Redox Potential and pH as Major Drivers of Fertility in Submerged Rice Soils: A Conceptual Framework for Management

Abstract

Submerging soil creates a series of changes that have important implications for fertility and its management in wetland rice. Wetland rice makes an important contribution to the global rice supply and is often cited as an example of a sustainable production system. We little realize that flooding soil is a powerful driver of changes in fertility and nutrient availability via two most important determinants of soil fertility—pH and redox potential (Eh). The fundamental role of pH in regulating the dynamics of major and micronutrients, toxins, and reduction products in soil solution is well known and used to optimize rice production through management; however, the role of Eh, although equally important, is not appreciated and hence not fully exploited in developing improved fertility management practices. From a synthesis of global literature, this article presents a conceptual framework for the dynamics of soil organic matter and plant nutrients in terms of the combined effects of pH and Eh in submerged rice soils. It is hoped that the conceptual framework proposed would aid in developing efficient agronomic practices for better management of rice-based systems.

Keywords:

• Amelioration
• Eh
• fertility
• nutrients
• organic matter
• pH