Category: Environment

The Climate Strategy for Agriculture and Food requires cost-efficient greenhouse gas mitigation measures. An Agroscope study shows which technical measures are effective and how much costs are influenced by the different implementation strategies.  

To achieve the Net Zero emissions target, Switzerland aims to lower greenhouse gas emissions from agricultural production by 40% compared to 1990 by the year 2050. Since emissions have barely declined in recent years, further emission reduction and carbon storage measures that maximise cost-efficiency are required. This study focuses on measures that would lead only to minor changes in the structure of the farms and of the Swiss agricultural sector.

Four consistently cost-efficient measures

Researchers analysed twelve mainly technical measures on the production side with two to three different implementation variants each. Four of these measures consistently proved cost-efficient:

1. Rewetting agriculturally used peatland soils
2. Feed additives for reducing methane emissions from ruminants
3. Increasing the productive lifespan of dairy cows
4. Nitrogen-optimised feeding of pigs.

Together, the cost-efficient measures achieved a reduction potential of 11−18% compared to 1990 (minus 797−1379 kilotonnes of carbon dioxide equivalents).

Costs vary significantly depending on assumptions

The total costs of all the examined measures ranged between CHF 87–1124 million per year, depending on the implementation assumptions. The range was particularly wide in agroforestry systems and biogas facilities (e.g. due to different-sized systems). The study clearly shows that cost data can only be meaningfully interpreted in the context of underlying assumptions. For this reason, it is important that these assumptions are always communicated transparently.

Total costs calculated from an agricultural perspective

For each scenario, the total costs of the measures were calculated, irrespective of who bears the costs (e.g. the agricultural sector, canton or federal government). This allows a comparison of the total costs, regardless of whether or not a measure currently receives state support.  

Benefits for planning and agricultural policy

The comparison of different cost scenarios forms a valuable basis for implementing measures and designing their respective funding instruments with a view to maximum efficiency. Hence, the added value of this study does not lie primarily in the precise determination of reduction costs, but rather in an enhanced understanding of the economic principles and framework conditions in relation to the potential greenhouse gas reductions.

Structural measures possibly more cost-efficient

Previous studies have suggested that structural measures such as a reduction of livestock numbers would be more cost-efficient from an economic perspective. A further investigation of structural measures at the level of the food system would therefore be a vital precondition to better understanding the social costs of agricultural climate-change mitigation. However, since such measures impact numerous stakeholders and processes, quantifying the total costs is a difficult process requiring complex models.

Comparison with long-term costs of climate change

As part of an overall economic assessment, the costs of greenhouse-gas mitigation measures should always be compared with the long-term costs of greenhouse gas emissions, and hence with the long-term costs of climate change. According to an earlier study conducted for the Swiss agriculture and food system, these could end up being 3 to 35 times as high as the estimated costs for the technical measures in this study (De Luca & Müller 2025).

Indicators from a 14-year monitoring programme show improvements in climate, water, soil and food supply.

Agriculture impacts the environment and natural resources in multiple ways – from nutrient inputs and plant protection products to tillage and the support of biodiversity. At the same time, it relies on intact ecosystems to enable sustainable production. Thus, continual monitoring of these environmental impacts is vital to observe trends and ensure that agricultural policy targets based on the Sustainability Ordinance are met.

Agri-environmental impacts: long-term data from a farm network

Switzerland uses various monitoring programmes, which either measure environmental statuses directly or record environmental impacts indirectly using agri-environmental indicators. Detailed farm data were collected from around 300 farms over a 14-year period and used to calculate agri-environmental indicators enabling regional conclusions to be drawn. An innovative statistical method produced reliable time series, even though the participating farms varied from year to year.

Mostly positive trends for environmental indicators

Most of the 13 indicators improved over time. Particularly significant progress was observed in the use of plant protection products (-31%), the humus balance (+25%) and the nitrogen balance (-11%). These trends indicate that management practices are becoming more environmentally friendly. The energy produced for human consumption also increased over time. Thus, it is clear that improvements to environmental impacts were not at the expense of food supply.

Comparison with national trends shows similarities and differences

Four of the indicators studied have national equivalents. These national indicators are based on other data and permit independent validation of the farm network indicators. While ammonia and greenhouse gas emissions follow similar trends to the farm network, the phosphorus balance time series differs considerably. These differences can be attributed to the composition of the farm network (focus on dominant farm types) and to the uncertainties of individual data bases (e.g. grassland yields). With the new Monitoring of the Swiss Agri-Environmental System (MAUS), which combines existing data with its own surveys, a partial improvement in the alignment between regional and national monitoring is to be expected in future.

Greenhouse gas accounting tools are important for quantifying reduction potentials and performance. Agroscope researchers conducted a review to analyse their potential applications. Considerable experience is needed to correctly interpret the results.

Agriculture must play its part in helping Switzerland achieve its net-zero goal. In highly developed agricultural systems like Switzerland’s, the feasible technological potentials to reduce greenhouse gas (GHG) emissions at farm level are estimated to be in the range of 10 to 20%. In order to exploit these potentials and measure the respective progress, stakeholders along the value chain depend on reliable and transparent data. Against this background, GHG accounting tools are being tested, developed and applied at Agroscope. Agroscope researchers have conducted a review to systematically analyse the opportunities and limitations of farm-level GHG accounting. In parallel, concrete accounting systems are being tested and developed at farm and product level in partnership with practitioners.

Different methods produce different results

Different GHG accounting tools can produce widely differing results due to variations in methodologies and system boundaries, which makes it difficult to compare the results. Furthermore, it was found that a comprehensive, global sustainability assessment requires shifting the focus from individual farms to the overall food system. These circumstances pose significant challenges for public and private decision makers.

Challenges of benchmarking and compensation mechanisms

Detailed farm data and accounting models are required to reliably capture the generally small effects of individual mitigation measures. In addition, a fair, solution-oriented interpretation of the results should be based on a set of indicators rather than restricted to a single metric. These factors make farm-level accounting projects time-consuming and extremely resource-intensive in terms of personnel and expertise. Accordingly, in practice, GHG accounting tools are mainly used for advisory purposes. To date, they have been of limited use for broad, results-based compensation mechanisms.

Measures-based approaches at production system level are a pragmatic alternative

The climate protection system used by IP-SUISSE and Bio Suisse is less complex and time-consuming. The modelling approach developed by Agroscope uses existing data to calculate the environmental impacts of the total production of the label organisations and allocate them to the corresponding products. The individual farms simply provide information about the type and number of implemented mitigation measures. Their impacts are aggregated and also allocated to the product level. This approach allows only limited conclusions to be drawn about individual farms. However, it provides reliable information about climate mitigation performance at the level of all farms and/or products within a production system. This is a valuable foundation for communication along the value chain and for the valorisation of sustainability.

Designation of regional nature parks in Switzerland significantly boosts the adoption of direct payment schemes aimed at promoting biodiversity conservation (agri-environment schemes, AES), particularly in regions with relatively more intensive farming and low prior uptake of such schemes.

Although both regional nature parks and agri-environment schemes (AES) aim to conserve biodiversity, the interaction between these two policy instruments is unknown. A recent study investigated the effects of designating a region in Switzerland as a regional nature park on the uptake of biodiversity conservation AES within the region.

Two policy instruments with one common objective: to promote biodiversity

Since 1993, agri-environment schemes (AES) focused on biodiversity have been a major policy instrument in Switzerland for integrating biodiversity conservation into agriculture. Farmers receive direct payments for fulfilling the requirements of the AES. There are currently three types of biodiversity conservation AES in Switzerland: action-based (Q1), result-based (Q2), and agglomeration payment schemes.

Regional nature parks are one type of large-scale, less stringent protected area supported by environmental policy. They do not restrict economic activities such as agriculture, but rather aim to integrate nature and biodiversity conservation into sustainable land use and socioeconomic development. In Switzerland, 15 regional nature parks were established in rural areas between 2008 and 2018 (Figure 1).

Both regional nature parks and biodiversity conservation AES have the objective of promoting biodiversity. Therefore, regional nature parks may influence farmers’ decisions to participate in AES. For instance, as part of their strategies to promote nature and biodiversity conservation in the region, many parks organise and coordinate projects to promote sustainable agriculture.

Researchers from Agroscope and ETH Zürich investigated the effect of regional nature parks on the uptake of AES. Using econometric methods, they analysed a combination of census data (AGIS) on the AES adoption of over 42,000 Swiss farms between 2005 and 2020 and survey data on AES-related support offered by 15 regional nature parks.

Synergies between regional nature parks and AES

The researchers found that overall, compared to non-park areas with similar natural and socioeconomic conditions, farmers in areas with regional nature parks on average increase their uptake of result-based AES (Q2) by 12% relative to the periods before parks are established. This indicates an overall synergy between parks and result-based AES, and thus between environmental and agricultural policy measures.

Synergies arise primarily in regions with more intensive agricultural production

The 15 Swiss parks span two major landscape types, the Alps and the Jura (Figure 1), which differ in agricultural production intensity and biodiversity conservation. Prior to park establishment, AES adoption was much higher in the Alps due to less intensive agriculture and richer biodiversity.

Further examining park effects on the adoption of AES over the two regions, the researchers found that the effects vary largely (Figure 2). In the Jura region with relatively more intensive agricultural production and lower pre-park AES adoption, parks on average increase the adoption of action-based (Q1), result-based (Q2) and agglomeration AES by 9.5%, 51%, and 74%, respectively. By contrast, establishing a park in the Alps has no effect on the adoption of AES.

Effects do not hinge on a particular form of support offered by the park

Using a survey among all 15 park offices, the researchers also investigated whether park effects on AES adoption vary depending on whether parks provide informational or financial support to farmers. They found no evidence that adoption is influenced by either type of support, suggesting instead that the combined set of park policies may shape farmers’ decisions on AES participation overall.

Duckweed can efficiently produce protein-rich biomass on nutrient-rich waters, such as wastewater or liquid farmyard manure, while simultaneously binding nitrogen and phosphorus. This presents potential for modern circular economy systems.

In recent years, numerous trials on various scales have been conducted at the Research Institute of Organic Agriculture – FiBL in Frick (CH) to evaluate and develop the possibilities and challenges to produce duckweed on diluted farmyard manure. As duckweed efficiently absorbs soluble nitrogen and phosphorus compounds from the nutrient medium and forms protein-rich biomass, it could serve as a link in a short on-farm N cycle. Nitrogen surpluses from farmyard manure could be depleted and, at the same time, an alternative protein source for animal feed could be produced.

Optimizing conditions for duckweed production

The basic feasibility has been demonstrated and optimised on various experimental scales. At optimal dilutions of manure (eight parts water, one part manure) and ammonium N concentrations (around 20 mg/L), nitrogen and phosphorus compounds from the medium are efficiently converted into plant material with around 30% crude protein in the dry matter. In this way, around 180 kg DM per 100 m^² per year could be produced. Converted to one hectare, this would be a yield of around six tonnes of crude protein per year, albeit a theoretical value.

Ecological assessment of the practice

However, as there were also nitrogen losses, the measurement and calculation of ammonia and nitrous oxide emissions is still a key prerequisite for the overall ecological classification of such a process. A study on this is currently being evaluated at FiBL.

Processing and use in animal nutrition

Another challenge lies in the processing of the biomass, especially drying and hygienisation. It has been shown that the hygienic quality was generally, but not always, very high and that the problem can be greatly reduced, especially by storing the manure appropriately before using it as a medium. In addition to drying, ensiling the duckweed is also an option for processing and has been carried out with good results on a laboratory scale.

Fish feeding trials showed its general suitability as a fishmeal substitute, but also its limitations. Poultry feeding trials are planned at FiBL soon.

Imports from abroad were incorporated into Switzerland’s farm-gate-budget-based agricultural nutrient budget calculation to expand it into a food-system budget. This allows assessment of self-sufficiency, nutrient use and circularity to be assessed in addition to nutrient surpluses.

The farm-gate budget is used to assess the nutrient flows of a country, region or farm. In Switzerland, it is also used at national level as an agricultural policy target indicator.  Among others, it covers inputs and outputs of nitrogen (N) and phosphorus (P) from feed, fertilisers, the purchase and sale of animals, and agricultural production.

This study expanded the system boundaries of the budget calculation by including food production and waste streams. Consequently, it also included the import, consumption and recovery of nutrients abroad. Based on different scenarios, the scope and potential for reducing losses were discussed:

1. Business as usual (BAU) – growing demand for food whilst production remains steady.
2. Optimised nutrient management – agricultural best-practice methods for increasing agricultural nutrient-use efficiency in livestock production, farm-manure management and fertilisation in plant production.
3. Food-waste reduction – reducing food losses across the entire food chain as a strategy for increasing resource-use efficiency and self-sufficiency.
4. Circular agriculture – plant production focuses on human nutrition. By-products are used as fertilisers and animal feed, and animal production is meant to be primarily grassland-based.
5. Combination – combines the strategies of food-waste reduction, circular agriculture and optimised nutrient management.

The results show that Swiss food consumption leads to significant nutrient surpluses not only in Switzerland but also abroad. Since Switzerland imports more feed and food than it exports, additional nutrient surpluses of around 37,000 tonnes of N and 2700 tonnes of P, i.e. 35% and 66%, respectively, are generated inside the country, are produced abroad. 

Combining the strategies with the highest potential

The three strategies – optimised nutrient management, circular agriculture with a plant-based diet and the combination of these two – proved effective for reducing internal nutrient surpluses compared to the present-day and ‘business as usual’ scenarios, achieving reductions of around 30%, 18% and 44% for nitrogen and 32%, 5% and 53% for phosphorus. Furthermore, they yield an improved degree of self-sufficiency. Future studies could focus on determining the most efficient production systems, thereby helping to develop and justify effective strategies.

Implementing these strategies is challenging, especially since agriculture is a heterogeneous sector with different types and sizes of farms and different geographic, socioeconomic and cultural framework conditions. What’s more, external factors (e.g. fertiliser and feed prices) influence the feasibility of the individual and combined measures.

Whereas technical and highly concrete measures such as the covering of slurry tanks or the optimisation of fertilisation can be implemented relatively quickly, strategic changes in sectors such as the conversion of cultivation and husbandry systems or even changes in the population’s diet require more time. It is important to bear this in mind when selecting, prioritising and combining measures.

Results-based biodiversity promotion is an approach that is being discussed in the context of agricultural policy as an alternative to the current system that is based on implementable measures. The survey shows that there is considerable interest among farmers.

Since the 1990s, Switzerland has had biodiversity contributions for agricultural land, which provide remuneration for the implementation of specific biodiversity-promoting measures. Despite these measures, biodiversity in Switzerland continues to decline. The results-based approach is seen as a promising alternative, as it rewards the actual ecological quality of an area. This gives farm managers freedom in choosing and implementing measures to promote biodiversity. Knowledge transfer and individual advice also play a key role. However, the approach also involves risks. External factors such as weather events can influence the achievement of the desired result.

Approval of Swiss farmers

Farmers were surveyed about their attitudes toward and willingness to implement results-based biodiversity promotion. The basis for this was the results-based approach that has been tested since 2020 in the targeted biodiversity promotion pilot project ZiBiF in the canton of Zurich. Under this approach, farmers receive compensation based on the actual ecological quality of their land and they also receive farm-specific advisory services.

295 Swiss farmers took part in the survey in 2024. The sample is comparable to the farms surveyed in the 2023 structural survey in terms of most characteristics, but not in terms of production system and farm size (organic and IP Suisse farms are overrepresented in this survey; part-time farms, small and mountain farms are underrepresented). The majority of respondents showed great interest in the results-based approach: 68,7 % found the approach good or very good, and 56,4 % could imagine implementing it on their own farms. More than 80 % said they welcomed more freedom and personal responsibility.

Importance of advisory services and knowledge

A key element of the ZiBiF project is the close support provided by advisors who help farmers choose appropriate measures. The survey revealed that this farm-specific advice is essential for the acceptance of the results-based approach. In addition, 87,3 % of respondents consider it good or very good to be able to make greater use of their knowledge of biodiversity.

Group-specific results

Organic farms are more willing to implement the results-based approach than IP Suisse and conventional farms. Approval was also higher among part-time and mountain farms. On the other hand, it was found that willingness to adopt the ZiBiF approach decreases with increasing surface of land managed. It also became clear that farms with a higher proportion of biodiversity promotion areas on their land were more likely to implement the results-based approach. Finally, farmers with higher levels of education and women were also more willing to adopt the approach.

Private initiatives such as carbon credit trading can support public policies aimed at reducing greenhouse gas emissions. Agroscope and ETH Zürich examined factors which influence the effectiveness of such initiatives.

The Swiss Climate Strategy 2050 emphasises the importance of private initiatives in achieving climate targets and urges all stakeholders in the value chain to take responsibility through their own actions. As a result, private stakeholders such as the Swiss producer cooperatives Mooh and Fenaco have launched schemes to offer carbon credits to farmers. Since participation in these private initiatives is voluntary, in addition to cost-benefit considerations, behavioural economic factors such as a reluctance to change or a desire to imitate colleagues play an important role in estimating the reduction potential of these carbon credits.

Modelling four behavioural scenarios

The agent-based model FARMIND developed by ETH Zürich was used to assess the impact of behavioural economic factors. It simulates farmer behaviour derived from purely profit-driven decisions and is based on interviews and surveys with 49 dairy and beef farmers in the Zürcher Flaachtal.

The study used the model to examine the contribution of two practice-based and easily controllable climate mitigation measures: using the feed additive 3-NOP (the active ingredient in the commercial product Bovaer) and substituting bought-in concentrates with farm-grown legumes.  Four scenarios with different behavioural patterns were simulated to evaluate the impact of behavioural factors on the uptake of the greenhouse gas (GHG) mitigation measures – and thus on their success.

• Scenario 1 (optimisation) assumes that farmers adopt purely profit-maximising strategies and serves as a reference to understand the impact of behavioural factors.
• Scenario 2 (imitation) assumes that farmers are inclined to adopt climate mitigation measures successfully implemented by other farmers in their social network.
• Scenario 3 (reluctance to change) models the tendency among farmers to stick to familiar practices without being influenced by their colleagues or maximising their profits.
• Scenario 4 (combined) combines the imitation of colleagues (Scenario 2) with reluctance to change (Scenario 3). This scenario takes into account specific empirical information about risk preferences and how sensitively farmers respond to changes made by colleagues in their social network.

Carbon credit prices ranging from zero to 200 Swiss francs were simulated for each scenario. By comparing the different scenarios, it was possible to estimate the overall GHG reduction potential relative to a pure profit maximisation strategy, and the impact of different pricing levels.

Imitating proven measures increases the GHG reduction potential

The results show that when profit-driven behaviour alone is considered, a carbon payment of 150 CHF could reduce emissions by up to 24% based on the maximum reduction potential of the feed additive 3-NOP (see Figure). However, when reluctance to change is taken into account, the reduction potential drops dramatically to just 7%.

When social effects through the imitation of successful adopter are considered, the results improve compared with the pure profit optimisation scenario, increasing the GHG mitigation potential to 19% in the simulations.

Maximum greenhouse gas reductions are achieved with a carbon credit price of 150 CHF per tonne of CO₂ equivalent. The potential for further GHG reductions stagnates at higher prices levels.

Private-sector initiatives support public climate mitigation policies

The simulations show that behavioural factors must be considered in addition to profit maximisation when evaluating the potential of private-sector initiatives – carbon credits in this case – to reduce greenhouse gas emissions. In this study, the behavioural factors under consideration reduce the reduction potential, although private-sector initiatives alone would not achieve the proposed targets of the Swiss Climate Strategy, which aims to reduce agricultural emissions by 25 per cent from 1990 levels by 2030 (see dotted line in Figure 1). Nonetheless, private-sector initiatives play a crucial role and support public climate mitigation measures.

The occurrence of per- and polyfluoroalkyl substances (PFAS) is widely documented in soils, water bodies, drinking water and foods. An analysis by Agroscope ranks the contribution made by plant-protection products and other sources to groundwater contamination with PFAS.

Scarcely a day goes by without a report in the media on the occurrence of PFAS in soils and water bodies, foods and the human body. Today, the use of a number of ‘classic” PFAS – i.e. longer-chain, highly fluorinated PFAS – is strictly regulated. Main reasons for this are the persistence of these substances in the environment and their toxicological properties.

Effects not yet fully explained

While we do not know enough about the effects of numerous other types of PFAS on human health or the environment, work is being done at the European level to bridge these knowledge gaps and improve regulation. Part of this involves determining maximum levels for PFAS in drinking water and groundwater.

The definition has evolved

The term ‘PFAS’ was long taken to mean only long-chain, highly fluorinated ‘per- and polyfluorinated alkyl substances’, encompassing around 1000 chemicals. Since 2021, however, a new and much broader OECD definition has been applied according to which over 10,000 polyfluorinated compounds now qualify as PFAS.

Plant protection product (PPP) active substances not part of ‘classic’ PFAS

There are no longer-chain, highly fluorinated PFAS that are approved as PPP active substances. There are, however, various fluorinated active substances that, according to the current broad definition, are now considered PFAS. The fluorine in the molecular structure of these active substances improves their stability and effectiveness. Conversely, fluorinated compounds often degrade more slowly in the environment.

TFA – a special PFAS compound

A breakdown product of most of these fluorinated active substances, trifluoroacetic acid (TFA) is also considered a PFAS according to the new definition and is found in groundwater throughout Switzerland. As with other PFAS, the effects of TFA on humans and the environment are not yet sufficiently understood.

Refrigerants and PPPs contribute to TFA in groundwater

Fluorinated refrigerants from air-conditioning units and cooling appliances that degrade in the atmosphere into TFA and enter the water cycle through rainfall are considered the main source of TFA in the environment, followed by fluorinated PPP active substances which break down into TFA in the soil. The share of groundwater contamination with TFA for which each of these two sources is actually responsible is influenced by various factors, and can therefore not be estimated at present. Whilst TFA is evenly deposited over all of a surface area with the rain, PPPs are only applied over part of an area. TFA concentration in rain has significantly increased since the 1990s, unlike the amount of TFA potentially produced from PPPs, which has remained around the same over the last 15 years.

PFAS-containing co-formulants in PPPs are very rare

In addition to active substances, PPPs also contain so-called co-formulants, which are occasionally named as a potential source of PFAS in the environment. Our analysis has shown that PFAS-containing co-formulants only occur in a very small number of PPPs. One product contains small amounts of a long-chain, highly fluorinated antifoaming agent; three products contain fluorinated propellants. Compared to other sources, the amounts sold with PPPs are small. Co-formulants do not contribute appreciably to the occurrence of PFAS in the environment, whether they be ‘classic’ PFAS or TFA.

Nitrogen from agriculture, traffic, and industry enters soils and water bodies via the air. A new study shows for the first time that increased nitrogen deposition has a negative impact on bird populations – even in semi-natural habitats.

Nitrogen from agriculture (65%), traffic (22%), and industry (10%) enters the atmosphere as ammonia and nitrogen oxides and can be transported over long distances before it deposits into soils and water bodies. This input into habitats such as forests, meadows, pastures, lakes, bogs, and wetlands is considered as one of the main drivers of biodiversity loss in Europe.

Until now, there have been few studies on the effects of nitrogen deposition on bird populations. Using data from the current Swiss Breeding Bird Atlas 2013–2016 and nitrogen deposition data from the Swiss Federal Office for the Environment (FOEN), we investigated the relationship between nitrogen deposition and territory density of 112 common breeding bird species in Switzerland.

Negative correlation between territory density and nitrogen deposition in many species

Fifty-five species showed a negative relationship with increasing nitrogen deposition. For 21 species a positive correlation was found, and 36 species showed no linear relationship. Particularly negatively affected were insectivores and seed-eaters, forest and wetland species, ground-nesting birds, and long-distance migrants. Among the 21 species with a positive correlation were several farmland species: These are common birds in Switzerland such as the Red Kite, White Wagtail, and Starling, which seem to cope with current nitrogen levels. Many of today’s rare farmland species, such as Corn Crake, Lapwing, Meadow Pipit, or Corn Bunting, require extensively used habitats (also for nesting) and are therefore expected to show a negative correlation with nitrogen deposition. However, due to their rarity, they could not be included in the analysis.

The effects of nitrogen on birds are likely due to changes in vegetation. Nitrogen deposition in nutrient-poor sites and ecosystems causes a fertilization effect, resulting in denser and more uniform vegetation, which makes foraging and nesting more difficult for some species. Additionally, vegetation in formerly nutrient-poor meadows grows faster and thicker, leading to earlier and more frequent mowing. This results in significant losses of insects, bird nests, and sometimes even adult breeding birds. All these changes also impair insect diversity, an important food source for many bird species.

Semi-natural habitats are also affected

The study shows: High nitrogen deposition from agriculture, industry, and traffic negatively affects many bird species – not only at the site of nitrogen emission but also in semi-natural habitats like forests and wetlands. In most ecosystems in Switzerland, airborne nitrogen deposition significantly exceeds the critical loads, beyond which biodiversity is impaired. Our findings highlight the urgent need for action. Current efforts to reduce nitrogen emissions show some success but fall far short of what is needed to effectively halt biodiversity loss.

Greenhouse gas emissions from drained carbon-rich soils are being underestimated in GHG accounting. To resolve this, their distribution and emissions need to be better assessed. Accordingly, improvements for the GHG reporting system are suggested.

Organic soils are carbon-rich soils that formed under water-logged conditions, in fens and raised bogs. They are known to have high greenhouse gas (GHG) emissions when drained, e.g. for agriculture. The emissions from carbon-rich organic soils are accounted for in Switzerland’s GHG inventory, which is compiled and submitted annually under the framework of the United Nations Framework Convention on Climate Change. There are however other soils, termed here ‘transition soils’, that are not carbon-rich enough to be considered organic soil for the GHG inventory, but also contain a lot of carbon which accumulated under water-logged conditions. They include carbon-poor organic soils, carbon-rich mineral soils, as well as any carbon-rich soils overlaid with a mineral layer, a practice carried out by some farmers e.g. to mitigate the negative effects of heavily subsided soils.

Transition soils lose carbon when drained

It is likely that transition soils also lose carbon when drained. Indeed, there is emerging evidence from other countries suggesting that their per hectare GHG emissions can be substantial, sometimes as high as those from carbon-rich organic soils. As in most other countries, these emissions are not accounted for in Switzerland’s GHG accounting, meaning we underestimate soil-borne emissions. Emissions from transition soils are often overlooked in part because of knowledge gaps, and in part because the reporting system is over-simplified, classifying soils only as either ‘organic’ or ‘mineral’ (i.e., non-organic soils).

GHG inventory may recognise additional soil categories

For GHG reporting, we suggest that as a mid-term solution, the GHG inventory recognises additional soil categories, so that the spectrum of soils –with respect to the carbon content– is better represented. These soil categories would need to have their own sets of emission factors, which could initially be derived from the scientific literature if sufficient data are available. In the long-term, we suggest that GHG accounting of soil-borne carbon-related emissions abandons the use of categories and associated emission factors, and instead makes use of models predicting GHG emissions as a function of carbon content and water level. Both these approaches require closing large knowledge gaps.

Soil mapping and field measurements needed

Firstly, more research is needed to assess where transition soils occur. With the new soil mapping methodology developed by the Swiss Soil Competence Centre (ccsols.ch), such soil properties will be quantified and recorded. The Swiss Federal Council has approved 2023 the concept for a national soil mapping survey, which is scheduled to begin in 2029. Secondly, field measurements are needed to assess how high the emissions of the different transition soils are, and how these are related to the main drivers of emissions, including carbon stocks and the ground water level. Lastly, measurements and / or estimates of peat depth, carbon density and ground water level across the landscape are necessary.

To date, figures on agricultural water use for irrigation in Switzerland have been quite patchy. In response, Agroscope has developed a method for estimating consumption volumes on behalf of the Federal Office for the Environment.

Until now, Switzerland has seldom been associated with water shortages. Increasingly, however, local bottlenecks have led to bans on surface-water withdrawal for agricultural irrigation. In the absence of comprehensive information on agricultural water consumption, the extent to which such problems will grow in future remains unclear.

The aim of the SwissIrrigationInfo Project carried out by Agroscope and the HAFL on behalf of the FOEN was to develop a method for gauging annual water consumption for agricultural irrigation in Switzerland. The method is based on a model approach of the FAO (FAO56) rooted in climate, soil and crop information. For ten crops and crop groups (annual and perennial berries, vegetables, potatoes, maize, apples, grapes, tobacco, grassland and sugar beet), the model was parameterised based on the literature, expert knowledge and real-life data to estimate customary irrigation practice.  

Highest water consumption for vegetables, fruit and grassland

Using these models for the various crops as well as climate, soil and land-use data available throughout Switzerland, water consumption for agricultural irrigation was estimated for the years 2021 to 2023. Accordingly, a consumption of around 9.5 mn m³ was estimated for the wet year of 2021 and of 41 mn m³ and 31 mn m³ for the warm, dry years of 2022 and 2023, respectively. The crops with the highest water consumption were vegetables, fruit and grassland. The results are largely congruent with the estimates of the Swiss Federal Statistical Office for 2023, which are based on random surveys.  

Comparisons of the model estimates with regionally recorded water withdrawal volumes for irrigation in Schaffhausen and Thurgau show that the model-based method substantially underestimates irrigation for the wet year of 2021. For the warm, dry years of 2022 and 2023, the modelled values were relatively congruent with the recorded withdrawal volumes, provided that information was available on the share of irrigated croplands for the respective region.

Without climate protection, irrigation demand could rise by around 20% by 2100

Future irrigation consumption was modelled on the basis of the CH2018 Climate Scenarios and extrapolated to the whole of Switzerland, with the assumption of no changes in land use. According to the said projections, by the end of the century water consumption would rise by around 21% without climate protection measures (RCP8.5) and by 6% with moderate climate protection measures (RCP4.5). These increases show that agricultural water management is confronted with growing challenges.

The reference information on real-life irrigation practices was invaluable for the project, allowing for optimal comparison of the model estimates with reality. However, it also emerged that there was a very high variance in the data on real-life irrigation, which could not be explained with the model. This variance resulted from the fact that irrigation decisions do not depend solely on soil moisture and plant water requirements, but that various business and personal considerations are also determining factors.

In a literature review, FiBL showed that protecting biodiversity requires both sustainably managed agricultural landscapes and suitable, undisturbed habitats.

Biodiversity conservation at the landscape level is a key issue in sustainable land use. Many countries have developed concepts and measures to this end, such as Switzerland with its ‘Swiss Biodiversity Strategy and Action Plan’. However, there is controversy over the best way to achieve this. In the context of agriculture, two opposing approaches often compete.

One calls for intensive production on less land, so that more unused land can be preserved as natural areas to promote biodiversity. Production and biodiversity conservation are kept as separate as possible (“land sparing”). The other approach emphasises the value of a landscape where sustainable agriculture and biodiversity promotion are closely interlinked on agroecological production and near-natural areas (“land sharing”).

The ideological debate on “land sparing” and “land sharing” is not constructive

This debate is often conducted using ideological arguments and entrenched positions, resulting in two sides that lead to very different recommendations for action. Some also argue that the debate does not do justice to the complexity of the topic and is not productive. Nevertheless, it remains a topic of discussion in sustainable agriculture and biodiversity policy. FiBL has therefore systematically compiled and analysed the available empirical studies on this topic. This clarifies the facts and contributes to a more constructive discussion.

The data available is sparse and irregular – important aspects are missing

There are only a few studies that present comparisons of the two strategies based on comprehensive field data. Of the 57 studies identified as relevant in the paper, only 17 provide the data needed to compare the strategies. The other 40 studies lack important aspects.

The studies focus on only one or a few animal or plant species groups, and the studies as a whole are also one-sided: 19 of the 27 comparisons included in the complete studies consider tropical forest birds, six consider various plants, and only two consider insects or soil organisms. Studies on microbes and fungi are missing entirely.

Furthermore, only a limited number of biodiversity indicators are covered. Most studies looked at species density (22 of the 27 complete comparisons). Analyses of species diversity, functional diversity, and other biodiversity indicators are lacking.

Biodiversity requires sustainably managed land and undisturbed habitats

The results of the 17 studies that allow a true comparison of sharing and sparing show that in 50 percent of cases, a context-specific combination of the two strategies delivers the best results for promoting biodiversity. Sparing is better in 40 percent of cases, but these cases mainly concern forest birds that require contiguous, near-natural habitats, which are often lacking in agricultural landscapes. Sharing is better in 10 percent of cases. Biodiversity, therefore, depends on both undisturbed habitats and sustainably managed landscapes.

The 40 studies with incomplete data primarily lack information on the type of agricultural production and yields. Without this information, it is not possible to assess which areas are farmed with what intensity in each strategy, to evaluate not only the advantages and disadvantages for biodiversity, but also agricultural production.

A focus on “sparing” with intensively used agricultural land is not a solution

The assessment of sharing and sparing strategies for promoting biodiversity at the landscape level must be carried out in a broader context. Intensive agriculture, characterised by high pesticide and fertiliser use, can deliver high yields but has significant negative impacts on biodiversity at the field level, in the landscape, and in water bodies. There is also a risk that yields will decline due to soil health loss and erosion. Extensive or organic farming, with its agroecological approaches, is good for biodiversity but is associated with lower yields.

It is essential to address the entire food system

We can use the aspects of sparing and sharing at the landscape level together and sustainably without jeopardising food security. However, this means considering productive, sustainable, biodiversity-friendly agriculture on limited land in a systemic context.

What is produced then becomes just as important as how it is produced: are we producing food or waste? In industrialised countries, one-third of production is wasted. Are we producing feed or food? In the European Union, feed is grown on 60 percent of arable land. With consistent waste reduction and targeted use of arable land for food production, all can be achieved: food security with sustainable agriculture and biodiversity protection.

How can urban agriculture in Zurich move toward the net-zero target? A FiBL study shows that major restructuring would be necessary to reach the goal – although smaller measures can still help bring it closer.

The city of Zurich aims to achieve net-zero direct greenhouse gas emissions (GHG) by 2040, which also includes the city’s agricultural areas.

Participatory scenario development and modelling

For the study, Zurich’s urban agriculture was modelled as a single enterprise. Using the current status quo as a baseline, four exploratory scenarios were developed through a participatory process involving stakeholders. The goal was to combine known measures to present a range of options. These measures include reduced tillage, lower livestock numbers by adapting them to locally available roughage, and using biomass for biogas production. The scenarios were evaluated using four quantitative indicators (GHG, fossil energy consumption, income effect, and food production).

Net-zero through far-reaching measures

Zurich can achieve the net-zero target, but this would require giving up livestock farming and compensating for remaining emissions through tree planting and biochar. Other effective measures include grassland-based dual-purpose breeds with extended lifespan for meat and milk production, reduced mineral fertilizer and feed imports, electrification of farming processes, and widespread biomass use for biogas. However, these alone do not lead to net-zero.

Efficient use of local resources reduces emissions while increasing output

The study reveals significant trade-offs between climate protection, economic viability, and food production. Measures known today and necessary for net-zero cause significant costs and income losses, as well as a 16 % drop in food production. In contrast, efficient local resource use and the abandonment of fertilizer and feed imports increase net GHGE but boost protein output by 55 % and reduce GHG per kilogram of protein. Economically, these measures perform relatively well.

Feed imports drive high fossil energy use

Abandoning imported feed and mineral fertilizers reduces fossil energy consumption by up to 85 %. Especially non-ruminants, such as boarding horses or pigs, could then only be kept to a limited extent.

Net-zero hampered by multifunctionality

Agriculture, especially in urban contexts, serves various roles, including food supply, biodiversity, education, and recreation. Focusing solely on climate goals may lead to conflicts depending on the measures taken.

Methodology as example for others

The modelling approach, involving practitioners, can serve as a model for similar processes. It enables participatory scenario development and lays the foundation for broader consensus on feasible climate protection measures.

A new study by Agroscope shows that despite higher subsidies, bushes continue to spread on alpine meadows.

Woody plant encroachment on Swiss summer farm pastures leads to loss of grassland and of the culturally typical landscape. It is the result of land abandonment and changes in the type and intensity of agricultural activities. Woody plant encroachment on Swiss summer farm pastures is dominated by Green Alder (Alnus viridis), which is responsible for a decline in species diversity (Meier et al. 2021).

Three policy measures for reducing woody plant encroachment

To counter land abandonment and thus biodiversity loss, farmers are granted a range of subsidies in the form of direct payments. Three different subsidies were increased or introduced for the first time in 2014:

1. Livestock subsidies per livestock unit were increased.
2. Result-based subsidies for ecological focus areas were introduced. These require the presence of non-woody indicator plant species in grasslands as well as landscape elements.
3. Landscape quality subsidies were introduced which compensate farmers for maintaining and enhancing regionally typical landscapes undisturbed by woody plant encroachment.

To date, however, there has been no empirical examination of how these measures affect woody plant encroachment and grassland conservation.

This study investigates how the three above-mentioned subsidies affect woody plant encroachment on summer farm pastures in Switzerland. To this end, we compiled a dataset linking farm-level data from summer farms in the Canton of Grisons with remote sensing data on woody plant encroachment.

Unintended effect of subsidies on grasslands

The empirical investigation suggests that increasing subsidies caused an average 2% loss of grasslands per farm through woody plant encroachment. This corresponds to an average of 4.7 ha grassland loss per farm within 10 years. Thus, subsidies can have unintended consequences. In this context, it is important to mention that the impact of subsidies on species richness, diversity of structural elements and income was not investigated.

Possible explanations

There are two main possible explanations for grassland loss observed in connection with subsidies:

1. The spatial distribution of livestock has changed. Ecological focus areas may have been excluded from grazing to protect the vulnerable species they host, with the unintended side-effect of increased woody plant encroachment. Because livestock is a key factor for controlling woody plant encroachment (Pauler et al. 2022), its exclusion can have negative consequences.
2. Subsidies may have led to a decrease in mulching on the newly established ecological focus areas. Mulching is considered to be the most effective and economical measure for preventing woody plant encroachment.

This combination of disincentives may have significantly encouraged the observed development. However, further research is needed to clarify these mechanisms.

References

Meier E., Lüscher G., Buholzer S., Herzog F., Indermaur A., Riedel S., Winizki J., Hofer G., Knop E. 2021, Zustand der Biodiversität in der Schweizer Agrarlandschaft: Zustandsbericht ALL-EMA 2015−2019. Agroscope Science, 111, 2021.

Pauler, C. M., Zehnder, T., Staudinger, M., Lüscher, A., Kreuzer, M., Berard, J., & Schneider, M. K. (2022). Thinning the thickets: Foraging of hardy cattle, sheep and goats in green alder shrubs. Journal of Applied Ecology, 59(5), 1394-1405.

Feeding food no longer suitable for human consumption (‘former food products’ or FFPs) to dairy cattle is a promising approach for reducing food waste. When included in dairy diets, FFPs do not affect the cow’s metabolism, but do not reduce methane production either. 

Feeding ruminants with resources that are unsuitable for humans, such as grass and ‘former food products’ (FFPs), helps to reduce feed-food competition. In addition, growing concern about food security is prompting research into alternatives to cereal grains as concentrates for livestock, such as food industry by-products. Despite this, the effects of FFPs on animals, and specifically on ruminants, have scarcely been investigated to date.

Studying the effect of replacing cereal grains by ‘former food products’ and cocoa bean shells

Agroscope studied how replacing cereal grains in concentrates with FFPs (leftovers from the bakery industry) – with or without the addition of cocoa bean shells (CBS) – affects ruminal fermentation, methane production and blood metabolites in early-lactating dairy cows on a grass-based basal diet. The addition of cocoa bean shells was tested in terms of the potential methane-reducing effect of the plant constituents (phenols) contained therein.

Thirty-four dairy cows (17 in the spring and 17 in the autumn; average milk yield, 35 kg/d) were fed for six weeks with fresh herbage cut daily and an additional 6 kg of one of three concentrate variants. The concentrate was either grain-based or contained 55% FFPs (corresponding to ~14% of the total diet measured on a dry matter basis), as well as no, or 5%, cocoa bean shells.

FFPs have a season-dependent effect, while CBS have no effect on metabolism or methane production

Feeding FFPs and CBS to cows over a 6-week period had no negative effects on milk yield or metabolism. The concentrate variants had different impacts on fermentation pattern and pH in the forestomachs, in some cases depending on season (spring vs. autumn). Seasonal changes in feed intake, herbage and possibly FFP composition are presumably at the root of interactions between season and concentrate variant. Methane production was unaffected by both concentrate variant and season.

Further clarifications needed

Combinations of herbage and FFPs, and in particular their effects on rumen health, nutrient intake and use by the entire organism including the mammary gland, should be investigated further. The effect on milk yield must also be confirmed over a longer time period and with a greater number of animals. Since the composition of FFPs available on the market generally varies considerably, the implications for dairy nutrition and milk yield should also be investigated in greater depth.

What is ‘former food’?
Former Food Products (FFPs) are processed food products originally intended for human consumption but which can no longer be sold due to manufacturing defects or faulty packaging. They form part of the approx. 2.8 million tonnes of food loss generated annually in Switzerland. Typical examples of FFPs come from the bakery and confectionery industry, e.g. doughs, sweet and savoury biscuits and crackers, sweets or broken chocolate. According to sustainability criteria, the use of FFPs as animal feed is the second-best utilisation option, right after reuse for human consumption. Despite their seasonally fluctuating composition, FFPs are increasingly prepared in a standardised manner for use in livestock feed.

To reduce the use of herbicides to control track-side vegetation, the Swiss Federal Railways (SBB) commissioned Agroscope and HEPIA to develop a low-growing plant mix for the track area.

The Swiss Federal Railways (SBB) have decided to restrict the use of chemical synthetic herbicides to an absolute minimum and promote alternative measures in line with the Alternatives to Herbicide Action Plan. One important consideration was that these measures should not reduce the service life of rail infrastructure or compromise train safety or availability.

‘Sowing instead of controlling’

The SBB commissioned Agroscope, the Haute école du paysage, d’ingénierie et d’architecture de Genève (HEPIA) and other partners to investigate whether the targeted greening of verges, maintenance and escape paths and track-side areas could be an alternative to the widespread use of herbicides. The aim was to establish a vegetation cover that supressed problem plants, maintained the safety of rail infrastructure and promoted biodiversity. At the same time, the spread of problem weed species to adjacent farmland was to be avoided through careful species selection.

Five specially developed seed mixes were tested at six sites in the Swiss Plateau. The mixes comprised species which were expected to meet the safety requirements (accessibility on foot, low growth, shallow roots, no trip hazards, no restriction of signal visibility, no impediment to track drainage) and the environmental requirements (ecotypes of native plant species).

Site and mix determine success

The long-term trial showed that successful greening of trackside areas can be achieved using selected species: the seed mixes meet the safety criteria, species diversity increases, soil temperature decreases, and the quality of the track-side landscape is enriched.

Two site factors are key to the establishment of the sown plants:

1. The organic matter content (which takes a number of years to accumulate on the existing, very poor gravelly soils)
2. An adequate water supply in the sowing year to enable the mixes to establish a seed bank in the substrate.

Two mixes, one covering a broad ecological spectrum and the other containing several pioneer species, achieved an average soil cover of over 70% after five trial years on a suitable soil substrate.

The proportion of sown species in the overall vegetation cover was significantly higher than that of spontaneous species at all sites during the trial period. Invasive native and non-native species were significantly scarcer than sown and unproblematic spontaneous species. The sowings increased species richness within the plant community by five species on average.

The study concluded that track-side greening is a realistic alternative to the use of herbicides. However, it will do little to reduce track-side maintenance, since targeted greening also needs regular upkeep. For instance, problematic scrambling and trailing plants from adjacent plots, such as ivy or brambles, still need to be controlled, as do tall plants and invasive non-native species.

Future approaches could involve a combination of mechanical, chemical and biological strategies to ensure optimal sustainability.

Agroscope has compiled a new map of Switzerland’s organic soils, which forms the basis for developing a strategy for managing these soils.

Organic soils are carbon-rich soils which have formed under water-saturated conditions, typically in raised peat bogs and peat fens. In the past, many of these areas were drained and today, most organic soils are farmed. Draining these soils leads to rapid peat decomposition. This in turn leads to soil subsidence, which hampers agricultural production on these soils in the longer term and incurs high costs as the drainage systems need to be replaced every few decades. Furthermore, the drainage causes these soils to become greenhouse gas emission hotspots. The current use of these soils is at odds with the Swiss Soil Strategy as well as the concept of agricultural practices adapted to local conditions. Furthermore, it poses an obstacle to achieving national climate targets. Organic soils must be re-wetted to reduce peat decomposition and associated greenhouse gas emissions.

Over half of peatlands are farmed

A new map of Switzerland’s organic soils shows that these soils are mainly used for agriculture (32% grassland and 29% arable; 61% in total) and forestry (19%). It also shows that while only 1.2% of agriculture occurs on organic soils, these areas account for 10% of agricultural greenhouse gas emissions. These emissions equate to a quarter of the greenhouse gas emissions that need to be cut by 2050 to meet climate targets for food and agriculture.

Although at national level, organic soils account for only a very small percentage of agriculture in terms of area, at regional level the picture is somewhat different.  In some regions (e.g. Zealand, the Orbe plain) a substantial proportion of agriculture occurs on these soils. Thus, the acceptability and economic consequences of changes to the management or use of organic soils can vary considerably depending on the region.

Paludiculture as a solution

The re-wetting of farmed organic soils and their removal from food production would significantly reduce greenhouse gas emissions, but would at the same time lead to a deficit of around 1,200 hectares (<1 %) of ‘crop rotation surface’ (legally required minimum quota of land available for cropping). Paludiculture – the production of biomass, fodder or food on wetland soils – offers a solution to re-wet these soils while at the same time maintaining their agricultural function. However, paludiculture for pure biomass production, for example bullrushes of reeds, is often associated with a reduced income. On the other hand, 30% of farmed organic soils are already managed in a way that is compatible with a raised water table (e.g. extensively managed meadows and pastures). Although there are still technical and financial hurdles to overcome, greenhouse gas emissions for roughly a third of the farmed organic soil surface could be reduced without changing the crop or grassland type cultivated.

An Agroscope study shows that the Suisse-Bilanz nutrient-balance calculation tool could serve as an environmental indicator for sustainable nutrient use – but only for phosphorus, not for nitrogen.

Sufficient availability of nutrients is crucial for optimal yields and high-quality plant products for human and animal nurition. Excess nutrients, particularly excess nitrogen (N) and phosphorus (P), pollute the environment and have been a key topic of agricultural and environmental policy in Switzerland and Europe for decades. In this area of conflicting priorities, it is important to strike an ideal balance between supplying crops with sufficient nutrients and minimising environmental impacts, i.e. using nutrients sustainably.

The aim of this study was to determine whether Suisse-Bilanz is suitable as an environmental indicator for sustainable nutrient use. Suisse-Bilanz is a supply-demand balance sheet that Swiss farms are obliged to draw up as part of the Proof of Ecological Performance (PEP) in order to receive direct payments. The Suisse-Bilanz results were compared with those of a soil-surface balance (the OECD balance) which is drawn up for farm and national agri-environmental monitoring. The data for the comparison stem from the Swiss Agri-Environmental Data Network (SAEDN) which collected data annually from around 300 farms from 2009 to 2022.

Deductions for nitrogen losses distort the result

The analysis showed that the nitrogen balances produced by Suisse-Bilanz and by the soil-surface nutrient-balance calculation tool correlate only weakly. Whereas the N balances of the soil-surface tool were mostly positive (between 58 and 83 kg total N per ha), they were slightly negative in Suisse-Bilanz (between −14 and −2 kg available N per ha). This is because nitrogen losses arising e.g. from animal housing or grazing, or from the storage and spreading of farmyard manures, can be deducted in Suisse-Bilanz, whilst these losses are not taken into account in the soil-surface tool, but are recorded as part of the balance. Unlike the Suisse Bilanz, the soil-surface balance does not show the plant-available nitrogen. This is why farms with large amounts of organic fertiliser or large herds have significantly higher values in the soil-surface balance than in Suisse-Bilanz.

Strong correlation of both balances for phosphorus

By contrast, the Suisse-Bilanz and soil-surface balance values were found to correlate well for phosphorus. Whereas the P soil-surface balances were balanced (between −2 and 0 kg P per ha), those of the Suisse-Bilanz balances exhibited only a slightly negative tendency (between −3 and −1 kg P per ha). The reason for this better correlation is that P is less volatile than nitrogen, so no deductions need be made for the P in farmyard manure.

The study shows that in its current form, the Suisse-Bilanz tool is not suitable for reliably quantifying N losses. The flat-rate deductions at animal housing-, storage- and spreading scales and the simplified calculation of the plant-availability of N for organic fertilisers prevent a specific representation of the actual N losses. The soil-surface balance offers a better basis for evaluating nitrogen surpluses. By explicitly taking account of the deductions in addition to the current balance, a surface-balance calculation tool balance can also be generated that ensures a more accurate estimate of the losses and is therefore more suitable as an environmental indicator.

Wanted: data for agri-environmental monitoring

Suisse-Bilanz is, however, a useful environmental indicator for phosphorus, since it is closely correlated with the soil-surface balance calculation tool. Additional consideration of the mandatory soil analyses recurring as part of PEP can further improve the calculation of regional phosphorus surpluses and the consequential risks of loss. Currently, however, neither the Suisse-Bilanz balances of the farm nor the farm-scale soil analyses are available to the Agroscope agri-environmental monitoring programme.

Methane emissions are rising rapidly and accelerating climate change. A new review reveals effective measures that can quickly reduce them.

Methane is a greenhouse gas that traps heat in the atmosphere far more effectively than carbon dioxide – with the small but significant difference that this happens over a far shorter time frame (decades instead of centuries). Cutting methane emissions can thus make a direct and substantial contribution to slowing global warming.

Atmospheric methane concentrations have been rising rapidly since 2007. This is due to emissions caused by human activities, for example agriculture, extracting and burning fossil fuels, and waste management. Most agricultural methane emissions are derived from livestock farming and rice cultivation.

New measurement methods can identify hotspots

This review summarises the rapid advances in direct practical methods to quantify and reduce agricultural methane emissions worldwide. The study identifies three hotspots where methane emissions can be quickly and easily reduced:

Hotspot No. 1 is biogas plants, which produce methane-rich biogas from organic waste. A UK study shows that biogas plants lose 5.2% of their methane production on average, with emission rates ranging from 1.4 to 12.7%. Since these plants are easily controlled and optimised, they are an obvious target for substantial emissions savings.

Hotspot No. 2 is manure management. Manure silos are important methane emitters because they provide an ideal environment for methane bacteria. Tighter coverings, better gas capture, solid-liquid separation or acidification can reduce emissions.

Hotspot No. 3 is the burning of crop waste, stubble and grass. Although very rare in Europe now, burning is widespread in India, Southeast Asia and Sub-Saharan Africa and produces high methane emissions and air pollution linked to 43,000 deaths a year. The waste could be used as animal feed, in biogas plants or for composting instead.

Improvements in rice cultivation…

Rice paddies in the tropics are another major methane emitter. It is estimated that rice cultivation produces 29 million tonnes of methane annually worldwide. Better water management, off-season straw removal and the conversion of straw to biochar could reduce emissions by 22 to 28%.

… and livestock farming

Better ruminant health can reduce methane because productivity increases, i.e. fewer animals are needed to produce the same amount of food. Breeding cattle that emit less methane and using feed additives could also reduce methane emissions.

It is difficult to estimate the global impacts of mitigation measures. According to this review, improvements to biogas plants and livestock management could save 30 to 40 million tonnes of methane annually. Better crop waste management, less burning and improved rice management could save a further 30 million tonnes – a total reduction of up to 60 million tonnes per year by 2050.

Methane destruction is another option: the gas can be converted to CO₂ by oxidation, thereby reducing its global warming potential. This may be feasible in cattle sheds, where high methane concentrations occur. Methane in landfill could be captured and used to generate electricity – especially in the tropics, where it could supplement solar energy.

Contribution to a healthier diet

Finally, changes to the human diet can also make a major contribution to reducing methane emissions. An appropriate diet that meets human nutritional needs can reduce per capita food consumption. This would lead to a reduction both in agricultural production and the amount of waste going to landfill.

Agroscope researchers conducted a literature review to summarise which measures are most effective in reducing food waste. Their findings contribute to better identification and implementation of effective interventions.

Generating over one billion tonnes of food waste per annum globally, consumers make a substantial contribution to the total volume of wasted food. It follows that interventions focusing on altering consumer behaviour are an important leverage for reducing or avoiding food waste. However, to effectively reduce food waste, in-depth knowledge on the effects of such interventions is essential.

Agroscope researchers therefore conducted a systematic literature review, analysing a total of 49 studies that investigated 54 interventions for reducing consumer-level food waste. Both consumption in the household and outside of the home (e.g. in restaurants, university canteens, etc.) was taken into account. The studies considered were evaluated according to three criteria (see Figure 1).

Intervention category

The majority of the 54 intervention studies investigated single-component interventions, such as nudges, knowledge enhancement, awareness raising, social influence or incentives. A ‘nudge’ involves the use of subtle tools to influence and modify consumer behaviour and decision-making: for example, using a smaller plate may lead to smaller portions being taken, and hence to less food left unconsumed on the plate. Only a few studies tested multi-component interventions. In these studies, nudges were frequently combined with other interventions. Most of the intervention studies were conducted in households (35%), followed by universities (24%), schools (18%), hotels (9%), supermarkets (6%), hospitals/care homes (4%), restaurants (2%) and campsites (2%). The target population varied according to the intervention settings, with household members, students, children and young people being the most frequent study participants.

Impact of the interventions

Most interventions led to a significant reduction of food waste (see Figure 2). For the following interventions – social influence, awareness raising, knowledge enhancement and nudges – there were several studies leading to no reduction in food waste. Multi-component interventions with nudges proved to be particularly promising for reducing food waste. The most effective reduction was achieved by a combination of nudges with knowledge enhancement. The use of individualised training sessions and customised solutions with a coach, including nudges such as tips by text, email or phone led to a significant reduction of food waste of up to 79%.

Based on the study results the Agroscope researchers also suggest measures for rendering food waste intervention studies even more efficient in future, inter alia larger study populations or studies in which people do not know that food waste is being investigated. More details can be found in the scientific article.