Lookup NU author(s): Dr Kirsten Brandt,
Dr Neil Gray,
Professor David Manning
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0).
Given the cost of conventional fertilizers and increasing demand from increasing population growth, new sources of potassium (K) for plant nutrition need to be considered. Readily soluble nutrients are rapidly lost from well-drained soils, and so it is appropriate to consider silicate minerals that release K slowly during weathering. In this paper, we compare the availability to plants grown in sandy soils of K from microcline (feldspar), biotite (mica), and nepheline syenite (nepheline + microcline) using leek (Allium ampeloprasum var. porrum L.) as a model plant. Pot experiments were carried out under controlled environmental conditions using natural and artificial soil. The performance of the minerals was compared to treatment with KCl and a negative control (no K added). Plant shoot diameter was measured weekly to assess growth rates. After 10 weeks, plant dry mass and soil and plant contents of soluble K were measured to determine offtake; mineralogical changes in biotite-treated soils were assessed. Results for artificial and natural soil differed, reflecting differences in their mineralogy. With no added K, plant growth ceased after two weeks. Growth rates were greatest for KCl, followed by biotite; linear growth continued for five weeks in the natural soil and for the entire ten weeks in the artificial soil. Growth rates with nepheline syenite (natural soil) and microcline (both soils) did not differ significantly from the negative control, but for nepheline syenite leek shoot K content was significantly greater, demonstrating availability of K from this source. X-ray diffraction analysis showed that biotite reacted to form vermiculite.
Author(s): Mohammed SMO, Brandt K, Gray ND, White ML, Manning DAC
Publication type: Article
Publication status: Published
Journal: European Journal of Soil Science
Print publication date: 29/09/2014
Online publication date: 12/09/2014
Acceptance date: 17/06/2014
ISSN (print): 1351-0754
ISSN (electronic): 1365-2389
Publisher: British Society of Soil Science
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