Abstract
Abstract. This study was designed to examine the fixation pattern and kinetics of zinc (Zn) in chelated (ethylenediaminetetraacetic acid, EDTA) and non-chelated mixed micronutrient systems of semi-arid alkaline soils from the Southern High Plains, USA. Soils were characterized for a suite of chemical and physical properties and data obtained from extraction experiments fitted to various kinetic models. About 30 % more plant-available Zn was fixed in the non-chelated system within the first 14 days with only about 18 % difference observed between the two systems by day 90, suggesting that the effectiveness of the chelated compounds tended to decrease over time. The strengths of the relationships of change in available Zn with respect to other micronutrients (copper, iron, and manganese) were higher and more significant in the non-chelated system (average R2 of 0.83), compared to the chelated (average R2 of 0.42). Fixation of plant-available Zn was best described by the power-function model (R2 = 0.94, SE = 0.076) in the non-chelated system, and was poorly described by all the models examined in the chelated system. Reaction rate constants and relationships generated from this study can serve as important tools for micronutrient management and for future micronutrient modeling studies on these soils and other semi-arid regions of the world.
Highlights
The soil, a subject of interdisciplinary study (Brevik et al, 2015), has numerous ecological functions, among which is the storage and cycling of plant-needed nutrients (Smith et al, 2015)
Soils were characterized for a suite of chemical and physical properties and data obtained from extraction experiments fitted to various kinetic models
The findings clearly indicate that chelating with EDTA reduced the amount of plant-available Zn fixed by soil constituents (Lopez-Valdivia et al, 2002; Chiu et al, 2005; Alvarez and Gonzalez, 2006)
Summary
The soil, a subject of interdisciplinary study (Brevik et al, 2015), has numerous ecological functions, among which is the storage and cycling of plant-needed nutrients (Smith et al, 2015). Micronutrient fixation, a process that leads to the reduction of plant-available portion of micronutrients, through the interactions with other soil constituents, limits crop productivity in most parts of the world (WHO, 2000). Reduction in the availability of micronutrient could be more pronounced in calcareous or alkaline soils due to their inherently high pH (Alloway, 2008; Havlin et al, 2013), which often results in decreased solubility of most metals, leading to increased fixation of most micronutrients such as copper (Cu), Fe, manganese (Mn), and zinc (Zn) in soil systems (Sparks, 2003). Climatic and/or environmental conditions such as flooding and temperature variation (cool or wet season) could affect Zn availability to plants (Slaton et al, 2005; Alloway, 2008, 2009; Havlin et al, 2013)
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