Spatiotemporal variability of soil-water content at different depths in fields mulched with gravel for different planting years

•The gravel-mulched field of northwestern China has a history of over 300 years.•The soil water contents in fields mulched with gravel for different lengths of time were analyzed.•The effect of period of gravel mulching on the spatial properties of soil water content was examined.•The data at various depths in four fields during 2013–2016 were analyzed.•The prediction accuracy of representative location was tested.