preplant (before water application) and subjected to the

 rainfall of the first field-planting season.

 (c) 400 kg/ha of 20-10-10 plus 50 kg P/ha as TSP applied before
 water application, but subjected to the rainfall of the

 second planting season.

 (d) 400 kg/ha of 20-10-10 divided such that 100 kg/ha was
 applied with 50 kg P/ha (TSP) before the addition of water

 to the column, and the remainder of split into 100 kg/ha

 portions applied after 4, 8 and 12 wk of simulated field

 "rainfall"; and

 (e) 1600 kg/ha of 20-10-10 and 450 kg P/ha as TSP applied before
 water application and subjected to the rainfall of the first

 planting season.

 The actual fertilizer rates applied to the columns were based on

the surface area of the column, and were three-fold those applied in the

field. This was to account for the field application of fertilizer in a

33-cm band within a 1-m row. The top 10 cm from each column were

removed, mixed with the appropriate preplant fertilizer, and replaced in

the column before addition of the first applications of water. Split

fertilizer applications were spread evenly over the surface of the

soil.

 Following the last simulated rainfall and solution-extraction

event, the columns were cut into 5-cm segments and each segment was

analyzed for gravel content, organic carbon, Mehlich I-extractable P,

Ca, Mg and K, and 1 M KCl-extractable Ca and Mg.