Paper Details

PJB-2025-241

Organic amendments improve rock phosphate solubilization and promote maize growth under alkaline soil conditions

Noor Us Sabah, Mukkram Ali Tahir, Muhammad Zeeshan Manzoor, Ahmed Elgharably, Shehla Shoukat, Abdullah, Tahreem Iftikhar, Khadija Gilani, Sumaira Salahuddin Lodhi, Johar Jamil and Ikram Ullah
Abstract

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Phosphorus (P) availability in alkaline soils is often limited due to its fixation and precipitation into insoluble forms. Rock phosphate (RP) is a natural P source, but its effectiveness in alkaline soils is pH constrained. Organic amendments proved to improve RP dissolution and resultantly improved the P availability and plant growth under high pH soils. This study investigated the effects of two RP types namely red (RPR) and brown (RPB) applied alone or in combination with filter cake press mud (FCP) or poultry manure (PM), on P availability and maize growth under alkaline soil conditions. Treatments included RP alone or combined with FCP or PM, plus nitrogen (N) and potassium (K) at recommended rates. A control (N and K only) was included. After 4 weeks of soil incubation, soil pH was measured, and maize was grown in pots containing 10 kg of amended soil. At harvest (60 days after sowing), plant growth parameters and P-related soil and plant traits were assessed. Application of RP alone slightly reduced soil pH, increased total and available P, and enhanced plant growth compared to the control, but had minimal effect on organic carbon. Co-application of FCP or PM with RP further decreased soil pH (3.2 % and 3.52%) and significantly improved soil organic carbon (20% and 40%), P availability (37 % and 50 %), and maize growth in the RP+PM and RP+FCP amended soil respectively. Maximum plant height (99.5 cm), shoot dry biomass (13.30 g) and root dry biomass (5.10 g), leaf P content (0.33 g kg^-1), relative growth rate (9.6 g g^-1) was observed when FCP was applied in combination with RP red. Among the organic amendments, FCP had a pronounced effect than PM. In conclusion, combining RP with organic amendments-especially FCP—can enhance P availability and uptake by improving soil chemistry, offering a sustainable strategy for managing P nutrition in alkaline soils.

 

To Cite this article: Sabah, N.U., M.A. Tahir, M.Z. Manzoor, A. Elgharably, S. Shoukat, Abdullah, T. Iftikhar, K. Gilani, S.S. Lodhi, J. Jamil and I. Ullah. 2026. Organic amendments improve rock phosphate solubilization and promote maize growth under alkaline soil conditions. Pak. J. Bot., 58(6): DOI: http://dx.doi.org/10.30848/PJB2026-6(4)  
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