Dynamics of soil water content during depletion cycles in peach orchards in a semiarid region

Due to the competition for water resources, increasing efforts are done in order to use more efficiently irrigation water in agriculture. The purpose of this paper is to find out daily soil water content (SWC) dynamics during depletion cycles in order to emphasize its pattern and compare daylight vs. night (dark) and morning vs. afternoon SWC dynamics in an irrigated peach (Prunus persica [L.] Batsch) orchard under various soil water regimes. To do this, four depletion cycles were studied after irrigation application in two treatments: fully irrigated (T1) and water stressed (T2), in a semiarid region of Romania. Soil water potential was continuously measured with Watermark resistance blocks. Daylight soil water discharge (SWD) is higher than night SWD (1.87 ratio in T1 and 1.50 in T2) mainly due to solar radiation (Rs), higher vapor pressure deficit (VPD), and wind speed (U), with crop transpiration and crop water uptake being higher during daylight vs. nighttime. SWD during 14:00-20:00 h is greater than 08:00-14:00 h due to higher afternoon values of air temperature (T), VPD, and U. The results help understand better the relations between the daily dynamics of SWC and Rs, T, VPD, and U, and could be utilized by fruit growers to improve water management and conservation in semiarid regions with similar environmental conditions.