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Purpose: Soil phosphorus (P) availability and microbial community are typically affected by agricultural land use. This study aimed to explore the link of soil available P and P-cycling-related bacteria and to distinguish P mobilization strategies between upland and paddy cropping systems. Materials and methods: A total of 120 soil samples were collected from 60 sites with adjacent upland and paddy soils in subtropical China. we analyzed soil P fractions and investigated bacteria-mediated P cycling by quantifying the abundance of genes involved in organic P (Po) mineralization (phoD, phoX, phoC), inorganic P (Pi) solubilization (pqqC, gltA), and P transport (pitA, pstS). Results and discussion: The abundance of P-cycling-related bacteria genes was significantly higher in paddy soils compared to upland soils. CaCl2-P, and enzyme-P levels were notably higher in upland soil. In upland soil, microbes harboring Po-mineralizing and Pi-solubilizing genes contributed indirectly to P availability by mobilizing enzyme-P. In paddy soil, citrate-P was strongly correlated with available P, suggesting that P availability is mainly controlled by organic acids released from root exudation and microbial activity. Conclusions: The microbes mainly affected P availability via Po mineralizing in upland soil. In contrast, microbes tend to secrete organic acids to mobilize Pi in paddy soil. [ABSTRACT FROM AUTHOR]

Lower soil phosphorus (P) availability in saline-sodic soils is due to high pH and salinity, which seriously limited crop growth. Manure application has a positive effect on soil properties and P availability. We conducted an experiment, which included five treatments with different durations of manure application: 11-, 16-, 22-, and 27-year manure treatments, and no manure as a control treatment (CK). The results showed that manure application decreased soil pH and electrical conductivity (EC) and increased soil organic matter (SOM). Soil available P content increased by 236.76 mg·kg−1 after applying manure for 27 years. Compared to the CK treatment, manure application significantly increased alkaline phosphatase (ALP) 3.36–6.05-fold and increased microbial biomass phosphorus (MBP) 3.69–15.90-fold (p < 0.05). The organic P (Po) and inorganic P (Pi) contents increased with manure application, except Ca10-P and O-P. Furthermore, we found that pH and EC were significantly negatively correlated with SOM (p < 0.05). MBP and ALP were significantly positively correlated with SOM (p < 0.05). Available P was mainly affected by Ca2-P (+0.71, p < 0.001). Overall, manure application in saline-sodic soils altered soil saline-sodic properties by increasing SOM. The results also indicated that enhanced soil available P is due to an increase in Ca2-P, Al-P, and Po mineralization, especially for Ca2-P. [ABSTRACT FROM AUTHOR]

Abstract Internal phosphorus loading (IPL), as an important part of lake phosphorus cycle and the key to solve the eutrophication problem, is still an important cause of regional and seasonal algal blooms for some mesotrophic lakes located in plateau areas. We investigated the composition, distribution of P fractions in sediments and suspended particulate matter (SPM) of Erhai Lake, southwest China, and explored the relationships between environmental variables and spatial-temporal variations of P fractions. The total P (TP) in surface sediments ranged from 817 to 1216 mg/kg, with inert Ca-P (32%) and Res-P (24%) predominating, at a moderate level. The comparison of short-term release fluxes (0.08 mg/(m2·d)) and long-term release fluxes (0.09 mg/(m2·d)) reflected that the northern region was recovering slowly from the previous P pollution. Mobile-P (the sum of loosely adsorbed P, iron bound P, and organic P) accounted for 52.3% of the TP in SPM and showed high spatial-temporal variations, which were closely related to the growth of algae throughout the investigation. The results suggested that sediments could make a sustained contribution to IPL, and that the P in SPM was highly active and significantly contributed to eutrophication in Erhai Lake especially at the time of seasonal alternations. Our data provided important theoretical bases for the relationship between internal phosphorus loading and eutrophication in plateau lakes.

Abstract Background Burkholderia is a phosphorus solubilizing microorganism discovered in recent years, which can dissolve insoluble phosphorus compounds into soluble phosphorus. To investigate the effects of Burkholderia and calcium phosphate on the composting of Torreya grandis branches and leaves, as well as to explain the nutritional and metabolic markers related to the composting process. Methods In this study, we employed amplicon sequencing and untargeted metabolomics analysis to examine the interplay among phosphorus (P) components, microbial communities, and metabolites during T. grandis branch and leaf waste composting that underwent treatment with calcium phosphate and phosphate-solubilizing bacteria (Burkholderia). There were four composting treatments, 10% calcium phosphate (CaP) or 5 ml/kg (1 × 108/ml Burkholderia) microbial inoculum (WJP) or both (CaP + WJP), and the control group (CK). Results The results indicated that Burkholderia inoculation and calcium phosphate treatment affected the phosphorus composition, pH, EC, and nitrogen content. Furthermore, these treatments significantly affected the diversity and structure of bacterial and fungal communities, altering microbial and metabolite interactions. The differential metabolites associated with lipids and organic acids and derivatives treated with calcium phosphate treatment are twice as high as those treated with Burkholderia in both 21d and 42d. The results suggest that calcium phosphate treatment alters the formation of some biological macromolecules. Conclusion Both Burkholderia inoculation and calcium phosphate treatment affected the phosphorus composition, nitrogen content and metabolites of T. grandis branch and leaf waste compost.These results extend our comprehension of the coupling of matter transformation and community succession in composting with the addition of calcium phosphate and phosphate-solubilizing bacteria.

Phosphatic fertilizers applied to soil, with time, alters into different insoluble soil phosphorus fractions. Since P fertilizers are expensive and raw material supplies are limited, it is essential to evaluate changes in phosphorus fractions and balance in soil in order to determine appropriate phosphorus fertilizer management strategies for sustainable yields. A long-term experiment (20 years) was conducted in an inceptisol with rice-rice cropping system. Soil samples were collected from six treated plots and one fallow; analyzed for phosphorus fractions using sequential extraction method. Phosphorus balance was computed. The results reveled that yield was 51.5, 112.0, 147.7 and 116.7% higher under 50% NPK, 100% NPK, 150% NPK and 100% NPK + FYM over control. Irrespective of the treatments, the abundance of the various fractions of phosphorus (P) in soil as follows: Organic P (32.4% of total P) > Calcium-P (27.76% of total P) > Mineral P (24.17% of total P) > Iron-P (6.65% of total P) > Aluminum-P (3.46% of total P) > Reductant soluble P (3.22% total P) > Occluded P (1.44% of total P) > Saloid P (0.89% total P). Phosphorus activation coefficient (%) was recorded higher under 150% NPK followed by 100% NPK + FYM > 100% NPK > 50% NPK > 100% N > control > Fallow. Hence, 100% NPK + FYM treatment has maintained phosphorus fractions in a good proportion and sustainable yields under rice-rice cropping system. [ABSTRACT FROM AUTHOR]

Background and Aims: Phosphorus (P) plays a vital role in plant physiology, and the soils of Chinese fir-producing areas are rich in aluminum and iron ions, making phosphorus highly susceptible to fixation. Insufficient phosphorus nutrient supply is a main constraint to the sustainability of Chinese fir plantations. The aim of this study is to ameliorate the problem of soil available phosphorus deficiency in Chinese fir plantations by changing the management mode, introducing local broad-leaved tree species to form multiple layers of different ages, thereby enhancing soil productivity. Methods: The properties and phosphorus fractions of the surface soils (0-20 cm), litter and leaf nutrients were determined, and macro-genomic technique was used to explore changes of soil phosphorus cycling (P-cycling) genes. Results: (1) The close-to-nature management (CNM) significantly increased soil organic carbon (SOC) and available phosphorus (AP) content and affected litter and plant nutrients. (2) The CNM affected the availability of soil phosphorus. The labile phosphorus (resin-P, NaHCO3-Pi) and moderately labile phosphorus (NaOH-Pi) were significantly higher in CNM forests than in Chinese fir plantation. (3) The relative abundances of most of the P-cycling genes differed between the forests, with higher abundances of P-solubilization (ppa), P-mineralization (phnL and opd) and P-regulatory (phoB) genes in CNM forests. Moreover, MBC (microbial biomass carbon), SOC, total nitrogen (TN) and LTP (litter total phosphorus) were the main factors affecting the composition of soil P-cycling genes. Conclusions: The CNM affected properties (soil, litter and plant) and improved soil phosphorus availability and the relative abundance of P-cycling genes. This study revealed the regulation mechanism of P-cycling in the CNM of Chinese fir plantation from microbial P-cycling genes perspective, which highlights the importance of P supply and microbial metabolic strategy by CNM of Chinese fir plantation. [ABSTRACT FROM AUTHOR]

Internal phosphorus loading (IPL), as an important part of lake phosphorus cycle and the key to solve the eutrophication problem, is still an important cause of regional and seasonal algal blooms for some mesotrophic lakes located in plateau areas. We investigated the composition, distribution of P fractions in sediments and suspended particulate matter (SPM) of Erhai Lake, southwest China, and explored the relationships between environmental variables and spatial-temporal variations of P fractions. The total P (TP) in surface sediments ranged from 817 to 1216 mg/kg, with inert Ca-P (32%) and Res-P (24%) predominating, at a moderate level. The comparison of short-term release fluxes (0.08 mg/(m2·d)) and long-term release fluxes (0.09 mg/(m2·d)) reflected that the northern region was recovering slowly from the previous P pollution. Mobile-P (the sum of loosely adsorbed P, iron bound P, and organic P) accounted for 52.3% of the TP in SPM and showed high spatial-temporal variations, which were closely related to the growth of algae throughout the investigation. The results suggested that sediments could make a sustained contribution to IPL, and that the P in SPM was highly active and significantly contributed to eutrophication in Erhai Lake especially at the time of seasonal alternations. Our data provided important theoretical bases for the relationship between internal phosphorus loading and eutrophication in plateau lakes. [ABSTRACT FROM AUTHOR]

Bioavailability, enrichment, and risk of phosphorus (P) and its fraction composition were monitored in the paddy soils of Kunnukara during the pre-cultivation and post-harvest periods in the years 2020 and 2021. Iron-bound P (≥ 105.56 ± 0.05 mg/kg) was found highest among the P fractions. The bioavailability of P was recorded at peak value during the post-harvest period, contributed by organic P, Iron bound P, and loosely bound P. Principal component analysis inferred that loosely bound P was pH-dependent and significantly influenced by cation exchange, particle density, soil aggregate stability, and total organic carbon (TOC) in the post-harvest soil, whereas TOC, aluminium-bound P, and calcium-bound P in the pre-cultivation soils. Additionally, physico-chemical parameters like electrical conductivity, bulk density, specific gravity, TOC, and soil aggregate stability have a significant impact on the composition of P fractions in the soil. Bioavailable phosphorus (BAP) ranged from 642.78 ± 0.49 to 594.20 ± 1.23 mg/kg during the post-harvest period. Moreover, the contribution of BAP to total P ranged from 99.45 to 99.54%, indicating the fact that soil is sufficient in BAP. Pollution indices revealed that the paddy soils are at risk of eutrophication. Phosphorus Pollution Index (PPI) > 1 exhibited moderate pollution (1.06 to 1.07) at the topsoil (0–15 cm) and PPI < 1, mild pollution (0.92 to 0.99) at 15–30 cm depths. The organic nitrogen index ≥ 0.133 indicates severe soil pollution in the study site. An extended fertilizer application in the field contributes to nutrient enrichment and warrants the risk of contamination in nearby riverine systems (River Periyar and River Chalakkudy). [ABSTRACT FROM AUTHOR]

Purpose: Investigating the contributions of different soil properties and their influences on changes in soil P fractions and availability is helpful for soil P management. Methods: Soil samples were collected in 2018 from a long-term red soil field experiment established in 1990. The unfertilized control (CK), chemical NK, NP, NPK, NPK with straw (S) (NPKS), NK + lime, NP + lime, NPK + lime, and NPKS + lime fertilization treatments, which were arranged in a randomized complete block design, were selected. Results: Compared with no lime, lime addition significantly increased the labile P/total P ratio in the NPK and NPKS treatments by 12.35% and 11.75%, respectively. The results further revealed that fertilization treatments without lime application (NK, NP, NPK, and NPKS) significantly reduced the soil pH, Mehlich-3 (M3)-Mg and M3-Ca compared with those in the CK and lime treatments during 2018. In contrast, lime application reduced the M3-Fe and M3-Al concentrations by 2% and 3%, respectively. Long-term P fertilization improved soil organic matter, M3-P, M3-Fe, and M3-Al. While soil pH exhibited a strong and positive relationship with M3-Mg (r = 0.780**) and M3-Ca (r = 0.788**) and a strong and negative correlation with M3-Fe (r = -0.395*) and M3-Al (r = -0.584**), the transformation and discharge of various P pools in red soil were facilitated by soil OM, M3-Fe, and M3-Al as the key contributors. Conclusion: NPK and NPKS combined with lime addition could be useful approaches for increasing the available P (labile P/total P) by enhancing M3-Ca and M3-Mg and soil pH while reducing M3-Fe and M3-Al in red acidic soil. [ABSTRACT FROM AUTHOR]

Background Burkholderia: is a phosphorus solubilizing microorganism discovered in recent years, which can dissolve insoluble phosphorus compounds into soluble phosphorus. To investigate the effects of Burkholderia and calcium phosphate on the composting of Torreya grandis branches and leaves, as well as to explain the nutritional and metabolic markers related to the composting process. Methods: In this study, we employed amplicon sequencing and untargeted metabolomics analysis to examine the interplay among phosphorus (P) components, microbial communities, and metabolites during T. grandis branch and leaf waste composting that underwent treatment with calcium phosphate and phosphate-solubilizing bacteria (Burkholderia). There were four composting treatments, 10% calcium phosphate (CaP) or 5 ml/kg (1 × 108/ml Burkholderia) microbial inoculum (WJP) or both (CaP + WJP), and the control group (CK). Results: The results indicated that Burkholderia inoculation and calcium phosphate treatment affected the phosphorus composition, pH, EC, and nitrogen content. Furthermore, these treatments significantly affected the diversity and structure of bacterial and fungal communities, altering microbial and metabolite interactions. The differential metabolites associated with lipids and organic acids and derivatives treated with calcium phosphate treatment are twice as high as those treated with Burkholderia in both 21d and 42d. The results suggest that calcium phosphate treatment alters the formation of some biological macromolecules. Conclusion: Both Burkholderia inoculation and calcium phosphate treatment affected the phosphorus composition, nitrogen content and metabolites of T. grandis branch and leaf waste compost.These results extend our comprehension of the coupling of matter transformation and community succession in composting with the addition of calcium phosphate and phosphate-solubilizing bacteria. [ABSTRACT FROM AUTHOR]

Summary: In severely phosphorus (P)‐impoverished environments, plants have evolved to use P very efficiently. Yet, it is unclear how P allocation in leaves contributes to their photosynthetic P‐use efficiency (PPUE) and position along the leaf economics spectrum (LES). We address this question in 10 species of Banksia and Hakea, two highly P‐efficient Proteaceae genera.We characterised traits in leaves of Banksia and Hakea associated with the LES: leaf mass per area, light‐saturated photosynthetic rates, P and nitrogen concentrations, and PPUE. We also determined leaf P partitioning to five biochemical fractions (lipid, nucleic acid, metabolite, inorganic and residual P) and their possible association with the LES.For both genera, PPUE was negatively correlated with fractional allocation of P to lipids, but positively correlated with that to metabolites. For Banksia only, PPUE was negatively correlated with residual P, highlighting a strategy contrasting to that of Hakea. Phosphorus‐allocation patterns significantly explained PPUE but were not linked to the resource acquisition vs resource conservation gradient defined by the LES.We conclude that distinct P‐allocation patterns enable species from different genera to achieve high PPUE and discuss the implications of different P investments. We surmise that different LES axes representing different ecological strategies coexist in extremely P‐impoverished environments. [ABSTRACT FROM AUTHOR]

Background and aims: Soil microbiome is the key driver mediating soil P transformation in agroecosystems. However, the underlying genomic information related to soil P cycling in response to organic C inputs is largely unknown. Methods: By using metagenomic sequencing, we investigated the effect of P fertilization and C input (i.e., glucose and lignin) on functional profiles of microbial genes related to P cycling in bulk and rhizosphere soils. Maize plants were grown for 47 days in Ultisols with or without P-fertilizer history. Results: Glucose decreased rhizosphere H2O-Pi concentrations in soil with P history, increased that in soil without P history; while lignin increased that in both soils. Ogranic C inputs increased the relative abundances of phnGHIJLMNP and pit genes by 17–138% and 2.3–31%, decreased those of phoB, phoR and pstABCS genes by 3.6–18%, 12–31% and 11–26%, respectively, in rhizosphere soils irrespective of P history. In the rhizosphere rather than bulk soil, the proportion of P starvation regulation-related genes was higher in lignin treated-soils without than with P history. Proteobacteria (10–89%) and Acidobacteria (0.41–57%) were the dominant phyla and main contributors to soil P transformation-related genes (e.g., appA, phoAD, gcd). Elevated soil pH induced by organic C inputs also diversified the composition of genes involved in P transformation. Conclusions: Organic C altered P cycling-related gene composition irrespective of soil P status, which facilitated P transformation. Proteobacteria and Acidobacteria were vital in mediating C and P metabolisms. [ABSTRACT FROM AUTHOR]

Effective phosphorus (P) management is crucial for optimal blueberry production. However, a comprehensive understanding of phosphorus distribution across soil depths and types after two decades of blueberry cultivation remains a challenge. This study examines pH, EC, SOC (soil organic carbon), Total N (total nitrogen), and phosphorus fractions in soils from Japanese blueberry fields that have been cultivated for over 20 years. The soils selected for this study represent typical soils from long-term blueberry-growing regions in Japan, ensuring the relevance of the findings to these key agricultural areas. Soil samples were gathered from depths of 0–30 cm and 30–60 cm, revealing significant variations in phosphorus content that are influenced by soil properties and fertilization history. Soil types such as KS (Kuroboku soils) and FS (Fluvic soils) show higher Total P accumulation in deeper layers, whereas BFS (Brown Forest soils) and RYS (Red-Yellow soils) accumulate more in shallower layers. Long-term cultivation has led to greater non-labile phosphorus (NLP) accumulation in shallower layers of KS, BFS, and FS soils, indicating strong phosphorus fixation. BFS soil also exhibits increased organic phosphorus (NaOH-Po) at deeper depths. NaOH-Po and NaHCO3-Po, through their interactions with EC and pH, critically modulate the transformation of NLP into labile phosphorus (LP), thereby influencing overall phosphorus and nitrogen dynamics in the soil. These findings underscore the importance of tailored phosphorus fertilization strategies based on blueberry field characteristics, providing a basis for low-input phosphorus fertilization approaches. [ABSTRACT FROM AUTHOR]

Despite continuous efforts, eutrophication is still occurring in freshwater and phosphorus (P) is the most important nutrients that drive the eutrophication in rivers and streams. However, little information is available about the distribution of P fractions in river sediment. Here, the sequential extraction approach was used to evaluate the sediment P fractionation and its content in the anthropogenically damaged river Ganga, India. Different sedimentary P fractions viz. exchangeable (Ex-P), aluminum bound (Al–P), iron bound (Fe–P), calcium bound (Ca–P), and organically bound phosphorus (Org-P), were quantified. Significantly higher level of total P was recorded in pre-monsoon season (438.5 ± 95.8 mg/kg), than other [winter (345.7 ± 110.6 mg/kg), post-monsoon (319.2 ± 136.3 mg/kg), and monsoon (288.6 ± 77.3 mg/kg)] seasons. Different P fractions such as Ex-P, Al–P, Fe–P, Ca–P and Org-P varied from 2.88–12.8 mg/kg, 7.64–98.8 mg/kg, 32.2–179.2 mg/kg, 51.97–286.1 mg/kg and 9.3–143.7 mg/kg, respectively, which correspondingly represented 0.5–10.54%, 3.41–20.18%, 17.27–37.82%, 37.35–60.2%, 4.15–25.88% of the Total P with a rank order of P-fractions was Ca–P > Fe–P > Org-P > Al–P > Ex-P. Bio-available P contributes a considerable portion (37.9–46.0%) of total P which may increase the eutrophication to overlying water. Results demonstrate that inorganic P species control the P bio-availability in both time and space. However, an estimated phosphorus pollution index based on sediment total P content showed no ecological risk of phosphorus to Ganga River sediment. [ABSTRACT FROM AUTHOR]

Large amounts of use of mineral fertilizers (MF) have brought about environmental pollution and soil problems, like soil degradation and acidification. The partial substitution of MF with organic fertilizer is considered eco-friendly and more efficient in improving soil fertility. In our study, the effects of MF alone and the combination of MF and organic fertilizers (MOF) on soil phosphorus (P) availability in infertile soil with P deficiency were studied with the initial soil without any addition as the control. The addition of MF and MOF increased the soil labile P (resin-P and NaHCO3-Pi) by 101.8% and 320.1%, respectively, compared to the control after 180 days of treatment. Resin-P was the predominant P fraction in MOF, accounting for 28.0% of the total P. The proportions of residual-P in MOF were 5.6% and 8.3% lower than those in MF and control, respectively. The P activation coefficient in MOF was the highest (15.0%), and was the main contributor to soil P fractions based on redundancy analysis. Our results suggest that the combined application of organic and mineral fertilizers is more efficient in improving soil P availability than mineral fertilizer alone. We highlight the joint application was beneficial to improve soil P activation coefficient.

This study investigated the distribution of sedimentary phosphorus (P) species along an area of a rapid current at the southern coast of Zhoushan Island. The objective of this study was to improve the understanding of P cycling in a zone of rapid water cycling. Results showed that the average percentage of each P form to total P (TP) was in the following order: apatite P (Ca-P; 52%) was found in the most abundant, followed by organic P (OP; 16%), exchangeable-P (Ex-P; 14%), detrital P (De-P; 11%), and iron-bound P (Fe-P; 7%). Ca-P showed a trend of an increasing concentration from a location at the west (ZS1 has mean Ca-P = 45.6 mg kg−1) toward the east (ZS2 has mean Ca-P = 82.69 mg kg−1) and south-east (ZS3 has mean Ca-P = 82.17 mg kg−1); De-P also increased from 15.12 mg kg−1 at ZS1 to 22.53 mg kg−1 at ZS2 and 27.45 mg kg−1 at ZS3, but the three bioavailable P species, OP, Ex-P, and Fe-P, decreased from the west toward the east of the coastal area. Results along the cores showed the occurrences of sediment P adsorption and release throughout the time span from the 1930s to the present, with an overall trend of decreasing Ca-P and TP from the bottom to surface sediments. There was a tendency of Ca-P formation at the expense of Ex-P and OP release during transport and organic matter decomposition. The likely impact of climate change in the coastal zone would be an increased temperature resulting in elevated organic matter decomposition and P release. [ABSTRACT FROM AUTHOR]

The nitrogen (N) and phosphorus (P) released from different fertilizers to soil solution is a factor that affects soil fertility and plant growth. To evaluate the impacts of amending soil with organic, chemical and bio-fertilizers solely or in combinations for uprising N, P available contents in soil and increasing the growth of black cumin (Nigella sativa L) plants. The consequences of these additives on soil chemical properties were a matter of concern herein. To attain this aim, incubation and a pot experiment was conducting at 50% level of adding rabbit manure and ureaform together or both separately, control without fertilization and bio-fertilizer single in a randomized block design which considering six equations (Zero-order, first-order equation, second-order equation, Pseudo-second-order, power function, and parabolic diffusion model) were used to describe variations among released N and P with incubation time. The results demonstrated that using chemical, organic, and bio-fertilizer resulted in considerable decrease in soil pH and increases in organic matter (SOM) and nutrients availability (N and P) by time progress for all treatments. Compared to other equations, the pseudo-second models provided a better description of the kinetics of changes in released N and P contents with time, with R² ranging from 0.99 to 1.00. The results show that the application of 50% Rabbit manure + 50% Ureaform + Bio-fertilizer (RUBF) significantly enhanced parameters of black cumin plants such as shoot dry weight, plant height, and stem diameter, chlorophyll a, b, and carotenoids ratio, dry weight capsules, number of capsules, and seed weight/plant. Our study is useful when using rabbit manure, ureaform and bio-fertilizers. That can be improving soil chemical properties, supplying available nutrients, the release kinetics and the factors related to the release of nutrients from these fertilizers are essential in planning strategies of nutrient management, additionally, boosted the growth, plants quality, yield and photosynthetic pigments. [ABSTRACT FROM AUTHOR]

Anthropogenic inputs of nitrogen (N) and phosphorus (P) to terrestrial ecosystems alter soil nutrient cycling. However, the global‐scale responses of soil P fractions to N and P inputs and their underlying mechanisms remain elusive. We conducted a global meta‐analysis based on 818 observations of soil P fractions from 99 field N and P addition experiments in forest, grassland, and cropland ecosystems ranging from temperate to tropical zones. Our global meta‐analysis revealed distinct responses of soil P fractions to N and P enrichment. For studies using the Chang and Jackson inorganic (Pi) method, we found that high N addition promoted the transformation of immobile Pi fractions into Ferrum/Aluminum‐bound Pi and available Pi in surface soils through soil acidification. However, this acid‐induced transformation of Pi fractions by N addition was observed only in Calcium‐rich soils, while in acidic soils, further acidification led to increase P binding. In contrast, additions of P alone or combined with N significantly increased all soil Pi fractions. Regarding the Hedley P fractions, N addition generally decreased labile organic P by enhancing soil acid phosphatase activity. The responses of other P fractions were influenced by soil pH, fertilization rates, ecosystem type, and other factors. P addition increased most soil P fractions. Overall, both P fractionation methods consistently demonstrate that N inputs deplete soil P and accelerate P cycling, while P inputs increase most soil P fractions, alleviating P limitation. These findings are crucial for predicting the effects of future atmospheric N and P deposition on P cycling processes. Plain Language Summary: Human activities have increased the amount of nitrogen (N) and phosphorus (P) in the environment, which has led to changes in the soil nutrients cycle. This study examined the global‐scale responses of soil P fractions to N and P inputs using a data set from 99 field experiments worldwide. The findings revealed distinct responses of soil P fractions to N and P enrichment. High N input resulted in the transformation of immobile inorganic P (Pi) fractions into available Pi in surface soils. This transformation was observed in calcium‐rich soils due to soil acidification. In contrast, in acidic soils, the acidification led to increased Pi binding. Moreover, N input generally decreased labile organic P, potentially by enhancing soil enzyme activity. Addition of P alone or combined with N significantly increased soil P fractions. These findings have important implications for predicting the effects of future N and P deposition on P cycling processes in the terrestrial ecosystems and understanding the impacts of nutrient enrichment on soil carbon storage and eutrophication. Key Points: Nitrogen inputs can accelerate phosphorus (P) transformation in Calcium‐rich soils but promote P binding in acidic soilsSoil acidification reduces inorganic P bioavailability by increasing the P fixation of Ferrum and Alumiium oxidePhosphorus input increases soil labile, moderately labile, and occluded inorganic P, enhancing soil available P [ABSTRACT FROM AUTHOR]

Abstract Background Little is known about the link between the fungal community and phosphorus fractions when land use is converted from cropland to grassland in saline-alkali soil in northeastern China. Therefore, in this study, the diversity, composition, and function of fungi, as well as phosphorus fractions including Olsen-P and inorganic phosphorus (Pi), were investigated under land use conversions from maize cropland (MC) to alfalfa (Medicago sativa L.) (AG), Leymus chinensis (LG), and natural restored grasslands (RG). Results The results showed that the Pi fractions of Ca8-P, Fe-P, Ca2-P, and Ca10-P were closely related with Olsen-P. Significantly increased Olsen-P content was found in 0–10 cm soil layer in the AG treatment, relative to LG and RG treatments (P

Background and aims: Cover cropping is a strategy to increase soil phosphorus (P) use efficiency in agroecosystems. We investigated adaptations on P acquisition strategies of nine cover crops grown in a calcareous and a non-calcareous chernozem with low available P. Methods: Through a 108-day pot experiment using a calcareous and a decalcified chernozem, we evaluated black oat (Avena strigosa Schreb.), white lupin (Lupinus albus L.), narrow-leaf lupin (Lupinus angustifolius L.), phacelia (Phacelia tanacetifolia Benth.), berseem clover (Trifolium alexandrinum L.), buckwheat (Fagopyrum esculentum Moench), linseed (Linum usitatissimum L.), ramtil (Guizotia abyssinica [Lf] Cass.) and white mustard (Sinapis alba L.) for their dry biomass production, tissue P concentration and uptake, and effects on soil pH, phosphatase activity, mycorrhiza infection rate and soil P fractions. Results: Cover crops differed in several parameters between the two soils. Dry biomass varied from 3.3 (white lupin) to 41.6 g pot-1 (mustard). Tissue P concentrations ranged from 0.046% (mustard) to 0.24% (clover). Species affected pH of both soils, ranging from − 0.66 to + 0.24. Acid phosphatase activity was higher in the decalcified soil, while alkaline phosphatases were higher in the calcareous soil. Root mycorrhizal infection rates ranged from 0 to > 50%. Most plants explored soil labile P exclusively, with organic P mineralization being more relevant in the calcareous soil. Conclusion: We confirm that cover crops favoured distinct strategies to access the predominant soil labile P forms in each soil. Mycorrhizal species were particularly efficient in the decalcified soil, while species with high phosphatase secretion accessed higher Po, especially in the calcareous soil. [ABSTRACT FROM AUTHOR]

Background: Little is known about the link between the fungal community and phosphorus fractions when land use is converted from cropland to grassland in saline-alkali soil in northeastern China. Therefore, in this study, the diversity, composition, and function of fungi, as well as phosphorus fractions including Olsen-P and inorganic phosphorus (Pi), were investigated under land use conversions from maize cropland (MC) to alfalfa (Medicago sativa L.) (AG), Leymus chinensis (LG), and natural restored grasslands (RG). Results: The results showed that the Pi fractions of Ca8-P, Fe-P, Ca2-P, and Ca10-P were closely related with Olsen-P. Significantly increased Olsen-P content was found in 0–10 cm soil layer in the AG treatment, relative to LG and RG treatments (P < 0.05). The occluded P content in 0–10 cm and the Al-P content in 10–20 cm in the RG treatment were the highest. The RG treatment increased the Shannon index of fungi, as well as the abundances of phyla Mortierellomycota and phyla Glomeromycota. Higher abundance of genus Mortierella and lower abundance of genus Cladosporium were observed at RG treatment. Moreover, the RG treatment greatly reduced the abundance of plant pathogens and enhanced the abundances of mycorrhizal and ectomycorrhizal. The Olsen-P was positively correlated with the abundance of plant pathogen (P < 0.01), and the Olsen-P, Ca2-P, and Fe–P were negatively correlated with both the abundances of mycorrhizal and ectomycorrhizal (P < 0.05). Conclusion: Land use conversion from maize cropland to natural restored grassland could reduce plant pathogens and enhance useful fungi by decreasing the availability of phosphorus. [ABSTRACT FROM AUTHOR]

Purpose: The water-level-fluctuating zone (WLFZ) is the buffer zone of energy and material exchange between terrestrial and aquatic ecosystems. Artificial vegetation restoration of WLFZ can improve the interception capacity of P pollution. The purpose of this study is to explore the effect of artificial vegetation restoration on the bioavailability of soil phosphorus (P) in the WLFZ. Material and methods: Soil samples from different spatial locations (natural vegetation zone, artificial vegetation restoration zone) and different altitudes of the WLFZ were collected in the Three Gorges Reservoir (TGR) region, Chongqing, China. Soil P fraction, microbial biomass P (MBP), and phosphatase activity were measured. Results and discussion: Artificial vegetation restoration changed the spatial distribution patterns of soil bioavailable P (Bio-P) in the WLFZ. The soil bioavailable inorganic P (Bio-Pi) in the artificial vegetation restoration zone was significantly higher than those at the natural vegetation zone (p < 0.05) and its content decreased with the decrease of altitude. The content of bioavailable organic P (Bio-Po) in the two transects was not significantly different in general, but was different at different altitudes. Phosphodiesterase (PDE) activity was negatively correlated with Bio-Po in artificial vegetation restoration zone (p < 0.01, R2 = 0.21), but significantly positively correlated with in natural vegetation zone (p < 0.05, R2 = 0.17); this suggests that the relationship between Bio-Po and PDE activity was altered by vegetation restoration. Moreover, the factors controlling the bioavailability of P in the WLFZ are discussed. Conclusion: Artificial vegetation restoration and altitude are the control factors of soil P fractions and bioavailability in WLFZ. Vegetation restoration can increase soil TP and Bio-Pi in general but has little effect on Bio-Po. [ABSTRACT FROM AUTHOR]

Sustainable agriculture plays a critical role in maintaining environmental health and also promotes long-term food security and the preservation of natural resources. We therefore, examined the response of intensified cropping systems over four years across five diverse cropland ecosystems viz. Basmati rice-Wheat-Cowpea, Basmati Rice-Potato-Wheat-Mixed Fodder (Maize + Cowpea + Charni), Basmati Rice-KnolKhol-Potato-Greengram, Basmati Rice-Radish-Green onion-French bean vegetable-Okra, and Rice-Fenugreek-KnolKhol-Green Onion-Dry Onion-Black gram to assess the changes in substrate availability and fertilizer application on nitrogen and phosphorus pools. Soil samples were collected from three different depths (0–5 cm, 5–15 cm, and 15–30 cm) during the kharif season. Significant results were observed in the mean values of mineralizable nitrogen, total nitrogen, ammonical nitrogen, nitrate nitrogen, and soil microbial biomass nitrogen at the 0–5 cm depth, with the highest values recorded under Rice-Fenugreek-KnolKhol-Green Onion-Dry Onion-Black gram. At the soil depth of 0–5 cm, available phosphorus and labile organic phosphorus exhibited significant differences, with the highest values observed in Basmati Rice-Potato-Wheat-Mixed Fodder. Moderately labile phosphorus reached its maximum values under T2 at both 0–5 cm, and at 5–15 cm depths. The peak values of non-labile organic phosphorus were found in T4 (Basmati Rice-Radish-Green onion-French bean vegetable-Okra) at the 0–5 cm soil depth. On a regional scale, the results suggest that more diversified cropping systems hold promise as sustainable agricultural practices that support nitrogen and phosphorus retention, contributing to overall soil sustainability.

Organic carbon (C) is often applied to agricultural soils to increase soil organic matter, however, its mechanistic effects on soil P transformations and availability resulting from stimulation of microbial activities and changes in microbial communities remain uncertain. This study investigated the responses of soil P availability, P fractions and phoD harboring bacterial and fungal communities to two dose rates (5 and 10 mg C g−1 dry soil) of labile C (glucose) in bulk and rhizosphere soils planted with maize in a P-deficient soil (Oxisol). Both doses of glucose significantly increased available P concentrations (over a 47-day period) in soils without maize, and in the bulk and rhizosphere soils of maize, resulting in the promotion of maize growth. Glucose additions altered soil phoD harboring bacterial and fungal community composition and stimulated the growth of keystone P-solubilizing microorganisms, such as Bradyrhizobium and Eupenicillium, in soils with maize. Co-occurrence network analysis showed that glucose enhanced interactions between phoD harboring bacterial taxa relative to that of fungal taxa, whether in individual networks or in combined networks. Our results highlight the importance of labile C in facilitating changes in soil P-solubilizing bacterial and fungal communities of a P-deficient soil. These findings provide crucial information to guide P-cycling management strategies via microbial regulation in agro-ecosystems.

Organic carbon (C) is often applied to agricultural soils to increase soil organic matter, however, its mechanistic effects on soil P transformations and availability resulting from stimulation of microbial activities and changes in microbial communities remain uncertain. This study investigated the responses of soil P availability, P fractions and phoD harboring bacterial and fungal communities to two dose rates (5 and 10 mg C g−1 dry soil) of labile C (glucose) in bulk and rhizosphere soils planted with maize in a P-deficient soil (Oxisol). Both doses of glucose significantly increased available P concentrations (over a 47-day period) in soils without maize, and in the bulk and rhizosphere soils of maize, resulting in the promotion of maize growth. Glucose additions altered soil phoD harboring bacterial and fungal community composition and stimulated the growth of keystone P-solubilizing microorganisms, such as Bradyrhizobium and Eupenicillium, in soils with maize. Co-occurrence network analysis showed that glucose enhanced interactions between phoD harboring bacterial taxa relative to that of fungal taxa, whether in individual networks or in combined networks. Our results highlight the importance of labile C in facilitating changes in soil P-solubilizing bacterial and fungal communities of a P-deficient soil. These findings provide crucial information to guide P-cycling management strategies via microbial regulation in agro-ecosystems.

The availability of soil phosphorus (P), a crucial nutrient influencing plant productivity and ecosystem function, is impacted by continuously increasing nitrogen (N) enrichment, which changes the soil P cycle. The effect of varying forms of N input on soil P dynamics in P-limited karst grassland ecosystems remains unclear. To address this knowledge gap, we conducted a greenhouse experiment to explore the effects of various forms of N addition [Ca(NO3)2, NH4Cl, NH4NO3, Urea] on soil P fractions in these ecosystems, applying two levels (N1: 50 mg N kg-1soil, N2: 100 mg N kg-1soil) of N input in two soils (yellow soil, limestone soil). Results indicated that P fractions in both soil types were significantly affected by N additions, with yellow soil demonstrating a higher sensitivity to these additions, and this effect was strongly modulated by the form and level of N added. High N addition, rather than low N, significantly affect the P fractions in both soil types. Specially, except for Ca(NO3)2, high N addition significantly increased the available P in both soils, following the order: Urea and NH4NO3 > NH4Cl > Ca(NO3)2, and decreased NaHCO3-Pi in both soils. High N addition also significantly reduced NaOH-Po and C.HCl-Po fractions in yellow soil. Additionally, the response of root biomass and alkaline phosphatase activity in both soils to N input paralleled the trends observed in the available P fractions. Notably, changes in soil available P were strongly correlated with plant root biomass and soil alkaline phosphatase activity. Our study highlights that the N addition form significantly influences soil P availability, which is closely tied to plant root biomass and alkaline phosphatase activity. This finding underscores the importance of considering N input form to boost soil fertility and promote sustainable agriculture. [ABSTRACT FROM AUTHOR]

The application of phosphate-solubilizing bacteria has been widely studied in remediating Cd-contaminated soil, but only a few studies have reported on the interaction of P and Cd as well as the microbiological mechanisms with phosphate-solubilizing bacteria in the soil because the activity of phosphate-solubilizing bacteria is easily inhibited by the toxicity of Cd. This paper investigates the phosphorus solubilization ability of Priestia aryabhattai domesticated under the stress of Cd, which was conducted in a soil experiment with the addition of Cd at different concentrations. The results show that the content of Ca2-P increased by 5.12–19.84%, and the content of labile organic phosphorus (LOP) increased by 3.03–8.42% after the addition of Priestia aryabhattai to the unsterilized soil. The content of available Cd decreased by 3.82% in the soil with heavy Cd contamination. Priestia aryabhattai has a certain resistance to Cd, and its relative abundance increased with the increased Cd concentration. The contents of Ca2-P and LOP in the soil had a strong positive correlation with the content of Olsen-P (p < 0.01), while the content of available Cd was negatively correlated with the contents of Olsen-P, Ca2-P, and LOP (p < 0.05). Priestia aryabhattai inhibits the transport of Cd, facilitates the conversion of low-activity P and insoluble P to Ca2-P and LOP in the soil, and increases the bioavailability and seasonal utilization of P in the soil, showing great potential in ecoremediating Cd-contaminated farmland soil with plant–microbe-combined technology. [ABSTRACT FROM AUTHOR]

This study investigated the concentration and fractionation of phosphorus (P) using sequential P extraction and their influencing factors by introducing the PLS-SEM model (partial least squares structural equation model) along this continuum from the Qinhuai River. The results showed that the average concentrations of inorganic P (IP) occurred in the following order: urban sediment (1499.1 mg/kg) > suburban sediment (846.1–911.9 mg/kg) > rural sediment (661.1 mg/kg) > natural sediment (179.9 mg/kg), and makes up to 53.9–87.1% of total P (TP). The same as the pattern of IP, OP nearly increased dramatically with increasing the urbanization gradient. This spatial heterogenicity of P along a river was attributed mainly to land use patterns and environmental factors (relative contribution affecting the P fractions: sediment nutrients > metals > grain size). In addition, the highest values of TP (2876.5 mg/kg), BAP (biologically active P, avg, 675.7 mg/kg), and PPI (P pollution index, ≥ 2.0) were found in urban sediments among four regions, indicating a higher environmental risk of P release, which may increase the risk of eutrophication in overlying water bodies. Collectively, this work improves the understanding of the spatial dynamics of P in the natural-rural–urban river sediment continuum, highlights the need to control P pollution in urban sediments, and provides a scientific basis for the future usage and disposal of P in sediments. [ABSTRACT FROM AUTHOR]

Large amounts of use of mineral fertilizers (MF) have brought about environmental pollution and soil problems, like soil degradation and acidification. The partial substitution of MF with organic fertilizer is considered eco-friendly and more efficient in improving soil fertility. In our study, the effects of MF alone and the combination of MF and organic fertilizers (MOF) on soil phosphorus (P) availability in infertile soil with P deficiency were studied with the initial soil without any addition as the control. The addition of MF and MOF increased the soil labile P (resin-P and NaHCO3-Pi) by 101.8% and 320.1%, respectively, compared to the control after 180 days of treatment. Resin-P was the predominant P fraction in MOF, accounting for 28.0% of the total P. The proportions of residual-P in MOF were 5.6% and 8.3% lower than those in MF and control, respectively. The P activation coefficient in MOF was the highest (15.0%), and was the main contributor to soil P fractions based on redundancy analysis. Our results suggest that the combined application of organic and mineral fertilizers is more efficient in improving soil P availability than mineral fertilizer alone. We highlight the joint application was beneficial to improve soil P activation coefficient. [ABSTRACT FROM AUTHOR]

Contrasting fertilization modifies soil phosphorus (P) transformation and bioavailability, which impact crop P uptake and P migration in the soil profile. A long-term (25-year) fertilizer experiment was employed to investigate crop yield, P uptake and changes in sequentially extracted P fractions in the soil profile, and their relationships on a calcareous soil derived from loess material under a winter wheat and summer maize double-cropping system. The experiment involved seven nutrient management treatments: control (CK, no nutrient input), N, NK, NP, and NPK, representing various combinations of synthetic nitrogen (N), phosphate (P), and potassium (K) applications, as well as combinations of NPK fertilizers with either crop residues (SNPK, where S refers to maize stalk or wheat straw) or manure (MNPK, where M refers to dairy manure). Wheat and maize yields were significantly higher with P input fertilizer relative to the P-omitted treatments. Long-term application of P-containing fertilizers markedly raised the contents of inorganic (Pi) and organic (Po) P fractions at 0–20 cm depth compared with the P-omitted treatments. Moreover, both Pi and Po fractions were markedly higher under MNPK than under NPK and SNPK treatments. For achieving high yield for wheat and maize, the critical contents of labile P were 54 and 63 mg kg−1, and those of moderately labile P were 48 and 49 mg kg−1, respectively, defined by the linear plateau model. In addition, the change points of labile P and moderately labile P were 99 and 70 mg kg−1, above which CaCl2-P content significantly increased. Moreover, long-term P input significantly accumulated different P fractions in the deeper soil layers up to 100 cm, with large portions of organic P being a composite of labile and moderately labile P, especially in MNPK treatment. Our results suggest that excessive P supply with organic manure resulted in massive P accumulation in the topsoil and promoted soil P fraction transformation and availability in the deep soil layers, especially in an organic P form that has often been neglected. [ABSTRACT FROM AUTHOR]

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Copyright of Journal of Ecology & Rural Environment is the property of Journal of Ecology & Rural Environment Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Purpose: The escalation of nitrogen (N) deposition has resulted in phosphorus (P) limitation in alpine grasslands on the Qinghai–Tibetan Plateau (QTP). However, the impact of N deposition affects soil P transformations in alpine grasslands, and whether there is a universal pattern of N-induced soil P fraction change in terrestrial ecosystems is still not well understood. Methods: We performed field experiments in two alpine grasslands on the QTP and a meta-analysis including 1033 records worldwide to analyze the responses of soil P fractions to N addition. Results: We found that N addition significantly altered soil P fractions in alpine meadow, whereas it induced a minor response in alpine steppe. The N addition induced a decrease in soil inorganic phosphorus (Pi) in the alpine meadow, resulting from occluded P (i.e., C.HCl-Pt and residual-Pt). Though N addition did not change total organic P (Po) concentration, there were remarkable changes among soil organic P fractions (C.HCl-Po, NaOH-Po, and NaHCO3-Po) in the alpine meadow, with an increase in NaOH-Po but a decrease in C.HCl-Po. Soil inorganic P in the alpine meadow was associated with Ca2+ and soil pH that was also reduced by N addition. By contrast, meta-analysis results showed that N addition significantly increased the lnRR of NaOH-Pi, but decreased lnRR of C.HCl-Pt and marginally reduced lnRR of NaHCO3-Po across all terrestrial ecosystems. Among multiple environmental and experimental variables, soil pH, mean annual temperature (MAT), mean annual precipitation (MAP), N forms, and soil phosphatase activity mainly drove the response of NaHCO3-Po to N addition at the large scale. Structural equation model (SEM) further showed that soil phosphatase activity was the main direct factor controlling NaHCO3-Po response. Conclusions: Our results suggest that soil P fractions are more sensitive to N addition in alpine meadow than in alpine steppe. The reduction of inorganic P fractions and uneven changes of organic P fractions in alpine meadow suggested that N addition may accelerate inorganic P dissolution but depress organic P mineralization. Environmental factor (e.g., MAP) and experimental variables (N rate) affected soil P fractions in response to N addition mediated by soil pH and enzymatic activities. Collectively, these findings improved our understanding of the consequences of N addition on soil organic and inorganic P transformations and predicted the trajectory of soil phosphorus fraction change under increasing N deposition. [ABSTRACT FROM AUTHOR]

Both community variation and phosphorus (P) fractions have been extensively studied in aquatic ecosystems, but how P fractions affect the mechanism underlying microbial beta diversity remains elusive, especially in sediment cores. Here, we obtained two sediment cores to examine bacterial and archaeal beta diversity from mesotrophic lakes Hongfeng Lake and Aha Lake, having historically experienced severe eutrophication. Utilizing the Baselga's framework, we partitioned bacterial and archaeal total beta diversity into two components: species turnover and nestedness, and then examined their sediment-depth patterns and the effects of P fractions on them. We found that total beta diversity, species turnover or nestedness consistently increased with deeper sediment layers regarding bacteria and archaea. Notably, there were parallel patterns between bacteria and archaea for total beta diversity and species turnover, which is largely underlain by equivalent processes such as environmental selection. For both microbial taxa, total beta diversity and species turnover were primarily constrained by metal oxide-bound inorganic P (NaOH-Pi) and sediment total phosphorus (STP) in Hongfeng Lake, while largely affected by reductant-soluble total P or calcium-bound inorganic P in Aha Lake. Moreover, NaOH-Pi and STP could influence bacterial total beta diversity by driving species nestedness in Hongfeng Lake. The joint effects of organic P (Po), inorganic P (Pi) and total P fractions indicated that P fractions are important to bacterial and archaeal beta diversity. Compared to Po fractions, Pi fractions had greater pure effects on bacterial beta diversity. Intriguingly, for total beta diversity and species turnover, archaea rather than bacteria are well-explained by Po fractions in both lakes, implying that the archaeal community may be involved in Po mineralization. Overall, our study reveals the importance of P fractions to the mechanism underlying bacterial and archaeal beta diversity in sediments, and provides theoretical underpinnings for controlling P sources in biodiversity conservation. [ABSTRACT FROM AUTHOR]

Aims: Crop straw return promotes microbial mediated phosphorus (P) cycling in soils, thereby increasing soil P availability. However, it remains unclear whether straw carbon (C) regulated organic phosphorus (Po) conversion is affected by soil P availability. Methods: Here, the responses to straw addition of soil microbial biomass, extracellular enzyme stoichiometry, bacterial community composition and P fractions were studied in soils with different available P contents. Results: Straw addition increased the organic P (Po) mineralization in the medium P (MP) soil, while decreased it in the low P (LP) and high P (HP) soils, respectively. Microbial nutrient limitation and community composition were co-regulated by soil C and P availability. LP and HP soils had the highest P and C limitations, respectively. In the MP soil, microbial P and C limitations lie between those of LP and HP soils. Straw addition decreased microbial P limitation in the LP and MP soils, while little change occurs in the HP soil. In addition, species number, diversity and the synergy of microbial communities were high in the MP soil. Straw addition induced a greater increase in the relative abundance of P-solubilizing microorganisms (e.g., Rhizobiales and Bradyrhizobium) in the MP soil compared to in the LP and MP soils. Conclusions: We concluded that straw addition promotes Po mineralization when the soil Olsen-P content was between 8.1–18.9 mg kg–1 and the corresponding MBC:P ratio was between 25.6–36.9. Our results highlight that the changes in microbial nutrient limitation and community composition caused by straw addition drive different soil P conversions. [ABSTRACT FROM AUTHOR]

Copyright of Forest Research is the property of Forest Research Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Understanding the characteristics and influences of various factors on phosphorus (P) fractions is of significance for promoting the efficiency of soil P. Based on long-term experiments on black soil, fluvo-aquic soil, and loess soil, which belong to Phaeozems, Cambisols, and Anthrosols in the World Reference Base for Soil Resources (WRB), respectively, five fertilization practices were selected and divided into three groups: no P fertilizer (CK/NK), balanced fertilizer (NPK/NPKS), and manure plus mineral fertilizer (NPKM). Soil inorganic P (Pi) fractions and soil properties were analyzed to investigate the characteristics of the Pi fractions and the relationships between Pi fractions and various soil properties. The results showed that the proportion of Ca10-P in the sum of total Pi fractions was the highest in the three soils, accounting for 33.5% in black soil, 48.8% in fluvo-aquic soil, and 44.8% in loess soil. Long-term fertilization practices resulted in periodic changes in soil Pi accumulation or depletion. For black soil and fluvo-aquic soil, the Pi accumulation was higher in the late period (10–20 years) of fertilization than in the early period (0–10 years) under NPK/NPKS and NPKM, whereas the opposite result was found in loess soil. The Pi accumulation occurred in all Pi fractions in black soil; mainly in Ca8-P, Fe-P, and Ca10-P in fluvo-aquic soil; and in Ca2-P, Ca8-P, and O-P in loess soil. Under CK/NK, the soil Pi was depleted mainly in the early period in each of the three soils. In addition to the labile Pi (Ca2-P) and moderately labile Pi (Ca8-P, Fe-P, Al-P), the Ca10-P in black soil and fluvo-aquic soil and O-P in loess soil could also be used by crops. Redundancy analysis showed that soil properties explained more than 90% of the variation in the Pi fractions in each soil, and the explanatory percentages of soil organic matter (SOM) were 43.6% in black soil, 74.6% in fluvo-aquic, and 38.2% in loess soil. Consequently, decisions regarding the application of P fertilizer should consider the accumulation rate and the variations in Pi fractions driven by soil properties in non-acidic soils.