Assessing marginality of Camelina (C. sativa L. Crantz) in rotation with barley production in Southern Europe: A modelling approach

Camelina (C. sativa L. Crantz) is a promising biofuel crop with high potential for cultivation on marginal soils. In this work, seed yields have been modelled to assess suitable areas based on experimental field trials, meteorological data from the Monitoring Agricultural ResourceS (MARS) gridded agro-meteorological in Europe, soil properties from LUCAS, topography and land cover. Potential yields for Camelina-Barley rotation (CAMBAR) were modelled for the past 20 years using the mechanistic crop growth model ARMOSA that can estimate quantitatively several soil and water parameters and future forcing scenarios (RCP4.5 and RCP8.5) using the generation model HadGEM2-ES. The term marginal land is found in the literature to indicate unused agriculture land such as abandoned, underused, degraded and fallow. In this work, marginality is considered the economic feasibility of cultivation, which aims to identifying land where cost effective agricultural production is not possible under a given set of conditions. Marginal lands were identified when the average Camelina seed yield from the crop growth modelling was lower than average in European countries based on a comprehensive literature assessment. The analysis was targeted at regions with a predominantly Mediterranean climate. Simulation by the mechanistic crop model was carried out on a 25 km grid for soil texture, soil carbon average stock, slope and aspect found in the MARS agricultural area mask. Spatial data and subsequent editing and processing of each simulation were allocated to a 500 m spatial resolution via a Geographic Information Systems (GIS). The study area covers around 500,000 km2. The CAMBAR scenario obtained an average yield of 2468 kg ha-1 yr-1, with standard deviation (+- 641) due to fluctuations for extreme weather patterns. Regarding soil organic carbon (SOC), CAMBAR showed an increase of + 43 kg ha-1 yr-1, which aligns with other studies carried out in Mediterranean or continental climates under crop rotation with minimum tillage and straw retention. The results of the present scenarios showed a slight increase in SOC stock (0.1–0.15 % yr-1). In regions with sufficient precipitation throughout the crop cycle, the increase of SOC is lower than the entire study area average, and in few cases, the SOC stock was drastically decreased. However, the model shows that SOC stock can increase when Camelina is introduced in rotation with cereals in areas with high desertification risk. In Spain, in the regions of Castilla La Mancha, Castilla y León and Comunidad de Madrid accounting for 40% of the total area of investigation in Spain, equivalent to an area of 88,233 km2, the SOC increase was + 188, + 255 and + 236 kg ha-1 yr-1, respectively. The results of this work constitute a key contribution to policy development at the sub-national, national and EU level, through the investigation of low LUC/ILUC biofuel from marginal areas before these are lost due to land degradation processes and other anthropogenic impacts. Mapping the marginal areas is fundamental to showing potential for producing advanced biofuel crops.