Influence of Soil Management on the Spatio-temporal Organization of Soil Moisture at the Field Scale.

Soil water content is a key variable for numerous physical, chemical and biological processes that take place at or near the soil surface and can therefore be considered as the most important link between the global energy, water and carbon cycles that govern the interactions between climate, soil and vegetation. In a context of changing global hydrological and biogeochemical cycles, efficient soil moisture monitoring becomes increasingly necessary in numerous agro-environmental applications at different spatio-temporal scales.

Spatial soil moisture patterns were monitored using a network of 90 low-cost capacitive soil moisture sensors that covered six 15 x 180 m experimental plots, subject to conventional and no tillage management. Seventy-two sensors were installed at a depth of 30 cm and 18 at a depth of 60 cm. Soil spatial variability was characterized using apparent electrical conductivity (EC_a) measured with an electromagnetic induction device (EM38-DD), and soil texture and the soil water retention characteristics (SWRC) at the sensor locations were determined in the laboratory.
The spatio-temporal soil moisture dynamics reflected clearly the effect of the differed soil management, and could be explained by differences in the SWRC. In addition, temporal stability of the spatial soil moisture pattern could be observed, especially in the direct drill plots, and was associated with EC_a and topography.
The prediction of temporally stable soil moisture patterns from readily available soil physical properties or surrogate variables can simplify and increase the cost-efficiency of monitoring networks for agro-environmental applications.