Soil iron fractionation and availability at selected landscape positions in a loessial gully region of northwestern China

Abstract

Soil Fe fractions and availability vary with landscape positions, because landscape position affects soil chemical properties and water conditions. In the present study, we investigated Fe fractions and availability at selected landscape positions in the loessial gully region of northwestern China. Four landscape positions, plateau, slope, terrace, and gully bottom were investigated. For each landscape position, soil samples were collected at 20-cm increments to a depth of 80 cm. Iron in the soil samples was fractionated by a modified sequential extraction method. Available Fe was assessed by diethylene thiamine pentacetic acid (DTPA) extraction procedure. The results showed that soil profile distributions of DTPA-Fe varied greatly with landscape position in the study area. The largest content of DTPA-Fe content was observed in the plateau soils, while the smallest content was observed in the gully bottom soils. Iron in soils existed mainly in the mineral bound fraction, which accounted for about 73 to 96% of the total Fe. The content of Fe in soil fractions varied greatly with landscape position. Exchangeable Fe and organic matter bound Fe were direct sources of available Fe, but exchangeable Fe contributed little to the total available Fe due to its low content in the soils. Oxides bound Fe was an indirect source of available Fe. The results of the present study indicate that landscape position strongly influences soil profile distribution and capacity of available Fe by influencing soil Fe fractions and organic matter distributions.

Iron Availability in Tropical Soils and Iron Uptake by Plants

“…, should really be narrower. Dry matter production and leaf concentration and content of Fe correlated positively with Fe p content (Equations 54, 55, and 56), indicating that the Fe fraction bound to the organic components of the soil was what most contributed to availability of the element to the plant, as found by Wei et al (2010).…”

Canopy influences of five range plant species on the redistribution of chemical forms of iron in a calcareous soil

“…Furthermore, Guo et al (2006) found that most Fe in surficial sediments was in the residual fraction. Wei et al (2010) observed that in most soil of the loessial gully region of northwestern China, Fe was in association with the mineral bound fraction (73-96%). Some chemical forms of metals such as SolEx-Fe, Car-Fe, and Om-Fe can be considered as reactive forms since these are readily available or potentially available forms (Ma & Uren 1998;Pietrzak & McPhail 2004).…”

“…However, CFeox-Fe was higher in the soils beneath canopy of all plants as compared to their interspace soils (Figure 2). Oxides forms of Fe may consider as indirect source of available Fe (Wei et al 2010) or as poorly available Fe (Walna et al 2010).…”

The effects of soil metals on the composition of oil ofPaeonia ostiiseeds

“…Fe is one of the major constituents of the lithosphere and pedosphere. The content of Fe in natural soils ranges between 7 and 42 mg/g (Wei et al, 2010). However, plant available Fe is low in most soils because the low solubility product of iron minerals makes the inorganic form of iron unavailable to plants and forms the most common widespread nutritional disorder world over (Chatterjee et al, 2006).…”