APPLICATION OF DISJUNCTIVE COKRIGING TO COMPARE FERTILIZER SCENARIOS ON A FIELD-SCALE

To evaluate the effect of various levels of fertilizer applications, six fertilizing scenarios were analyzed by computer simulations using a process-based simulation model. By using simulation results of one of the fertilizer scenarios as a covariable in disjunctive cokriging (DCK), the number of simulations in the remaining scenarios could be reduced to 20% of the original number, while the prediction quality in fifty test points still satisfied two criteria based on the sample variance. When the conditional probability of exceeding a threshold value is to be mapped, an expanded data set is of limited use because some variance is lost in the expansion process.