Soil Phosphorus in an Integrated Crop-livestock System under Anticipated Phosphates Fertilization

Abstract

ABSTRACT Conservation agriculture (CA) practices and fertilization strategies can increase soil phosphorus (P) concentrations. Thus, soil P tests should be effective to guarantee correct interpretations of P. We evaluated the P concentrations in soil and the efficiency of the P extraction procedures by Mehlich-1 extractant and by ion exchange resin (IER) method, over time, due to the anticipated application of phosphates on surface broadcast, in an integrated crop-livestock system (ICLS). Three sources of P were used (triple superphosphate, rock phosphate and magnesium thermophosphate), and three doses of P (60, 120 and 180 kg ha−1 of P2O5) plus an unfertilized treatment (0 kg ha−1 of P2O5) applied annually for 60 months. The soil samples collected in the 0 to 5, 5 to 10, 10 to 15, 15 to 20, and 20 to 30 cm layers were evaluated P concentrations by extraction methods. The P concentrations increased over time with the application of water-soluble and insoluble sources in ICLS. The IER method proved to be more accurate as a soil P test, regardless of phosphate applied on surface broadcast.