Spatial variation analysis of soil characteristics and crop growth across the land-partitioned boundary. 1; Spatial variation of soil physical properties.

To study spatial variability of soil physical properties across the land-partitioned boundary on Hwadong silt clay loam soil (Fine clayey, mixed, mesic family of Aquic Hapludalfs), all measured data were analyzed with kriging, fractile diagram, smooth frequency distribution, and autocorrelation. Sampling for soil particle size distribution analysis was made at 225 intersections of 15 x 15 grid with 10m interval. Field capacity, bulk density and saturated hydraulic conductivity were measured at 594 intersections of 33 x 18 grid with 2.5m interval in only 6,000m** (2) reselected from 22,500m** (2) of sampling area. Measured soil depths were 0 to 10cm, 25 to 35cm and 50 to 60 cm. The coefficient of variance (CV) of various physical properties ranges from 4.8 to 128.8 %. Saturated hydraulic conductivity is classified into the high variation group with CV greater than 100 %, while the low variation group with CV smaller than 10 % consisting of bulk density. Other properties belong to the medium variation group with CV between 10 and 100 %. The number of soil samples for the determination of various physical properties with error smaller than 10 % are calculated as 1 for bulk density, 6 for field moisture capacity, 16 for silt, 19 for clay, 69 for sand and 686 for saturated hydraulic conductivity. Smooth frequency distribution and fractile diagram show that saturated hydraulic conductivity is in log-normal distribution. Serial correlation analysis reveals that soil physical properties have spatial dependence between 2 nearest neighbouring grid points. Autocorrelation analysis of physical properties measured between the serial grid points in the direction of south to north following section boundary shows that the zone of influence has stationarity ranges from 7.5 to 40m. In the direction of east to west across section boundary, the autocorrelogram of many physical properties shows peaks with the periodic interval of 30m which are similar to the partitioned land width. This reveals that the land partitioned boundary causes soil variability.