Phosphorus fractions in apple orchards in southern Brazil

• Main Authors: Djalma Eugênio Schmitt, Gustavo Brunetto, Elaine dos Santos, Winiciu de Lima Wagner, Paula Beatriz Sete, Monique Souza, Vítor Gabriel Ambrosini, Matheus Ademir dos Santos, Luciano Colpo Gatiboni, Admir Giachini
• Format: Article
• Language: English
• Published: Instituto Agronômico de Campinas
• Series: Bragantia
• Subjects: apple orchard; phosphate fertilization; P chemical fractionation
• Online Access: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87052017005008104&lng=en&tlng=en

ABSTRACT Phosphorus (P) applications at dosages higher than the necessary may cause P buildup in the soil labile fractions and, consequently, pollution of water sources. This study aimed to assess accumulation of P fractions as well as the parameters of adsorption isotherms in soil profiles having a history of application of phosphate fertilizers and cultivated with apple trees. Soil samples were collected from an area with no history of cultivation and 2 apple orchards cultivated for 8 (P8) and 18 (P18) years, in the city of Urubici, Santa Catarina, southern Brazil. Soil samples were air dried, sieved in a 2-mm mesh, and subjected to chemical analyses (P adsorption) besides P chemical fractionation. Applications of phosphate fertilizers to the orchards, particularly P18, increased the inorganic and organic concentrations of P in all fractions. The distribution of P in organic and inorganic forms in the planted soils was similar to the distribution observed for the native vegetation soil. The highest inorganic labile P fraction, the lowest maximum P adsorption capacity, and the highest equilibrium concentration values at P18 are indicators of a higher environmental pollution risk of the orchards soils compared to the native soil.