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The main discoveries and advances in the development of industrial processes for the most commercially used phosphate fertilizers in the world (single superphosphate, triple superphosphate, monoammonium phosphate, and diammonium phosphate) occurred from 1830 to 1970, followed by improvements and investments to expand worldwide production capacity. A main opportunity now is aggregating new technologies to conventional phosphate fertilizers so they may become even more efficient in supplying P to plants, which involves research related to the technologies for reduction in soil P losses. Thus, some innovations and technologies have begun to be developed and marketed and continue in continual refinement and adoption in agriculture worldwide to reduce conversion of soluble P applied through conventional phosphate fertilizers into unavailable forms in the soil. This is the case of enhanced efficiency fertilizers, which includes groups of phosphate fertilizers with fixation inhibitors and the chemically modified, controlled-release, blends, multifunctional, and synergistic phosphate fertilizers. The technologies presented in detail in this paper were developed to improve the agronomic efficiency of phosphate fertilization in comparison with conventional fertilizers, with costs varying according to raw materials, production technologies, and distance from the consumer market. This synthesis expands knowledge regarding technologies in use, stimulating the development and application of technologies that increase nutrient efficiency, based on results obtained through suitable methods and equipment along with laboratory, greenhouse, and field results. Increased fertilization efficiency should always be linked with greater economic profitability and the lowest environmental impact, following the principles of sustainability and circular economy. The great challenge for innovation is transforming the knowledge generated regarding fertilizers present in patents and scientific publications into technologies appropriate for the fertilizer market and for adoption in agriculture.

Phosphate rock (PR) is an important mineral resource with numerous uses and applications in agriculture and the environment. PR is used in the manufacture of detergents, animal feed, and phosphate (PO4 3–) fertilizers. Leaching or runoff losses from PR products like PO4 3– fertilizers, animal feeds, and detergents could cause eutrophication of surface waters enriched in PO4 3– by these losses. Although direct application of PR reduces pollution by acting as a slow-release fertilizer, its effectiveness is limited by several factors. The major limitation of PR in direct application is its low solubility, which reduces its availability for soil reactions or plant uptake. Strategies used to increase the effectiveness of directly applied PR are based on increasing acidity, as this increases PR solubility. The application of PR in agriculture may have adverse effects because it contains hazardous elements that could be transferred to the soil through the application of fertilizers, especially after long term use. Chemical analysis of PR obtained from top PR-producing countries, however, shows that hazardous elements contained therein are below tolerable limits for PO4 3– fertilizers. Studies have also reported that the radionuclides in PR do not pose any radiological risk. The presence of these elements in PR can be put to positive use if they are extracted before they are applied to farmlands. This makes PR a source of rare earth metals and radionuclides that could be used in technological development and as a future energy source. The affinity of PR for metals makes it a useful adsorbent for the removal of metals from aqueous solutions and an excellent material for metal immobilization in contaminated soils. PR is a very important finite resource but its applications have adverse environmental implications.

Phosphorus (P) is a non-renewable resource extracted from phosphate rock to produce agricultural fertilizers. Since P is essential for life, it is important to preserve this resource and explore alternative sources of P to reduce its criticality. This study aimed to assess whether fertilizing with sludge-based phosphate fertilizers (SBPF) can be a suitable alternative to doing so with fertilizers produced from phosphate rock. Environmental impacts of production and land application of SBPF from four recovery processes were compared to those of two reference scenarios: triple super phosphate (TSP) and sewage sludge. To avoid bias when comparing scenarios, part of the environmental burden of wastewater treatment is allocated to sludge production. The CML-IA method was used to perform life cycle impact assessment. Results highlighted that production and land application of SBPF had higher environmental impacts than those of TSP due to the large amounts of energy and reactants needed to recover P, especially when sludge had a low P concentration. Certain environmental impacts of production and land application of sewage sludge were similar to those of SBPF. Sensitivity analysis conducted for cropping systems highlighted variability in potential application rates of sewage sludge or SBPF. Finally, because they contain lower contents of heavy metals than sewage sludge or TSP, SBPF are of great interest, but they require more mineral fertilizers to supplement their fertilization than sewage sludge. Thus, SBPF have advantages and disadvantages that need to be considered, since they may influence their use within fertilization practices.

A low-cost laser-induced breakdown spectroscopy (LIBS) instrument equipped with a charge-coupled device (CCD) was tested in the atmospheric environment for the quantification of K, Ca, Mg, and Mn in some organo–mineral fertilizers, mineral P fertilizers, and rock fertilizers of various compositions and origins, using flame atomic absorption spectrometry (FAAS) as the reference technique. The correlation analysis performed between each CCD pixel and the corresponding element concentration measured by FAAS allowed to choose the most appropriate K, Ca, Mg and Mn emission lines for LIBS analysis. The normalization process applied to LIBS spectra to correct physical matrix effects and small fluctuations was able to increase the linear correlation of the calibration curves between LIBS data and FAAS data by an average of 0.15 points of the R-value for all elements of interest. The R values of calibration curves were 0.97, 0.96, 0.86 and 0.84, for K, Ca, Mg and Mn, respectively. The limits of detection (LOD) were 66 mg/kg (K), 35 mg/kg (Ca), 5.4 mg/kg (Mg) and 0.8 mg/kg (Mn) when using LIBS in the quantification model. The cross-validation (leave-one-out) analysis yielded an absolute average error of 12% (K), 21% (Ca), 8% (Mg) and 13% (Mn) when LIBS data were correlated to FAAS ones. These results showed that the calibration models used were close to the optimization limit and satisfactory for K, Ca, Mg, and Mn quantification in the fertilizers and rocks examined.

A nitrogenous bio-fertilizer comibination was prepared contain Azospirillum lipoferum, and Azotobacter chroococcum bacteria. A phosphate bio-fertilizer consisting of Bacillus megaterium and Glomus mosseae fungus was also prepared. vermicompost was produced from earthworms imported from Iran and others isolated locally. A factorial experiment was carried to evaluate the effect of the interaction between these combinations and vermicompost types under levels of 0 % , 25 % and 50 % of NPK. The results showed a significant superiority of the bio-fertilizer (nitrogen and phosphate) treatment in available nitrogen in the soil after harvest, number of tubers, yield per plant, and the total yield with 39.70 mg N kg -1, 11.03 tuber plant -1, 1367.40 g plant-1, and 43.76 Mg ha-1 respectively. While phosphate bio fertilizer treatment giving available phosphorus in the soil by 22.74 Mg P kg -1, vermicompost produced from imported earthworms was superior in giving available phosphate in the soil with value 22.74 mg p kg -1. While the tri interaction was superior for all studied characteristics. حضرت توليفة سماد حيوي نتروجيني مكونة من بكتريا lipoferum Azospirillum و Azotobacter chroococcum كما حضرت توليفة سماد حيوي فوسفاتي مكونة من بكتريا Bacillus megaterium و فطر mosseae Glomus، تم إنتاج السماد الدودي من ديدان أرض مستوردة من أيران و أخرى عزلت محليا. نفذت تجربة عاملية لتقييم تأثير التداخل بين هذه التوليفات و نوعي السماد الدودي تحت مستويات صفر و 25% و 50% من NPK أظهرت النتائج تفوق معاملة توليفة السماد الحيوي الخليط (النتروجيني و الفوسفاتي) معنويا في النتروجين الجاهز في التربة بعد الحصاد و عدد الدرنات و حاصل النبات الواحد و الحاصل الكلي لتعطي قيم 39.70 ملغم Nكغم-1 و 11.03 درنة نبات-1 و 1367.40 غم نبات-1 و 43.76 ميكا غرام هـ-1 على التتابع فيما تفوقت معاملة السماد الحيوي الفوسفاتي في إعطاء فسفور جاهز في التربة بلغ 22.74 ملغم P كغم-1 كما تفوق السماد الدودي المنتج من ديدان أرض مستوردة في جميع الصفات المدروسة. و تفوق التداخل الثلاثي على المعاملات بشكل منفرد و لجميع الصفات المدروسة.

Fluorides are emitted in both gaseous and particle forms in the industrial sector. However, studies usually only report total fluoride content. Therefore, the study aimed to assess the particulate, gaseous fluoride and correlate it with the respirable dust particles in Single Super Phosphate (SSP), Granular Single Super Phosphate (GSSP), and administration divisions of the industry. Respirable dust particles, particulate fluoride, and hydrogen fluoride in the work environment were collected on a filter cassette containing an MCE filter paper (0.8 micron 37-mm) and Na2CO3 impregnated backup pad, respectively, using a personal sampler. The fluoride samples were analyzed using Ion Selective Electrode (ISE) and expressed as milligrams per meter cube (mg.m-3). The respirable dust, particulate, and gaseous fluoride content were found to have statistically significant differences (p<0.001) between the divisions (SSP, GSSP, and administration) in the static monitoring, whereas, in the case of personal monitoring, no significant differences were observed. Average airborne respirable, particulate, and gaseous fluoride levels in static monitoring were 1.37, 1.03, 0.20 mg.m-3, 0.018, 0.008, 0.001 mg.m-3, and 0.808, 0.403, 0.026 ppm in SSP, GSSP and administration respectively, whereas in personal monitoring the average respirable, particulate and gaseous fluoride concentrations were 1.18, 0.85, 0.30 mg.m-3, 0.0013, 0.007, 0.002 mg.m-3 and 0.356, 0.258, 0.011 ppm in SSP, GSSP and administration respectively. The present study observed that the levels of fluoride decreased with an increase in distance from SSP, followed by GSSP and administration. It indicates that the fluoride exposure was inversely proportional to the distance of the source. This study outcome will help to design a policy and intervention to mitigate fluoride exposure among workers.

Phosphates are known to be essential for plant growth and development, with phosphorus compounds being involved in various physiological and biochemical reactions. Phosphates are known as one of the most important factors limiting crop yields. The problem of phosphorus deficiency in the soil has traditionally been solved by applying phosphate fertilizers. However, chemical phosphate fertilizers are considered ineffective compared to the organic fertilizers manure and compost. Therefore, increasing the bioavailability of phosphates for plants is one of the primary goals of sustainable agriculture. Phosphate-solubilizing soil microorganisms can make soil-insoluble phosphate bioavailable for plants through solubilization and mineralization. These microorganisms are currently in the focus of interest due to their advantages, such as environmental friendliness, low cost, and high biological efficiency. In this regard, the solubilization of phosphates by soil microorganisms holds strong potential in research, and inoculation of soils or crops with phosphate-solubilizing bacteria is a promising strategy to improve plant phosphate uptake. In this review, we analyze all the species of phosphate-solubilizing bacteria described in the literature to date. We discuss key mechanisms of solubilization of mineral phosphates and mineralization of organic phosphate-containing compounds: organic acids secreted by bacteria for the mobilization of insoluble inorganic phosphates, and the enzymes hydrolyzing phosphorus-containing organic compounds. We demonstrate that phosphate-solubilizing microorganisms have enormous potency as biofertilizers since they increase phosphorus bioavailability for the plant, promote sustainable agriculture, improve soil fertility, and raise crop yields. The use of phosphate-solubilizing microbes is regarded as a new frontier in increasing plant productivity.

【Objective】 Improving water and nutrient use efficiency is essential for promoting sustainable agriculture. This study investigates the combined effects of water and phosphorus applications on growth, photosynthetic characteristics, and yield of alfalfa. 【Method】The experiment was conducted in the Yinda Irrigation District of Gansu Province using the variety Jieyi alfalfa as the model plant. The experiment consisted of three water treatments with soil moisture content kept at 45%-60% (low, W1), 60%-75% (medium, W2), and 75%-90% (high, W3) of the field capacity. For each soil moisture treatment, there were three phosphorus treatments by applying 0 (low, P0), 50 kg/hm2 (medium, P1) and 100 kg/hm2 (high, P2) of phosphorus fertilizer. In each treatment, we measured plant traits, photosynthesis, and hay yield. 【Result】① Under low and medium soil moisture conditions, plant height, stem diameter, leaf-to-stem ratio, photosynthetic performance, and irrigation water use efficiency all increased with phosphorus applica

In order to maintain high yields and protect the environment, the replacement of chemical fertilizers with organic ones has received increasing attention in recent years. A 2-year field experiment (2015-2016) was carried out to assess the effects of substituting equal amounts of mineral fertilizer with organic manure on the yield, dry matter (DM), and nitrogen (N) uptake of spring maize (Zea mays L.) and on the mineral N (Nmin) distribution in the soil profile. The treatments included chemical fertilizer; different amounts of maize straw, cow manure, and chicken manure; and an unfertilized control (CK). Compared with the chemical fertilizer treatments, equal amounts of substitutions with cow manure or chicken manure increased production, and a 25% nutrient substitution resulted in the best yield increase. Straw return had no effect on maize production, and 100% straw return resulted in reduced production. The N accumulation and DM content both exhibited a slow-fast-slow growth trend throughout the various growth stages, and the average N uptake and DM accumulation in response to the treatments followed the order of chicken manure > cow manure > chemical fertilizer > straw return > CK. The Nmin content in the profile not only increased as the Nmin application rate increased but also showed greater increases at certain depths than at the surface, indicating that excessive N led to leaching. These results suggest that an appropriate proportion of organic substitution not only provides enough nutrients but also improves the soil environment and leads to increased yields. This technique represents a practical method of continuously increasing production and reducing the risk of N leaching.

This review covers the literature data on plant growth-promoting bacteria in soil, which can fix atmospheric nitrogen, solubilize phosphates, produce and secrete siderophores, and may exhibit several different behaviors simultaneously. We discuss perspectives for creating bacterial consortia and introducing them into the soil to increase crop productivity in agrosystems. The application of rhizosphere bacteria—which are capable of fixing nitrogen, solubilizing organic and inorganic phosphates, and secreting siderophores, as well as their consortia—has been demonstrated to meet the objectives of sustainable agriculture, such as increasing soil fertility and crop yields. The combining of plant growth-promoting bacteria with mineral fertilizers is a crucial trend that allows for a reduction in fertilizer use and is beneficial for crop production.