TY - JOUR

T1 - Release of potassium accompanying the dissolution of rice straw phytolith

AU - Nguyen, Minh Ngoc

AU - Dultz, Stefan

AU - Picardal, Flynn

AU - Bui, Anh Thi Kim

AU - Van Pham, Quang

AU - Schieber, Juergen

N1 - Funding Information: This research was funded by the Vietnam National Foundation for Science & Technology Development (Project 105.08-2013.01). X-ray-tomographic microscopy was performed with skilful help by Julie Fife at the TOMCAT beamline of the synchrotron facility of the Paul Scherrer Institute, Villigen, Switzerland. Great help of Sarah B. Cichy and Karl-Ingo Friese for morphological characterization of phytoliths from the tomographic dataset is acknowledged. We would like to thank Ph.D. Erika Elswick, Department of Geological Sciences, Indiana University for her support during the work.

PY - 2015/1

Y1 - 2015/1

N2 - In rice, Si assimilated from the soil solution is deposited in inter- and intracellular spaces throughout the leaf and stems to form silicified structures (so-called phytoliths). Because K is also present in significant concentrations in rice stems and leaves, the question arises if K is immobilized in the mineralized silica during the precipitation of Si. This work determined whether desilification of the phytolith is a factor regulating K release by implementing batch experiments. Solubility of Si and K of the rice straw heated at different temperatures were examined to identify effect of pretreatment. Analyses of phytoliths using SEM-EDX and X-ray tomographic microscopy in conjunction with the results from batch experiments revealed that K might co-exist with occluded organic matter inside the phytolith structure. In the kinetic experiments, corresponding increases of K and Si concentrations in the supernatants were observed which suggested that desilification of the phytolith is a main factor regulating K release. The extent of heat pretreatment of the rice straw is of significant importance with respect to dissolution of the phytolith by affecting organic removal and surface modification. At temperatures lower than 600. °C, corresponding increases of the soluble Si and K with heating temperature have been obviously observed. In contrast, the solubility of Si and K gradually decreased at temperatures above 600. °C. This work provides insights into factors that control release of K and Si from phytolith and a practical recommendation for practices of burning rice straw that may maximize subsequent release of Si and K for crops.

AB - In rice, Si assimilated from the soil solution is deposited in inter- and intracellular spaces throughout the leaf and stems to form silicified structures (so-called phytoliths). Because K is also present in significant concentrations in rice stems and leaves, the question arises if K is immobilized in the mineralized silica during the precipitation of Si. This work determined whether desilification of the phytolith is a factor regulating K release by implementing batch experiments. Solubility of Si and K of the rice straw heated at different temperatures were examined to identify effect of pretreatment. Analyses of phytoliths using SEM-EDX and X-ray tomographic microscopy in conjunction with the results from batch experiments revealed that K might co-exist with occluded organic matter inside the phytolith structure. In the kinetic experiments, corresponding increases of K and Si concentrations in the supernatants were observed which suggested that desilification of the phytolith is a main factor regulating K release. The extent of heat pretreatment of the rice straw is of significant importance with respect to dissolution of the phytolith by affecting organic removal and surface modification. At temperatures lower than 600. °C, corresponding increases of the soluble Si and K with heating temperature have been obviously observed. In contrast, the solubility of Si and K gradually decreased at temperatures above 600. °C. This work provides insights into factors that control release of K and Si from phytolith and a practical recommendation for practices of burning rice straw that may maximize subsequent release of Si and K for crops.

KW - Phytolith

KW - Potassium

KW - Release

KW - Rice straw

KW - Silicon

UR - http://www.scopus.com/inward/record.url?scp=84911425865&partnerID=8YFLogxK

U2 - 10.1016/j.chemosphere.2014.06.059

DO - 10.1016/j.chemosphere.2014.06.059

M3 - Article

C2 - 25061942

AN - SCOPUS:84911425865

VL - 119

SP - 371

EP - 376

JO - CHEMOSPHERE

JF - CHEMOSPHERE

SN - 0045-6535

ER -