## 1 Introduction  
According to _Agrimonde_ (_Scenarios and Challenges for Feeding the World in 2050_), the increasing rate of agricultural production will be considerably lower than in previous decades, with an estimate of 1.15% per year for the 2003-2050 period [1]. Hence, more than 9000 million people will have to be fed in 2050 [2]; to meet the demand for food in 2050, agriculture will have to produce almost 70% more [3]. Potato crops have been increasing their production since 2012, more in the developing world than in developed countries [4]. The environmental cost to achieve this purpose could be very high, considering that agriculture is a major contributor to global greenhouse gas (GHG) emissions [5]. However, agriculture also represents a carbon sink, capturing atmospheric carbon dioxide (CO\({}_{2}\)) into the biomass and soil. [6] This is the paradox of agriculture, from the point of view of climate change, which can contribute to both climate change and its mitigation. In terms of mitigation, a key ecosystem process to decrease the atmospheric CO\({}_{2}\) is to remove it from the atmosphere by increasing the vegetation carbon sequestration or uptake [7] during photosynthesis, as gross primary productivity (GPP). However, GPP can greatly vary across biomass, as it is strongly influenced by multiple meteorological drivers [8]. In optimal water availability conditions, the photosynthetic photon flux density (PPFD) is the main factor driving GPP [9]. However, under water-limited conditions, Soil Water Content (SWC) deficit leads to a depression of the rate of carbon uptake [10], hence, reductions in GPP. Under water-limited conditions, an SWC increase could increase GPP, indicating that irrigated agriculture has a potential role as a carbon sink [9]. Irrigation systems could slow down the return of stored carbon as CO\({}_{2}\) via respiration and improve the photosynthetic input of carbon [11]. However, about 82% of the total agricultural land in the world is under rainfed agricultural systems [12], and potato crop fields are no exception. In Colombia (2019), 78% of the total area potato production had no irrigation. These differences in crop water management might imply differences in GPP and CO\({}_{2}\) sink potential that are currently unknown. Several methods have been used to estimate GPP, using an extrapolating chamber and biometric measurements [13], also canopy process modeling [14]. However, the eddy covariance (EC) technique has been recognized as the most efficient method for measuring fluxes of energy, CO\({}_{2}\), other GHG gases, and water between the terrestrial biosphere and the atmosphere, on an ecological scale [15], and at the whole production system level. Previous potato GPP estimations using the EC method in non-tropical conditions have reported high carbon uptake of potatoes and relatively larger magnitudes of GPP than other crop sites [16]. However, there is a lack of detailed information about carbon balances and key factors that control GPP related to water availability and management. Additionally, the available studies were carried out in non-tropical conditions, which may imply different biophysical and eco-physiological responses of the growing agroecosystems to climate drivers. Potato is an important agroecosystem for worldwide carbon and GHG balances due to its sizeable cultivated area (more than 19 million hectares) [17] and its extraordinary adaptive range. In Colombia and the world, potato is the primary source of income of thousands of small-scale producers and the most crucial staple food, playing a significant role in the maintenance of food security and nutritional status [18]. This study reports CO\({}_{2}\) fluxes and GPP determinations from rainfed and irrigated potato fields in Cundinamarca, Colombia. We hypothesized that the GPP responses are largely determined by the soil water content (SWC) as a direct consequence of irrigation practices.