Evidence for the Role of Potassium Nutrition in Drought Management: A Scoping Study and Meta-Analysis.

Adequate potassium (K) nutrition may reduce the negative impacts of drought on crop yield and water productivity, however, prevailing wisdom on the topic has been extrapolated from case study analysis.  Our objective was to evaluate the existing body of work and apply a statistical method of cross-study comparison to quantify the impacts of K nutrition on crop water productivity.  Based on the growing role of meta-analysis in agronomic and plant sciences, we conducted a scoping study and preliminary meta-analysis of the published data available for cross-study comparison to address the following questions: 1. Does increased availability of potassium improve yield under drought conditions? 2. How does crop water productivity respond to the increased availability of potassium?  A systematic review was conducted using library databases, online search engines, and reference mining to identify greenhouse and field studies across disciplinary journals (N=50).  To be included in the analysis, studies had to evaluate crop growth and/or transpiration measurements for plants exposed to variable rates of potassium with or without the presence of water stress.  Study diversity required the use of a calculated response ratio for quantification of main effects in MetaWin using a factorial approach to control-treatment pairings.  Significance of main effects will be reviewed, as will qualitative outcomes that focus on current limitations of published work in the context of meta-analysis.  This includes discussion regarding best practices for methods and results reporting in agronomic publication.