Phosphate Reserves Research Articles

Wastewater-Derived Struvite has the Potential to Substitute for Soluble Phosphorus Fertiliser for Growth of Chickpea and Wheat

Phosphorus (P) recycling from wastewater can reduce the reliance on the primary source for P fertilisers―rock phosphate reserves. In light of this, we compared the effects of struvite (ST), a sparingly soluble P product derived from wastewater, and readily soluble KH2PO4 (KP) on chickpea (Cicer arietinum L.) and wheat (Triticum aestivum L.) growth and P acquisition. Plants were grown in a temperature-controlled glasshouse in plastic pots containing a soil mixture with low P availability, with ST or KP applied at five P rates (7, 14, 28, 56 and 112 µg P g− 1 dry soil). Plants were harvested 56 days after sowing when there were visible differences in above-ground growth. Chickpea and wheat growth positively responded to increasing P rates of KP and ST. At low and medium P rates (7, 14, 28 and 56 µg P g− 1 dry soil) of KP and ST, the plants acquired similar amounts of P, while at a higher P rate (112 µg P g− 1 dry soil), plants supplied with ST, accumulated 1.2- to ~ 2.0- fold higher P than KP. Rhizosheath soil pH increased by ~ 0.1–0.7 units under ST than KP for both species. Wheat produced greater total root length but lower amount of rhizosheath carboxylates than chickpea under KP and ST, and wheat accumulated more P than chickpea under KP and ST. Chickpea and wheat can well access P from ST, indicating the great potential of ST as an alternative P fertiliser.

Divergent responses of phosphorus solubilizing bacteria with P-laden biochar for enhancing nutrient recovery, growth, and yield of canola (Brassica napus L.)

The growing global population has led to a heightened need for food production, and this rise in agricultural activity is closely tied to the application of phosphorus-based fertilizers, which contributes to the depletion of rock phosphate (RP) reserves. Considering the limited P reserves, different approaches were conducted previously for P removal from waste streams, while the adsorption of ions is a novel strategy with more applicability. In this study, a comprehensive method was employed to recover phosphorus from wastewater by utilizing biochar engineered with minerals such as calcium, magnesium, and iron. Elemental analysis of the wastewater following a batch experiment indicated the efficiency of the engineered biochar as an adsorbent. Subsequently, the phosphorus-enriched biochar, hereinafter (PL-BCsb), obtained from the wastewater, underwent further analysis through FTIR, XRD, and nutritional assessments. The results revealed that the PL-BCsb contained four times higher (1.82%) P contents which further reused as a fertilizer supplementation for Brassica napus L growth. PL-BCsb showed citric acid (34.03%), Olsen solution (10.99%), and water soluble (1.74%) P desorption. Additionally, phosphorous solubilizing bacteria (PSB) were incorporated with PL-BCsb along two P fertilizer levels P45 (45 kg ha−1) and P90 (90 kg ha−1) for evaluation of phosphorus reuse efficiency. Integrated application of PL-BCsb with half of the suggested amount of P45 (45 kg ha−1) and PSB increased growth, production, physiological, biochemical, and nutritional qualities of canola by almost two folds when compared to control. Similarly, it also improved soil microbial biomass carbon up to four times, alkaline and acid phosphatases activities both by one and half times respectively as compared to control P (0). Furthermore, this investigation demonstrated that waste-to-fertilizer technology enhanced the phosphorus fertilizer use efficiency by 55–60% while reducing phosphorus losses into water streams by 90%. These results have significant implications for reducing eutrophication, making it a promising approach for mitigating environmental pollution and addressing climate change.

Formal education in Nauru: A Pacific development assistance story

Formal education in Nauru can only be fully understood in the light of the external influences, mostly Australian in origin, acting upon it as a small island state in the Central Pacific. Australia's influence began in the early 1900s as a leading stakeholder in Nauru's lucrative phosphate reserves. In the last few decades Nauru's dramatic economic decline has meant it has come into the orbit of Australia's official development assistance (ODA) to the Pacific region. However, Australia has ties to Nauru that go beyond mere economic and development assistance, for example, the country is a crucial site in Australia's own immigration policy and the offshore processing of asylum seekers bound for Australia. Geopolitically, Nauru is also important to Australia as one of a decreasing number of Taiwan‐loyal Pacific nations in the face of China's increasing assertiveness in the region. The nature of the relationship with Nauru has meant that for many decades Australia has provided an almost exclusive conduit of educational ideas, values, beliefs and practices flowing into the country to uniquely shape formal education provision. The purpose of this article is twofold. Firstly, via a synthesis of research literature and debate, it critiques the long‐running, primarily, Australia‐facing relationship Nauru has in terms of the educational assistance it receives, including the Nauru Education Program, a significant Australian development assistance initiative about to commence through to 2030. Secondly, with a basis in the advocacy literature of the Rethinking Pacific Education Initiative, the article highlights the possibility of a much more Pacific regionally facing Nauru over the next few decades as a result of relatively recent regional instrumentalities such as the Pacific Island Forum's 2050 Strategy for the Blue Pacific Continent.

Reaction of organic phosphates with oxides: Effects on pH, the equation used to describe the reaction, and on desorption

AbstractOrganic phosphates are an important component of soil phosphate reserves. We studied the sorption of three organic phosphates by goethite and by aluminium oxide and compared them with the sorption of inorganic phosphate (Pi). The organic phosphates were inositol hexa‐phosphate (IHP), glycerol phosphate (GlyP), and glucose‐6‐phosphate (G6P). We used five different initial pH values and 10 different initial concentrations. We measured both sorption and desorption. We used an equation which we call the Sibbesen‐Langmuir equation to successfully describe the observations over a 10,000 fold concentration range. Sorption increased the pH. The effects were largest at low pH and low initial concentration and were in the sequence Pi > IHP > G6P > GlyP. This sequence was a consequence of differences in ion size and mean charge. The different feedback effects of the different ions affected the shape of plots of sorption against concentration; similarity to the Langmuir shape was in the opposite sequence. Desorption curves always fell to the left of sorption curves; that is, there was always hysteresis. Part of this was an experimental artefact because desorption was measured at lower pH than sorption, but we provide evidence that this caused only part of the effect. The effects were greatest for Pi and least for IHP. We think that this hysteresis occurs because the adsorbed molecules diffuse into faults in the reacting medium. This would be more difficult for organic phosphate than for inorganic phosphate. Although hysteresis was smaller for organic phosphates, it was nevertheless substantial. We suggest that this is an important factor in their stability in soils.

Iron-coated nutshell waste bioadsorbents: Synthesis, phosphate remediation, and subsequent fertilizer application

The increasing incidence of freshwater nutrient pollution worldwide has highlighted the need for improved phosphate capture technologies. Successful phosphate recovery from agricultural sources and commercial wastewater can help prevent freshwater algal bloom contamination, while also reducing the dependency on finite phosphate reserves. Biodegradable biosorbents have the potential to remove phosphate from water; however, their potential as slow-release fertilizers has not been tested. Novel biosorbents were developed by coating pistachio and walnut shells with iron oxides; batch and column experiments were conducted to investigate their adsorption capacities and performances. Surface characterization studies were also conducted to investigate changes in the surface area and morphology. The potential of using iron-coated shells loaded with phosphorus as slow-release fertilizers was also evaluated. Advanced characterization techniques (scanning electron microscopy, Brunauer-Emmett-Teller (BET) physisorption analysis, and x-ray diffraction) showed that hematite was successfully coated onto the surface, resulting in increased surface area and roughness. The iron-coated pistachio and walnut shell phosphate removal capacity was 12.63 mg g−1 and 9.25 mg g−1, respectively. The phosphate sorption data fitted well with the Freundlich isotherm model and pseudo-second-order kinetics. Inner sphere complex formation, coprecipitation, diffusion, and electrostatic attraction were the main uptake mechanisms. Results from sequential release experiments with simulated pore water suggested both fast and slow desorption components. The Mehlich-3 extraction revealed that more than 90% of the released phosphate was available for plant uptake. In addition, nutrient priming showed that corn seed shoot growth increased by more than 43% when pretreated with phosphate-loaded biosorbents, demonstrating that the released phosphate could be used for plant growth. This research provides a pathway for two important zero-waste, cyclical economic goals: (1) the beneficial use of agricultural waste, and (2) a low-cost technology that can recover phosphorus from waste streams while potentially adding an additional unconventional phosphate source to apatite mineral ores.

Design of acid-geopolymers based on clays by-products for methylene blue removal from wastewater

Morocco has significant phosphate reserves, but the extraction process generates a lot of waste rock. To tackle this problem, this study aims to make use of clay, a by-product of phosphate mining, to create acid-activated geopolymers. Four formulations of geopolymers were prepared by combining metakaolin (MK) and calcined clay (CC) in different proportions, which were then activated using phosphoric acid. Different techniques were performed for the characterization of raw and calcined clays as well as the elaborated geopolymers. Based on the XRD, FTIR, and SEM results, it was observed that an increase in the level of CC replacing MK led to the formation of new crystals like Monetite, Newberyite, and Brushite. The quantity of CC influenced the type of crystals formed. Moreover, the specific surface area analysis revealed that the geopolymer (GP2) containing 25% of CC exhibited the highest specific surface area. These materials were then tested for their ability to eliminate methylene blue (MB) from wastewater. The results indicated that GP2, a geopolymer made with 75% MK and 25% CC had the highest efficiency in removing MB with a rate of 98%. The material was highly reactive and achieved adsorption equilibrium in just 15 minutes. It was found to be effective in both acidic and alkaline environments. Furthermore, studies have shown that the Temkin isotherm model best explains how MB (a dye) is absorbed by GP2, with a high correlation coefficient. Additionally, the pseudo-second-order kinetic model was a better fit, suggesting that chemical interactions are more significant than physical interactions. Notably, the use of phosphoric acid to activate GP2 was found to selectively adsorb cationic dyes.

Metabolic Consequences of Polyphosphate Synthesis and Imminent Phosphate Limitation.

Cells stabilize intracellular inorganic phosphate (Pi) to compromise between large biosynthetic needs and detrimental bioenergetic effects of Pi. Pi homeostasis in eukaryotes uses Syg1/Pho81/Xpr1 (SPX) domains, which are receptors for inositol pyrophosphates. We explored how polymerization and storage of Pi in acidocalcisome-like vacuoles supports Saccharomyces cerevisiae metabolism and how these cells recognize Pi scarcity. Whereas Pi starvation affects numerous metabolic pathways, beginning Pi scarcity affects few metabolites. These include inositol pyrophosphates and ATP, a low-affinity substrate for inositol pyrophosphate-synthesizing kinases. Declining ATP and inositol pyrophosphates may thus be indicators of impending Pi limitation. Actual Pi starvation triggers accumulation of the purine synthesis intermediate 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR), which activates Pi-dependent transcription factors. Cells lacking inorganic polyphosphate show Pi starvation features already under Pi-replete conditions, suggesting that vacuolar polyphosphate supplies Pi for metabolism even when Pi is abundant. However, polyphosphate deficiency also generates unique metabolic changes that are not observed in starving wild-type cells. Polyphosphate in acidocalcisome-like vacuoles may hence be more than a global phosphate reserve and channel Pi to preferred cellular processes. IMPORTANCE Cells must strike a delicate balance between the high demand of inorganic phosphate (Pi) for synthesizing nucleic acids and phospholipids and its detrimental bioenergetic effects by reducing the free energy of nucleotide hydrolysis. The latter may stall metabolism. Therefore, microorganisms manage the import and export of phosphate, its conversion into osmotically inactive inorganic polyphosphates, and their storage in dedicated organelles (acidocalcisomes). Here, we provide novel insights into metabolic changes that yeast cells may use to signal declining phosphate availability in the cytosol and differentiate it from actual phosphate starvation. We also analyze the role of acidocalcisome-like organelles in phosphate homeostasis. This study uncovers an unexpected role of the polyphosphate pool in these organelles under phosphate-rich conditions, indicating that its metabolic roles go beyond that of a phosphate reserve for surviving starvation.

Ditching Phosphatic Fertilizers for Phosphate-Solubilizing Biofertilizers: A Step towards Sustainable Agriculture and Environmental Health

Chemical phosphatic fertilizers are mainly produced from phosphate rocks, a natural reserve that is depleting rapidly. These chemical phosphatic fertilizers are polluting the environment at an alarming rate as a result of injudicious application to farmlands. On the other hand, phosphate-solubilizing biofertilizers (PSBs) are often considered better alternatives to industrial phosphatic fertilizers in many ways. PSBs are microorganisms capable of solubilizing insoluble forms of phosphate into soluble plant-usable forms. This paper is written with the objective of discussing the impacts of phosphatic fertilizers and making the case for why we should shift to PSBs instead. Phosphatic fertilizers have numerous impacts on the environment (water bodies, land resources, and air), and micro- and macro-organisms, including humans. Chemical fertilizers also tend to be more expensive, especially for farmers in developing countries. On the contrary, PSBs tend to be safer and way more beneficial than their chemical counterparts in that they are environmentally friendly and cheaper options of availing plant-usable phosphorus. PSBs are also involved in other beneficial roles such as the production of phytohormones and secretion of anti-phytopathogenic metabolites. The phytohormones enhance plant growth and the metabolites render crops immunity against phytopathogens. Hence, it is vital to replace chemical phosphatic fertilizers with PSB inoculants both to prevent the irreversible impacts of chemical fertilizers and to take advantage of the numerous benefits of PSBs. Moreover, it does not seem as if there is an option given the fact that the global phosphate reserve is depleting and the impact of fertilizer on the environment is worsening as time goes by.

Phosphorus responses of Trifolium pallescens and T. occidentale, the progenitors of white clover (T. repens)

Context Rock phosphate reserves are decreasing, and requirements to mitigate environmental impacts of farming soils with excess phosphorus (P) are increasing. Aims White clover is an allotetraploid hybrid between Trifolium pallescens and T. occidentale. Understanding the P response characteristics of these progenitor species will allow selection of germplasm for development of synthetic white clovers with improved phosphorus-use efficiency (PUE). Methods Shoot and root weights and P nutrition characteristics were compared for three Trifolium pallescens, six T. occidentale accessions, and a white clover cultivar in a glasshouse experiment using a low P soil amended with five rates of P. Key results White clover had the highest and most P responsive shoot and root dry weights (DW), and T. pallescens was least responsive to P. In the highest P treatment, T. pallescens had the highest shoot and root %P and the lowest shoot DW:total plant P ratio. There was significant variation among progenitor accessions. Spanish accessions of T. occidentale had comparable shoot DW to white clover and higher PUE. Traits of T. pallescens indicated strong adaptation to low P but low productivity, while traits of T. occidentale were more aligned with the white clover cultivar. Conclusions The substantial variation in P nutrition characteristics within the progenitor species of white clover could be exploited in breeding programs. Implications Comparing the P responses of a wider range of progenitor accessions could inform breeding to improve white clover’s low soil P tolerance through development of synthetic white clovers.

Characterization of plant growth promoting activities of indigenous bacteria of phosphate mine wastes, a first step toward revegetation.

Morocco holds the vast majority of the world's phosphate reserves, but due to the processes involved in extracting and commercializing these reserves, large quantities of de-structured, nutritionally deficient mine phosphate wastes are produced each year. In a semi-arid climate, these wastes severely hamper plant growth and development leading to huge unvegetated areas. Soil indigenous Plant Growth-Promoting Bacteria (PGPB) play a pivotal role in restauration of these phosphate mining wastes by revegetation, by increasing plants development, soil functioning, and nutrient cycling. The development of a vegetative cover above the degraded phosphate wastes, could stabilize and reintegrate these wastes in the surrounding environment. The current study's objectives were to isolate, characterize, and identify indigenous bacterial strains, and test their PGP activity in vitro and, for the best-performing strains in planta, in order to assess their potential for acting as biofertilizers. A quantitative test for the synthesis of auxin and the production of siderophores as well as a qualitative test for the solubilization of phosphate were performed on all isolated bacterial strains. The production of hydrogen cyanide (HCN), exopolysaccharides (EPS), and enzymes were also examined. Three bacteria, selected among the best PGPB of this study, were tested in planta to determine whether such indigenous bacteria could aid plant growth in this de-structured and nutrient-poor mining soil. Using 16S rRNA gene sequencing, 41 bacterial strains were isolated and 11 genera were identified: Acinetobacter, Agrococcus, Bacillus, Brevibacterium, Microbacterium, Neobacillus, Paenibacillus, Peribacillus, Pseudarthrobacter, Stenotrophomonas, and Raoultella. Among the three best performing bacteria (related to Bacillus paramycoides, Brevibacterium anseongense, and Stenotrophomonas rhizophila), only Stenotrophomonas rhizophila and Brevibacterium anseongense were able to significantly enhance Lupinus albus L. growth. The best inoculation results were obtained using the strain related to Stenotrophomonas rhizophila, improving the plant's root dry weight and chlorophyll content. This is also, to our knowledge, the first study to show a PGP activity of Brevibacterium anseongense.

Phosphorus requirement of barley and wheat for seed and food quality

While geological phosphate reserves are continually depleting and effective phosphorus (P) recycling methods are still being developed, more efficient fertilisation of P can help to avoid unnecessary losses of this nutrient. In this way, environmental damage resulting from excessive P inputs to agricultural soils could also be reduced. The aim of this study is to identify a P concentration which is optimal for high seed quality of one cultivar of spring wheat and spring barley in addition to possessing a high nutritional value. While a critical threshold at 1.65 mg P/g grain for the studied barley cultivar has been identified, above which germination capacity and power were close to 100%, no such concentration was applicable to wheat. This concentration is well below the widely accepted doctrine, which calls for a P concentration of 2 mg/kg and could thus lead to a lower and thus more efficient use of the nutrient. Furthermore, in this study, an estimation of food quality by the molar ratio of phytate of the two micronutrients iron and zinc illustrates that such a concentration could only be found for zinc but not for iron.

Carbohydrate utilization by belowground organs defines the capacity of faba bean to exploit organic phosphorus sources

AbstractBackgroundLimited phosphate (Pi) reserves and the economic and adverse environmental impacts of excessive application of mineral fertilizers in soils are alarming. Therefore, the use of organic phosphorus (Porg) is suggested to reduce reliance on chemical fertilizers.AimsThere is currently little information regarding the accessibility of Porg to N2 fixation plants. Therefore, the present study aims to address the question of to what extent Porg substrates can serve as reliable sources of phosphorus (P) for faba bean in its nodulated phase. Specifically, we intended to explore whether N2‐fixing plants employ intrinsic mechanisms to facilitate Porg availability.MethodsA pot experiment was conducted to assess the inherent capacity of two faba bean varieties (Tiffany vs. Mallory) to utilize Porg supplied as phytic acid and Ca‐glycerophosphate. Plants were inoculated with Rhizobium leguminosarum bv. viciae 3841 strain and cultivated on sterilized loamy sand under greenhouse conditions.ResultsPhytic acid was relatively less efficient than Ca‐glycerophosphate in sustaining plant growth. Compared to Mallory, the variety Tiffany displayed a higher capability to use Porg, as evidenced by the relatively higher biomass production, nodulation, phosphorus use efficiency, and P‐ and N‐accumulations in plant tissues. Porg exploitation was intimately linked to the efficient utilization of the host's carbohydrate budget into nutrient‐acquiring structures (roots and nodules). In addition, the preferential allocation of Pi to prolific nodules is essential for plants to thrive best under these circumstances.ConclusionsTogether with N profitability, these findings suggested that N2‐fixing plants (e.g., faba bean) can promote the sustainable exploitation of Porg, thereby diminishing the sizeable environmental footprint.

Application of phosphate solubilizing fungi and lime altered the soil inorganic phosphorus fractions in an Ultisol of north-eastern India

ABSTRACT The gradually dwindling reserves of rock phosphate, the primary material used in the manufacturing of phosphatic fertilizers, encourages researchers to look for ways to exploit the accumulated fixed P pool in soil. Phosphate solubilizing microorganisms (PSM) could be a viable option for addressing the problem at a lower cost. Keeping these in mind, the present study was undertaken to evaluate the changes in the distribution of P in soil as affected by P fertilization, phosphate solubilizing fungi (PSF) and liming vis-à-vis the contribution of these fractions toward P nutrition of a test crop soybean (Glycine max L.). A bulk surface soil sample (0–15 cm) was obtained from Negheriting tea estate of Golaghat district of Assam, India (Ultisol, pH = 4.23) and after processing, three levels of P [0, 50, and 100% of recommended dose of P (RDP)], two levels of lime [No lime, 1/10th of Lime Requirement (LR)] and two levels of PSF (No-PSF, PSF) were applied in a completely randomized design with three replications. Sequential P fractionation was done in the post-harvest soil. On an average, the abundance of different P fractions in the soil, expressed as % of total P, followed the order: residual P (67.5%)> Fe bound P (12.1%)> reductant soluble P (8.85%)> Al bound P (4.04%)> occluded P (3.79%)> Ca bound P (3.11%)> soluble and loosely bound P (0.46%). All the inorganic P fractions except the residual P, increased significantly with P fertilization. Either liming or PSF application significantly increased the soluble and loosely bound P fraction and decreased the Al bound and Fe bound P fractions in soil. Positive growth response of soybean was obtained due to the application of P, lime, and PSF. Liming increased the P uptake by 30.4% and dry matter yield of soybean by 18.5% over no liming. On the other hand, PSF inoculation increased the P uptake by 16.7% and dry matter yield by 7.77% over no inoculation. So, it is evident that in short term, either liming or PSF was able to solubilize the native soil P. Phosphorus×lime and lime×PSF interactions should also be exploited in future endeavors.

Narrowing down molecular targets for improving phosphorus-use efficiency in maize (Zea mays L.).

Conventional agricultural practices rely heavily on chemical fertilizers to boost production. Among the fertilizers, phosphatic fertilizers are copiously used to ameliorate low-phosphate availability in the soil. However, phosphorus-use efficiency (PUE) for major cereals, including maize, is less than 30%; resulting in more than half of the applied phosphate being lost to the environment. Rock phosphate reserves are finite and predicted to exhaust in near future with the current rate of consumption. Thus, the dependence of modern agriculture on phosphatic fertilizers poses major food security and sustainability challenges. Strategies to optimize and improve PUE, like genetic interventions to develop high PUE cultivars, could have a major impact in this area. Here, we present the current understanding and recent advances in the biological phenomenon of phosphate uptake, translocation, and adaptive responses of plants under phosphate deficiency, with special reference to maize. Maize is one of the most important cereal crops that is cultivated globally under diverse agro-climatic conditions. It is an industrial, feed and food crop with multifarious uses and a fast-rising global demand and consumption. The interesting aspects of diversity in the root system architecture traits, the interplay between signaling pathways contributing to PUE, and an in-depth discussion on promising candidate genes for improving PUE in maize are elaborated.

Validity and reliability of a unique aerobic field test for estimating VO2max among basketball players

This study aimed at developing and validating an innovative field test for measuring the aerobic capacity of basketball players during games. Such capacity is necessary for recovering from high frequency anaerobic actions such as sprinting and continuing to perform well. To recover, the body must rebuild its creatine phosphate reserve and emit accumulated phosphate in very short periods of time. The participants included 21 male basketball players on an elite youth league in Israel, aged 16.4 years on average. In addition to participating in the proposed test (Yo-Yo Recovery Test for Basketball Players) twice (test/re-test), the players also performed three previously validated tests (Bruce Protocol Stress Test, Yo-Yo Intermittent Recovery Level 1 Test, and Yo-Yo Endurance Test). For each test, the players’ time and distance covered were documented, as were their maximum oxygen consumption and heartrate during recovery, and their perceived level of exertion. Our findings indicate the validity and reliability of the proposed aerobic field test for basketball players. Moreover, the test requires shorter times and distances for obtaining results than the other three tests. As such, this tool could be highly beneficial for basketball coaches in creating optimal training programs and game plans for each individual player and for the entire team.

Gravity study of the Western Bahira Basin and the Gantour Phosphatic Plateau, central Morocco: Interpretation and hydrogeological implications

The Western Bahira Basin (WBB), located in Central Morocco, is known for its large reserves of phosphate, which are currently being extracted through open pit mines within the Gantour Phosphatic Plateau (GPP). This mining activity, as well as the increasing agricultural development that this region has been experiencing during the last few decades, has subjected the groundwater in this semi-arid region to intense exploitation through pumping. Consequently, thorough knowledge of the underground water resources is essential for sustained activity.This study uses gravity data to investigate the deep geologic structure of the western Bahira and Gantour plateau area. Its main purpose is to improve the knowledge of this structure that influences the groundwater dynamics.The methodology involves, in addition to the qualitative and quantitative interpretation of the gravity data, the use of various filtering and analysis techniques to highlight the major geological structures. In fact, a qualitative analysis of the residual gravity map shows that the observed anomalies can be explained in terms of the bedrock topography of the study area. Positive anomalies spatially correlate with the outcrops of this bedrock in the Hercynian massifs of Jebilet and Rehamna, as well as with the Douar Rhirat structural high. The negative anomalies, on the other hand, tend to reflect increased thicknesses of sedimentary sequences, such as in the southern part of the WBB. Moreover, the Brikyine granite in the north of the study area is noticeably associated with the highest amplitude negative anomaly.Analysis of the residual gravity data using the total horizontal gradient, upward continuation, and Euler deconvolution techniques provides a quantitative assessment of the geologic structure. These methods help delineate various structures oriented in two main directions: N45E and N105E. Among these structures, several major faults have been identified. They are rooted at a maximum depth in excess of 2800 m. These faults are responsible for the general structure of the study area and the morphology of the basement.Furthermore, the 2D forward modeling, performed across the main negative gravity anomalies of the WBB, helps characterize the Paleozoic bedrock topography and provides more constraints on its variation. The resultant gravity models clearly show an asymmetric structure for the western Bahira trough. This depression is filled by sedimentary formations whose thickness at the depot-center can locally reach 1200 m. Additional analysis of piezometric data shows that the groundwater flows are controlled by the gravity structures highlighted in this study.

ПОДВИЖНОСТЬ И РАСПРЕДЕЛЕНИЕ ФОСФОРА В ЧЕРНОЗЕМЕ ОБЫКНОВЕННОМ ПРИ РАЗЛИЧНЫХ АГРОТЕХНОЛОГИЯХ

The study of the features of the content and profile distribution of total and available phosphates, depending on the applied agrotechnologies (traditional, minimal and No-till), was carried out. The object of the study was Haplic Chernozem carbonate of the southern zone of the Rostov region. The significant influence of the applied agricultural technology on the phosphate state of winter wheat agrocenoses was noted. The use of resource-saving technologies contributes to the accumulation of potential phosphate reserves in the upper horizons of the soil in comparison with the traditional technology with dump ploughing. The involvement of soil in agricultural production leads to an increase in the content of available phosphates (by 28-64 % in the Ap horizon, compared to virgin soil). The intensity of agricultural technology affects the mobility of phosphorus in the soil differently. In areas with dump ploughing, the maximum increase in the content of available phosphates was noted, both in comparison with the Chernozem of the virgin soil, and with the introduction of resource-saving agricultural technologies.

A transcription factor STOP1-centered pathway coordinates ammonium and phosphate acquisition in Arabidopsis

Phosphorus (P) is an indispensable macronutrient required for plant growth and development. Natural phosphate (Pi) reserves are finite, and a better understanding of Pi utilization by crops is therefore vital for worldwide food security. Ammonium has long been known to enhance Pi acquisition efficiency in agriculture; however, the molecular mechanisms coordinating Pi nutrition and ammonium remains unclear. Here, we reveal that ammonium is a novel initiator that stimulates the accumulation of a key regulatory protein, STOP1, in the nuclei of Arabidopsis root cells under Pi deficiency. We show that Pi deficiency promotes ammonium uptake mediated by AMT1 transporters and causes rapid acidification of the root surface. Rhizosphere acidification-triggered STOP1 accumulation activates the excretion of organic acids, which help to solubilize Pi from insoluble iron or calcium phosphates. Ammonium uptake by AMT1 transporters is downregulated by a CIPK23 protein kinase whose expression is directly modulated by STOP1 when ammonium reaches toxic levels. Taken together, we have identified a STOP1-centered regulatory network that links external ammonium with efficient Pi acquisition from insoluble phosphate sources. These findings provide a framework for developing possible strategies to improve crop production by enhancing the utilization of non-bioavailable nutrients in soil.

NH787 EMS mutant of rice variety Nagina22 exhibits higher phosphate use efficiency

Rice (Oryza sativa L.), a major dietary source, is often cultivated in soils poor in available inorganic orthophosphate (Pi), which is a key nutrient for growth and development. Poor soils are amended by phosphorus (P) fertilizer, which is derived from the non-renewable rock phosphate reserves. Therefore, there is a need for developing rice varieties with high productivity under low P conditions. At the ICAR-IIRR, ethyl methanesulfonate (EMS) mutagenized rice genotype Nagina22 (N22) were screened for high grain yield in Pi-deprived soil, which led to the identification of ~ 10 gain-of-function mutants including NH787. Here, detailed comparative morphophysiological, biochemical, and molecular analyses of N22 and NH787 were carried out in hydroponics and potting soil under different Pi regimes. Under Pi-deprived condition, compared with N22, NH787 exhibited higher root and vegetative biomass, the number of tillers, and grain yield. The augmented agronomic traits of NH787 were corroborated with significantly higher photosynthetic rate, pollen fertility, stigma receptivity, and the activities of antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT). Further, several genes involved in the maintenance of Pi homeostasis (GPH) were differentially regulated. The study thus revealed a wide-spectrum influence of the mutation in NH787 that contributed towards its higher Pi use efficiency (PUE).

An overview on deficit and requirements of the Irish national soil phosphorus balance

Phosphorus (P) is an essential life-supporting nutrient for which there is no substitute. Modern farming practice and food production are supported by the application of mineral P fertiliser derived from finite mined phosphate rock. The European Union does not have indigenous mineral phosphate reserves, which poses a significant issue to food security. This research paper assesses the potential of indigenous recycled P sources to replace imported P fertiliser within the Republic of Ireland. The research is undertaken at NUTS 3 (Nomenclature of Territorial Units) regional level, the nutrient soil P requirement is established, and the extent to which the regional production of indigenous recycled P sources can offset this requirement is determined. The soil P requirement was derived from analyzing the regional soil P indexes, stocking rate and land-use. It was established that to optimise Irish agricultural production, approximately 95,500 t of P fertiliser is required by Irish agriculture per annum. Indigenous P sources were reviewed to determine their contribution to the Irish P balance; the sources included sewage sludge, dairy processing waste, and animal manures. Regional indigenous P quantities vary greatly with the South-West Region producing the largest quantity of indigenous recycled P at 42.4% of required P than the Mid-West Region only producing 22.0% of its P requirement indigenously. Sources of indigenous P also vary greatly from region to region depending on population and industry, with the highest quantity of sewage sludge being produced in the Dublin plus Mid-East Region while the greatest contributor of dairy waste is the South-West Region. In total, over 28,500 t of P is recovered from indigenous sources per annum. This indicates that approximately 30% of the national P requirement could be met by indigenous P recycling.