Multi-scale variability of soil salinity in the Yellow River Delta

Abstract

Analysis and interpretation of spatial variability of soil salinity is a keystone in site-specific farming. To better understand patters of multi-scale spatial variability in soil salinity, soil samples (30 to 40 cm depth) were collected with separation distances of 0.04, 0.2, 1 and 6 km in the Yellow River Delta of China. Laboratory measurements of soil salt content were also made from these samples (n = 239). Moran's 1 autocorrelation coefficient was computed at preselected lag distances and correlograms were plotted to examine trends in autocorrelation. Spatial autocorrelation was found at scales ranging from 0.7 km to more than 75 km, depending on the sampling scale considered. A correlation range in regional scale appeared to be associated with elevation height, while a shorter range in field scale was likely influenced by alternating land use / land cover or microtopography types. Moran's I correlogram calculated with salinity data from all of the sampling locations suggested spatial pattern detection for soil salinity can be achieved with a sampling interval of approximately 2 km or less. The magnitude and spatial patterns of soil salinity have implications for devising appropriate schemes to improve land productivity and design of soil sampling strategies in the Yellow River Delta.