Citric acid loaded nano clay polymer composite for solubilization of Indian rock phosphates: a step towards sustainable and phosphorus secure future

ABSTRACT

Non-renewable nature of rock phosphate (RP) reserves coupled with open ended nature of P cycle makes it imperative for maximum utilization of available P resources. In this context, use of Indian RPs from Purulia and Udaipur along with citric acid loaded nanoclay polymer composite (CA-NCPC) as P source to costly diammonium phosphate (DAP) was investigated through an incubation experiment followed by a greenhouse experiment with wheat-rice cropping sequence in a Luvisol (pH 5.14, available P 13.5 mg kg⁻¹). Soil available P, crop yield parameters and dynamics of soil P fractions were taken to judge the efficacy of CA-NCPC in solubilizing RPs. Application of CA-NCPC and DAP resulted in 82% and 69% increase in available P over control, respectively under incubation study. Direct effect of treatment receiving CA-NCPC + RP on yield and P uptake by wheat was comparable with DAP but residual impact of CA-NCPC + RP (16.7 g pot⁻¹) was better than DAP (13.8 g pot⁻¹) in rice. The changes in inorganic P fractions were also significant as inclusion of RP increased calcium-P from 16.1 to 61.5 mg kg⁻¹. Results indicated potentiality of RPs treated with CA-NCPC as an alternate P source which could prove promising amidst P scarcity.

KEYWORDS:

• Organic acid
• nanoclay polymer composite
• indigenous rock phosphates
• inorganic P fractions
• P solubilization

Acknowledgments

The authors would like to thank the Director, Indian Agricultural Research Institute (IARI), New Delhi, India for providing facilities for conducting the experiments. Authors also thank to Head, Agricultural Entomology and Plant Pathology for providing instrumental facilities like FTIR and SEM. They would also like to acknowledge and thank Dr. B.K. Agarwal and Dr. D.K. Shahi from Birsa Agricultural University, Ranchi, India for collection of bulk soil sample used for this study.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Indian Council of Agricultural Research (ICAR), New Delhi, India for providing financial support as Senior Research Fellowship to carry out the doctoral research program to senior author.