic farming has positive effects on biodiversity. On average (median), the number of species on arable land is 95% higher under organic management, 61% higher for field seed banks, and 21% higher for field margin vegetation. In the case of birds, the variety and abundance of field species is 35% and 24% (median) higher, respectively, for organic farming. For pollinating insects, these values are 23% and 26% higher for the organic variant. Organic farming shows distinct advantages in 86% (flora) and 49% (fauna) of comparative pairs. Only 2 of 75 studies found negative effects from organic management.
Climate Protection and Adaptation: on average, organically managed soils have a 10% higher organic carbon content and a higher annual carbon sequestration rate of 256 kg C /ha. Nitrous oxide emissions average 24% lower for organic farming, which results in a cumulative climate protection performance of 1,082 kg CO equivalents per hectare per year. However, due to lower yield levels in organic farming, yield-related climate benefits in organic farming are likely comparable to those of conventional agriculture. Carbon content and aggregate stability in soil is on average 26% and 15% higher (median) in organic farming; infiltration differs by 137%. Higher infiltration reduces soil erosion and soil loss, which means that organic farming reduces these occurences by ‐22% and ‐26%, respectively. At the landscape level, factors other than agricultural management, such as landscape structure, form, rainfall and runoff regimes play an important role in erosion and flood protection.
Resource efficiency: results show significantly lower nitrogen and energy inputs in organic farming, but also nitrogen and energy output due to lower yields. The nitrogen balances (area‐related nitrogen loss potentials) were significantly lower in organic farming than in conventional agriculture (median ‐40% to ‐70%). In 46% of comparative pairs, nitrogen efficiency is higher under organic management. For energy efficiency, this value lies at 58%. Overall, the difference between organic and conventional agriculture was most pronounced at the farm level, rather than at the crop or crop rotation level.
Animal Welfare: the study shows no clear differences between organic management and conventional husbandry in 46% of comparative pairs. In 35% of comparative pairs organic husbandry does show advantages whereas conventional husbandry performed better in 19%. This indicates that management factors are of greater importance than production methods. Studies indicate animal behavior and emotional state benefit from organic livestock husbandry, e.g., due to larger spaces or access to pasture. The study suggests that organic standards should implement outcome‐based assessments to safeguard animal health and welfare.
Visit the Thünen Institute's website to read and download a PDF version of the full publication (Edition 65, available only in German).