Disjunctive Kriging in Agriculture

Abstract

Farmers apply fertilizers, treat their land or livestock with trace elements and apply remedial treatments for salinity on the basis of estimates from soil samples. If the estimates are less than specified thresholds (for plant or animal nutrients) or more (for salt concentration) then farmers are advised to act. Such estimates are subject to error, and farmers should be better equipped to make their decisions and avoid risks if they know the probabilities of deficiency or toxicity.

Disjunctive kriging should be valuable in these circumstances, and this paper describes feasibility studies of its application to agriculture. The paper presents variograms of the phosphorus status of an arable farm in eastern England, cobalt deficiency in the soil of southeast Scotland which causes poor health in sheep and cattle there, and salinity in the Jordan Valley of Israel. It maps the estimated concentrations of these in the soil and the conditional probabilities that the true values are less than the recommended minima for phosphorus and cobalt, and exceed the recommended maximum for salinity.