Muhammed Mustapha Ibrahim

The stability of soil organic carbon (SOC) is critical for climate change mitigation and underpins key ecosystem services by regulating soil health, nutrient dynamics, and ecosystem resilience. While climate and nitrogen are well‐known factors of SOC content and composition, soil total phosphorus (STP) is positively correlated with SOC and exerts a strong but underrepresented control on its persistence. However, the mutuality and mechanisms of the SOC‐STP linkage remain insufficiently resolved, limiting its integration into predictive ecosystem C models. This review synthesizes global observational datasets and experimental evidence to evaluate the bidirectional linkage between SOC and STP (and STP pools). Predictive models indicate that SOC and STP are strong mutual predictors globally, reflecting shared controls and feedback due to coupled SOC‐organic P cycling. This coupling reflects constrained C:P stoichiometry, declining from 300:1–1300:1 in plant litter to 50:1–300:1 in soil organic matter. These patterns are regulated by plant and microbial P acquisition and utilization strategies, whose quantitative effects remain incompletely constrained. In contrast, predictive models indicate that the SOC‐inorganic P (Pi) pools associations are weaker and dynamic. While co‐stabilization by metal‐bridging regulates the positive SOC‐Pi correlation, competitive sorption can reduce Pi retention by 20%–60% and mobilize SOC by 20%–80%. Although these SOC‐Pi interactions may exert important local or short‐term influences on SOC dynamics, their quantitative ecosystem‐level controls remain insufficiently constrained, making them a key but uncertain component of the SOC‐STP linkage. Current models simulating SOC‐STP linkages remain limited by incomplete/oversimplified representations of plant‐microbe‐soil mineral feedbacks, challenges in partitioning P between multiple biotic and abiotic sinks, and scarce long‐term observations. We propose a dual‐pathway framework combining coordinated long‐term field studies in understudied ecosystems with next‐generation process‐based models that explicitly integrate stoichiometric constraints alongside geochemical feedbacks. These advances are essential to improve SOC projections and inform sustainable P management and climate change mitigation strategies.

Background and Objective: Rice is a staple crop critical to global food security, yet sustainable fertilizer management remains challenging. While organic and inorganic fertilizers are widely used, their specific impacts on germination and early growth of different rice varieties are poorly understood. This study evaluates the effects of these fertilizers on the germination and growth of Bijinbira and Jirani Bazawara rice varieties, addressing a key gap in knowledge and contributing to sustainable agricultural practices. Materials and Methods: Samples of Bijinbira and Jirani Bazawara rice seeds were obtained from Dankure Market. Poultry droppings from Dankure market. Cow dung and NPK fertilizer were collected from the Kara market. The rice seeds were assessed using a water flotation test. The experiment used a Completely Randomized Design (CRD) with four treatments: Cow dung, poultry droppings, NPK fertilizer, and a control (no fertilizer) over five weeks. Germination was assessed by counting seeds with the first count on the fifth day to measure seed vigor and the final count on the tenth day for the germination percentage. The length and width of seeds from each treatment group were measured using a digital caliper. Descriptive statistics (mean and SD) were calculated for germination percentages, seed lengths, and widths, followed by independent t-tests to compare means between two rice varieties, with significance set at ppost hoc Tukey’s HSD tests were used to analyze and identify significant differences (pResults: The germination percentages of Bijinbira and Jirani Bazawara showed significant variation, with Bijinbira achieving the highest germination rate of (90.00%) under combined poultry and cow dung, while the control treatment exhibited the lowest germination at (30.00%). Seed length and width were also measured, with Jirani Bazawara seeds recording the highest seed length (10.15 mm) and Bijinbira seeds achieving the widest seed width (2.21 mm). The results indicate that organic fertilizers, particularly poultry droppings and cow dung, enhance germination and seed development more effectively than inorganic fertilizers. The findings align with previous research supporting the use of organic fertilizers to improve plant growth in nutrient-deficient soils. Conclusion: This study concludes that organic inputs are more beneficial for the early growth stages of these rice varieties and recommends further research into optimizing fertilizer application rates. Farmers are encouraged to adopt organic fertilizers to improve crop productivity sustainably. APA-7 Style Mustapha, I.M., Karaye, I.U., Shehu, ., Shehu, A. (2025). Comparison of Organic vs Inorganic Fertilizers on Germination and Growth of Bijinbira and Jirani Bazawara Rice Varieties. Asian Journal of Biological Sciences, 18(2), 467-475. https://doi.org/10.3923/ajbs.2025.467.475 ACS Style Mustapha, I.M.; Karaye, I.U.; Shehu, .; Shehu, A. Comparison of Organic vs Inorganic Fertilizers on Germination and Growth of Bijinbira and Jirani Bazawara Rice Varieties. Asian J. Biol. Sci 2025, 18, 467-475. https://doi.org/10.3923/ajbs.2025.467.475 AMA Style Mustapha IM, Karaye IU, Shehu , Shehu A. Comparison of Organic vs Inorganic Fertilizers on Germination and Growth of Bijinbira and Jirani Bazawara Rice Varieties. Asian Journal of Biological Sciences. 2025; 18(2): 467-475. https://doi.org/10.3923/ajbs.2025.467.475 Chicago/Turabian Style Mustapha, Ibrahim, Muhammad, Ibrahim Umar Karaye, Abdulkadir Shehu, and Abubakar Shehu. 2025. "Comparison of Organic vs Inorganic Fertilizers on Germination and Growth of Bijinbira and Jirani Bazawara Rice Varieties" Asian Journal of Biological Sciences 18, no. 2: 467-475. https://doi.org/10.3923/ajbs.2025.467.475

Subtropical forests store significant amounts of soil organic carbon (SOC) and are important in the global C cycle. Current understandings based on controlled experiments indicate that phosphorus (P) availability promotes SOC decomposition by alleviating microbial P limitation or rendering SOC available for microbial decomposition. While no alternative mechanism is currently known, it is uncertain if this mechanism holds across soils or P supply levels at the field scale. We formulated an alternative mechanism for acidic subtropical forest soils where organic C (OC) is bound to iron (Fe). Our hypothesis proposed that P supply would promote Fe-bound P formation and desorption of OC previously bound to Fe, and the microbial utilization of the desorbed OC for P-cycling contributes significantly to CO₂ emission. We tested our hypotheses by utilizing a forest P addition platform to explore C-dynamics, its regulators, and utilization across four P supply levels: 0, 25, 50, and 100 kg P ha^-1 yr^-1 (Con, P1, P2, and P3, respectively) for one year. Phosphorus supply significantly increased the periodic and cumulative dissolved OC (DOC) concentration, especially in P3, and was associated with increased iron (Fe)-bound P formation. With increased DOC following P addition, microbial biomass P (MBP) significantly increased, while MBC remained unchanged. The significantly positive relationship between MBP:MBC ratio and DOC, significant increase in MBP and carbon dioxide (CO₂) emission with P addition, and the reduction in CO₂ emission with increasing MBC:MBP ratio (0–10 cm) supports our results that the desorbed-C alleviated microbial C-limitation induced during P-cycling, particularly, MBP incorporation, to drive CO₂ emission. Structural equation modeling and multivariate analyses projected MBP as a critical factor inducing CO₂ emission. Besides, insignificant alterations in the relative abundance of C-degrading functional genes and reductions in P- and C-degrading enzyme activity indicated the sufficiency of desorbed OC for microbial use without further SOC degradation. Our study provides an alternative mechanism of P's impact on soil C-cycling processes in acidic subtropical forest soils vital for constraining process-based C models.

Subtropical forests store significant amounts of soil organic carbon (SOC) and are important in the global C cycle. Current understandings based on controlled experiments indicate that phosphorus (P) availability promotes SOC decomposition by alleviating microbial P limitation or rendering SOC available for microbial decomposition. While no alternative mechanism is currently known, it is uncertain if this mechanism holds across soils or P supply levels at the field scale. We formulated an alternative mechanism for acidic subtropical forest soils where organic C (OC) is bound to iron (Fe). Our hypothesis proposed that P supply would promote Fe-bound P formation and desorption of OC previously bound to Fe, and the microbial utilization of the desorbed OC for P-cycling contributes significantly to CO₂ emission. We tested our hypotheses by utilizing a forest P addition platform to explore C-dynamics, its regulators, and utilization across four P supply levels: 0, 25, 50, and 100 kg P ha^-1 yr^-1 (Con, P1, P2, and P3, respectively) for one year. Phosphorus supply significantly increased the periodic and cumulative dissolved OC (DOC) concentration, especially in P3, and was associated with increased iron (Fe)-bound P formation. With increased DOC following P addition, microbial biomass P (MBP) significantly increased, while MBC remained unchanged. The significantly positive relationship between MBP:MBC ratio and DOC, significant increase in MBP and carbon dioxide (CO₂) emission with P addition, and the reduction in CO₂ emission with increasing MBC:MBP ratio (0–10 cm) supports our results that the desorbed-C alleviated microbial C-limitation induced during P-cycling, particularly, MBP incorporation, to drive CO₂ emission. Structural equation modeling and multivariate analyses projected MBP as a critical factor inducing CO₂ emission. Besides, insignificant alterations in the relative abundance of C-degrading functional genes and reductions in P- and C-degrading enzyme activity indicated the sufficiency of desorbed OC for microbial use without further SOC degradation. Our study provides an alternative mechanism of P's impact on soil C-cycling processes in acidic subtropical forest soils vital for constraining process-based C models.

Subtropical forests store significant amounts of soil organic carbon (SOC) and are important in the global C cycle. Current understandings based on controlled experiments indicate that phosphorus (P) availability promotes SOC decomposition by alleviating microbial P limitation or rendering SOC available for microbial decomposition. While no alternative mechanism is currently known, it is uncertain if this mechanism holds across soils or P supply levels at the field scale. We formulated an alternative mechanism for acidic subtropical forest soils where organic C (OC) is bound to iron (Fe). Our hypothesis proposed that P supply would promote Fe-bound P formation and desorption of OC previously bound to Fe, and the microbial utilization of the desorbed OC for P-cycling contributes significantly to CO₂ emission. We tested our hypotheses by utilizing a forest P addition platform to explore C-dynamics, its regulators, and utilization across four P supply levels: 0, 25, 50, and 100 kg P ha^-1 yr^-1 (Con, P1, P2, and P3, respectively) for one year. Phosphorus supply significantly increased the periodic and cumulative dissolved OC (DOC) concentration, especially in P3, and was associated with increased iron (Fe)-bound P formation. With increased DOC following P addition, microbial biomass P (MBP) significantly increased, while MBC remained unchanged. The significantly positive relationship between MBP:MBC ratio and DOC, significant increase in MBP and carbon dioxide (CO₂) emission with P addition, and the reduction in CO₂ emission with increasing MBC:MBP ratio (0–10 cm) supports our results that the desorbed-C alleviated microbial C-limitation induced during P-cycling, particularly, MBP incorporation, to drive CO₂ emission. Structural equation modeling and multivariate analyses projected MBP as a critical factor inducing CO₂ emission. Besides, insignificant alterations in the relative abundance of C-degrading functional genes and reductions in P- and C-degrading enzyme activity indicated the sufficiency of desorbed OC for microbial use without further SOC degradation. Our study provides an alternative mechanism of P's impact on soil C-cycling processes in acidic subtropical forest soils vital for constraining process-based C models.

Subtropical forests store significant amounts of soil organic carbon (SOC) and are important in the global C cycle. Current understandings based on controlled experiments indicate that phosphorus (P) availability promotes SOC decomposition by alleviating microbial P limitation or rendering SOC available for microbial decomposition. While no alternative mechanism is currently known, it is uncertain if this mechanism holds across soils or P supply levels at the field scale. We formulated an alternative mechanism for acidic subtropical forest soils where organic C (OC) is bound to iron (Fe). Our hypothesis proposed that P supply would promote Fe-bound P formation and desorption of OC previously bound to Fe, and the microbial utilization of the desorbed OC for P-cycling contributes significantly to CO₂ emission. We tested our hypotheses by utilizing a forest P addition platform to explore C-dynamics, its regulators, and utilization across four P supply levels: 0, 25, 50, and 100 kg P ha^-1 yr^-1 (Con, P1, P2, and P3, respectively) for one year. Phosphorus supply significantly increased the periodic and cumulative dissolved OC (DOC) concentration, especially in P3, and was associated with increased iron (Fe)-bound P formation. With increased DOC following P addition, microbial biomass P (MBP) significantly increased, while MBC remained unchanged. The significantly positive relationship between MBP:MBC ratio and DOC, significant increase in MBP and carbon dioxide (CO₂) emission with P addition, and the reduction in CO₂ emission with increasing MBC:MBP ratio (0–10 cm) supports our results that the desorbed-C alleviated microbial C-limitation induced during P-cycling, particularly, MBP incorporation, to drive CO₂ emission. Structural equation modeling and multivariate analyses projected MBP as a critical factor inducing CO₂ emission. Besides, insignificant alterations in the relative abundance of C-degrading functional genes and reductions in P- and C-degrading enzyme activity indicated the sufficiency of desorbed OC for microbial use without further SOC degradation. Our study provides an alternative mechanism of P's impact on soil C-cycling processes in acidic subtropical forest soils vital for constraining process-based C models.

Human activities have globally increased atmospheric nitrogen (N) deposition, which has enhanced the risk of ecosystem N losses. Phosphorus (P), as a macroelement required for life, is closely linked to the biogeochemical cycle of N. Therefore, quantifying how soil N cycle responds to different P supply levels is important. Here we examined the responses of soil N dynamics to altered P supply using a P addition experiment (+0, +25, +50, +100 kg P ha−1 yr−1) in an evergreen broadleaf mixed plantation in subtropical China. We found that P addition led to a more open soil N cycle in the forest ecosystem. The primary source of N2O emissions in the study plots was fungal denitrification, which accounted for 41%-52% of the total N2O emissions, based on δ18O-N2O, δ15Nα-N2O, δ15Nbulk-N2O and SP measurements. Nitrogen loss by gas or water and N assimilation by plants were found to be coupled processes at +25 kg P ha−1 yr−1 addition level. The δ15N-NO3− and δ18O-NO3− values in runoff and leaching water from different depths were all depleted from −10‰ to +0‰ in the wet season. This result indicates that soil N has a short residence time and rapid NO3−-N loss in the forest ecosystem, and with fewer nitrogen conversions according to the isotope fractionation theory. These observed varied responses of soil N transformation, gaseous loss, and liquid loss to different P supply levels provide new insights into our understanding of N-P relationships in broadleaf forest plantations.

Subtropical forests store significant amounts of soil organic carbon (SOC) and are important in the global C cycle. Current understandings based on controlled experiments indicate that phosphorus (P) availability promotes SOC decomposition by alleviating microbial P limitation or rendering SOC available for microbial decomposition. While no alternative mechanism is currently known, it is uncertain if this mechanism holds across soils or P supply levels at the field scale. We formulated an alternative mechanism for acidic subtropical forest soils where organic C (OC) is bound to iron (Fe). Our hypothesis proposed that P supply would promote Fe-bound P formation and desorption of OC previously bound to Fe, and the microbial utilization of the desorbed OC for P-cycling contributes significantly to CO₂ emission. We tested our hypotheses by utilizing a forest P addition platform to explore C-dynamics, its regulators, and utilization across four P supply levels: 0, 25, 50, and 100 kg P ha^-1 yr^-1 (Con, P1, P2, and P3, respectively) for one year. Phosphorus supply significantly increased the periodic and cumulative dissolved OC (DOC) concentration, especially in P3, and was associated with increased iron (Fe)-bound P formation. With increased DOC following P addition, microbial biomass P (MBP) significantly increased, while MBC remained unchanged. The significantly positive relationship between MBP:MBC ratio and DOC, significant increase in MBP and carbon dioxide (CO₂) emission with P addition, and the reduction in CO₂ emission with increasing MBC:MBP ratio (0–10 cm) supports our results that the desorbed-C alleviated microbial C-limitation induced during P-cycling, particularly, MBP incorporation, to drive CO₂ emission. Structural equation modeling and multivariate analyses projected MBP as a critical factor inducing CO₂ emission. Besides, insignificant alterations in the relative abundance of C-degrading functional genes and reductions in P- and C-degrading enzyme activity indicated the sufficiency of desorbed OC for microbial use without further SOC degradation. Our study provides an alternative mechanism of P's impact on soil C-cycling processes in acidic subtropical forest soils vital for constraining process-based C models.