Table 3. Semi-variogram analysis of SOC and STN and its parameters.

Soil nutrients‡	Data Item	Active lag distance(m)	Lag interval(m)	Model	Nugget C 0	Sill C 0+C	Nugget/Sill C 0/(C 0+C) (%)	Range (m)	R 2
SOC	residual error(RK)	1285.15	280	Spherical	0.0100	6.5230	0.2	365	0.996
STN	residual error(RK)	1285.15	280	Gaussian	0.0001	0.0779	0.1	424	0.915
SOC	raw data(OK)	1285.15	250	Spherical	0.6500	6.5740	9.9	288	0.880
STN	raw data(OK)	1285.15	250	Spherical	0.0031	0.0817	3.8	399	0.908

“‡” SOC  =  soil organic carbon; STN  =  soil total nitrogen; RK  =  regression-kriging; OK  =  ordinary kriging.