Plant Phosphorus Availability in Latosols and Luvisols from Northeastern Semi-arid Brazil

• Published in: Communications in soil science and plant analysis Vol. 34; no. 3-4; pp. 407 - 425
• Main Authors: Araújo, M. S. B., Schaefer, C. E. R., Sampaio, E. V. S. B.
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA Taylor & Francis Group 01.03.2003; Taylor & Francis
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Chemical, physicochemical, biochemical and biological properties; Fundamental and applied biological sciences. Psychology; Mineral components. Ionic and exchange properties; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Soil science; South America; Brazil; America; Monocotyledones; Soil fertility; Extraction process; Available nutrient; Phosphorus; Brachiaria; Inorganic element; Tropical soil; Absorption; Luvisols; Gramineae; Semi arid zone; Soil horizons; Angiospermae; Nutrient; Herbaceous plant; Spermatophyta; Chemical composition; Comparative study; Speciation; Ferrallitic soil
• ISSN: 0010-3624; 1532-2416
• DOI: 10.1081/CSS-120017829

Phosphorus (P) availability to plants in samples of soil horizons of up-, mid-, and downslope positions of three toposequences of Latosols and three of Luvisols from Northeastern semi-arid Brazil was evaluated cultivating brachiaria grass, in pots, during 4 months. Plant uptake was compared to changes in soil P fractions, determined before and after cropping, by a modified Hedley sequential extraction in the following order: resin-P, NaHCO 3 -P (inorganic and organic), NaOH-P (inorganic and organic), H 2 SO 4 -P, and H 2 SO 4 /H 2 O 2 digestion (residual P). In general, different horizons and slope positions of the same soil classes had similar P fraction decreases with cultivation. Readily available inorganic P fractions (resin and NaHCO 3 ) were the most depleted ones (40-90% and 43-76% of the original P, respectively). Luvisol samples had significantly larger readily available inorganic P decreases than Latosol ones but differences in total P decreases were not significant. Inorganic fractions losses were higher at the surface, whereas losses of organic fractions were higher at subsurface horizons. In both soil classes, dry matter production and plant P uptake were highly correlated to the decreases in readily available inorganic P fractions.