Quantifying moisture availability in soil profiles of cherry orchards under different irrigation regimes

Abstract

Quantification of the availability of soil moisture at different depths of the soil profile to crop water uptake facilitates the development of scientific water management strategies. A three-year field irrigation experiment was conducted in a cherry orchard in north China under three micro-irrigation under mulch (MIM) situations, and furrow irrigation (FI) was set as control treatment. The objectives of this study were to (i) study the dynamic variation of soil moisture at different cherry tree growth stages; (ii) further quantify the contribution ratio of soil moisture to water uptake of cherry tree by employing hydrogen isotope abundance measurement; and (ⅲ) finally discuss the mechanism of specific contribution ratios under different irrigation regimes. The contribution ratio of soil moisture to water uptake of cherry tree in the main root zone (0–60 cm) was significantly enhanced by three MIM treatments. When compared with FI, the contribution ratios were increased by 11%–28%, 49%–59% and 16%–33% during the leaf expansion stage, flowering stage and maturation stage, respectively. Moreover, a significant linear relationship (P < 0.05) between the contribution ratio and the dynamic variation coefficient of soil moisture was achieved, indicating that the contribution ratio estimated by hydrogen isotope abundance was consistent with the actual variation of soil moisture in the profile. Further analysis revealed that a higher NO3-N concentration and better coupling of water and nitrogen fertilizer in the main root zone may lead to higher contribution ratio of soil moisture to cherry tree water uptake under MIM treatments.