Iron Availability in Tropical Soils and Iron Uptake by Plants

Abstract

Given the increase in crop yields and the expansion of agriculture in low fertility soils, deficiency of micronutrients, such as iron, in plants grown in tropical soils has been observed. The aim of this study was to evaluate Fe availability and Fe uptake by corn (Zea mays L.) plants in 13 different soils, at two depths. Iron was extracted by Mehlich-1, Mehlich-3, and CaCl 2 (Fe-CC) and was fractionated in forms related to low (Fe o ) and high (Fe d ) crystallinity pedogenic oxyhydroxides, and organic matter (Fe p ) using ammonium oxalate, dithionite-citrate, and sodium pyrophosphate, respectively. In order to relate Fe availability to soil properties and plant growth, an experiment was carried out in a semi-hydroponic system in which part of the roots developed in a nutrient solution (without Fe) and part in the soil (the only source of Fe). Forty-five days after seeding, we quantified shoot dry matter and leaf Fe concentration and content. Fe d levels were high, from 5 to 132 g kg -1

Diagenesis of archaeological bone and tooth

“…The soil profile generally exhibits a succession of chemical regimes with oxygen reduction in the uppermost levels; underlain by successive levels of nitrate reduction; εn 4+ reduction, Fe 3+ reduction; sulphate reduction and methane fermentation at the lowest levels. Bones from anoxic layers tend to be stained brown or black from manganese and iron oxides adsorbed onto the pore structure or fixed within the tissues since their solubilities, and hence availability to enter the pore structure of buried remains and interact with either the collagen or mineral, are dependent upon both pH and Eh (εielki et al, 2016;Rengel, 2015) . Redox and pH values also influence the availability of fulvic and humic acids which stain bone tissues anything from pale brown to dark brown or almost black such as the almost black bones of two women recovered from the Oseberg Ship burial in Norway (Holck, 2007, pers comm).…”

Early Response of Soil Properties under Different Restoration Strategies in Tropical Hotspot

“…Iron and manganese usually occur in low levels, and their amount depends on the material of origin and degree of soil weathering [60]. The ways in which these micronutrients are available to plants are related to soil properties such as organic matter, pH, and moisture [61][62][63][64]. In our study, soil from the hillside had significantly lower Fe and significantly higher Mn content in the comparison with the pasture located on the flat area.…”

Assessment of the Effect of Glycine, Oxalic Acid and Nitrogen-Phosphorus-Potassium (NPK) Fertilizer as Nutrient Supplement Using Phosphate and Oxalic Acid as Indices

“…Oxalic acid and glycine which released higher amounts of phosphate in the study may be due to their ability to lower the pH which increase solubilisation, displacement and liberation of insoluble phosphate, increase saturation of adsorption sites and decrease binding energy that offer greater stability [9,19,20]. The addition of glycine and oxalic acid will be more effective for the treatment of phosphorus deficiencies in soils, useful for application in plants which requires higher phosphorus content for survival, beneficial support for improvement and restoration of vegetation.…”