The effects of land use on soil moisture dynamics in loamy soils of southwest hungary

Over the past, increasingly severe hydrological extremes, droughts, floods, and changes in soil moisture have been significant consequences of climate change in the Carpathian Basin. These changes adversely affect agricultural yields, soil hydrological processes, leading to water scarcity, substantial economic damage, environmental losses, a reduction in surface water, and declining groundwater levels.

In this study, we aimed to compare the soil moisture dynamics (SM) of three land use types (pasture, ploughland, and orchard). All sites had soils of silt loam texture. As a second objective we aimed at analyzing the applicability of Hydrus 1D for simulating soil moisture dynamics in silty loam soils under three different land use types.

The three study areas are in the Transdanubian Hills (SW Hungary), a region of subhumid continental climate where matric potential, soil moisture, and rainfall were measured for the period of January 1, 2019, till February 28, 2023, for three land use types. Two monitoring stations were set up at each study site, one shoulder and a second one at foothill position. Volumetric soil moisture contents and matric potentials were measured at depths of 10 and 30 cm at each station (Teros-12 and Teros-21, respectively, Meter Group Inc., Pullman, WA, US). Data was stored in 15-minute intervals. The Blaney- Criddle formula was used for calculating aridity indices (ratio of annual evapotranspiration to annual precipitation total) for the summer of 2022.

Although the three sites were in relative proximity to each other, pasture had the most positive water balance, whereas orchard had the most negative, especially in 2022, when cherry trees were removed. Aridity indices in 2022 were 0.97, 1.18, 1.42 for the pasture, ploughland and orchard, respectively. Mean soil moisture values were 0.26, 0.21, and 0.21 (m³ m^-3 ) for the pasture, ploughland and orchard for 10 cm, and 0.3, 0.22, and 0.22 (m³ m^-3 )  for the pasture, ploughland and orchard for 30 cm, respectively. Pasture also demonstrated the lowest fluctuation of SM, whereas ploughland proved to have the poorest soil moisture dynamics over the studied period.

For the sensitivity test of Hydrus-1D, the largest difference was found for the orchard site at a depth of 30 cm in a shoulder position (RMSE = 0.029), whereas lowest difference was observed for the pasture at a depth of 10 cm in a foothill position (RMSE = 0.021).

We conclude that soil moisture dynamics was controlled by the cultivation methods. Our results confirmed the findings of (Horel et al., 2022) who found negative climate change effects on the SM content of vineyard and cropland soils. Hence, site-specific mapping and analyses of factors responsible for efficient moisture retention are indispensable for the maximization of agricultural productivity and the optimization of the efficiency of ecosystem services. Our findings could be valuable for the promotion of sustainable agricultural activities where loamy soils and subhumid continental climates prevail.