SOIL CHEMISTRY AT PETOA: PHOSPHORUS

Soils were sampled on a 2 sq. m lattice grid that covered the eastern two-thirds of the plaza (36 m by 25 m), and were processed in the same fashion as those from El Coyote’s main plaza. The figure to the left shows the distribution of P concentrations. The cross shrine is marked in the lower right-hand corner of the map by high P concentrations that surround it. A path of high P is visible connecting the shrine to the southwest corner of the churchyard. Interestingly, the communal area around the tree is relatively low in P, compared to the space surrounding the shrine. This is probably the case because, as it has been observed, trash that accumulates around the benches is removed generally on a weekly basis and so phosphates would not be present long enough to be fixed to the topsoil. A temporary midden of plaza trash, including any materials deposited around the tree, often forms in the space between the tree and the shrine. This trash is either burned in situ or deposited elsewhere, usually once a week.