Methods for evaluation of easily-reducible iron and manganese in paddy soils

Abstract

Iron (Fe) and manganese (Mn) toxicity can be an important limitation to flooded rice cropping. Flooding causes several physical and chemical alterations that affect the dynamics of these elements in the soil environment. The objective of this study was to develop procedures of soil analysis, that enable the assessment of easily reducible Fe and Mn availability and uptake by plants. Surface samples (0 -20 cm) of ten lowland soils from the State of Minas Gerais, Brazil, were used. The experiment consisted of a factorial randomized block design of ten soils and five liming levels, with five rice plants grown in pots containing 2 dm 3 of soil with permanent flooding. The concentrations of Fe and Mn were evaluated in the soil solution and in the aerial parts of the rice plants. The air-dried samples were analyzed for Fe and Mn with sodium-citrate dithionite, ammonium oxalate, Melich-1, 3009 ORDER REPRINTS 0.1 mol L 21 HCl, ammonium acetate-EDTA, and DTPA -TEA extractants. The Fe concentration in the soil solution was most highly correlated with Melich-1 ðr ¼ 0:87Þ; while DTPA -TEA showed the highest correlation with the amount of Fe in the plant ðr ¼ 0:62Þ: For Mn, DTPA -TEA was the best predictor of both soil solution Mn and plant Mn ðr ¼ 0:87 and r ¼ 0:80; respectively).

Influence of liming on the spatial and temporal variability of Mehlich-1 extractable Fe in a rice field

“…It has been suggested that 0.5 N HCl extracts all of the reduced Fe and no oxidized forms (e.g. van Bodegom et al, 2003) and, consequently, that Mehlich-1 extracts all of the reduced plus a given percentage of oxidised Fe (Borges et al, 2001).…”

Physiological and cellular aspects of phytotoxicity tolerance in plants: the role of membrane transporters and implications for crop breeding for waterlogging tolerance

“…Iron toxicity was repeatedly named as a primary limitation to rice cropping in flooded areas around the globe (Borges et al. , 2001; Shimizu et al.…”

“…Iron toxicity was repeatedly named as a primary limitation to rice cropping in flooded areas around the globe (Borges et al, 2001;Shimizu et al, 2005). High concentrations of both Mn 2+ and Fe 2+ in waterlogged soils were also named as major constraints for growing sensitive wheat cultivars in waterlogging-prone areas of Western Australia and northeastern Victoria wheat belts (Khabaz-Saberi et al, 2010), with two-to ten-fold increase in the shoot Mn and Fe concentrations reported (Khabaz-Saberi et al, 2006).…”

Heavy Metal Availability in Soil Amended with Composted Urban Solid Wastes

“…The DTPA (diethylenetriamine-pentaacetic acid) is an effective reagent used for predicting the soil capacity to supply essential nutrients to plants (Mortvedt et al, 1991). It has been used (DTPA-TEA) as extractant to evaluate metal mobility in flooded soils (Borges Jr. et al, 2001). This paper presents the pH measurements and the concentrations of available Zn, Cu, Mn, Pd, and Ni concentrations in a Brazilian Oxisol amended with composted urban solid wastes.…”