## 1 Introduction  
Climate change projections point to a substantial increase in greenhouse gas (GHG) emissions and a consequent rise in temperatures, extreme weather events, and water scarcity [1; 2], especially in certain regions, with southern Europe being a case in point [3; 4]. Agriculture, forestry, and other land use activities account for 22% of these emissions [1]. However, agriculture can also play an important role as a sink for atmospheric carbon, helping achieve a climate-neutral economy [5], as outlined in the Paris Agreement. Certain agricultural practices significantly enhance the ability of soils and crops to act as carbon sinks, thereby mitigating atmospheric CO\({}_{2}\) levels. Practices falling under the umbrella of conservation agriculture include no-till farming, crop rotation and cover crops to reduce soil disturbance, which helps maintain soil organic matter and sequester carbon in the soil [6; 7]. The Intergovernmental Panel on Climate Change (IPCC) defines carbon offset as \"A unit of CO\({}_{2}\)-equivalent emissions that is reduced, avoided, or sequestered to compensate for emissions occurring elsewhere\". In this sense, a carbon credit certifies that a practice hasremoved 1 ton of carbon dioxide (CO\({}_{2}\)) from the atmosphere [8]. Companies or individuals that demonstrate CO\({}_{2}\) sequestration practices can join the voluntary carbon market to receive economic compensation [9]. These credits can be traded in the voluntary carbon market, providing an additional revenue stream for farmers while contributing to global climate mitigation efforts. The growing interest in regenerative agriculture has further boosted the importance of this market, with studies indicating that such practices can significantly reduce the carbon footprint of farming operations [10; 11]. The terrestrial ecosystem stores 25-30% of anthropogenic CO\({}_{2}\) emissions [12; 13]. This carbon quantification demands a comprehensive understanding of Earth's complex biogeochemical processes. One of these processes, the relationship between Net Ecosystem Exchange (NEE), Ecosystem Respiration, and Gross Primary Productivity (GPP) is a fundamental aspect in understanding the carbon dynamics within an ecosystem. The GPP of ecosystems represents the total amount of CO\({}_{2}\) that plants convert into organic matter through photosynthesis [14]. NEE represents the net carbon flux, which is the difference between the carbon dioxide (CO\({}_{2}\)) uptake through photosynthesis during GPP and the CO\({}_{2}\) release through ecosystem respiration. Accurate quantification and accounting of GPP provide a robust framework for assessing ecosystem potential in sequestering atmospheric CO\({}_{2}\), with the subsequent implications for climate change mitigation strategies [15; 16]. In this context, understanding the carbon dynamics of specific agricultural systems, such as almond production, is crucial, as it contributes to our broader knowledge of the role different crop systems can play in carbon sequestration. A small number of studies have been published reporting values of the GPP for different woody crops, such as olive [17; 18; 19; 20; 21], citrus [22; 23] and apple [24; 25]. However, to the best of our knowledge, the literature lacks reports on important crops such as almond and other fruit tree species. In this sense, during the last 70 years, world almond production has increased with a linear trend of ca. 5000 tons per year, and the area of cultivation has grown ca. 2000 ha per year [26]. Spain is the country with the largest cultivated area of almond trees with more than 760,000 ha, followed by the United States of America with about 540,000 ha [27]. Specifically in Spain, there has been a significant increase in irrigated almond orchards over the last decade, reaching 142,000 ha (19% of the total harvested almond area) [28].