Sustainable Phosphorus Management Research Articles

Single-cell exploration of active phosphate-solubilizing bacteria across diverse soil matrices for sustainable phosphorus management.

Phosphate-solubilizing bacteria (PSB) are crucial for enhancing phosphorus bioavailability and regulating phosphorus transformation processes. However, the in situ phosphorus-solubilizing activity and the link between phenotypes and genotypes for PSB remain unidentified. Here we employed single-cell Raman spectroscopy combined with heavy water to discern and quantify soil active PSB. Our results reveal that PSB abundance and in situ activity differed significantly between soil types and fertilization treatments. Inorganic fertilizer input was the key driver for active PSB distribution. Targeted single-cell sorting and metagenomic sequencing of active PSB uncovered several low-abundance genera that are easily overlooked within bulk soil microbiota. We elucidate the underlying functional genes and metabolic pathway, and the interplay between phosphorus and carbon cycling involved in high phosphorus solubilization activity. Our study provides a single-cell approach to exploring PSB from native environments, enabling the development of a microbial solution for the efficient agronomic use of phosphorus and mitigating the phosphorus crisis.

Scenario Analysis of Food Phosphorus Footprint in Kisumu, a Lakeside East African City in Lake Victoria (Kenya).

Increased food production and consumption patterns have resulted in higher urban food phosphorus footprints, leading to a series of resource and environmental problems worldwide. We quantified the food phosphorus footprint of the African city of Kisumu using substance flow analysis. Our aim was to develop Kisumu's sustainable phosphorus management framework so that the city would reduce phosphorus losses into the food system. Our results show that in the year 2023, the import and export of food phosphorus in the Kisumu food system was 2730.26 ± 2.7% t P yr-1 and 3297.05 ± 2.4% t P yr-1, respectively. There was -566.79 ± -18% t P yr-1 food phosphorus deficit in the Kisumu food system. Crop planting subsystem runoff/leaching/erosion loss, household consumption subsystem waste loss, and pit latrine subsystem blackwater loss are the major pathways of phosphorus losses into the environment and the main contributors to the food phosphorus footprint in the city. The 2030 scenario analysis shows that implementing a comprehensive scenario scheme throughout the entire lifecycle process from phosphorus input to waste disposal is the best choice for reducing phosphorus losses and suppressing the growth of food phosphorus footprint in the future. Our study shows that the food phosphorus footprint in the Kisumu food system was 0.67 kg P cap-1yr-1 in 2023, which is still at a low level but may enter a continuous upward trend with the improvement of socio-economic development of the city. In our framework, we have proposed a few essential measures that include urine separation, installation of septic tank, adjustment of dietary structure, flexible layout of sanitary disposal facilities, and separation of organic waste streams to reduce food phosphorus footprints in Kisumu. Given the similarity of cities along the shores of Lake Victoria, our calculation methods and management strategies can be applied to other cities in the region.

Unveiling the complexities of sustainable urban phosphorus management based on lifecycle assessment and decomposition analysis

To address global phosphorus reduction challenges, we establish a quantitative framework for anthropogenic phosphorus emissions using a lifecycle model and decomposition analysis. Focusing on China's Pearl River Delta urban agglomeration, we highlight persistent difficulties in controlling phosphorus emissions from agricultural fertilizers and the emerging issue from industrial products. Emission intensity is a crucial factor for phosphorus reduction, yet gradually offset by affluence and population growth. Prioritizing agricultural control with supplementary industrial reduction, we delve into the decoupling challenge between phosphorus emissions, population expansion, and economic development. Proposing green economic development, our approach contributes to achieving sustainable phosphorus management goals.

A systematic view of phosphorus loss and its retention: Pathways, mechanisms, and measures

Persistent phosphorus losses (PLs) are exacerbated by a complex interplay of human-induced factors. To mitigate the inexorable PLs, a systematic approach is needed to identify the underlying determinants among various factors affecting PLs. We analyzed the key drivers of phosphorus losses based on the phosphorus flows and human behaviors in human-environment systems. We then developed a framework to characterize and categorize the determinants of PLs and their associated pathways, systematically categorizing PLs into a hierarchical scheme consisting of three primary categories and a total of thirteen distinct subcategories, to facilitate the development of sustainable phosphorus management strategies to slow down PLs. Each subcategory possesses distinct attributes in mechanism, media, scope, and behavior, which can be leveraged to devise effective and practicable phosphorus retention measures. This systematic scheme lays a foundation for understanding the relationship between PLs and the corresponding phosphorus retention strategies.

An Integrated and Multi-Stakeholder Approach for Sustainable Phosphorus Management in Agriculture

Conventional agriculture relies on non-renewable rock phosphate as a source of phosphorus. The demand for food has led to increased phosphorus inputs, with a negative impact on freshwater biodiversity and food security. The importation of phosphorus fertilizers makes most food systems vulnerable to phosphorus supply risks. The geopolitical instability generated by the pandemic and the current Russia–Ukraine conflict, which has led to a 400% increase in phosphorus commodity prices, offers the international community and institutions an opportunity to embrace the global phosphorus challenge and move towards a more circular system. Here, we discuss an integrated and multi-stakeholder approach to improve phosphorus management in agriculture and increase the efficiency of the whole chain, highlighting the contribution of conventional breeding and genetic engineering, with a particular focus on low-phytic-acid (lpa) crops, whose grains may help in reducing phosphorus-management-related problems. In recent decades, the choice of short-term strategies—such as the use of phytase as a feed additive—rather than lpa mutants, has been carried out without considering the long-term money saving to be derived from lpa crops. Overall, lpa crops have the potential to increase the nutritional quality of foods and feeds, but more research is needed to optimize their performance.

Sorption-Desorption of Phosphorus on Manure- and Plant-Derived Biochars at Different Pyrolysis Temperatures

Sustainable phosphorus (P) management is essential to preventing mineral fertilizer losses, reducing water pollution, and addressing eutrophication issues. Phosphorus sorption and mobility are strongly influenced by the properties of biochar, which are determined by pyrolysis temperature and type of feedstock. This understanding is crucial for optimizing biochar application for soil nutrient management. Therefore, a batch sorption-desorption experiment was conducted to examine P sorption-desorption in plant-based (parthenium, corn cobs) and manure-based (farmyard manure, poultry manure) biochars prepared at both 400 °C and 600 °C. Manure-based biochars demonstrated higher P sorption at 400 °C, with less sorption at 600 °C, while plant-based counterparts exhibited lower sorption capacities. Phosphorus desorption, on the other hand, increased at 600 °C, particularly in manure-based biochars. The scanning electron microscopy (SEM) and Fourier-transform infrared spectra (FTIR) analysis suggested that a lower pyrolysis temperature (400 °C) enhances P sorption due to higher specific surface area and different functional groups. Additionally, the manure-based biochars, which were enriched with calcium (Ca) and magnesium (Mg), contributed to increased P sorption. In summary, P sorption is enhanced by a lower carbonization (400 °C) temperature. Although manure-based biochars excel in retaining P, their effectiveness is limited to shorter durations. In contrast, plant-based biochars showcase a prolonged capacity for P retention.

Using bone char as phosphate recycling fertiliser: an analysis of the new EU Fertilising Products Regulation

BackgroundPhosphorus recycling is an important cornerstone of sustainable phosphorus management and required to establish a circular economy in line with the EU Green Deal. Animal bones contain phosphate which can be recovered and processed into bone char. Animal bone char has a fertiliser potential. In the past, the EU lacked measures to market these fertilisers on the internal market. With the adoption of the Fertilising Products Regulation in 2019, the EU sought to incentivise recycling fertiliser production. Against this backdrop, the aim of this paper is to first provide the key elements of the new regulation and to second assess the extent to which it enables marketing bone chars as fertilisers. To this end, a qualitative governance analysis is applied.ResultsResults show that the Fertilising Products Regulation closes an important regulatory gap by establishing the legal framework for diverse recycling fertilisers, including bone char fertilisers. However, a lengthy adoption process hinders the marketing of bone char fertilisers and contaminant limits require improvement.ConclusionsUltimately, the promotion and use of recycling fertilisers is a necessary but complementary approach for the circular economy. A comprehensive transformation of the sector is needed to align it with global environmental goals.

Molecular transformation pathway and bioavailability of organic phosphorus in sewage sludge under vermicomposting

Phosphorus reclamation from sewage sludge is essential for sustainable phosphorus management, as large quantities of phosphorus afflux into wastewater treatment plants and are finally enriched in sewage sludge via phosphorus removal technologies. Meanwhile, vermicomposting is a cost-effective biotechnique for sludge stabilization. This work unveiled the molecular transformation pathway and bioavailability of organic phosphorus (OP) in sludge under vermicomposting with solution 31P NMR, FT-ICR MS and enzymatic hydrolysis assay. In conclusion, vermicomposting transformed OP in two stages. In stage I (day 0 to 14), macromolecule CHONP such as phospholipids, phosphoproteins and nucleic acid were decomposed into orthophosphate and high bioavailability OP including flavin mononucleotide, flavin mononucleotide hydrate and N6-isopentenyladenosine 5′-monophosphate under the action of earthworm intestinal flora. This resulted in the bioavailability of OP reaching a maximum of 13.58 mg/L on day 14. In stage II (day 14 to 28), the enzyme in vermicompost began to dominate the transformation of OP. Under the catalysis of phosphate, high bioavailability orthophosphate monoester was decomposed into orthophosphate. Nitrogen-containing aromatic OP polymerization produced humic acid-like OP under the catalysis of ligase. And phytic acid-like OP were produced under the catalysis of transferase. These led to the OP bioavailability decreasing to 5.60 mg/L on day 28. This work provides a new perspective on sludge phosphorus recovery and use.

Enhanced phosphorus-fertilizer-use efficiency and sustainable phosphorus management with intercropping

Enhanced phosphorus-fertilizer-use efficiency and sustainable phosphorus management with intercropping

Global phosphorus cycling: The impact of international commercial trading and the path towards sustainable phosphorus management

Phosphorus is vital for global food production, but its use in commercial fertilizers has led to significant changes in the global P cycle. This has resulted in the depletion of phosphate rock deposits and increased eutrophication in lakes and oceans. While attempts have been made to quantify phosphorus flow at a country or regional level, there is still a lack of comprehensive understanding of how international commercial trading affects global phosphorus cycling over time. Through substance flow analysis, this research has found that the total global P flows through the five major P trade products have increased by around 5.4 Tg P between 2000 and 2019, with agricultural products trade having the fastest growth rate. The net P budget in the global trade of products changed among countries throughout these twenty years and relates to local natural resources and policies. Overall the global P flow has shifted from phosphate rock dominated structure to phosphate fertilizers and phosphoric acid dominated structure from 2000 to 2019, with centralized production reducing P resource losses during manufacturing. However, there are risks associated with P redistribution, including P resource shortages in certain countries/regions (e.g. Japan) and P pollutant accumulations in others (e.g. Brazil). These results highlight the importance of trade on the global phosphorus cycle and the need for both consuming and supplying countries/regions to work together to propose effective solutions for sustainable management of P in the future.

Responses of total, reactive and dissolved phosphorus pools and crop yields to long-term fertilization

Maintaining an appropriate soil phosphorus level is key to ensure sustainable phosphorus management for crop production and to minimise phosphorus losses to water bodies. However, the effects of long-term fertilization on different soil phosphorus pools, crop yields and phosphorus loss risk remain unclear. This requires insights into the responses of soil phosphorus pools, crop phosphorus uptake with related crop yields and phosphorus loss to long-term phosphorus inputs. Changes in four soil phosphorus pools (PCACL2, POLSEN, POX and PTOTAL, respectively) and crop yield responses to various fertilization rates were examined in a 29-year long-term phosphorus fertilization experiment in China. Results showed that the increase in the four soil phosphorus pools was proportional to the accumulated phosphorus surplus, i.e., the input minus uptake. POLSEN and POX increased linearly with continuous phosphorus application and peaked at a phosphorus accumulation near 3200 kg P ha−1. Beyond this threshold, continuous phosphorus application caused a gradual increase in PTOTAL and a linear increase in PCACL2, which implies an increasing risk for leaching. The POX pool accounted for 87% of the accumulated phosphorus surplus until soil phosphorus saturation occurred. The crop yields of wheat and maize responded clearly to changes in PTOTAL, POX, POLSEN and PCACL2, with POX explaining most of the yield variation. Furthermore, POX was highly correlated with PCACL2, being a risk indicator for phosphorus leaching. Given that POX explains best how much of phosphorus surplus accumulates in soil, the variation in crop yield, and the risk for P leaching, it can be used as a valuable and reliable indicator to manage phosphorus sustainably.

Reagentless electrochemically assisted desorption for selective phosphate recovery from wastewater: Proof of concept and mechanism

Adsorption is a promising technology for removing and recovering phosphorus (P) from wastewater. However, the chemical-intensive regeneration of adsorbents increases carbon emissions and introduces potential secondary pollution. Most existing approaches cannot achieve simultaneous P desorption and selective recovery. For this purpose, a new-type electrochemically assisted phosphate desorption and recovery (EPDR) process was investigated and developed for the efficient desorption and recovery of P and simultaneous regeneration of the adsorbent in situ. In the EPDR process, the adsorbent amorphous zirconium oxide (am-ZrO2) coated carbon felt (CF) was employed as a cathode in an anion-exchange membrane (AEM) water electrolysis cell for P adsorption/desorption and recovery. The P desorption and recovery efficiency from the adsorbent were over 90% at 3.5 V. It was found that the high concentration of OH– at the cathode surface derived from water splitting reaction and electrodialysis under the applied electric field was playing a critical role in the desorption process. Low concentrations of P in actual wastewater were effectively removed, concentrated and recovered under multiple adsorption–desorption cycles with easy-to-scale-up stacked EPDR. The nature of reagent-free, high efficiency and selectivity make EPDR the foundation for developing a cost-effective and green technology for sustainable phosphorus management.

Integrated application of phosphorus-accumulating bacteria and phosphorus-solubilizing bacteria to achieve sustainable phosphorus management in saline soils

The challenge of managing agricultural phosphorus (P) in saline regions entails both reducing leaching for environmental protection and maintaining soil available P levels for crop production, which could be achieved through functional microorganisms that can facilitate P transformation processes like P assimilation, inorganic P solubilization, and organic P mineralization. In this study, we proposed an integrated utilization of phosphorus-accumulating bacteria (PAB) and phosphorus-solubilizing bacteria (PSB) to reach the goal of alleviating P leaching while improving soil available P levels. The study conducted a microcosm experiment that combined a soil column test, soil incubation, and pot experiment to evaluate the effect of bacterial inoculants on soil P leaching, soil P availability, and plant P accumulation. The results showed that the application of PAB reduced 22.6 % of dissolved P leaching through the absorption of labile phosphate in the soil, and 17.3 % of particulate P leaching through the promoted soil aggregation. The integrated inoculation of PSB and PAB synergistically improved soil available P content by 18.3 % through the mineralization of soil organic P, and remarkably boosted wheat growth and its P accumulation. Microbial community analysis revealed that the integrated microbial treatment decreased the diversity of soil bacterial community and increased the abundance of native microbial species, i.g. Lysobacter and Ramlibacter, which were positively correlated with soil available P content and alkaline phosphatase level. In conclusion, the integrated microbial strategy based on halotolerant PAB and PSB has great potential for sustainable P management in saline areas and agricultural activities.

Enhanced phosphorus-fertilizer-use efficiency and sustainable phosphorus management with intercropping

Enhanced phosphorus-fertilizer-use efficiency and sustainable phosphorus management with intercropping

The role of transdisciplinarity for mineral economics and mineral resource management: coping with fallacies related to phosphorus in science and practice

Mineral economics is a genuine multidisciplinary field dealing with economic and policy matters related to the production, distribution, and consumption of mineral commodities. We discuss why the increasing complexity, ambiguity, ambivalence, and social contestation of subjects of mineral economics promote the participation of mineral economists in transdisciplinary processes. These processes relate (a) knowledge from targeted interdisciplinary processes and (b) mitigated discourses among different stakeholders to provide (c) a shared problem definition and to attain shared basic knowledge about problem transformation science and practice. We discuss known examples of misperceptions regarding minerals (phosphorus), such as an imminent scarcity threat, the incorrectly understood causations of the 2007/2008 price peak and present the phosphorus ore-grades increased by 3.2% between 1983 and 2013 fallacies (which is based on the Simpson’s paradox), and only few countries have mineable reserves fallacy. Here, we also illuminate motivations underlying several mineral economics–related misunderstandings. We argue that societally relevant questions require an honest mineral economics knowledge brokership. The example of the Global TraPs project, which targeted sustainable phosphorus management, is presented. Honest brokership to attain a clearinghouse function of science requires trust formation in society. We argue that this calls for increasing the understandability of relationships that are not well-understood, such as “if prices rise, so do stocks.” Wellmer and Becker-Platen’s feedback control cycle may be considered an example of how complex mineral economics can become and how challenging it is to be understandable to scientists from different disciplines and faculties as well as to practitioners whose knowledge may well be used to cope with the complexity of given problems. Thus, the present paper represents a plea for mutual learning between science and practice in order to understand the complex social and economic challenges of mineral resource dynamics.

Soil type affects biological phosphorus cycling more than soil management

There is a need for more sustainable management of phosphorus (P) fertilization including reutilization of wastes and taking more advantage of the biological cycling of P in the crop-livestock-soil system to comply with the Sustainable Development Goals. The objective of the present study was to evaluate the effect of soil type and management on microbial carbon (C) and P transformations (mineralization-immobilization processes) and their seasonal fluctuations throughout the year to assess the feasibility of enhancing biological P cycling by changing crop rotations. A sandy loam petrocalcic Paleustoll with a calcium carbonate hardpan at approximately 0.8 m depth, and a sandy typic Ustipsamment were selected in the Argentinean semiarid Pampa. Soil management treatments were a 50-year-old Weeping Lovegrass pasture (PP) and three agricultural plots belonging to long-term trials with and without cover crops under no-till: maize monoculture (M−M), maize-rye (M−R), and maize-vetch (M−V). Soil microbial biomass C and P (MBC, MBP), soil respiration, metabolic quotient, P mineralization rate, and anion exchange membrane extractable P (solution P) were determined during winter and spring of 2017, and summer and autumn of 2018 at 0–0.05 and 0.05–0.10 m depth. Results indicated that differences in the relationships between MBP and MBC were mostly influenced by soil type. In the Paleustoll, this relationship showed a threshold value of 94.7 µg MBC g−1 where soil microbial biomass P reached a maximum value of 6.6 ug MBP g−1. No relationship between P mineralization rate and MBP was observed in this soil indicating P limitation explained by the negative relationship between exchangeable calcium and solution P. On contrary, a positive and linear relationship between MBP and MBC was found in the Ustipsamment, which was affected by the season of the year. A nonlinear relationship between metabolic quotient and MBP was found in the Ustipsamment but not in the Paleustoll. Soil management was more related to microbe-plant P competition during periods of active growth in the Paleustoll, while in the non-P limited soil (Ustipsamment), environmental conditions and the presence of active rhizosphere stimulate microbial activity, shown by seasonal variations, increasing P mineralization rates to sustain microbial and plant P demand.

Effect of Consecutive Application of Phosphorus-Enriched Biochar with Different Levels of P on Growth Performance of Maize for Two Successive Growing Seasons

Sustainable management of phosphorus (P) is one of the burning issues in agriculture because the reported P losses, when applied in the form of mineral fertilizer, give rise to another issue of water pollution as P is considered one of the limiting nutrients for eutrophication and so results in costly water treatments. In the present study, the enrichment of biochar with mineral P fertilizer was supposed to reduce such losses from the soil. Additionally, P can also be recycled through this technique at the same time as biochar is derived from biomass. Biochar was prepared using wheat straw followed by its enrichment with di-ammonium phosphate (DAP) at the ratio of 1:1 on a w/w basis. The first pot trial for spring maize (cv. Neelam) was conducted using phosphorus-enriched biochar (PEB) at 0% and 1% with different levels of recommended P (0%, 25%, 50%, and 100%). The treatments were arranged factorially under a complete randomized design (CRD) with three replications. After harvesting the spring maize, pots were kept undisturbed, and a second pot trial was conducted for autumn maize in the same pots to assess the residual impact of 1% PEB. In the second pot trial, only inorganic P was applied to respective treatments because the pots contained 1% PEB supplied to spring maize. The results revealed that the application of 1% PEB at P level 50% significantly increased all the recorded plant traits (growth, yield, and physiological and chemical parameters) and some selected properties of post-harvest soil (available P, organic matter, and EC) but not soil pH. In terms of yield, 1% PEB at 50% P significantly increased both the number of grains and 100-grain weight by around 30% and 21% in spring and autumn maize, respectively, as compared to 100% P without PEB. It is therefore recommended that P-enriched biochar should be used to reduce the inorganic P fertilizer inputs; however, its application under field conditions should be assessed in future research.

Mycorrhiza and Phosphate Solubilizing Bacteria: Potential Bioagents for Sustainable Phosphorus Management in Agriculture

Phosphorus (P) is a critical nutrient that plays an essential role in improving soil fertility for optimum plant growth and productivity. It is one of the most deficient macro-nutrients in agricultural soils after nitrogen and is considered inadequate for plant growth and production. To P availability in soils, the farmers are applying huge amounts of synthetic P fertilizers that adversely affect the wider environment, groundwater, soil fertility and microbial population. Many beneficial microbes are known to release and supply soluble P for improving growth and yield of a variety of plants in a sustainable manner in P deficient soils. Thus, inoculation of these microbes, including arbuscular mycorrhizal fungi (AMF) and phosphate solubilizing bacteria (PSB) to soil to enhance crop production without harming the environment, is an alternative approach to chemical fertilizers. The combined role of AMF and PSB in P solubilization is not well understood and the application and mode of action of these microbial groups are often naive due to variation in the environment. Therefore, the current review article would develop a better understanding of the interactive role and mechanisms of AMF and PSB in improving P availability from both organic and inorganic sources in a sustainable crop production system. Finally, the current review would loop out further avenues for researchers interested to commercially produce effective AMF and PSB-based biofertilizers for sustainable management of phosphorus over a wide range of agricultural crops worldwide.

Using knowledge-based management for sustainable phosphorus use in China

Sustainable phosphorus (P) management presents challenges in crop production and environmental protection; the current understanding of chemical P-fertilizer manufacturing, rock phosphate (RP) mining, P loss within supply chains, and strategies to mitigate loss is incomplete because of a fragmented understanding of P in the crop production supply chain. Therefore, we develop a knowledge-based management theoretical framework to analyze P supply chains to explore ways to mitigate China's P crisis. This framework connects upstream P industries and crop production, addressing knowledge gaps and stakeholder involvement. We demonstrate the potential to improve P use efficiency in the supply chain, thereby mitigating the P crisis using optimized P management. Our results showed that P footprint and grain production demand for RP can be reduced without yield penalty using a crop-demand-oriented P supply chain management that integrates P use in crop production, P-fertilizer manufacturing, and RP mining. Food security and P-related environment sustainability can be achieved by sharing responsibility and knowledge among stakeholders.

Threshold phosphorus level of acidic soils of eastern India

It is imperative to have a practical indicator for assessing the potential for phosphorus movement from soil to surface waters causing environmental pollution. The present study was undertaken with two groups of acidic soils from the terai and red and laterite agro-climatic zone of eastern India to estimate their phosphorus threshold values and establish a simple model with the clay content as the principal variable. The mean phosphorus adsorption maximum and phosphorus buffering capacity were higher in lateritic than terai soil. The change-point soil test values at which water soluble phosphorus enhanced abruptly ranged from 32 to 68mgkg-1 and 28 to 63mgkg-1 with Bray-1 and Mehlich-1 method, respectively, for the soils of the terai zone. Similarly, it varied from 47 to 90mgkg-1 and 44 to 89mgkg-1, respectively, for the lateritic soils. Application of phosphatic fertilizers should not be allowed beyond the threshold level, which was considered 75% of the change-point soil test value to avoid the risk of the soil becoming a source of phosphorus pollution for surface water bodies. The simplified models of phosphorus threshold level (mg kg-1) developed with either of the extractants were "4.75 × clay content (%) - 30" and "6.00 × clay content (%) - 75" for terai and lateritic soil, respectively. These models can be extended to the soils with similar mineralogy but varying in clay content for sustainable phosphorus management without limiting crop production.