South Africa's land redistribution aims to redress the historical injustices of apartheid. This paper evaluates the efficacy of an agent-based model to support and refine the process. Using the Impacts of Land Use Patterns in South Africa model, developed from surveys of 658 commercial farmers and 833 commercially oriented smallholders, we simulate three scenarios: the current willing seller, willing buyer mechanism as our baseline, a second scenario that includes land subdivision to produce emerging farm parcels, and a third scenario that includes expropriation of underperforming farms. We find that the current mechanism is likely to redistribute only 14% of the targeted 30% of commercial farmland. Including land subdivision increases the number of beneficiary farms from 4,383 to 73,600, improving access to land but reducing farm sizes and thus possibly economic sustainability. Including expropriation adds about 2.4 million hectares, mainly for grazing, with a small allocation for field crops and horticulture. All three scenarios could reduce production volumes, with marked differences in impact across agricultural subsectors in the subdivision scenario. Realising these scenarios over an eight-year period is projected to require substantial financial investment, with estimated costs ranging from R422 billion to R626.9 billion, heavily weighted towards operational capital to maintain farm productivity and viability. The study demonstrates the model's value for policymakers, enabling them to explore and evaluate the outcomes of different land redistribution strategies, ensuring more informed and effective policy-making.

The world's food supply is becoming increasingly vulnerable because of rising political and climatic crises. To identify food supply vulnerabilities at an early stage, this paper proposes a multifactorial and standardized import vulnerability index (IVI). The IVI encompasses (i) an exporter vulnerability index (EVI) consisting of four exporter-specific factors and (ii) a product vulnerability index (PVI) consisting of three product-specific factors. We applied a robust principal component analysis to derive weights to combine these individual factors into a standardized IVI. The IVI was applied to food import-dependent Switzerland from 2014 to 2019 as an empirical case study. The results showed that a large share of Swiss food imports mainly originated from neighboring countries, indicating a very low to moderate EVI. Regarding the PVI, only product groups that were imported from a small number of countries (e.g., oilseeds) or that showed a low self-sufficiency ratio (e.g., coffee) or high price volatility (e.g., meat) exhibited a high value. Moreover, the findings demonstrate that the IVI showed neither large fluctuations nor a decreasing or increasing trend. With regular updates, the proposed indicator can become a valuable monitoring tool for food supply security.

[This corrects the article DOI: 10.1016/j.heliyon.2024.e27058.].

This paper explores the prospects of commercial producers who would be willing to exit voluntarily in the near future to make land available in the market. In addition, it also considers what factors are restricting the acceleration of this rate of exit from a land-supply perspective with respect to barriers to exit. The prospect of structural change from such acceleration is also explored using three scenarios. An agent-based mathematical model is used to implement the three scenarios. This model is constructed from a dataset of 450 commercial producers across South Africa. The results suggest that a reasonable amount of arable land could be available for redistribution, with only modest structural change regarding animal production, despite drastic alterations in veld. These results provide some guidelines on how assistance for struggling producers can make land available for efficient producers, which could make the sector stronger. All potential exiting commercial producers have common reasons for doing so, which could be used to initiate a positively inclined, structured discussion on land supply.

CONTEXT: Most Western-European countries exceed the critical loads for nitrogen (N) losses. High nitrogen (N) inputs make agriculture one of the largest contributors to N pollution. There might be a potential to reduce this losses with an output tax on animal products, as they have low N use efficiency and a tax has the potential to reduce the consumption of this products. OBJECTIVE: We want to assess the potential of a food tax on animal products to reduce the N surplus of Swiss agriculture. METHODS: We implemented a tax on meat and a tax on milk and meat in the agent-based model SWISSland. The model combines an agent-based model with a microeconomic model at the farm scale. To better understand the low response of the food tax, we applied in a second step a robust two-step global sensitivity analysis of abatement costs of individual model agents. RESULTS AND CONCLUSIONS: Imposing a tax led to an N surplus reduction of 2.1% where only meat was taxed and 2.3% where both milk and meat were taxed. The sensitivity analysis showed that distinct agents reacted nonuniformly to changing prices, so that the effect of the tax was sometimes even cancelled out. This calls for more differentiated policies to reduce the negative impact of N losses. SIGNIFICANCE: The overall impact of the food tax was minor as the distinct agents react not uniformly to lower producer prices.

Although the supply situation of the Swiss population is sufficient in terms of food security, contributions to security of food supply have been made since 2014 as part of the country's current agricultural policy. Amounting to around CHF 1.17 billion, such contributions account for more than a third of Switzerland's total direct payments budget. The effectiveness and the efficiency of this policy in terms of both calorie production and income transfer were analysed. With the help of an agent-based model approach, the extent to which the achievement of targets is guaranteed in the long term was examined. Possible gains in efficiency become visible alongside a stepwise reduction in the levels of the contributions. If the current policy is continued, Switzerland will barely achieve its actual operationalised calorie production targets. A focus on demand during times of supply shortages and a stronger focus on maintaining production factors could release the resources necessary to close existing gaps in relation to meeting targets. With an income ratio of about 0.3, the payments have a high income transfer effect and, therefore, make a major contribution to securing agricultural income. This fact is not evident in either the formulation of targets or the labelling of the policy. The present study contributes to the discussion concerning the possible reasons and likely impacts for the mislabelling of this policy measure.

A Swiss popular initiative reflecting large public concerns about the negative environmental impacts of agricultural production launched a proposal to rigorously tighten environmental cross-compliance standards. The so-called drinking water initiative (DWI) proposes restricting direct payments to farms that (1) preserve biodiversity, (2) do not use any pesticides, (3) adapt their livestock to their on-farm feed capacity and (4) do not use antibiotics regularly or prophylactically. Based on the recursive-dynamic, agent-based agricultural sector model SWISSland, we assessed, ex-ante, the impacts of the initiative on environmental and economic indicators at the farm- and sector-level. Stakeholders from both groups, supporters and opponents of the initiative, were involved in the assessment. We found that the incorporation of far more stringent environmental standards into the cross-compliance system caused a larger number of farms to opt-out: For 33–63% of the pork and poultry farms and 51–93% of the vegetable/orchards/winery farms, it was more profitable to forego direct payments. However, the majority of the ruminant farms (87%) were expected to comply with the standards. Although the non-complying farm types were associated with the most severe environmental impacts, we found that the initiative nonetheless had positive effects on water quality at the sectoral level in Switzerland: e.g., the share of pesticide-free arable land increased to 70–92%, those of the permanent cropland to 11–52%, and the nitrogen surplus decreased. However, the total agricultural production measured in calories decreased (12–21%), and therefore agricultural imports would increase. If the current direct payment budget goes completely to the complying farms, and if these farms receive a price premium, then we predict an average farm income increase of 2–34% for the complying farms; otherwise, a decrease of 6–22% will be found depending on the scenario. A sensitivity analysis showed that price uncertainties had the highest impact on farm income.

This study evaluates linear programming (LP) and positive mathematical programming (PMP) approaches for 3,400 farm-level models implemented in the SWISSland agent-based agricultural sector model. To overcome limitations of PMP regarding the modelling of investment decisions, we further investigated whether the forecasting performance of farm-level models could be improved by applying LP to animal production activities only, where investment in new sectors plays a major role, while applying PMP to crop production activities. The database used is the Swiss Farm Accountancy Data Network. Ex-post evaluation was performed for the period from 2005 to 2012, with the 2003-2005 three-year average as a base year. We found that PMP applied to crop production activities improves the forecasting performance of farm-level models compared to LP. Combining PMP for crop production activities with LP for modelling investment decisions in new livestock sectors improves the forecasting performance compared to PMP for both crop and animal production activities, especially in the medium and long term. For short-term forecasts, PMP for all production activities and PMP combined with LP for animal production activities produce similar results.

italianoPer assicurare l’approvvigionamento della popolazione con derrate alimentari, dal 2014 la Confederazione destina contributi per la sicurezza in materia di approvvigionamento per un ammontare di 1.1 miliardi di franchi, il che rappresenta una grande fetta dei pagamenti diretti. Ora Agroscope ha verificato l’efficacia di questo strumento su mandato dell’Ufficio federale dell’agricoltura e propone dei miglioramenti. Gli obiettivi dovrebbero essere piu precisi, meglio misurabili ed essere maggiormente destinati all’approvvigionamento sufficiente in tempi di crisi. E importante la disponibilita dei fattori di produzione, in particolare di suoli coltivabili, sementi, macchine, energia, concimi, prodotti fitosanitari e know-how. Occorre esaminare l’abolizione della «condizione di accompagnamento» come la densita minima di animali e la graduazione del contributo per superfici per la promozione della biodiversita. Per la sicurezza in materia di approvvigionamento e molto efficace la promozione di colture strategicamente piu importanti come patate, cereali panificabili, barbabietola da zucchero o colza nonche la preservazione di superfici coltivabili. Se gli obiettivi fossero meno incentrati sulla produzione di calorie, bensi maggiormente sulla preservazione dei fattori di produzione, i fondi liberati potrebbero essere utilizzati per colmare le lacune esistenti a livello degli obiettivi. La valutazione mostra inoltre che i fondi utilizzati contribuiscono considerevolmente ad assicurare il reddito nell’agricoltura, aspetto che va considerato nel caso di modifiche dello strumento. MultipleDepuis 2014, la Confederation a mis en place des contributions a la securite d’approvisionnement pour assurer l’approvisionnement de la population en denrees alimentaires. Avec 1,1 milliard de francs par an, ces contributions representent une part importante des paiements directs. L’Office federal de l’agriculture a mandate Agroscope pour verifier l’efficacite de cet instrument et proposer des ameliorations. Les resultats de l’etude montrent que les objectifs des contributions devraient notamment etre plus precis et plus faciles a mesurer. Ils devraient en outre se concentrer davantage sur la maniere d’assurer un approvisionnement suffisant en periode de crise. L’important, c’est la disponibilite des facteurs de production, en particulier les terres arables, les semences et les machines, l’energie, les engrais et les produits phytosanitaires ainsi que le savoir-faire. Agroscope a egalement etudie une eventuelle suppression de la «condition necessaire» prealable, telles que la charge minimale en betail et l’echelonnement des contributions pour les surfaces de promotion de la biodiversite. La promotion de cultures strategiquement importantes, comme les pommes de terre, les cereales panifiables, les betteraves sucrieres ou le colza, ainsi que la preservation des surfaces cultivables sont des mesures tres efficaces pour la securite d’approvisionnement. En axant les objectifs davantage sur le maintien des facteurs de production que sur la production de calories, les fonds ainsi debloques pourraient etre utilises pour combler les lacunes existantes. L’evaluation montre aussi que les moyens utilises contribuent pour beaucoup a garantir les revenus dans l’agriculture, ce qui devrait etre considere en cas de modification de l’instrument. EnglishSince 2014, the Swiss Confederation has made food-supply security payments to ensure the reliable supply of food to the population. At CHF 1.1 billion per annum, these account for a large proportion of direct payments. Agroscope has now tested the effectiveness of this instrument on behalf of the Federal Office for Agriculture, and is proposing improvements. These involve making objectives more precise and more measurable, as well as more strongly geared to sufficient supply in times of crisis. The availability of production factors – in particular, arable soils, seed and machinery, energy, fertilisers and plant-protection products, know-how – is important. The abolition of the ’accompanying constraint’ such as minimum animal stocking density and incremental subsidisation of biodiversity priority areas is to be examined. The promotion of strategic staple crops such as potatoes, bread grains, sugar beet or oilseed rape and the conservation of arable land are highly effective tools for achieving security of supply. If the objectives focused less on the production of calories and more on the conservation of production factors, the resources thereby freed up could be used to bridge existing target gaps. Furthermore, the evaluation shows that the resources used make a substantial contribution to income security in agriculture, which should be borne in mind when changing the instrument.

Food security payments: refining objectives and using resources more efficiently Since 2014, the Swiss Confederation has made food-supply security payments to ensure the reliable supply of food to the population. At CHF 1.1 billion per annum, these account for a large proportion of direct payments. Agroscope has now tested the effectiveness of this instrument on behalf of the Federal Office for Agriculture, and is proposing improvements. These involve making objectives more precise and more measurable, as well as more strongly geared to sufficient supply in times of crisis. The availability of production factors - in particular, arable soils, seed and machinery, energy, fertilisers and plant-protection products, know-how - is important. The abolition of the 'accompanying constraint' such as minimum animal stocking density and incremental subsidisation of biodiversity priority areas is to be examined. The promotion of strategic staple crops such as potatoes, bread grains, sugar beet or oilseed rape and the conservation of arable land are highly effective tools for achieving security of supply. If the objectives focused less on the production of calories and more on the conservation of production factors, the resources thereby freed up could be used to bridge existing target gaps. Furthermore, the evaluation shows that the resources used make a substantial contribution to income security in agriculture, which should be borne in mind when changing the instrument.

Economic and ecological assessment of scenarios for nutrient reduction in water bodies Four different scenarios for the reduction of diffuse nutrient inputs from agriculture to water bodies in Switzerland were analysed for the period 2010 to 2025 in a multidisciplinary project. The agricultural sector model SWISSland was used to examine the economic and structural effects, and the influence on the direct payments budget and sectoral income, following implementation of emission mitigation measures. The substance flow model MODIFFUS was employed to estimate the diffuse nitrogen and phosphorus inputs from agriculture into bodies of water. The agricultural life cycle assessment method SALCA was used to determine the environmental effects, including those of imported products. All four scenarios lead to extensification in arable farming and forage crop production. Depending on the scenario, nitrogen inputs from farmland are projected to decline by 5-25 % from 2010 to 2025, and phosphorus losses by 7-20%. Domestic production would decrease for many products and import volumes would rise. The reduction in nutrient inputs into water bodies in Switzerland would therefore lead to a shifting of environmental impact to other countries.

Quatre scenarios differents visant a reduire les elements fertilisants issus de l’agriculture dans les eaux en Suisse ont ete analyses pour la periode allant de 2010 a 2025 dans le cadre d’un projet multidisciplinaire. Le modele SWISSland a servi a etudier les repercussions economiques et structurelles pour le secteur agricole, ainsi que l’impact, sur le budget des paiements directs et le revenu agricole, de la mise en place de mesures visant a reduire les emissions. Le modele de flux de substances MODIFFUS a permis d’estimer les apports diffus de phosphore et d’azote provenant de l’agriculture dans les eaux. Les impacts environnementaux, produits d’importation compris, ont ete determines a l’aide de la methode d’analyse de cycle de vie SALCA. Les quatre scenarios conduisent a une extensification des grandes cultures et de la production fourragere. Dans ces conditions, de 2010 a 2025, les apports d’azote issus de la surface agricole utile diminuent de 5 a 25 % suivant le scenario et les pertes de phosphore de 7 % a 20 %. Pour beaucoup de produits, la production nationale baisserait, tandis que les quantites importees augmenteraient. Par consequent, la reduction des apports de substances dans les eaux en Suisse entrainerait une delocalisation des impacts environnementaux vers l’etranger.

Simulation results can be highly sensitive to the way agents are upscaled to a larger organizational and spatial level. This paper tests an ex-post validation method for forecasting models by using old base years and forecasting into recent years for which observed data is already available. Our case in point is a comparison between different upscaling methods in the agent-based agricultural sector model SWISSland. It is shown that individual-farm extrapolation factors strongly enhance alignment with the total population in the base year. However, they may cause inconsistencies in those agent-based models in which relations between the farms are an important part. Therefore, an adjustment of the sample by making almost no use of some farms whilst making highly disproportionate use of others turned out to be the most suitable method for the SWISSland model.

Simulation results can be highly sensitive to the way agents are upscaled to a larger organizational and spatial level. This paper tests an ex-post validation method for forecasting models by using old base years and forecasting into recent years for which observed data is already available. Our case in point is a comparison between different upscaling methods in the agent-based agricultural sector model SWISSland. It is shown that individual-farm extrapolation factors strongly enhance alignment with the total population in the base year. However, they may cause inconsistencies in those agent-based models in which relations between the farms are an important part. Therefore, an adjustment of the sample by making almost no use of some farms whilst making highly disproportionate use of others turned out to be the most suitable method for the SWISSland model.

This paper analyses the impact of tradable and non-tradable single farm payment (SFP) entitlements for farm successors on structural change and the lease market. Using the example of Swiss agriculture, the effects on rental-price trends and farm-exit rates are investigated. An ex-ante normative impact analysis is performed with the agent-based agricultural-sector model SWISSland, which simulates structural change processes and income trends in Swiss agriculture over a period of up to 15 years. A land market implemented at municipality level simulates the plot-by-plot leasing of land to surrounding neighbouring agents that is common in Switzerland. Allocation of plots to tenants as well as lease pricing is modelled taking into account the farm-specific land rents. The results show that personalised SFP entitlements which could not be transferred to a farm successor not only cause an intensification of structural change, but would also thus lead to a substantial reduction in rental prices. SFP entitlements which were successfully transferred to farm successors have only a slight impact on structural change and the rental prices of arable land. Only for grassland in the mountain region does a stronger shift result in a significant reduction in rental prices.

Le modele multi-agents SWISSland pour le secteur agricole simule les processus de changement structurel et les evolutions de revenu dans l�agriculture suisse. L�objectif est de representer les comportements des exploitations agricoles en demeurant le plus proche possible de la realite. Cet article decrit une methode pour deduire au mieux les coefficients de couts et de temps de travail qui ne sont pas explicitement disponibles sous forme de donnees comptables dans les activites de production des cultures maraicheres, branche de production heterogene. Il s�agit d�estimer les couts specifiques et le temps de travail necessaire a partir de la prestation brute par hectare specifique a l�exploitation. Les previsions realisees avec SWISSland pour le secteur agricole indiquent une tendance positive pour l�avenir, dans la mesure ou la politique agricole prevue pour 2014 a 2017 et la reforme du systeme des paiements directs seront mises en pratique.