Phosphorus movement in the topsoil layer after long-term surface broadcast amendment: field and controlled conditions studies

Phosphorus movement into soil profile might be increased when coupling no-till crop production with surface broadcast phosphorus (P) application. The objective of this study was to evaluate soil P movement in the topsoil layer affected by P application via surface broadcast and its availability evaluated by two soil test methods. Field research in a long-term experiment (Ultisol) was used to evaluate corn and wheat yields affected by P application. After 429 days we evaluated soil P distribution in topsoil layer. Laboratory research was carried out in soil columns to compare soil P movement in two different soils (Ultisol and Oxisol) affected by P application. In the laboratory research we evaluated soil P availability by Mehlich-1 and resin strips (previously buried) in different soil depths to access P movement into the soil profile 180 days after P application. Soil P movement in topsoil layer of field research increased according to P rates applied until 6 cm (Mehlich-1) and 10 cm (resin), while in laboratory research soil P movement evaluated by Mehlich-1 and resin was greater until 6 cm in the Ultisol and was greater until 2 cm in the Oxisol. Surface broadcast application of soluble P in rates above that those recommended to adequate crop yield increases soil P availability in concentrations higher than the critical level, mainly in soil surface increasing soil P movement in soil profile and more this effects is more evident in sandy soils.