Public benefits of organic agriculture for environment and society

Background and Objective

Organic farming is regarded as a sustainable land use system and is therefore given specific political support in Germany. Although the interdependencies between organic farming and the provision of public goods are increasingly recognised, the potential of organic farming to meet the environmental and resource policy challenges of our time continues to be assessed differently.

The aim of the research project "Public services of organic agriculture for the environment and society" is therefore to compare and evaluate the public services provided by organic and conventional agriculture in the areas of water protection, soil fertility, biodiversity, climate protection, climate adaptation, resource efficiency and animal welfare on the basis of a comprehensive analysis of scientific studies.

Approach

For each area, a comprehensive systematic literature analysis was carried out with the help of various databases between April 2017 and March 2018. In addition, conference contributions, project reports and other relevant publications were evaluated. A total of around 12,000 studies published on this topic over the past 30 years were evaluated.

The quantitative analysis was based on the results of around 2,700 pair comparisons with one organic and one conventional variant each. The results were statistically evaluated descriptively and graphically illustrated using box plot diagrams. The number of pair comparisons in which the organic variant performs better or worse was also investigated.

Results

Across all indicators for the fields of environmental protection and resource conservation, organic management showed advantages over conventional management in 58 % of the pairs analysed. No differences were found for 28 %, and in 14 % of the comparison pairs, the conventional management was more advantageous. No clear picture was drawn regarding animal welfare. No substantial differences were found between organic and conventional livestock across all animal species and production forms in 46 % of the comparison pairs. The organic management showed advantages in 35 % of the pairs, whereas the conventional version performed better in 19 % of the pairs. However, very few studies have been found considering animal welfare in a comprehensive sense. The most important results of the individual environmental factors can be summarized as follows:

• Water protection: Organic agriculture shows a high potential for the protection of groundwater and surface water, demonstrable especially for the seepage of nitrate and pesticides. On average, organic farming in the evaluated studies reduces nitrogen inputs by 28 % (median). The entry of active substances with potentially high environmental toxicity is prevented with the avoidance of chemical pesticides. Veterinary treatments are also expected to have significantly lower inputs due to the production rules of organic animal husbandry. Also, restrictions on phosphorous indicate a lower environmental burden. Enough studies available for a well-founded statement are not yet available, especially since comparative studies on the erosion of phosphorus are lacking. The evaluation of the investigations shows that in 71 % of the pairs, the organic variant with regard to the discharge of critical substance groups (nitrogen, pesticides) had clear advantages over conventional management. In this respect, organic farming can be recommended in particular for the management of water conservation areas.
• Soil fertility: The evaluation of the scientific literature on soil fertility shows clear advantages of organic farming. The abundances and biomass of earthworm populations were 78 % and 94 % higher under organic management (median). In 62 % of the pairs, organic farming in the topsoil was associated with lower acidification (difference totalling 0.4 pH units). With regard to the content of available phosphorus in the top soil, no clear tendency toward one or the other form of management could be determined. Different fertilization management approaches and various P‐analysis methods make it difficult to interpret the data. A high penetration resistance into the soil is an indicator for compaction damage. On average, the penetration resistance in organic farming was lower (median ‐22 %). However, this result is based on only four studies. Taking all indicators into account, 56 % of the pairs showed advantages for organic farming in terms of soil fertility.
• Biodiversity: Positive effects of organic farming on biodiversity can be clearly demonstrated for the species groups studied. On average (median), the average species numbers on arable land were 95 % higher under organic management as well as 61 % higher for field seed bank and 21 % higher for field margin vegetation. In the case of the field birds, the number of species was 35 % higher and the abundance 24 % (median) for organic farming. At 23 % and 26 %, respectively, these values were higher for flower‐visiting insects. Overall, 86 % (flora) and 49 % (fauna) of the pairs showed distinct advantages through organic farming. Only two out of 75 studies found negative effects from organic management in 12 out of 312 pairs based on the classification made. It should be noted that the landscape structure has a significant impact on biodiversity, especially on the fauna, and this can overlap greatly with the effects of land use.
• Climate protection: The comparison of soil‐based greenhouse gas emissions from organic and conventional agriculture in temperate climates based on empirical measurements shows positive effects from organic management. On average, organically managed soils have a 10 % higher organic carbon content and a higher annual carbon sequestration rate of 256 kg C / ha. The nitrous oxide emissions are on average 24 % lower according to the studies evaluated. These values result in a cumulative climate protection performance of organic farming of 1,082 kg CO2 equivalents per hectare per year. Due to the lack of robust, empirical comparative studies, the yield‐scaled climate protection performances were assessed qualitatively. Here organic farming seems to be likely to provide services comparable to conventional agriculture in terms of yield‐adjusted greenhouse gas emissions from soil or plants. In addition, metabolism‐related methane emissions per kg of milk in organic cattle farming are probably higher than in conventional cattle farming. Total emissions per kg of milk from organic and conventional milk production are considered to be comparable.
• Climate adaptation: Important topsoil features that contribute to erosion prevention and flood protection have comparable or better values under management. Corg content and aggregate stability were 26 % and 15 % higher on average (median) in organic farming; infiltration showed a difference of 137 %. Since higher infiltration reduces soil erosion and soil loss, these mean values (median) were also lower under organic farming (‐22 % and ‐26 %, respectively). This was mainly due to the clover and alfalfa grass cultivation. In contrast, no noteworthy differences were found in bulk density (‐4 %). With regard to the indicators selected to assess climate change performance (i.e., erosion and flood protection), organic farming showed clear benefits at field level (Corg content, aggregate stability, infiltration), with significant expected benefits from crop rotation level (C‐factor of the general soil erosion equation) and associated landscape‐level benefits (surface runoff, soil erosion). At landscape level, other factors besides agricultural management, such as landscape structure, form, rainfall and runoff regimes play an important role in erosion and flood protection.
• Resource efficiency: Resource efficiency was studied using the example of nitrogen efficiency (nitrogen input, nitrogen output, nitrogen balance, nitrogen efficiency) and energy efficiency (energy input, energy output, energy efficiency) in crop production. The literature review compared the resource efficiency of organic and conventional agriculture at crop rotation and wheat crop levels. In addition, results from the network of pilot farms were included in the system comparison at farm level. The 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 % depending on the level of consideration). In 46 % of the pairs, nitrogen efficiency was higher under organic management; regarding energy efficiency, this was the case for 58 % pairs. The differences between organic and conventional agriculture were more pronounced at farm level than at crop and crop rotation level.
• Animal welfare: Across all livestock species the results did not provide a clear picture if organic is more welfare friendly than conventional husbandry. The evaluated comparative studies focus mostly on health‐related aspects and mainly on dairy cows. Animal health was not substantially different except lameness and leg injuries. This indicates that management factors are of greater importance than production methods. Taking into account all welfare indicators and animal species, organic husbandry showed advantages in 35 % of the pairs, whereas conventional husbandry performed better in 19 % of the pairs. No clear differences were found in 46 % of the pairs. Organic farms perform better if the main risk factors for animal health problems are addressed within the EU Organic Regulations. Thus, for example, the requirements for litter and space have a positive effect on the lameness prevalence and leg health. Only a few studies take animal welfare into account by more comprehensive evaluations. The existing studies indicate animal behaviour and emotional state benefits of organic livestock husbandry, e.g., due to greater space or access to pasture. In conclusion, the literature review showed that organic farming has potential to achieve good welfare states (e.g. regarding lameness). However, together with less than optimal management (e.g. regarding udder health) it may not be beneficial. Outcome‐based assessments should therefore be implemented in organic standards in order to consider and safeguard the health‐related aspects of animal welfare.