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Fluid Journal : Fluid Journal 2005-2007
14 Fluid Journal FALL 2007 DRS. G. HETTIARACHCHI, M. MCLAUGHLIN, K. SCHECKEL, D. CHITTLEBOROUGH, M. NEWVILLE, E. LOMBI SUMMARY Millions of acres of arable land worldwide, particularly in arid and semi-arid regions, are deficient in plant available micronutrients. The major reason for the widespread occurrence of deficiency of micronutrients in soils is their low availability to plant roots rather than their low concentration in soils.Various organic and inorganic Mn and Zn fertilizers have been used to correct their deficiencies. Inclusion of Mn and Zn as well as other micronutrients in commercial macronutrient fertilizers is a common practice throughout the world because it is much more practical than a separate application of micronutrients. The cost of these fertilizers, as well as yield loss due to Fluids Excel In Supplying Mn And Zn In Calcareous Soils Australian microscopic and spectroscopic studies show superiority of fluids over granular. The benefits of trace elements (Mn and Zn) supplied in fluid forms over conventional granular products in calcareous sandy loam soils have been agronomically demonstrated. We hypothesized that the differences in the effectiveness between granular and fluid micronutrient fertilizers may be due to different reaction processes in and around fertilizer granules and fluid fertilizer bands. We employed a combination of 1) several laboratory based x-ray techniques, 2) scanning electron microscopy combined with energy dispersive x-ray analysis, and 3) synchrotron based x-ray techniques to identify chemical forms of different fertilizer-derived Mn and Zn in highly calcareous soils. Combined use of these different x-ray techniques suggested that when fluid micronutrients were supplied to the soil, Mn and Zn remained in comparatively more soluble solid forms whereas granular Mn and Zn tended to transform into comparatively less soluble solid forms. This confirmed findings from previous studies using isotopic dilution analyses, and from field agronomic studies. their inefficient use, is considerable, which is why the most efficient use of micronutrients in such compound fertilizers by plants is very important. Recent field studies conducted by our group have shown an increased response to fluid Mn and Zn (concentration in grain and/or grain yield) compared to granular fertilizers in calcareous sandy loam soils. Further, recent laboratory experiments using isotopic dilution techniques using Mn and Zn revealed that granular Mn and Zn did not diffuse readily from the point of application in soil nor did they enter or remain in the labile (available) pool compared to fluid fertilizer micronutrients. The purpose of this study was to investigate the reaction products of Mn and Zn in fertilizer in highly calcareous South Australian soils using several laboratory and synchrotron based x-ray techniques after addition of these micronutrients to the soil either in granular or fluid form. Movement Manganese. Most of the fertilizer Mn diffused out of the granular Mn sources but was retained/ precipitated around the granule whereas fluid Mn diffused farther away from the point of application. This pattern was confirmed by the microphotograph of the granular Mn extracted from the soil (Figure 1). This observation is in agreement
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