Synergistic Effects of Humic Acid and Phosphate Solubilizing Bacteria with Reduced Phosphorus Fertilization on Root Development and Microbial Activity in Direct-Seeded Rice

Sk Asraful Ali; Vipin Chandra Dhyani; Anjali Kumari; Sumit Chaturvedi; Krishna K.M.; Tony Manoj Kumar Nandipamu; Nilutpal Saikia; Shashank Shekher Singh

doi:10.56093/ijas.v95i11.167027

Authors

Sk Asraful Ali ICAR-Indian Agricultural Research Institute, Pusa Campus, New Delhi, 110012
Vipin Chandra Dhyani
Anjali Kumari
Sumit Chaturvedi
Krishna K.M.
Tony Manoj Kumar Nandipamu
Nilutpal Saikia
Shashank Shekher Singh

https://doi.org/10.56093/ijas.v95i11.167027

Keywords:

Direct-seeded rice, Humic acid, Phosphate solubilizing bacteria, Phosphorus use efficiency, PSB counts

Abstract

Inefficient phosphorus use (10-15% only) caused by rapid soil immobilization and limited plant uptake combined with the looming depletion of high-quality rock phosphate, underscores the necessity of sustainable phosphorus management. This study investigated synergistic effects of humic acid (HA) and phosphate solubilizing bacteria (PSB) with reduced P fertilization on root development and microbial activity in DSR. Experiment was carried out during the kharif seasons of 2022 and 2023 with 12 treatment combinations in factorial RBD. The treatments consisted of 3 phosphorus levels (control, 50%, and 100%, corresponding to 0, 30, and 60 kg of P2O5/ha) and 4 phosphate solubilizers (control, humic acid (HA) @ 10 kg/ha, phosphate solubilizing bacteria (PSB) @ 10 g/kg seed, and HA @ 10 kg/ha + PSB @ 10 g/kg seed) aimed to assess the effects of applying 50% of the recommended phosphorus fertilizer rate along with HA and PSB on root development and microbial activity in direct-seeded rice. Results indicated that higher phosphorus levels significantly enhanced root dry weight and volume densities, with the combined application of HA and PSB yielding the most substantial improvements. Notably, the application of 50% of the recommended phosphorus rate, along with HA and PSB, effectively maintained root growth and microbial activity comparable to full phosphorus application, thereby optimizing phosphorus use efficiency (PUE). Integration of HA and PSB with reduced P fertilizer not only sustains root growth, microbial populations, and enzyme activities, but also maximizes PUE, reduces fertilizer expenses and sustains rice productivity.

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