Effect of mulch on soil moisture and temperature under golden currant (Ribes aureum Pursh.) plantation and their effect on some plant parameters

Golden currant cultivars 'Laila' and 'Uzbekistanskaya Krupnoplodnaya' were planted in 2017 at Jelgava, Latvia. The vegetation seasons of 2019 and 2020 are described. Plots with pine tree bark mulch in 10 cm depth and bare soil were established. The goal of the study was to reveal an effect of organic mulch on soil moisture and temperature in connection with development parameters of the plants. Soil moisture samples were taken from two layers, 0-20 and 20-40 cm, and temperature was measured in 5 and 25 cm depth periodically in the season. In 2019, significantly higher soil moisture in mulched (15.2-19.6%) than bare soil plots (12.5-16.2%) was observed in layer 0-20 cm, and moisture content decreased slowly in both variants until July 1; later moisture increased because of rainfall. In the depth 20-40 cm it changed less in time (14.7-19.5%) with no significant differences between mulched and bare soil plots. In reality, soil in both variants and depths stored water well despite water deficiency period from April 1 to July 1. In 2020, when most of the season rainfall was at equilibrium level or higher, significantly higher soil moistures were observed only in April 19 and August 18 in mulched plots in level 0-20 cm and general tendency of higher water content on top soil level under the mulch layer were maintained. Tendency was observed that soil in the depth of 20-40 cm contained more water than in the depth of 0-20 cm, though only after prolonged dry period in July 1, 2020, this difference was significant. Soil temperature was significantly higher in bare soil plots in 5 cm depth compared to mulched plots and 25 cm depths, all temperatures levelled off only after August 2. No significant differences in shoot growth and yield were found between cultivars, as well as between mulched and bare soil plots. Also differences in full bloom date were small, all plants reached that stage within the same 3 days. Lower temperatures in the mulched plots could negatively influence root activity thus neutralizing the effects of improved water regimes on plant growth and development.