Analysis of spatial variability of soil characteristics and crop yield under subsurface drainage

Research of spatial structures of soil properties and crop characteristics is essential on improving farm management level. The spatial variability of soil water content, salinity, and sodicity at different soil depths, as well as crop height and yield in a cornfield (Zea mays L.) with subsurface drainage was calculated and analyzed. The experimental results indicated that the autocorrelation distances of soil moisture contents at various depths were smaller than 5 m except at the depth of 0.3～0.6 m, in which it was 20 m. The autocorrelation distances of electric conductivity (EC) and sodium adsorption ration (SAR) in saturated soil paste extracts increased with soil depth but decreased during corn growth period, and they usually were less than 40 m. The autocorrelation distances of corn height, dry matter weight, and grain yield were 20～25, 10, and 22～42 m, respectively. Corn height and yield were positively correlated with soil water content but negatively with soil salinity. Soil salinity affected on crop grain yield more seriously than on dry matter formation, so saline soil is more suitable to growth of forage crops.