Potassium Supplying Capacity and Contribution of Non-Exchangeable Potassium in Wetland Rice Soils in Bangladesh

ABSTRACT

Information on soil potassium (K) supplying capacity, K-depletion, and contribution of exchangeable and non-exchangeable K in wetland rice ecology is limited. Understanding of K dynamics of different soil types can be a guideline for better K-fertilizer management and sustainable soil K use to achieve sustainable rice yields. To understand this soil K-supplying capacity to rice plants, a pot study with two K levels (K0 and K100 mg K kg-1 soil) was conducted with seven successive rice crops grown up to the panicle initiation stage using 18 different soils collected from across Bangladesh. The cumulative soil K-supplying capacity (242–758 mg K kg-1 soil) varied significantly (P ≤ .001) among soils, showing a strong positive relationship (R2 = 0.78) with NH4OAc K. The potential K-supplying capacity of these soils was the highest (758 mg K kg-1 soil) in Mithapukur (AEZ 3-Tista Meander Floodplain) and the lowest (242 mg K kg-1 soil) in Barura (AEZ 19-Old Meghna Estuarine Floodplain). In K0 soils, the successive cycles of rice resulted in continuous depletion of both non-exchangeable and exchangeable K pools. The concentration of both exchangeable and non-exchangeable K was maintained and almost balanced in K100 soils compared to K0 with successive rice cropping. Non-exchangeable K contribution to K nutrition of rice plants during the seventh cropping ranged, respectively, from 83% to 93% and 26% to 55% in K0 and K100 soils. Results reveal the importance of a non-exchangeable K pool in K-supplying to plants in wetland rice production systems with different soil types.

KEYWORDS:

• Potassium depletion
• potassium dynamics
• potassium uptake
• soil mineralogy
• successive rice cropping

Acknowledgements

The authors give special thanks to funding organizations, International Plant Nutrition Institute (IPNI) and Australian Centre for International Agricultural Research (ACIAR) for providing funds (IPNI-BGD-6/2010 and ACIAR CIM/122/2017/CSE/2011/077, respectively) to the first author to conduct his Ph.D. research. The authors also wish to acknowledge Bangladesh Rice Research Institute (BRRI) for providing their net house facilities to conduct pot experiments. We acknowledge the technical support of the One CGIAR regional integrated initiative Transforming Agrifood Systems in South Asia (TAFSSA; https://www.cgiar.org/initiative/20-transforming-agrifood-systems-in-south-asia-tafssa/). Authors would also like to thank Abu Saleque (BRRI) and Roland Buresh (IRRI) for their advice during the planning and conduct of the research. We are also grateful to farmers of different locations for providing soils from their lands and the Lab technicians of BRRI for taking care and maintenance during the conduct of the experiment.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary data

Supplemental data for this article can be accessed online at https://doi.org/10.1080/00103624.2023.2240853

Additional information

Funding

The work was supported by the Australian Centre for International Agricultural Research [CIM/122/2017/CSE/2011/077]; African Plant Nutrition Institute (APNI) [IPNI-BGD-6/2010].