Organic and inorganic amendment of wetland paddy soil for five years: effects on phosphorus fraction dynamics

ABSTRACT

Soil phosphorus (P) fractions indicate the P-supplying capacity to plant, which could be affected by fertilizer management systems. Information regarding the changes in P pools under different fertilizer management systems is essential for the sustainability of the systems. We studied the effects of different fertilizer practices on P fraction dynamics and associated soil properties under wetland double rice cropping system. Soil samples were collected from four depths (0–5, 5–10, 10–15, and 15–20 cm) of a five-year field experiment that received four treatments: soil-test-based NPKS fertilizer (STB), 3 t ha⁻¹ cow dung (CD) + NPKS as integrated plant nutrition system (IPNS) [CD+IPNS], 2 t ha⁻¹ poultry manure (PM) + NPKS as IPNS [PM+IPNS] and P control. Different P forms (solution P, NaHCO₃-extracted P, NaOH-extracted inorganic P, NaOH-extracted organic P, acid P, and residual P) and soil properties (phosphate-solubilizing bacteria, acid phosphatase activity, and organic carbon) differed significantly with fertilizer treatments and soil depths. Different P forms and soil properties were remarkably increased with PM+IPNS compared to STB and CD+IPNS and were mostly concentrated at the topmost layers. The correlation analysis showed strong positive correlations among different P forms and soil properties. Application of PM (2 t ha⁻¹) in each cropping season could supplement the P requirement of rice crop, maintaining P pools in the wetland paddy soils. Moreover, the application of PM will reduce chemical fertilizer use, farmers’ fertilizer cost, and environmental pollution. Thus, PM could be effectively utilized as a P source for rice production.

KEYWORDS:

• Acid phosphatase activity
• cow dung
• poultry manure
• integrated plant nutrition system
• organic carbon
• soil depth

Acknowledgments

The authors are thankful to the Soil Science Division, Bangladesh Rice Research Institute for providing supports to conduct field experiments and laboratory facilities. This research did not receive any specific funding.

Disclosure statement

No potential conflict of interest was reported by the authors.