Application Of Phosphate Fertilizers Research Articles

DETERMINATION OF THE ECOLOGICAL STATE OF THE KREMENCHUK RESERVOIR ON THE BASIS OF INFORMATION ENTROPY

It was established that the water does not meet the upper limit of the 1st quality class according to DSTU 4808:2007 by all indicators except for chloride ions, SPAR and suspended substances. There is a decrease in the level of BSK5 at the monitoring post in the lower part of the reservoir, which indicates the entry of substances into the watercourse that inhibit biochemical processes. There is also an increasing trend in the content of sulfates, phosphates, nitrogen compounds and HSC in water for control points located within the influence of industrial cities, along the reservoir. The highest values of the entropy index of water quality are characteristic of points p2, p. Adamivka, Chygyryn district (0.59015) and p3, village. Pronozivka Globyn district, (0.63092). These control points are located at a considerable distance from industrial centers, so pollution caused by agricultural production (application of phosphate and nitrogen fertilizers) probably plays a decisive role in the formation of water quality. The smallest value of the index (0.39397) is characteristic of item p1 – c. Sokirne, drinking water intake in the city of Cherkasy. The value of the non-torsion water quality index is in the range from 0.39397 (point p1) to 0.63092 (point p3).

Effects of different fertilization methods on Lolium multiflorum Lam. growth and bacterial community in waste slag.

Waste slag has low nutrient content, so it has insufficient nutrient cycling and transformation in the soil ecosystem. There are few studies on the application of oligotrophic phosphate-solubilizing bacteria and phosphate (P) fertilizer to improve the properties of waste slags. In this study, three oligotrophic bacterial strains with P solubilizing activity, namely, Bacillus subtilis 2C (7.23μg/mL), Bacillus subtilis 6C (4.07μg/mL), and Bacillus safensis 2N (5.05μg/mL), were isolated from waste slags. In the pot experiment, compared with no application of P fertilizer, inoculation of Bacillus subtilis 2C with a 50% recommended dose of P fertilizer significantly increased the available phosphorus (AP), total phosphorus (TP), and total nitrogen (TN) in slag by 33.16%, 76.70%, and 233.33%, respectively. The N, P uptake and fresh weight of Lolium multiflorum Lam. were significantly improved by 114.15%, 139.02%, and 100%, respectively. The analysis of the bacterial community showed that the application of P fertilizer decreased the diversity and richness of the bacterial community, and with the addition of phosphorus fertilizer and Bacillus subtilis 2C, the bacterial community in the slag developed towards eutrophication. Redundancy analysis (RDA) showed that the TP content in the slag was significantly correlated with the bacterial community (P = 0.001, < 0.01), followed by the TN content. This study on different P fertilizer application methods can provide some basic ideas for improving the performance of waste slag.

The effects of ammonium phosphate fertilization on yield and yield components of Mustard varieties in chernozem soil

Mustard seed is primarily used in the food or condiment industries in the form of either ground seeds or oil, and plays a significant role in agriculture. Especially in the intensive agricultural system where chemical fertilizers are used, little is known the impact of ammonium phosphate (Ammophos, 12% N, 52% P2O5) fertilizer applications on the yield and yield component of mustard under chernozem soil conditions. The objective of this study was to investigate the effects of seven doses of ammonium phosphate fertilizer applications on the seed yield and yield components of two different mustard varieties [Rushen (Brassica juncea (L.) Czern.) and Profi (Sinapis alba L.)] under chernozem soil conditions in Northern Kazakhstan. According to field experiment results, there were significant differences among the treatments in relation to yield and yield components (oil content, dry matter accumulation, NPK uptake, NPK contents in seeds) of mustard varieties. The higher seed yield for the N34.6 P150 treatment in Rushen and N41.5 P180 treatment in Profi than for any of the other rates of ammonium phosphate fertilizer application under the agro-ecological conditions of Akmola region, Northern Kazakhstan.

Forms of Toxic and Trace Metals in Grassland Soils of Galicia, Spain

The application of cattle slurry to agricultural soils contributes to the circular economy, while enriching the soil in macro and micronutrients and organic matter. However, this practice can have deleterious environmental effects, by adding toxic metals and other contaminants. The pseudo-total concentrations of nine potentially toxic and trace metals (Fe, Mn, Zn, Cu, Ni, Co, Cr, Cd and Pb) as well as metals extracted by DTPA, Mehlich 3 and 0.01 M CaCl2 were determined in Galician (NW Spain) grassland soils regularly receiving cattle slurry. Four soil depths (0–5, 5–10, 10–20 and 20–40 cm) were sampled and analysed. The pollution condition was assessed by comparing the pseudo-total concentrations with generic reference levels for Galician soils and by using pollution indices. The results indicated the absence of soil pollution by Fe, Ni, Co, Cr and Pb and a situation of no pollution to moderate pollution by Mn, Zn and Cu. Cd was the element most frequently enriched in the studied soils according to the pseudo-total, DTPA and Mehlich-3 concentrations, while the extraction by CaCl2 pointed to no environmental risk. The study supports the lithogenic character of Fe, Ni, Co and Cr, the mixed lithogenic and anthropogenic nature of Mn, Zn and Cu and the anthropogenic origin of Cd in these soils. The latter element can be added by both the application of cattle slurry and inorganic phosphate fertilisers.

Fertilization can modify the enantioselective persistence of penthiopyrad in relation to the co-influence on soil ecological health

Penthiopyrad is a widely used chiral fungicide for controlling rust and Rhizoctonia diseases. Development of optically pure monomers is an important strategy to realize amount reduction and increment effects of penthiopyrad, wherein, fertilizers as the co-exiting nutrient supplement may alter the enantioselective residues of penthiopyrad in soil. In our study, influences of urea, phosphate, potash, NPK compound, organic granular, vermicompost and soya bean cake fertilizers on enantioselective persistence of penthiopyrad were fully evaluated. This study demonstrated that R-(−)-penthiopyrad dissipated faster than S-(+)-penthiopyrad during 120 days. High pH, available nitrogen, invertase activities and reduced available phosphorus, dehydrogenase, urease, catalase activities were situated to benefit removing the concentrations of penthiopyrad and weakening enantioselectivity in soil. With respect to the impact of different fertilizers on soil ecological indicators, vermicompost contributed to enhanced pH. Urea and compound fertilizer played an absolute advantage in promoting available nitrogen. All fertilizers didn't go against available phosphorus. Dehydrogenase responded negatively to phosphate, potash and organic fertilizers. Urea increased invertase, besides, it and compound fertilizer both diminished urease activity. The catalase activity was not activated by organic fertilizer. Based on all the findings, soil application of urea and phosphate fertilizers was recommended and considered as a better option to exhibit high efficiency for the dissipation of penthiopyrad. The combined environmental safety estimation can effectively guide the treatment of fertilization soils in line with the nutrition requirements and pollution regulation from penthiopyrad.

Efficiency Recycling and Utilization of Phosphate from Wastewater Using LDHs-Modified Biochar.

The excessive application of phosphate fertilizers easily causes water eutrophication. Phosphorus recovery by adsorption is regarded as an effective and simple intervention to control water bodies' eutrophication. In this work, a series of new adsorbents, layered double hydroxides (LDHs)-modified biochar (BC) with different molar ratios of Mg2+ and Fe3+, were synthesized based on waste jute stalk and used for recycling phosphate from wastewater. The prepared LDHs-BC4 (the molar ratio of Mg/Fe is 4:1) has significantly high adsorption performance, and the recovery rate of phosphate is about 10 times higher than that of the pristine jute stalk BC. The maximum adsorption capacity of LDHs-BC4 for phosphate was 10.64 mg-P/g. The main mechanism of phosphate adsorption mainly includes electrostatic attraction, ion exchange, ligand exchange, and intragranular diffusion. Moreover, the phosphate-adsorbed LDHs-BC4 could promote mung bean growth, which indicated the recovery phosphate from wastewater could be used as a fertilizer.

The Status and Research Progress of Cadmium Pollution in Rice- (Oryza sativa L.) and Wheat- (Triticum aestivum L.) Cropping Systems in China: A Critical Review.

The accumulation of cadmium in rice (Oryza sativa L.) and wheat (Triticum aestivum L.) is a serious threat to the safe use of farmland and to the health of the human diet that has attracted extensive attention from researchers. In this review, a bibliometric analysis was performed using a VOS viewer (1.6.18, Netherlands) to investigate the status of cadmium contamination in rice and wheat growing systems, human health risks, mechanisms of Cd uptake and transport, and the corresponding research hotspots. It has a certain reference value for the prevention and control of cadmium pollution in rice and wheat planting systems in China and abroad. The results showed that the Cd content in rice and wheat planting systems in the Yangtze River Basin was significantly higher than that in other areas of China, and the Cd content in rice and wheat grains and the hazard quotient (HQ) in Hunan Province was the highest. The average Cd concentration exceeded the recommended limit by about 62% for rice and 81% for wheat. The main reasons for the high Cd pollution in rice and wheat growing areas in Hunan are mining activities, phosphate fertilizer application, sewage irrigation, and electronic equipment manufacturing. In this review, we demonstrate that cadmium toxicity reduces the uptake and transport of essential elements in rice and wheat. Cadmium stress seriously affected the growth and morphology of plant roots. In the shoots, Cd toxicity was manifested by a series of physiological injuries, such as decreased photosynthesis, soluble protein, sugar, and antioxidant enzyme activity. Cadmium that accumulates in the shoots is transferred to grains and then passes up the food chain to people and animals. Therefore, methods for reducing cadmium content in grains of rice and wheat are urgently needed, especially in Cd-contaminated soil. Current research on Cd pollution in rice and wheat planting systems focuses on the bioavailability of Cd, soil rhizosphere changes in wheat and rice, and the role of antioxidant enzyme systems in alleviating heavy metal stress in rice and wheat.

Combined Application of Calcium-Magnesium Phosphate Fertilizer with Soluble Phosphorus Improves Maize Growth in a Calcareous Soil

Combined Application of Calcium-Magnesium Phosphate Fertilizer with Soluble Phosphorus Improves Maize Growth in a Calcareous Soil

The Application of Fertilizer Phosphorus Affected Olsen P and the Phosphorus Fractions of Hedley Method in Black Soil

Olsen phosphorus (Olsen P) is an important indicator of soil labile phosphorus. Determining the effect of fertilization on Olsen P and P fractions (labile phosphorus, medium labile phosphorus and stable phosphorus) can guide the application of phosphate fertilizer. Therefore, it is of great significance to clarify the changes of Olsen P and P fractions and the influencing factors under long-term fertilization. This study investigated changes in Olsen P and P fractions in haplic phaeozems soils (0–20 cm) in two 30-year fertilization sites (Harbin, Gongzhuling) of northern China. Four treatments were examined: treatment with no fertilizer or manure (CK), nitrogen and potassium (NK), nitrogen, phosphorus and potassium (NPK), and manure, nitrogen, phosphorus and potassium (MNPK). The results showed that after NK application, Olsen P decreased by an average of 1.5 mg kg−1 for every 100 kg ha−2 of soil phosphorus lost due to continuous phosphorus uptake by the crop; with NPK, Olsen P increased by an average of 17.6 mg kg−1 for every 100 kg ha−2 of P surplus; with MNPK, the increase curve of Olsen P was similar to an S-curve with periods of rapid growth and periods of equilibrium. In the equilibrium period of Olsen P, the equilibrium values were 52.0 and 156.2 mg kg−1 in Harbin and Gongzhuling. After 20 years of long-term different fertilization, labile P (LP), medium labile P (MLP) and stable P (SP) decreased by 21.1, 16.6 and 15.1 mg kg−1 on average for the treatment without P application (NK), and the percentage decreases were 2.8, 5.7 and 2.1%, respectively. With the treatment of NPK, LP and MLP increased by 25.5 and 79.2 mg kg−1, and the percentage increases were 1.8 and 16.1%. With the treatment of MNPK, the increase in LP and MLP was significantly higher than that with NPK. Soil organic carbon (SOC), total nitrogen (TN) and carbon/nitrogen (C/N) had the greatest effects on Olsen P and P fractions and the total contribution rate was &gt;40%. In summary, fertilization system caused significant changes in Olsen P and P fractions. After about 20 years of long-term combined application of MNPK, the growth of Olsen P can be kept constant. SOC and TN had important effects on Olsen P and P fractions in black soil. Therefore, the application of phosphorus fertilizer should be adjusted according to the type and time of fertilization in black soil in order to avoid waste of phosphorus fertilizer.

Effects of straw mulching and phosphorus application on forms and availability of soil phosphorus in hilly dryland of Sichuan, China

We conducted a two-factor split-plot experiment to examine the alteration of soil inorganic phosphorus forms and phosphorus availability under straw mulching and phosphorus fertilizer rates. The main factor was straw mulching and non-mulching, while the sub-factor was phosphorus supply rates, including 0, 75, and 120 kg·hm-2. We analyzed the characteristics of phosphorus adsorption-desorption, the content of inorganic phosphorus components and their relationship with available phosphorus in hilly upland purple soil in Sichuan. Results showed that compared with the non-mulching, the maximum phosphorus adsorption capacity of straw mulching was notably decreased by 7.7% and 7.4% in the two experimental years from 2018 to 2020. The degree of phosphorus saturation and readily desorbable phosphorus of straw mulching were remarkably increased by 35.4% and 21.6% in 2019 and 18.6% and 35.2% in 2020, respectively. The maximum buffer capacity of phosphorus was not different between straw mulching and non-mulching. The maximum phosphorus adsorption capacity and maximum buffer capacity of phosphorus were significantly lower, and the degree of phosphorus saturation was notably higher in the phosphorus application treatment than that under no phosphorus treatment. The readily desorbable phosphorus increased with the increases of phosphorus rates. The contents of dicalcium phosphate (Ca2-P), octa-calcium phosphate (Ca8-P) and iron phosphorus (Fe-P) in straw mulching treatment were notably higher than those in non-mulching treatment, whereas the content of aluminum phosphorus (Al-P) significantly lower under the straw mulching. Meanwhile, the contents of occluded phosphate (O-P) and apatite (Ca10-P) tended to decrease in the straw mulching compared with that under the non-mulching. Phosphorus application increased the content of different inorganic phosphorus components. Compared with the non-mulching, soil available phosphorus content and the phosphorus activation coefficient of straw mulching remarkably increased by 23.2% and 21.3% in 2019, and 9.6% and 8.9% in 2020, respectively. Soil available phosphorus content and phosphorus activation coefficient increased with the increases of phosphorus rate. Results of regression analysis showed that the contribution of inorganic phosphorus components to the availability of available phosphorus in purple soil was Ca2-P > Fe-P > Al-P > Ca8-P > Ca10-P > O-P. Therefore, straw mulching combined with a reasonable phosphorus fertilizer rate could promote the decomposition and transformation of insoluble soil phosphorus to moderately active or easily absorbed phosphorus forms, reduce soil phosphorus adsorption, stimulate soil phosphorus desorption, and improve soil phosphorus availability. Based on the economic benefits, phosphate fertilizer application at the rate of 75 kg·hm-2 combined with straw mulching was recommended in Sichuan hilly dryland, which would be more beneficial in improving soil phosphorus availability.

Adaptive strategies of plants to conserve internal phosphorus under P deficient condition to improve P utilization efficiency.

Phosphorus (P) is one of the limiting factors for plant growth and productivity due to its slow diffusion and immobilization in the soil which necessitates application of phosphatic fertilizers to meet the crop demand and obtain maximum yields. However, plants have evolved mechanisms to adapt to low P stress conditions either by increasing acquisition (alteration of belowground processes) or by internal inorganic P (Pi) utilization (cellular Pi homeostasis) or both. In this review, we have discussed the adaptive strategies that conserve the use of P and maintain cellular Pi homeostasis in the cytoplasm. These strategies involve modification in membrane lipid composition, flavanol/anthocyanin level, scavenging and reutilization of Pi adsorbed in cell wall pectin, remobilization of Pi during senescence by enzymes like RNases and purple acid phosphatases, alternative mitochondrial electron transport, and glycolytic pathways. The remobilization of Pi from senescing tissues and its internal redistribution to various cellular organelles is mediated by various Pi transporters. Although much efforts have been made to enhance P acquisition efficiency, an understanding of the physiological mechanisms conserving internal Pi and their manipulation would be useful for plants that can utilize P more efficiently to produce optimum growth per unit P uptake.

Phosphorus fractions and their relationships with soil chemical attributes in an integrated crop-livestock system under annual phosphates fertilization

The main factors affecting phosphorus (P) availability in soils are mineralogy, acidity, and concentration of elements in the soil solution. Moreover, P fertilizer sources and amounts can affect P cycling and adsorption of this element on colloids. In this research, we hypothesized that the use of phosphate sources of different solubilities can alter soil P adsorption process, due to chemical compositions of these sources and, in ICLS, the soil-plant-animal system can change the P forms distribution on soil profile and its interactions with the soil chemical attributes. To examine these hypotheses, a field experiment was conducted over 5 years, under a Haplic Cambisol, in an incomplete factorial scheme, with the treatments being composed of three P sources (triple superphosphate, rock phosphate—Arad and magnesium thermophosphate), three doses of total P2O5 (60, 120, and 180 kg ha−1) plus a treatment without application of phosphate fertilizer. Phosphate applications occurred annually, broadcast without incorporation, at the time of sowing the annual winter forage, in a crop rotation system that included pasture in autumn-winter and grain crops in spring-summer. Soil samples were collected at depths of 0 to 5, 5 to 10, 10 to 15, 15 to 20, and 20 to 30 cm and evaluated by Hedley P fractionation and the soil chemical attributes were quantified. The use of different phosphates applied broadcast without incorporation did not influence the concentrations of soil P fractions over a 5 year study. Phosphate fertilizer doses above 120 kg ha−1 of total P2O5 increased moderately labile and non-labile P fractions. The highest concentration of labile P was found up to 15 cm soil depth. It was found that P lability is strongly associated with calcium and total organic carbon concentrations in the soil profile. High concentrations of basic cations and sulfate in the soil solution increased moderately labile and non-labile P fractions. The complexity of ICLS interactions to maintain phosphorus dynamics in the soil was shown to be an intricate P release/adsorption process associated with soil chemical attributes.

The fate of Cd during the replacement of Cd-bearing calcite by calcium phosphate minerals

Carbonate-bound speciation is a critical sink of potentially toxic elements (PTEs) like cadmium (Cd) in soil and sediment. In a phosphate-rich environment, carbonate minerals could be replaced by phosphate minerals such as dicalcium phosphate dihydrate (DCPD, also known as brushite), octacalcium phosphate (OCP), and hydroxylapatite (HAP). Currently, it is unclear the migration and fate of PTEs during the replacement of PTEs-bearing carbonates by HAP and related intermediate minerals. Therefore, we synthesized Cd-bearing calcite by the coprecipitation method and converted it to DCPD, OCP, and HAP to investigate the redistribution and fate of Cd. The results showed that Cd incorporation in calcite significantly inhibited their replacement by DCPD and OCP, respectively. 1.26% of Cd in calcite was released into the solution when DCPD replaced calcite, and subsequently, most of the released Cd was recaptured by OCP. Significantly, the released Cd was below 0.05‰ when all the solid converted to HAP. These results suggested that with the application of phosphate fertilizer in alkaline soil, the secondary calcium phosphate minerals could control the environmental behavior of Cd.

Cadmium in soils and potato tubers under grower management in two contrasting soil types of Hokkaido, Japan

ABSTRACT In Japan, little has been reported on cadmium (Cd) concentration in upland soils, and its relation to Cd concentration in crops and vegetables other than rice. Cd concentration in the surface soils and potato tubers of growers’ fields in two main potato production areas in Japan with contrasting soil types (Andisols and Inceptisols) was investigated. Soil and tuber samples were obtained from 90 growers’ fields with variable management histories. Total and Mehlich-3 soil Cd concentration were determined, and Cd concentration in the peeled potato tubers was also measured. A significant positive correlation was found between total Cd and phosphorous concentration in the soils reflecting the historical heavy application of phosphate fertilizer in both soil types. Although the total Cd concentration was much higher in Andisols, the Mehlich-3 Cd as well as tuber Cd concentration was lower in Andisols than in the Inceptisols, suggesting that Cd in Andisols may be specifically adsorbed by humic substances and amorphous clay minerals. The Cd concentration of the peeled potatoes in all samples was less than 100 μg kg−1 fresh weight below the threshold set by the Codex Alimentarius guidelines. The Cd concentration in the tubers tended to be higher when the soil phosphate retention index and base saturation were lower, and this tendency was stronger when both conditions are satisfied. Differences in soil properties and not the total soil Cd concentration were the dominant factor affecting potato tuber Cd accumulation. It is quite possible to reduce the amount of phosphate fertilizer appropriately to minimize the accumulation of Cd in both soil types as well as by increasing the soil base saturation to suppress the transfer of Cd from the soils to the potato tubers is especially important in the Inceptisols.

Di-ammonium phosphate (DAP) and plant density improve grain yield, nodulation capacity, and profitability of peas (Pisum sativum L.) on ferralsols in eastern D.R. Congo

Sustaining high crop yield and profitability on marginal soils, such as degraded ferralsols, calls for the use of adequate farming practices. In this study, we assessed for four cropping seasons the effect of di-ammonium phosphate (DAP) fertilizer application doses (100, 150, and 200 kg ha−1) and plant densities (100,000, 166,666, and 250,000 plants ha−1) on growth, yield, nodulation capacity, and profitability of two pea varieties (Adei and Rwanda) under degraded ferralsols in eastern Democratic Republic of Congo (DRC). Results showed that pea growth, yield, nodulation, and profitability were significantly affected by the DAP dose and the plant density. Application of 150 kg ha−1 of DAP improved pea yields from 730 to 1720 kg ha−1 and nodulation from 17 to 22 nodules per plant. The number of active nodules was positively correlated with total number of nodules, DAP doses, yield parameters, and plant height. High grain yield was recorded during the long rainy season (1400 kg ha−1) compared to the short one (930 kg ha−1). All DAP doses were profitable according to the agronomic efficiency (AE) and value–cost ratio (VCR) analyses. For improved and profitable pea production on degraded South-Kivu ferralsols, applying 150 kg ha−1 of DAP combined with low plant density are to be recommended and preferably in the long rainy season.

Layered application of phosphate fertilizer increased winter wheat yield by promoting root proliferation and phosphorus accumulation

Reducing the possibility of a potential phosphorus (P) resource crisis and increasing P use efficiency (PUE) by improving P fertilizer management is of paramount importance for truly sustainable agricultural production. However, information on how layered application of phosphate fertilizer at different soil depths affects yield and PUE in winter wheat (Triticum aestivum L.) is limited. Here, a 2-year field experiment was conducted in Gleyic Luvisols (ISSS, Isric, F.A.O, 1998) soil to compare the effects of surface fertilization (0–8 cm) with those of layered fertilization (LF) treatments including, uniform layered fertilization (1:1:1), elliptical layered fertilization (1:2:1), and trapezoidal layered fertilization (1:2:3), at soil depths of 0–8, 8–16, and 16–24 cm, on the spatial distribution of roots in different soil layers, and P accumulation at different growth stages of winter wheat in the 2016–2017 and 2017–2018 growing seasons. Our results showed that, compared with surface fertilization, all the LF treatments significantly increased yield by 6.3–20.6% and PUE by 4.7–11.2% points. Furthermore, elliptical layered fertilization resulted in the highest yield and PUE rate. The LF treatments effectively reduced topsoil (0–8 cm) root distribution by 10.8–14.7%, and increased deep-soil (8–100 cm) root distribution by 14.7–21.1% compared with surface fertilization. Linear regression analysis indicated that available P at 0–8 and 8–16 cm soil depths significantly correlated with yield. Additionally, results of structural equation modeling showed that available P at soil depths of 0–8, 8–16, and 16–24 cm had a significant positive effect on root morphology, but only at the 8–16 cm soil layer did available P have a significant positive effect on P accumulation of winter wheat. Overall, our findings suggest that elliptical layered fertilization effectively increased yield and PUE by promoting root proliferation and P accumulation in winter wheat.

Dynamic Changes in Soil Phosphorus Accumulation and Bioavailability in Phosphorus-Contaminated Protected Fields.

Soil phosphorus accumulation resulting in a high risk of phosphorus pollution is due to high multiple vegetable cropping indexes and excessive fertilizer input in protected fields. Therefore, this study explored the bioavailability of soil-accumulated phosphorus to improve fertilization and reduce the risk of soil phosphorus contamination in protected fields. A field trial was performed in Yanbian Prefecture, China to study the phosphorus bioavailability after continuous spinach planting without phosphate fertilizer applications. Results indicated that with increasing numbers of planting stubbles, soil inorganic phosphorus and occluded phosphorus changed little, while water-soluble and loose phosphorus, aluminum-phosphate, iron-phosphate, and calcium-phosphorus decreased first and then increased. Soil available phosphorus declined linearly. For planting spinach in protected fields, the threshold of soil phosphorus deficiency is 200 mg kg−1. A soil phosphorus supply potential model was established between x (the soil available phosphorus) and y (the numbers of planting stubbles): y = 6.759 + 0.027x, R = 0.99, which can be used to predict how planting stubbles are needed to raise the soil available phosphorus above the critical value of phosphorus deficiency for spinach. These results will provide the theoretical guidance for rational phosphorus fertilizer applications and control agricultural, non-point pollution sources in protected fields.

Effect of phosphorus activators on soil legacy phosphorus availability and its uptake by maize hybrid COH(M) 6 in calcareous soil

Continuous application of phosphatic fertilizers in association with its low recovery results in the insoluble legacy P buildup in agricultural soils. In this study, a field experiment was conducted with maize hybrid COH(M) 6 to know the effect of different P activators (Farmyard Manure, Humic acid, Phosphorus Solubilising Bacteria, and Phytase) on increasing the legacy phosphorus (P) availability. The P activators were combined and applied along with the different doses of P fertilizer (100%, 75%, and 50% soil test dose of P fertilizer). The results showed that the application of Farmyard manure (FYM) and Humic acid (HA) significantly (p &lt; 0.05) increased the soil available P (18.54 kg ha-1) and notably reduced the calcium P fraction (93.08 mg kg-1). The application of FYM and HA with 100% soil test dose of P showed a similar grain (9.98 kg ha-1) and stover P uptake (12.67 kg ha-1) response as that of FYM and HA with 75% soil test dose of P. The study suggested that FYM and HA application has activated the fixed calcium phosphorus in soil and increased its availability for crop utilization. The findings have illustrated that even the reduced dose of P fertilizer application can support the nutrient uptake if they are applied along with P- activators such as FYM and HA. This could promote soil health by reducing the P overload and further P loss in soil.

Cadmium exposure in adults across Europe: Results from the HBM4EU Aligned Studies survey 2014-2020.

The objectives of the study were to estimate the current exposure to cadmium (Cd) in Europe, potential differences between the countries and geographic regions, determinants of exposure and to derive European exposure levels. The basis for this work was provided by the European Human Biomonitoring Initiative (HBM4EU) which established a framework for alignment of national or regional HBM studies. For the purpose of Cd exposure assessment, studies from 9 European countries (Iceland, Denmark, Poland, Czech Republic, Croatia, Portugal, Germany, France, Luxembourg) were included and urine of 20-39 years old adults sampled in the years 2014-2021 (n=2510). The measurements in urine were quality assured by the HBM4EU quality assurance/quality control scheme, study participants' questionnaire data were post-harmonized. Spatially resolved external data, namely Cd concentrations in soil, agricultural areas, phosphate fertilizer application, traffic density and point source Cd release were collected for the respective statistical territorial unit (NUTS). There were no distinct geographic patterns observed in Cd levels in urine, although the data revealed some differences between the specific study sites. The levels of exposure were otherwise similar between two time periods within the last decade (DEMOCOPHES - 2011-2012 vs. HBM4EU Aligned Studies, 2014-2020). The age-dependent alert values for Cd in urine were exceeded by 16% of the study participants. Exceedances in the different studies and locations ranged from 1.4% up to 42%. The studies with largest extent of exceedance were from France and Poland. Association analysis with individual food consumption data available from participants' questionnaires showed an important contribution of vegetarian diet to the overall exposure, with 35% higher levels in vegetarians as opposed to non-vegetarians. For comparison, increase in Cd levels due to smoking was 25%. Using NUTS2-level external data, positive associations between HBM data and percentage of cropland and consumption of Cd-containing mineral phosphate fertilizer were revealed, which indicates a significant contribution of mineral phosphate fertilizers to human Cd exposure through diet. In addition to diet, traffic and point source release were identified as significant sources of exposure in the study population. The findings of the study support the recommendation by EFSA to reduce Cd exposure as also the estimated mean dietary exposure of adults in the EU is close or slightly exceeding the tolerable weekly intake. It also indicates that regulations are not protecting the population sufficiently.

Assessing the Lead Accumulation Risks of Wheat Grain by Developing a Source-Specific Accumulation Risk Assessment Model

Characterizing the lead (Pb) transfer in the "source-soil-wheat" chain is of great importance for the prevention and control of the Pb accumulation risk in wheat grain harvested from the croplands of China. In this study, we used the Jiyuan City, northern China, as a case study to investigate the influence of contamination sources and soil factors on the accumulation of Pb in wheat grain. A site-specific source risk assessment model (SRAM), coupling the positive matrix factorization model, Freundlich-type function, and the Monte Carlo simulation method, was developed to estimate the risk of Pb accumulation in wheat grain harvested from different scenarios. Based on the results of the spatial analysis, the effectiveness and potential risk of the control measures applied in the study area was also evaluated. Atmospheric deposition and phosphate fertilizer application were identified as major sources contributing to 29.0% of the Pb accumulations in wheat grain. Soil pH and cation-exchange capacity (CEC) were the primary causative factors affecting the Pb accumulation in wheat grain. Cropping wheat in the high Pb continuation risk areas (western and northwestern areas) of Jiyuan City caused a 10.5% likelihood of Pb to accumulate above the China food standard limit of 0.2 mg·kg-1 (DW). This risk was significantly decreased to 2.39% when the CEC levels of affected soils was improved to 20 cmol·kg-1 and above.