TY - EJOU AU - O, Barresi AU - Chiocchio, VM AU - Lavado, RS TI - Changes in soil phosphorus fractions caused by cropping without nutrient reposition. A case study T2 - Phyton-International Journal of Experimental Botany PY - 2018 VL - 87 IS - all SN - 1851-5657 AB - Previous studies in soils of the Pampas region indicate the prevalence of calcium phosphates within the very complex mix of phosphorus (P) compounds in the soils. We studied the changes in P fractions in a punctual situation in the Pampas region. The sampling was carried out in a farm located near the city of Junín (-34.585; -60.9589) and the soil was Junín series Typic Hapludoll. The farm was devoted to grazing and sporadic crops, but from the last 30 years changed to continuous agriculture. At no time fertilization matched nutrients removal by crops. The soil P fractions were determined using an improved version of the classical Chang and Jackson method. Phosphorus linked to calcium decreased in absolute and relative terms (49.1%) and P linked to aluminum and iron increased (144.8 and 100.4%, respectively). However, the proportion of latter fractions was affected by the changes in organic and residual P fractions. If present punctual finding could be generalized, it would indicate a change in the composition of P fractions in the most cropped soils of the region. KW - Phosphorus fractionation; Calcium linked to phosphorus; Mollisols; Effect of agriculture DO - 10.32604/phyton.2018.87.014