Tillage effects on the spatial dependence of above-ground biomass of wheat and maize were studied in one-year two-crop rotation in a field of Humic Andosol. Minimum tillage (MT) plots were tilled with a rotary tiller and conventional tillage (CT) plots were tilled with a moldboard plow and disc-harrowed. Above-ground biomass was measured at harvest at 10 locations with 5 m spacing on two along-row lines in each plot. The existence of spatial dependence was examined with the range obtained by fitting the linear model to semivariograms. The frequencies of spatial dependence with range larger than 5 m were 46 % (MT) and 62 % (CT) for wheat and 27 % (MT) and 42 % (CT) for maize. The frequency of spatial dependence was apparently higher under CT than under MT and values for the range were larger under CT than under MT. Wheat showed stronger spatial dependence than maize, showing higher proportion of semivariograms with spatial dependence. Conventional tillage seemed to enhance the feasibility of site-specific soil and crop management (SSCM) in the direction of farming operations.
Above-ground biomass, Precision farming, Site-specific soil and crop management, Spatial dependence, Tillage.