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Fig. 1. Soil series maps and location of the soil samples collected from (a) Field A and (b) Field B in Shiawassee County, MI, in 1999 and 2000, and (c) nested sampling design with geometric progression–reduced distances. Distances between pairs of samples are indicated; the direction in which two consecutive samples were oriented was randomly selected. This design was applied within 50- by 50-m cells of a grid centered in each field. In Fig. 1a and 1b, black circles indicate sets of sample locations in selected cells for both 1999 and 2000, and the crosses indicate the locations of the additional samples collected in 2000 from alternate nodes of a 25- by 25-m grid. Soil series maps were digitized from Threlkeld and Feenstra (1974).
