No abstract

<p>Soil water content (SWC) and temperature (ST) are key parameters in farmland, but are difficult to predict. Under no-tillage (three mowing passes per year) and homogeneous ground (permanent cover of resident vegetation), soil (no significant difference within each soil layer) and topographic (steep and straight slope near the divide) conditions, this study quantified the index of temporal stability (ITS) of the soil hydro-thermic response in a rainfed organic vineyard with humid climate –in Galicia, NW Spain– and two cultivars (Agudelo –Ag– and Blanco Legítimo –BL–). By using 12 capacitance-based technology probes (six per cultivar: 3 per row (R) and 3 per inter-row area (IR)), SWC and ST were measured every 15 min at 5, 15 and 25 cm depth over the crop cycle (242 days). On average, wetter and cooler values appeared in Ag than in BL that may be associated with differences in vine water demand. IR had wetter and cooler conditions than R due to higher water consumption by vines. Time-series analysis was split into three periods: Drying and warming (spring), dry and warm (summer), and wetting and cooling (autumn). The vertical analysis of the relative differences (soil layers) showed that the lowest values of ITS<sub>V</sub> appeared at 15 cm in all cases for ST, regardless the hydro-thermic periods, vine varieties and field zones, and also at 15 cm for SWC, especially in R over the three periods, and during spring and autumn in IR. The prevailing conditions observed at this layer were the representative conditions of the field during the crop cycle. Conversely, the less representative conditions of the hydro-thermic status of the soil were those obtained in the upper-most layer in all cases of ST and almost all cases of SWC. At 25 cm, the representativeness of SWC and ST was intermediate, but the most representative conditions of SWC appeared at 25 cm during the summer. The horizontal analysis of the relative differences (zones and cultivars) revealed that the values of ITS<sub>H</sub> showed a homogeneous pattern of soil moisture: R always had more representative values of SWC than IR in the three layers and during the three periods. Regarding ST, the pattern was more variable and R only had more representative values than IR at 15 cm in summer and at 25 cm in spring and summer. The behaviour of SWC and ST differed in terms of temporal stability and spatial representativeness. When the varieties were analysed, BL had more representative values of SWC than Ag, but Ag always had more representative values of ST than BL. These findings explained the low correlation between ITS<sub>H</sub>-SWC and ITS<sub>H</sub>-ST. For the first time, ITS was calculated for SWC and ST in a woody crop. These findings prove the complex and distinct spatial and temporal dynamic of SWC and ST in a commercial vineyard, even under homogeneous physiographic conditions, and support the necessity of implementing precision farming practices based on soil water and temperature management.</p>

<p>This study evaluates the soil moisture response time to rainfall of a small vineyard with two varieties of grapes (Blanco legítimo –BL–, and Agudelo –Ag–) and a permanent ground cover of resident vegetation with numerous plant species (<em>n</em> > 12). No tillage was done and weed control included three mowing passes. The soil –Umbrisol–, is shallow (35 cm depth), stony (36.1% weight of rocks), rich in organic matter (7.2%) –specially in the topsoil (10.0%)– and no difference was observed throughout the field. The study area is located in the municipality of Betanzos (43° 15' 56.20" N; 8° 12' 1.32" W), A Coruña, Spain; under a temperate oceanic climate. The time of response between each precipitation peak and its corresponding peak of soil moisture was calculated for a 242-day period (26<sup>th</sup> February – 25<sup>th</sup> October 2021), covering the whole crop cycle. The determined parameters were: (I) volumetric water content (ΔS, %), (II) the peak to peak time (TP2P, min), and (III) the initial response time (Ti, min). A weather station was installed in the field, along with 12 capacitance-based technology soil moisture sensors, 6 in the rows (R) and 6 in the inter-row areas (IR) for the two cultivars. Each probe measured at 5, 15 and 25 cm depth, every 15 minutes. During the study period, a total number of 118 rainfall events were recorded, observing a clear response in 96, 82 and 75 events at 5, 15 and 25 cm depth. No response was observed in 22 events of low rainfall. To refine the analysis, three hydro-thermic periods were identified: Drying and warming (spring), dry and warm (summer), and wetting and cooling (autumn). In the events of longer duration, no defined patterns were observed in responses to moisture between the three layers, but differences were observed in response to rainfall at the depth of 25 cm. In rainfall events of short duration (15-30 min), the pattern in response to soil moisture at 5 and 15 cm was similar in the 3 parameters (ΔS, P2P and Ti). With respect to the minimum values, there was a rise of moisture within the profile, specifically, in R and an interspersed pattern in IR. For the maximum values, there was a descending pattern within the profile regardless the zone or variety with the exception of Ag in IR. In Ag cultivars, both variety and zone were affected by depth, with the lowest correlation at 5 cm. However, in BL cultivars the correlations did not vary clearly between depths or zones. In response to rainfall, the highest correlations were observed at 25 cm and the lowest at 5 cm for variety and zone. On average, Ti was 67, 127 and 160 min at 5, 15 and 25 cm, and P2P was 228, 344 and 378 min at 5, 15 and 25 cm depth. The hydro-thermic periods as well as the intensity and duration of the precipitation events clearly modulated the moisture response to rainfall in the studied soil.</p>