Effect of Acid and Sub-Soiling on Available Phosphorus in a Calcareous Rhodic Luvisol Planted with Two Corn Materials in Yucatan, Mexico

The optimal soil pH for maximum phosphorus (P) availability ranges from 6.0-7.0. When the pH values are alkaline, as in the case of the Yucatan Peninsula (YP), the availability of P, in its anionic form of H₂PO₄^-  can be reduced when reacting with the cationic forms of calcium (Ca² ) or magnesium (Mg² ). Deficiencies have been documented in different soils of the YP, including the red rhodic Luvisols. These soils, in addition to show chemical constraints, are facing other disadvantages such as the underground compaction due to intensive use of machinery for corn and other cultivated crops. However, applying agricultural acids and sub-soiling could overcome the problem. In this work, the effect of sulfuric acid and sub-soiling on P availability in a rhodic Luvisol was assessed. Statistical differences were found between treatments and the P-Olsen contents as compared to the Official Mexican Standard were above the average ranges of 5.5 to 11 ppm. In Chichen, a significant increase of P in the Rhizosphere was observed with acid, and the highest level (44.4 ppm) was with no sub-soiling (T4). No acid but sub-soiling (T1) had the lowest level of P in Chichen (19.80 ppm). In contrast, in the Hybrid the acid induced a reduc-tion of P contents, but with the same trend as Chichen, lower P when sub-soiling. Subsoiling itself, without acid application, can reduce P from 19% (Hybrid) to 25% (Chichen). Subsoiling can induce P losses by leaching since this practice increases the water infiltration.