Diffusion and uptake of phosphorus, and root development of corn seedlings, in three contrasting subtropical soils under conventional tillage or no-tillage

Abstract

Soil mineralogy and management can have substantial effects on phosphorus (P) diffusion in soil and hence on root morphology. The aim of this study was to assess these effects in soils differing widely in P-sorbing components. Samples of a Rhodic Paleudult (RP), a Rhodic Hapludox (RH), and a Humic Hapludox (HH) under conventional tillage (CT) or no-tillage (NT) were placed in Petri dishes to assess P diffusion. Performance and root morphology in corn grown on soil samples subjected to three different P fertilization treatments (no fertilizer, surface, and deep fertilizer application) were examined. Phosphorus diffusion was slower in the HH than in the other soils by effect of its high P adsorption capacity because of its mineralogy. Soil management had no effect on P diffusion. Fertilization with P only affected plant-related variables in RH: surface fertilization increased root biomass, and deep fertilization shoot biomass and proportion of thick roots. Soil management affected plants growing on HH and RP: the plants grown under NT were taller (RP) and developed more fine roots (HH) than those under CT. Fertilization with P had little effect on plant growth in the goethite-rich soil (HH) or the one with high content in available P (RP). Our results suggest that management system in these soils has therefore greater influence on fertility than fertilization treatment.

Iron oxides and organic matter on soil phosphorus availability

“…A sound knowledge of the interaction of iron oxides and organic matter with soil P is essential with a view to developing effective nutrient management strategies for agro-ecosystems allowing crop productivity to be maintained or even increased with a concomitant reduction in phosphate fertilizer use. Recent studies in highly weathered Brazilian soils have shown that organic matter and various iron oxides have a direct effect on P adsorption/ desorption and availability (Bortoluzzi et al, 2015;Fink et al, 2016bFink et al, , 2014. As a result, fertilizer recommendation systems based on soil buffering categories established in terms of clay content may be ineffective.…”

“…Inorganic P species derived from orthophosphoric acid (H 3 PO 4 ) such as H 2 PO 4 -and HPO 4 2-are preferentially absorbed by plants. To what extent P remains in the soil solution depends on the degree to which it is adsorbed, desorbed and mineralized (Hinsinger, 2001;Fink et al, 2016b). Most tropical and subtropical soils in Brazil are low in available P because of strong phosphate adsorption on soil minerals (Almeida et al, 2003;Johnson;Loeppert, 2006;Bortoluzzi et al, 2015).…”

“…Soil weathering causes dissolved phosphate from primary minerals to (a) precipitate with some cations and lead, for example, to the neo-formation of calcium phosphate in alkaline soils (Beck and Sánchez, 1994); (b) be adsorbed by functional groups of iron or aluminium oxides to form thermodynamically stable complexes (Bortoluzzi et al, 2015;Fink et al, 2016b) or (c) form biologically active organic compounds that remain as organic P in soil (Conte et al, 2002;Martinazzo et al, 2007;Dodd;Sharpley, 2015). Transformations between inorganic and organic forms of P are governed by factors affecting its mineralization and immobilization (e.g., microbial activity, moisture, physico-chemical and mineralogical soil properties) (Santos et al, 2008;Shen et al, 2011;Tiecher et al, 2012).…”

“…The role of hematite and goethite in P adsorption in subtropical soils Fink et al, 2014;2016a;2016b Phosphorus adsorption, desorption, diffusion and absorption in soils rich in goethite, hematite or kaolinite.…”

Phosphorus sources: effects on mahogany nursery trees

“…On the high lands of Amazon rain forest, the use of water-soluble P (WSP) sources as the triple superphosphates (TSP) and single superphosphate (SSP) provide a ready P release, increasing the P adsorption and precipitation with Fe and Al, consequently decreasing its availability (FINK et al, 2016). Alternatively, the low water-soluble P (LWSP) sources such as Arad and Gafsa can increase the P availability to the plants, especially to those with low rate of growth such as mahogany.…”