Assessing plant soil water availability in drought conditions: A comparative analysis of conventional and minimum tillage, example from Slovenia

Tillage systems, such as conventional tillage (CT) and minimum tillage (MT), with reduced tillage and incorporation of surface crop residues, lead to changes in soil properties, including organic matter content and soil structure, and can alter water infiltration and water retention. This study aimed to assess plant soil water availability by observing soil water status and soil penetration resistance (SPR) in fields under CT and MT in two climate zones (Temperate Mediterranean and Humid Continental) and pedologically diverse river basins in Slovenia. Soil water content and matric potential were continuously measured throughout one growing season and SPR twice at all CT and MT fields with an identical crop rotation (maise - winter wheat - rapeseed/clover grass mixture) and tillage practice. Measurement indicates that, on average, matric potential between CT and MT in the study sites is not statistically different. The mean SPR was higher under MT in the first 30 cm soil layer. Soil matric potential categorised into four categories of plant-available water indicated severe drought conditions lasting for several months in most CT and MT fields. The findings suggest no statistically significant differences in plant soil water availability between the two evaluated tillage methods. Results indicate that a change in the tillage method alone did not substantially enhance plant water availability. Consequently, additional strategies, such as education, training, and support for farmers, alongside technological and technical measures advancements like irrigation and decision support systems, are necessary to adapt to climate change effectively and enhance plant water availability in agricultural soils.