Impact of COVID19 on winter cereals growth and harvest – Spain

It is now recognized that the lockdown due to COVID19 outbreak has led to severe restrictions in seasonal workers movements and to a sharp decline in demand on perishable produce such as fresh vegetables (e.g. asparagus) and fruits (e.g. red berries). It is also important to know if the pandemic could impact the growth or harvest of main staple crops as well and thus have a direct incidence on national food security. Even if staple crops are a priori less sensitive to a lack of foreign workers and a drop of demand, production could still be affected by shortages of inputs such as fertilizers and veterinary medicines or lack of labor and spare parts in case of farm equipment problems [1]. Such potential limitations create uncertainty in the food commodity markets which satellite Earth Observation (EO) can help reduce with timely and transparent information – a goal the GEOGLAM initiative is addressing [2].

In Spain, winter cereals are cultivated over around 1.975.000 hectares, corresponding to a production of 7.575.000 tons [3]. They are mainly found in the autonomous regions of Castilla y León, Andalucia, Castilla-la-Mancha and Aragón. These regions represent more than 80% of the national area cultivated with winter cereals and are responsible for a bit less than 80% of the national production. Castilla y León and Castilla-la-Mancha are in the top three EU regions for production of winter wheat and barley.

Sentinel-1, Sentinel-2 and Landsat-8 sensors offer a unique dataset to monitor the potential delay or disruption of the winter cereals harvest thanks to the combination of a high spatial resolution (10 meters enabling a parcel-based monitoring) and a very high temporal revisit (up to 2 or 3 days depending on the sensor). Time series of Sentinel-2 vegetation indices and Sentinel-1 backscatter and coherence values have been processed [4] and analyzed building on the open source Sen4CAP (and upcoming Sen4Stat) processing systems.

The harvest evolution is monitored in near-real time, at parcel-level over the whole country. Parcels dataset have been kindly shared by the national Paying Agency “Fondo Español de Garantía Agraria O.A.” (FEGA) which also provided advices on the results interpretation along with the regional paying agency of Castilla y León. Each week, the percentage of harvested parcels and harvested area has been computed and their cumulated proportion is reported and compared to 2019 for each autonomous region. The 2020 harvesting season started by mid of June which is later than the average crop calendar for winter cereals in Spain. Compared to 2019 it also shows a time lag which can be partly explained by a specific climatic situation in 2019 leading to an unusual early harvest last year [5].

Therefore, the assessment of COVID19 impacts on the 2020 harvest must consider the inter-annual variability caused by the specific climatic conditions in 2019. In any case, these satellite based indicators demonstrate existing capacities to monitor the growth and harvest of staple crops at national scale providing timely information on the winter cereal production in an uncertain situation during the COVID19 outbreak and its upcoming recovery.