Modeling inter-row grass growth, soil water content and carbon cycle in vineyard

The agriculture sector plays a contrasting role in climate change mitigation, which results from the balance between carbon sequestration capacity of soil and perennial crops (e.g. vine) and, the negative impact of the highly productive cropping systems characterized by elevated greenhouse gases (GHGs) emissions. In the Mediterranean agricultural sector, viticulture represents a widely spread activity, which may partially contribute, if sustainably managed, to carbon sequestration and to the challenge against climate change. However, the high inputs and some agronomic practices may potentially increase GHGs emissions, by converting this activity from carbon sink to carbon source. In this context, crop models implemented for describing biogeochemical cycles (carbon, nitrogen, water, etc.) may provide an overview of the GHGs mitigation potentiality of these systems. However, to our best knowledge, no crop models were so far developed for assessing the entire vineyard agro-ecosystem carbon emissions considering also the role of management in the carbon cycle. With these perspectives, the original UNIFI.GrapeML model (Leolini et al., 2018) was improved by coupling it with the soil carbon module RothC (Coleman & Jenkison, 1996; Sierra et al., 2012), in order to estimate the soil water content (SWC), the gross primary production and the respiration of vine and grass components jointly with the soil respiration. In this work, we present the new integrated model architecture and the preliminary calibration results for the inter-row grass growth and SWC of a ‘Barbera’ vineyard located in Northern Italy (Lat: 44°40’ N; Long: 8° 37’’ E) in order to assess the contribution of the grass cover to carbon and water cycles. The preliminary results showed satisfactory performances at simulating inter-row grass dry matter under grass cover (GC: r = 0.68; RMSE = 76.33 g m-2 d.m.) and conventional tillage (CT: r = 0.60; RMSE = 60.58 g m-2 d.m.), as well as to reproduce SWC for both managements (GC: r = 0.79; RMSE = 0.06; CT: r = 0.70; RMSE = 0.06). These results lay foundations to test the multi-layer vineyard model for carbon and water fluxes in other vineyards, in the perspective to provide a new accurate tool for improving carbon footprint and life cycle assessment analysis with estimates of carbon emissions from cropping systems.