Abstract

POSE, Nélida Nancy; ZAMUNER, Ester Cristina  and  ECHEVERRIA, Hernán Eduardo. Degree of saturation and risk of phosphorus loss in a mollisol under a potato crop in Southeastern Buenos Aires. Cienc. suelo [online]. 2012, vol.30, n.1, pp.01-08. ISSN 1850-2067.

Phoshorus (P) loss by runoff, erosion, or leaching through the profile increase with high concentrations of available P and favorable conditions for transport. The P loss potential from a Typic Argiudoll cultivated with potato and fertilized with P was estimated with some indicators. Soil samples were taken from two trials with four P fertilization treatments (0, 100, 200 and 400 kg P ha-1) in a randomized complete block design with three replications. Fertilization with 100 kg P ha-1 on a soil with medium available P (19.3 mg kg-1) increased Bray1 and crop yield . Fertilization with 200 and 400 kg P ha-1 in a soil with high Bray1 (28,4 mg kg-1) increased P availability and crop yield remained unchanged. The Phosphorus Soil Index did not change significantly (average 209 mg P kg-1). Soil Phosphorus Degree (GSP) reached 25% at tuber initiation when fertilized with 400 kg P ha-1. The GSP risk point threshold from the literature is 20-30%. Bray 1 and P CaCl2 values greater than 52.4 and 1.72 mg P kg-1 respectively, correspond to this threshold and alert of the risk of P loss and possible adverse environmental impacts of these crop management practices.

Keywords : Sorption; Extractable phosphorus; Environmental risk; Runoff.

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