Effects of land use on spatial patterns of soil properties in a rocky mountain area of Northern China

In the rocky mountain area of North China, soil fertility has decreased with severe soil and water losses under various land uses. Land use has been proven to affect soil fertility spatial distribution patterns at larger scales. However, less information is available about these effects in field scale plots. Soil samples were collected at 2-m intervals by grid sampling from an area (18?×?18 m) within three land use types (poplar woodland, rotation cropland with peanut and sweet potato, and peach orchard). Soil properties including soil particle composition, soil organic matter, total nitrogen (TN), nitrate nitrogen (NO₃ ^?-N), total phosphorus (TP), and available phosphorus (AP) were measured for each sample. The spatial variability and spatial pattern of the soil properties were assessed for the three contrasting land use types. NH₄ ⁺-N, NO₃ ^?-N, and AP in the peach orchard and NO₃ ^?-N in the poplar woodland exhibited strong variation (coefficient of variance >100 %). Other properties showed moderate variations. With annual plowing and fertilization, soil properties in the rotation cropland had less variability and greater spatial autocorrelated ranges. The spatial dependences of sand content, TN, NO₃ ^?-N, and SWC in both the peach orchard and the rotation cropland were weaker than those in the poplar woodland, but the spatial dependences of TP and AP in the peach orchard were stronger than those in either the rotation cropland or the poplar woodland. Human activities such as plowing, fertilization, and harvesting had obvious effects on the spatial variability and spatial pattern of soil properties.