Calcareousness of soil is a great challenge for attaining sustainable agriculture. Plants suffer from severe nutrient deficiency in these soils, especially P as an important yield limiting factor. At present time, P deficiency is an important issue of agricultural sector especially in high pH soil of the world, in Asian countries, specifically Pakistan, where, high pH and CaCO3 contents are major hindrance with respect to nutrients availability. Among various practices, Sº along with manure in presence of SOB, is one the most commonly practiced strategies in high pH soil to enhance the nutrients availability now a days. So, to figure out the stated issue, this research was carried out to formulate an acidified amendment by inoculating Sº amended cow manure with SOB. Research was consisted of lab (incubation studies for formulation and rate optimization of product), pot and field studies to determine the influence of the acidic formulation on growth, yield, quality, physiology and P uptake in maize plant. First study of this research was SOBs isolation from different ecologies, selection of efficient strain on the basis of pH lowering, sulfate ion production and P solubilization, then their characterization on the basis of phytohormones, siderophore and biofilm formation. Afterwards, on the basis of all of these results, 3 potential SOB isolates were screened out for proceeding trials. § In first incubation study, efficient fifty strains were selected from different ecologies and then, out of these, 17 potential SOBs were secerned on the basis of incubation time. Further, potential of these selected strains to produce sulfate ion and acidity was figured out and 7 isolates were selected for further studies. § According to objectives of research, P solubilization of isolates both qualitatively and quantitatively were determined and according to the fallout maximum solubilization of P, 449.80%, 405.69% and 377.17% was recorded from strains ARS-4, ARS-7 and ARS-5, respectively, in Sº amended media. § In case of Phytohormones, siderophore and biofilm formation, strains ARS-4, ARS-7 and ARS-5 showed highest outcomes. § As strains showed P-solubilization from RP and tri-calcium phosphate, attributed by the production of organic acids so, organic acids were also measured and fallouts showed strains ARS-4, ARS-7 and ARS-5 produced maximum amount of acids. Citric acid was the dominating acid produced by the strains in as high concentration as 436.08 ±4.32 µg/ml and 399.43 ±6.45 µg/mL in Sº amended media and in absence of Sº, respectively, by ASR-4 (Lysinibacillus sp.). After isolation and characterization of the strains, 2nd study was the formulation of acidified product through oxidation of sulfur amended manure in presence of SOB. After formulation, optimization of the product was done for various growth conditions such as temperature, moisture contents, bio-augmentation for attaining minimum pH in least days. A number of incubation trials were designed under controlled conditions to prepare a low pH product in short period of time. Both acids, H2SO4 and HNO3 showed lowering of pH compared to Sº in 1st week of incubation, but in second week of incubation, sole application of Sº start lowering the pH and after few more days’ level of pH in case of sulfur was almost same as in case of acids, which was 2.5. § Bio-augmentation of SOB showed better results compared to control treatments and among all strains, ARS-4 (Lysinibacillus sp.) showed minimum pH and selected for further studies, both in sterilized and unsterilized conditions. § Inoculation of SOB strains at 30 ºC boosted up the rate of reaction and resultantly time of product formation was reduced to 19 days compared with 10, 20 and 40 ºC of temperature. § 0.35% rate of molasses with ARS-4 (Lysinibacillus sp.) showed minimum pH (2.1) as well as rate of reaction was also increased due to application of substrate. § Due to aerobic nature of SOBs, effect of moisture was also determined which showed that 60-70% is the most suitable moisture level for maximum activity and proliferation of SOBs, additionally, moisture contents above and below this range negatively affected the activity. In third study, rate optimization of the product and its impact on soil pH, P mobilization and microbial count was determined. § For further application, different dilutions of the product was prepared and among them three dilutions 5, 10 and 15% of the acidified product were selected on the basis of pH and economics. § To determine the effect of acidified amendment, it was applied in soil as fertigation. On 1st day, the soil pH reduced from 7.98 to 7.23 due to sudden pH shock, but, on 2nd day, pH elevated again due to high buffering capacity of soil, while on 3rd and 4th day, it backslid, near to 7.98. § Following the same trend for P release, that soon after application of product, P was mobilized due to acidity but at 2nd day, mobilization was again decreased. § Surprisingly, microbial count was also increased in soil where extract was applied. Acidified product positively affected the microbial count as it was observed maximum at 4th day within treatments where acidulated extract was applied. § Additionally, 10% and 15% dilutions of the extract showed similar response in all parameter such as pH lowering, P-solubilization and microbial growth, so, it was useless to apply 15% dilution and 10% dilution of extract for proceeding studies. Next to the incubation studies was to assess the practical importance of product. For this, 4th and 5th study were conducted in green house and field, respectively, in presence of maize crop. Product was applied to maize at four critical stages and its impact on growth, yield, physiology, quality parameters and P uptake by maize was determined. Site for pot experiment was green house and for field trial, research area of the Institute of Soil and Environmental Sciences, University of Agriculture, Faisalabad, Pakistan was selected. § Acidulated extract was applied to maize plants at the rate of 100 liter/acre. The application was done at four critical growth stages including leaf blade formation, stalk development, cob/tassel/husk formation and grain development. Three different sources of P (DAP, SSP and RP) were applied to determine their response with acidified extract and without acidified extract, and DAP was used as reference treatment to measure the response of RP and SSP. § Maximum plant growth was recorded in acidified extract + P containing treatments. Alone application of DAP and SSP showed good response compared to RP but when RP was applied with extract it showed elevated outcome over alone DAP and SSP which was most interesting. § Root growth parameters were at maximum in treatments where acidified extract + P was applied. RP applied treatments showed minimum results but on addition of extract with RP, it showed 15.6% and 17.10% increment over alone DAP and SSP. DAP and SSP with extract enhanced the growth more than any treatment but it was obvious because of acidified nature of extract and fertilizers’ efficiency. § Yield and cob related parameters of maize were determined after harvesting and results showed that experimental units where extract was applied with P fertilizers showed bumper results that were also statistically significant (P≤0.05). DAP, SSP and RP with extract containing treatments showed maximum out comes, but mainly, the focus was on RP results because it is a cheap source, yet, with extract, it showed similar results as in case of DAP and SSP alone. Concluding, application of RP + extract could be more beneficial and less costly compared to any P fertilizer especially the most expensive DAP. § Physiological parameters i.e., chlorophyll contents SPAD, carotenoids, transpiration, photosynthesis and water use efficiency were also recorded and according to fallouts, soil where P + acidified extract was applied in combination showed prominent results, further, treatment with DAP, SSP and RP showed highest physiological activities. § Statistically significant (P≤0.05) results were obtained for uptake of phosphorus by shoot, root and grain of maize. These results were normal for treatments with alone application of fertilizers due to high fixation of P fertilizers in calcareous soil and in case of RP, results were minimum. However, when extract was applied in field, soil P contents were increased and resultantly plant P uptake was also increased. Interestingly, RP results with acidified extract were close to, and in some cases, were higher than DAP and SSP alone. Phosphorus contents of soil were recorded after harvesting and results showed that after application of extract due to sudden pH shock indigenous P was solubilized which increase its concentration in soil solution. But after some time, due to high buffering of soil, pH of soil again increased which locked the available P and made it unavailable for plants. Conclusively, phosphorus being the 2nd most important macronutrient and major growth limiting nutrient. But, pH is a controlling factor as far as the availability of P in calcareous natured soil is concerned , so, the introduction of innovative as well as costeffective technologies are indispensable for growth promotion. As in this case, the performance of this low pH product was pinning the target when applied along with P fertilizers to enhance the bioavailability of added and indigenous P. Produced acidity by the product acted as a driving force for nutrient uptake to improve the crop growth and yield. Moreover, the additional benefit from this approach is the application of RP, the most economical, compared to DAP, most expensive though commonly used in our country. As, this study aimed to prepare a cost effective and farmer friendly strategy which could be more beneficial for farmer. The technology discussed has the potential to achieve the aim with proper dissemination of the knowledge to farmer’s community for which there is a dire need to activate the extension wings of agriculture sector to create awareness among the farmers for proper application with due understanding of the mechanism pursued by this technology. The most vital benefit to the farmer is the onsite production of the amendment with on farm available raw material i.e., manure, that is otherwise a waste form. Initially, free of cost knowledge dissemination and provision of the amendment for field trials to the local community could be helpful. Monitoring and follow up programs for knowing the impact of the amendments on different pockets of soils for long duration, in different seasons and climatic regimes will aggravate the beneficial effects of using this technology. In addition, this could prove to be an economical as well as eco-friendly organic amendment. Slight manipulation of pH at the right time by virtue of bio augmenting novel bacteria can improve bioavailability of P within soil to ultimatey improve the crop production and product qualityFood Security." xml:lang="en_US