Assessment of phosphorus availability in soil cultivated with ruzigrass

Autor(es)

Almeida, Danilo S. ^[1] ; Penn, Chad J. ^[2] ; Rosolem, Ciro A. ^[1]

Afiliação do(s) autor(es)

^[1] Sao Paulo State Univ, Coll Agr Sci, Dept Crop Sci, 1780 Jose Barbosa de Barros St, BR-18610307 Botucatu, SP - Brazil

^[2] USDA, Natl Soil Eros Res Lab, 275 S Russell St, W Lafayette, IN 47907 - USA

• Tipo de documento: Artigo Científico
• Fonte: Geoderma; v. 312, p. 64-73, FEB 15 2018.
• Citações Web of Science: 7

Resumo

Growing ruzigrass (Urochloa ruziziensis) in crop rotation systems has been suggested as a strategy to increase soil phosphorus (P) cycling and P availability. However, despite increased P lability shown in routine soil analysis, decreased grain yields of crops grown after ruzigrass have been observed. The objective of this study was to evaluate soil P availability to maize (Zea mays) in low or high-P soil cropped to ruzigrass. Soil P lability was evaluated using Hedley fractionation and pearl resin extractions, and P desorption/adsorption was assessed by isothermal titration calorimetry (ITC). Phosphorus changes in soil-P fractions in the maize rhizosphere were studied in a greenhouse experiment. Growing ruzigrass resulted in higher resin-extractable P and soil organic matter (SOM) contents than fallow. However, in soil cropped with ruzigrass, maize P uptake and P desorption were lower, and P adsorption to soil was higher than soil under fallow. In general, organic P bound to Fe and Al was non-available. Phosphorus sorption as assessed with ITC was a better indicator of P bioavailability to maize than pearl resin and Hedley fractionation, and suggested that P was less bioavailable after ruzigrass due to increased SOM, which resulted in the formation of metal phytate and more effective organo-metal sites for ligand exchange. Greater P solubility and availability in fallowed soil appeared to be partly due to the dissolution of Ca-related P, greater P desorption, and less potential for P adsorption. Isothermal titration calorimetry is a useful semi-quantitative tool for understanding P sorption behavior. (AU)

• Processo FAPESP: 12/18509-4 - Disponibilidade de fósforo em solo cultivado com braquiária em rotação com soja
• Beneficiário: Danilo Silva Almeida
• Modalidade de apoio: Bolsas no Brasil - Mestrado