The effect of plot-level soil erosion risk exposure on soil conservation schemes adoption: The case of the reduced tillage scheme in Switzerland

Summary

Agricultural production is the primary cause of soil erosion worldwide (Borrelli et al., 2017; Wuepper et al., 2020). On average, 2.8 tonnes per hectare are eroded globally per year, equivalent to a total of 35.9 billion metric tons of soil per year (Borrelli et al., 2017; FAO, 2017). Soil erosion, which occurs at up to 100 times the rate of natural soil formation in conventional tillage systems, has major negative impacts on land productivity and thus also for long-term food security and economic viability of agriculture. Degradation of the soil via soil erosion greatly affects the capture and retention of carbon and other nutrients in the soil (Borrelli et al., 2023; IPCC, 2019; Sartori et al., 2019). Likewise, soil degradation also contributes significantly to soil-based emissions of carbon that is currently held in the soil, of up to the equivalent of 1.2 billion metric tons of carbon per year (Chappell et al., 2016; Lal, 2003). These impacts are likely to be further exacerbated and compounded by changing weather patterns due to climate change (Borrelli et al., 2020). Given that soils contain approximately 80% of the terrestrial organic carbon stock and that soil is critical for food production, preventing soil erosion is of great interest to policy makers to help meet the challenges of climate and a growing population (FAO, 2019; IPCC, 2019; Lehmann et al., 2020; Panagos et al., 2020, 2016).
In efforts to incentivize greater use of soil conservation practices, and to help alleviate some of the uptake costs, the Swiss federal government offers several incentive schemes to promote the protection of arable soils. Farmers have the option to enrol in a range of the production system schemes managed by the FOAG, which include the reduced tillage subsidy scheme and the continuous soil cover scheme. Under the reduced tillage scheme, farmers can earn up to CHF 250 (≈ 290 USD) per hectare enrolled for performing cultivations that are less intensive on the soil. For the continuous soil cover scheme farmers must maintain continuous plant coverage on the enrolled area through the crop rotation, minimizing bare periods by planting cover-crops or green manures to ensure soil coverage, for which they earn CHF 200 per hectare. Both reduced tillage and maintenance of soil cover have been shown to reduce the risk of soil erosion as well as improve the overall health of the soil (Adetunji et al., 2020; Chahal et al., 2021; Cooper et al., 2020; Jordon et al., 2022; Krauss et al., 2022). While farmers can voluntarily enroll in such schemes, the measures are often costly and/or complicated for farmers to introduce without support and/or the right equipment, and consequently the actual participation in the schemes may not effectively target the most problematic areas spatially.
Theoretically, soil erosion on a given farmer's field should result in a loss of utility of that field to the farmer in the medium and long-term. Accordingly, one would expect that farmers with a greater exposure to erosion risk will more actively orientate their crop management choices to mitigate the risk. However, in practice, farmers often make cropping and cultivation decisions on a shorter-term basis, and these decisions do not only consider the soil erosion risk. The theoretical loss in utility from higher soil erosion risk exposure, which could be difficult for a farmer to evaluate or prioritize, likely gets crowded out by the perceptions of greater short-term utility gains from pursuing other production strategies. The complex combination of factors affecting soil protection practice adoption likely also reduces the financial pain inflicted in the short-term if the soil quality of the plot is actually degraded, meaning that the realized incentives to protect and improve the soil may be less than would be desirable to meet policy goals.