Monoammonium Phosphate Research Articles

Polymer-Modified Fertilizers for Mitigating Strawberry Root Burn

Polymer-modified fertilizers (PMFs) with prolonged nutrient release present a promising solution to address the challenges associated with conventional fertilization practices, particularly for sensitive crops such as strawberries. This study investigates the effectiveness of biodegradable PMFs in maintaining nutrient availability at optimal levels while minimizing root burn and nutrient losses. In a factorial field experiment, we obtaineda total of 3780 sets of parallel measured time series for soil EC, moisture, and temperature as well as two sets of harvest data to evaluate the impact of varying concentrations of polyvinyl alcohol (PVA) on the nutrient release rates from complex NPK fertilizer and monoammonium phosphate. Results indicate that polymer modifications significantly slow down nutrient release, leading to optimal salt levels and maximizing yield while remaining low enough to prevent the risk of root burn (EC of soil solution below 1 mS/cm). Consequently, the application of PMFs enhances strawberry yield surplus (on average 2.8 times in the second harvest) by ensuring a steady supply of nutrients throughout the growing season without inducing stress, which reduces the yield by nearly half. This research provides valuable insights into the development of more effective fertilization strategies for strawberry cultivation and other sensitive crops using PMFs.

Arsenic, cadmium, and chromium concentrations in contrasting phosphate fertilizers and their bioaccumulation by crops: Towards a green label?

Potentially toxic elements such as arsenic (As), cadmium (Cd), and chromium (Cr) are severely regulated in fertilizers and deserve continuous investigation. Phosphate-derived Cd has been a stepping-stone toward achieving sustainable and safe worldwide food production, especially after a new regulation aiming for reduced limits of Cd in P fertilizers (EU, 2019/1009). Three pot experiments were conducted to assess the variability of As, Cd, and Cr concentrations - with a particular focus on Cd - from monoammonium phosphates (MAP 1, MAP 2, and MAP 3 from different geographic origins) and their accumulation in limed and unlimed soils, and contrasting crops, representing staple food and significant sources of these elements for humans (i.e., potato, tobacco, and rice). A diverse array of sensitive techniques for trace elements determination were used to reveal the highest level of Cd of MAP 3 (20.71 mg kg−1 MAP), which loaded the highest amounts of this element to the soil matrix and solution, plant shoots, and xylem sap, contrasting with results for MAP 1 (0.87 mg kg−1 MAP), which has almost ten times less Cd than that required for low-Cd labeling of P fertilizers (≤20 mg Cd kg−1 P2O5). MAP 3 also had the highest Cr concentration (139.3 mg kg−1 MAP). Among crops, rice accumulated 16-fold less Cd than potato plants. Liming decreased Cd in tobacco and potato shoots up to 35%. Moreover, reductions of about 20% were also observed for Cd accumulation in tubers and sap. Conversely, Cd from MAP 3 was always much more accumulated in soil solution, achieving up to 20 μg L−1, while values < 5 μg L−1 (i.e., a groundwater limit) were obtained from MAP 1. Our findings may be used as a reference in developing green labels for fertilizers in scenarios where Cd accumulation represents a potential risk for soil and human health.

Investigating the Potential Use of End-of-Life Fire Extinguisher Powder as a Soil Amendment in Different Soil Types: A New Approach Following a Circular Economy Model

A first attempt to assess the potential alternative use of fire extinguisher filler powder after its exhaustion has been investigated in the present research. The chemical composition of fire extinguisher filler powder, specifically type ABC 40%, consists of monoammonium phosphate and ammonium sulfate. As its nitrogen and phosphorus content is particularly high, the thought of its possible use as a fertilizer and/or a soil amendment is a challenge. For this purpose, a pot experiment was carried out and two leafy vegetables (spinach and lettuce) were used as biomarkers. Two soil samples from rural areas, one acidic (pH = 5.8 ± 0.1) and one alkaline (pH = 8.2 ± 0.7), were selected for the experiments. Filler powder from a used fire extinguisher was added to the soil samples in two levels (1 and 2% v/v). It was found that the addition of fire extinguisher filler powder caused no toxicity to either of the two plants studied. On the contrary, an increase in their above-ground biomass was observed, proportional to the amount of powder added. It was established that in the pots where the powder was added, in both plant species observed, the plant height, root length, and chlorophyll content of leaves increased, the total antioxidant capacity was enhanced, and the concentrations of nitrate and phosphate in the leaves and roots of plants also increased, compared to the soil without the addition of fire extinguisher powder. The early signs appear to be encouraging, as an increase was observed in almost all aspects. The mandatory end of the life cycle of the powder as a fire-extinguishing agent and its disposal is also a challenge in the context of the circular economy, as reducing the energy requirements for fertilizer production is one of the objectives of sustainable development.

The Synergistic Effects of Different Phosphorus Sources: Ferralsols Promoted Soil Phosphorus Transformation and Accumulation

Phosphorus (P) application can enhance soil P availability and alter P fractions. However, the P accumulation and transformation of different P sources in low-phosphorus red soil remain unclear. Two-year (2018–2019) field experiments were conducted to investigate the effects of five P source treatments (CK—no phosphorus; SSP—superphosphate; MAP—calcium–magnesium phosphate; DAP—monoammonium phosphate; and CMP—diammonium phosphate) on the P accumulation of maize and soil P fractions in low-P red soil using the Hedley Sequential Method. The results showed that P application significantly increased P uptake, Olsen-P, total phosphorus, and most of the soil P fractions. Compared to the CMP, MAP, and DAP treatments, SSP had a relatively higher P accumulation and labile P pool, with a slightly lower moderately labile P pool. The SSP treatment mainly increased soil-available P content and crop P uptake by increasing the labile P pool (resin-P and NaHCO3-Pi) and reducing the moderately labile P pool and non-labile P pool. The P activation coefficient (PAC%) and Olsen-P were positively correlated with labile P (resin-P, NaHCO3-Pi, and NaHCO3-Po) and moderately labile P (NaOH-Pi and 1 M HCl-Pi) and negatively correlated with Fe2O3 and Al2O3. The results suggest that SSP has a priority effect on the crop P uptake and soil P availability in low-P red soil.

Effects of phosphorus fertilizer type and dripline depth on root and soil nutrient distribution, nutrient uptake, and maize yield under subsurface drip fertigation

ContextSubsurface drip irrigation can potentially increase nutrient uptake by altering the spatial distribution of nutrients and roots, but the efficiency enhancement potential of different phosphorus (P) sources combined with varying dripline depths still requires further evaluation. MethodsWe established a 2-year field experiment with spring maize in 2021 and 2022 to determine the regulatory effects of three P sources [P1, monoammonium phosphate (MAP); P2, ammonium polyphosphate (APP); and P0, no P] and three dripline depths (D0, surface drip irrigation, 0 cm; D15, subsurface at 15 cm depth; and D30, subsurface at 30 cm depth) on the soil NO3-N, NH4-N and Olsen-P distribution, root distribution, nitrogen (N) fertilizer partial factor productivity (PFPN) and P use efficiency (PUE), and grain yield. ResultsWe found a significant coupling effect between the P source and dripline depth, both of which significantly impacted soil nutrients and root distribution, grain yield, PFPN, and PUE. In P1D15 and P2D15, the highest soil NO3-N and Olsen-P contents were observed at soil depths of 0–30 and 10–20 cm and at 0–30 and 10–30 cm, respectively. Similarly, in P1D30 and P2D30, which were 20–40 and 20–40 cm, and 20–40 and 30–60 cm, respectively. Compared to the other treatments, P2D15 and P1D30 exhibited considerable increases in root length density at the 30–60 cm soil depth of 37∼52 % and 28∼58 %, respectively. Regardless of the dripline depth, P0 resulted in the lowest yield during both growing seasons. P1D30 and P2D15 were found to be the optimal combinations for achieving higher grain yield, PFPN, and PUE, as they were able to achieve a high degree of coordination between soil available N and Olsen-P, as well as root distribution. ConclusionsThe recommended approach for optimizing nutrient and root spatial distributions under subsurface drip irrigation systems involves the use of poly-P fertilizer (APP) in conjunction with shallow dripline depth and ortho-P fertilizer (MAP) paired with deep dripline depth, which provides valuable guidance for co-fertigation practices involving N and P fertilizers.

33P‐isotope labelling ammonium phosphate fertilizers reveals majority of early growth maize phosphorus is soil‐derived

AbstractIn soils managed to have adequate to high Mehlich‐3 phosphorus (P) concentrations throughout the US Maize Belt, the majority of crop P is soil‐derived. Struvite, a low water solubility ammonium phosphate fertilizer, may be therefore substituted for relatively high water‐soluble monoammonium phosphate (MAP) without adversely impacting maize (Zea mays L.) P uptake and growth, while minimizing fertilizer P loss risk. We determined the relative contribution of struvite and MAP to maize P uptake and soil solution P in soils representative of the US Maize Belt by radiolabelling fertilizers with 33P. We found 8% (struvite) to 22% (MAP) of early‐to‐mid vegetative growth stage (V7) maize P was fertilizer‐derived, and thus, 78%–92% was soil‐derived. Despite similar aboveground P uptake and maize growth, maize P use efficiency (PUE) determined directly by 33P was &lt;5% for MAP (4.9%) and struvite (1.9%) indicating that in soils with adequate to high crop‐available P, early season fertilizer PUE is relatively low. If prorated to harvest stage, in‐season PUE was estimated to be 8% for struvite and 20% for MAP. MAP and struvite did not differ in relative contributions to water‐extractable P, a proxy for P loss risk, potentially reflecting lag effects in struvite P dissolution and/or the relatively fine particle size of synthesized fertilizers (&lt;0.1 mm diameter). Since maize aboveground biomass and P uptake were similar for both struvite and MAP, struvite could be an effective P fertilizer for soils with adequate to high Mehlich‐3 P concentrations common across the US Maize Belt.

Effect of mechanochemically modified MoO3–ZnO on Mo supply to plants when co-granulated with macronutrient fertilizers

Molybdenum (Mo) is an essential micronutrient required for plant growth but is prone to leaching from neutral and alkaline soils. The use of slow-release Mo sources could potentially reduce leaching losses from soils and increase crop yields. In this study, we assessed mechanochemistry as a green method to produce slow-release Mo sources. Molybdenum compounds (MoO3 or (NH4)6Mo7O24·4H2O) were mechanochemically (MC) treated with ZnO to synthesize compounds with a Mo content of 1–36%. Reduced Mo solubility after MC treatment, compared to the initial Mo source, was obtained with the MoO3 source and these composites were used for co-compaction with macronutrient fertilizers. Macronutrient pellets with 0.2% Mo were compacted using the 4% Mo and 36% Mo (characterized as ZnMoO4) compounds. A column dissolution test showed that the 4% Mo compound in a macronutrient carrier (DAP and MAP) only released around 40% of the total Mo compared to 80% for a non-MC treated control over 72 h. Column leaching using two soils revealed that the release behavior of Mo was strongly related to the pH of the leachate, which was affected by both the soil pH and the macronutrient carrier. More Mo was released when the MC-treated compound was co-compacted with diammonium phosphate (DAP) compared to monoammonium phosphate (MAP). The MC-treated compound with 4% Mo showed significantly less leaching than the control without ball milling when co-compacted with both MAP and DAP. In a pot trial with simulated leaching, the uptake of Mo was greater for the MC-treated 4% Mo compound co-compacted into DAP than for the other Mo sources. Overall, our results indicate that MC-treated MoO3–ZnO could be used as a slow-release Mo source in high-rainfall areas.Graphical

Enhancing maize phosphorus uptake with optimal blends of high and low-concentration phosphorus fertilizers.

High-concentration phosphorus (P) fertilizers are crucial for crop growth. However, fertilizers with lower P concentrations, such as calcium magnesium phosphate (CMP) and single super phosphate (SSP), can also serve as efficient P sources, especially when blended with high-concentration P fertilizers like diammonium phosphate (DAP) or monoammonium phosphate (MAP). In this study, we conducted a 48-day pot experiment to explore how blending low-P fertilizers could optimize maize P utilization, using CMP to replace DAP in acidic soil, and SSP to replace MAP in alkaline soil, with five SSP+MAP and CMP+DAP mixtures tested. Key metrics such as shoot and root biomass, shoot P uptake, root length, and soil P bioavailability were measured. We found that maize biomass and P uptake with 100% DAP were comparable to those with 50% CMP and 50% DAP in acidic soil. Similar results were observed for 100% MAP compared to 50% SSP and 50% DAP in alkaline soil. Root biomass and length were largest with 100% MAP in acidic soil and at 100% DAP in alkaline soil, with no significant differences at 50% SSP or CMP substitutions for MAP and DAP, respectively. Furthermore, 50% SSP or CMP substitutions for MAP and DAP increased the content and proportion of the labile inorganic P (Pi) pool (H2O-Pi and NaHCO3-Pi), had a direct and positive effect on Olsen-P. Our findings reveal that 1:1 blends of SSP and MAP in acidic soil, and CMP and DAP in alkaline soil, effectively meet maize's P requirements without relying solely on high-concentration P fertilizers. This indicates that strategic blending of fertilizers can optimize P use, which is crucial for sustainable agriculture.

Optimizing co-application of starter ammoniacal-N and K-containing fertilizers for barley in the seed-furrow

It is unclear how seed-placed starter ammoniacal-N-and-K fertilizers influence barley (Hordeum vulgare L.) seed-crop emergence, and its early establishment, due to salt injury and potential ammonia production and toxicity within the soil profile under different placement rates. Keeping in this view, the study was undertaken to experiment the effects of different fertilizer types, and rates using three different soil types characterized by fine (G1), medium (G2), and coarse (G3) textures when simultaneously placed with barley seed and establish safe-starter fertilizer recommendation models. The fertilizers were applied at varying rates from 0 to 60 kg N ha−1 and 0 to 74 kg K ha−1 alongside barley seeding. Maximum predicted safe starter ammoniacal-N-fertilizer rates were as follows: urea = 15, 35 and 26 kg N ha−1 is safe for G1, G2 and G3 soils, respectively. DAP (Diammonium phosphate), 52 kg N ha−1 is safe for fine textures whilst 12 and 37 kg N ha−1 for medium and coarse textures. MAP (Monoammonium phosphate) is safely placed at 55, 11 and ≥60 kg N ha−1 for G1 – G3 soils. For MOP (Muriate of Potash) and SOP (Sulfate of Potash), 67 and ≥74 kg K ha−1 were ideal for improved barley emergence across all the soil types. Visual appearances including delayed seed emergence, leaf chlorosis, and stubby coleoptiles were observed at varying seed-placed N and K rates. Intricate relationships among various emergence parameters, root architecture, aboveground and root biomass, chlorophyll content, all showing significant interrelationships. Data indicate that cubic model could be used for predicting seed-safe rates for multiple fertilizer types.

Availability of phosphorus and nitrogen from modified mono-ammonium phosphate (MAP) fertiliser compounds

Availability of phosphorus and nitrogen from modified mono-ammonium phosphate (MAP) fertiliser compounds

Effect of coating phosphorus with humic acids and micronutrients on yield of soybean and maize in succession

The increasing the efficiency of phosphate and micronutrient fertilization in tropical soils should be better studied to close crop yield gaps. The aim of this study was to evaluate the effect of a soluble P source with or without humic acids (HA) and micronutrients (M) on P-availability and maize and soybean yield in Minas Gerais State, Brazil. The crops were grown under a rainfed and no-till cropping system, with maize grown in the 2016/2017 rainy summer season, wheat grown as a cover crop in the 2017 winter season, and soybean grown in the 2017/2018 crop year. The field trial was organized in a 4 × 2 factorial arrangement [4 sources of P in combination with 2 forms of M supply]. The coated monoammonium phosphate (MAP) P source was supplied in three ways: 1) MAP, 2) MAP + HA, and 3) MAP + HA + M (B, Cu, Mn, and Zn), plus a control for P (no P). The micronutrient supply was 1) Mn + Zn + Cu + B (MZCB) and 2) control for MZCB (no M supply). Coating MAP with HA increased soil P availability but did not increase P content within the soybean leaves. The multivariate approach also showed that soybean yield can increase in response to coating MAP with HA. The study showed that MAP + HA increased soil P content. However, this increase was diminished when micronutrients were included in the same granule (MAP + HA + M). However, P sources raised P in soybean leaves equally compared to control for P. Soybean yield was unaffected by the P source, likely due to adequate leaf P concentrations across all treatments. However, soybean yield generally increased with micronutrient supply. For maize, yields were unaffected by supplying micronutrients with the P source. Conversely, maize yields typically decreased with micronutrient supply, except when using the MAP + HA + M combination granule.

Adjusting Irrigation and Phosphate Fertilizer to Optimize Tomato Growth and Production

The efficient use of phosphate fertilizers and optimization of the amounts of irrigation water can maximize tomato growth and fruit production. This study aimed to evaluate the effects of different phosphorus (P) doses and sources on the growth and production components of tomato plants of the cultivar Gaúcho Melhorado Nova Seleção subjected to different irrigation water percentages. To achieve this, we set up an experiment using a factorial design to test the effects of four doses of P2O5 (corresponding to 25%, 50%, 100%, and 200% of the recommended dose), two P sources (monoammonium phosphate—MAP and organomineral—OM), and four irrigation water percentages (50%, 75%, 100%, and 125% of field capacity). Tomato plant growth improved when water was supplied at a percentage close to 100% of field capacity, with increased plant height, leaf length, and number of flowers observed (increases of 11.95%, 7.33%, and 13.87%, respectively, compared to 50% of field capacity). However, both excess and deficit irrigation resulted in morphological changes in tomato plants. Additionally, we observed that OM was more effective than MAP in increasing plant diameter and number of flowers, with increases of up to 36.4% and 227.6%, respectively, when using OM. Conversely, tomato growth was negatively affected by higher doses of MAP doses, suggesting that 25% of the recommended dose may yield the best growth rates. We verified that tomato plants can compensate for low phosphorus doses by increasing productivity with higher water amounts (125%–42.40 t ha−1), but high phosphorus doses result in greater fruit production with lower water percentages (50%–41.52 t ha−1).

Bioremediation of crude oil polluted surface water using specialised alginate-based nanocomposite beads loaded with hydrocarbon-degrading bacteria and inorganic nutrients

This study explored the elimination of petroleum from river water using matrix-bound composites of iron oxide nanoparticles (IONPs) decorated on biochar with immobilized hydrocarbon-degrading bacteria (HCB) and monoammonium phosphate (MAP) at 10%v/v pollution levels. The beads containing biochar and IONPs (BCNP) showed better pollutant removal than those with biochar alone (BC). The treatment with beads containing biochar, IONPs, HCB and MAP had the highest removal efficiency for TPH (98.5%) and PAH (93.7%) and the lowest biodegradation half-lives. The removal efficiency for TPH and PAH was greater in the treatment microcosms than in the controls with significant differences (p ≤ 0.05) between the two groups. TPH and PAH elimination levels differed significantly (p ≤ 0.05) between systems with the BC bead and those with the BCNP beads. The study revealed a steady increase in the abundance of the total cultivable heterotrophic bacteria and cultivable hydrocarbon utilizing bacteria in the treatment microcosms after an initial decline, with strong negative correlation between bacterial abundance and TPH and PAH concentrations based on r values (0.5 − 1.0) and shared variances obtained. Bacillus, Pseudomonas and Klebsiella pneumoniae dominated as the drivers of the bioremediation process while organic acids and esters (25.0%) and ketones (14.3%) were the main biodegradation metabolite groups.

Early Season Wheat Response to Electrochemically Precipitated Struvite in Various Soils in the Greenhouse

Fertilizer-phosphorus (P) materials can be recovered from wastewater and used to supplement mined phosphate rock, where one such material is struvite [MgNH4PO4·6(H2O)]. This study aimed to compare electrochemically precipitated struvite (ECST) reclaimed from synthetic wastewater to other commercial fertilizer-P sources in cultivated soils from Arkansas [silty clay loam (AR-SiCL) and silt loam (AR-SiL)], Missouri [(silt loam; MO-SiL 1 and 2)], and Nebraska [silt loam (NE-SiL) and sandy loam (NE-SL)]. A greenhouse pot study was conducted for 60 days with unvernalized wheat (Triticum aestivum) using five fertilizer-P sources [ECST, chemically precipitated struvite (CPST), monoammonium phosphate (MAP), triple superphosphate (TSP), and an unamended control (UC)] to evaluate treatment effects on below (BG)- and aboveground (ABG) and total dry matter (DM) and tissue-N, -P, -K, -Ca, -Mg, and -Fe uptakes. The ECST treatment produced 44 g m−2 larger ABG-DM than CPST in the AR-SiCL, but 181 g m−2 larger than the UC in the MO-SiL 1. The ECST had similar or larger nutrient uptakes than CPST, MAP, TSP, and UC. Belowground-P, -N, and -Mg uptakes for ECST were generally similar for all soil-fertilizer-P source combinations, where ECST was 0.3 to 2.6 g m−2 larger than all other fertilizer-P sources. Plant property response from ECST was generally similar to or greater than CPST, MAP, TSP, and the UC across all soils. Results suggest that ECST is a prime candidate to be used as an effective, alternative fertilizer-P source, suitable for use in wheat production across multiple soil textures.

Fire Properties of Paper Sheets Made of Cellulose Fibers Treated with Various Retardants.

This article presents the results of flame-retardancy tests conducted on cellulose sheets produced using a Rapid Köthen apparatus treated with retardants. The agents used were potassium carbonate (PC) K2CO3 (concentrations of 20; 33.3; and 50% wt/wt), monoammonium phosphate (MAP) NH4H2PO4 (concentrations of 35% wt/wt), diammonium phosphate (DAP) (NH4)2HPO4 (concentrations of 42.9% wt/wt), and bisguanidal phosphate (FOS) C2H10N6 (concentrations of 22.5% wt/wt). The agents were used to improve Kraft cellulose-based sheets' flame-retardant properties and compare their performances. As part of the study, the flammability of the materials was determined by the following methods: an oxygen index (OI) test, a mass loss calorimeter (MLC) test, and a mini fire tube (MFT) test. All formulations showed an increase in flame retardancy compared to the control test. All protected samples were non-flammable for OI determinations, and DAP-protected samples showed the highest OI index. For the MLC test, DAP-protected and MAP-protected samples showed the best heat-release rate (HRR), total heat release (THR), and average heat-release rate (ARHE) (samples did not ignite for 600 s). In the MFT test, all treated samples had comparably reduced weight loss. The best parameter was achieved for MAP and DAP (15% weight loss).

Fertilization efficiency of thirty marketed and experimental recycled phosphorus fertilizers

Recycling phosphorus (P) from waste streams like sewage sludge, animal manures or food industry by-products is required to sustain soil fertility without depleting non-renewable P resources. Several technologies are available for P recovery, leading to fertilizers differing in P solubility and bioavailability. In this study, thirty fertilizers obtained through different technologies were tested to assess if their fertilization efficiency was equivalent to mineral soluble fertilizer applied as triple superphosphate (TSP). The main selection criteria were (1) ensuring a wide chemical diversity, and (2) choosing products already on the market or at a late stage of development, to encompass a representative selection of current and future recycled fertilizers. The products were classified according to their organic carbon content and neutral ammonium citrate (NAC), and the main P species of each fertilizer was determined through K-edge and L2,3-edge X-ray absorption near edge structure spectroscopy (XANES). Three pot experiments with wheat, barley and ryegrass were conducted in three growing substrates with contrasting properties, all within a pH range of 5.8–6.9. Fertilizers containing ammonium magnesium phosphate, monoammonium phosphate, monocalcium phosphate, and dicalcium phosphate type species as dominant P species showed a similar fertilization efficiency to TSP, while fertilizers with hydroxyapatite, tricalcium phosphate, phytic acid or iron phosphates as their main P species had lower fertilization efficiencies. We conclude that while the trend towards high-efficiency, refined inorganic recycled P fertilizers is positive, lower-performing, mostly unrefined fertilizers must be assessed in light of their long-term P supply potential and additional benefits to soil health owing to their content of organic matter and other nutrients.

The Impact of Different Phosphorus Fertilizers Varieties on Yield under Wheat–Maize Rotation Conditions

The global phosphate (P) rock shortage has become a significant challenge. Furthermore, the misalignment between crops, soil, and P usage exacerbates P rock wastage in agriculture. The distinctions among various types of phosphorus fertilizers influence the phosphorus cycle, which subsequently impacts biomass, the number of grains per ear, the weight of a thousand grains, and, ultimately, the overall yield. In a four-year field experiment conducted from 2017 to 2021, we assessed the impact of various P fertilizer types on crop yield in a continuous wheat–maize rotation system. Prior to planting the crops, P fertilizers were applied as base fertilizers at a rate of 115 kg P2O5 ha−1 during the wheat season and 90 kg P2O5 ha−1 during the maize season. Additionally, nitrogen (N) was applied at rates of 120 kg ha−1 for wheat and 180 kg ha−1 for maize. The P fertilizers used included ammonium dihydrogen phosphate, ammonium polyphosphate, calcium–magnesia phosphate, ammonium phosphate, and calcium superphosphate. Urea was used as the N fertilizer with a split application—60% at planting and 40% at the jointing stage for wheat or the V12 (twelve leaf collar) stage for maize. The results showed that different P fertilizers increased the average yield of wheat and maize by 21.2–38.0% and 9.9–16.3%, respectively. It was found that ammonium polyphosphate, calcium superphosphate, and monoammonium phosphate were more suitable for application in a summer maize–winter wheat rotation system on loess soil.

Impact of Contrasting Rates of Phosphate Fertiliser Addition in Two Vertisols: Effects of Fresh Application and Residual Fertiliser on Sorption and Plant Uptake

Cropping systems in many sub-tropical and tropical regions rely on phosphorus (P) fertilisers to maintain crop yields. However, crop responses are often spatially and temporally inconsistent. This study evaluated P availability from dispersed applications of fresh phosphate fertiliser and their residual effect in two contrasting Vertisols - a major soil type for crop production. We collected soils that had received mono-ammonium phosphate (MAP) fertiliser four years prior to sampling (residual), as well as unfertilised soils to which we applied MAP at equivalent rates (‘fresh’). Soil P tests quantified the potential P availability arising from the residual and fresh P applications, and P sorption curves were generated to describe the P sorption/desorption dynamics. A 45-day pot trial evaluated wheat growth and P uptake from fresh and residual P applications in both soils. Soil tests and sorption curves reflected differences in P addition in the two soils, although the sorption characteristics did not differ appreciably in response to residual P. Crop growth and P uptake strongly increased with increasing P availability, with greater responses for the freshly applied P. Low P recovery from aged fertiliser applications demonstrated that the availability of residual P for crop uptake after dispersed applications is limited in Vertisols. P-tests and sorption measurements could collectively capture potential soil P reactions and plant P availability in two contrasting Vertisols. Residual P benefits from dispersed applications remained low. Enrichment in a defined soil volume (i.e., banding) merits further investigation in this soil type.

Soil profile distribution of nutrients in contrasting soils amended with struvite and other conventional phosphorus fertilizers

AbstractPhosphorus (P) can be recovered from wastewater and used as an alternative fertilizer, namely, struvite [MgNH4PO4·6(H2O)]. However, the soil mobility of wastewater‐derived P and other nutrients needs to be evaluated. The objective of this study was to compare the vertical distribution of water‐soluble (WS) soil P and other nutrients from a synthetic‐wastewater‐derived electrochemically precipitated struvite (ECST) to that from a chemically precipitated struvite (CPST), triple superphosphate (TSP), monoammonium phosphate (MAP), and a control in six soils from Arkansas (AR; loam [L] and silt loam [SiL]), Missouri (MO; SiL 1 and SiL 2), and Nebraska (NE; sandy loam [SL] and SiL). A column‐leaching experiment was conducted with the six soils and five fertilizer‐P treatments. Water‐soluble (WS) P from the two struvite materials generally did not differ (p &gt; 0.05) and was similar to that of MAP in the depths of 0–3, 3–6, and 6–10 cm, but was greater than that of TSP in the top 6 cm in four of the six soils. WS P from CPST in the MO‐SiL 2 and NE‐SL soils (6.6 and 12.7 mg kg−1, respectively) was larger than that from ECST, MAP, and TSP. In the AR‐L and MO‐SiL 1 soils, TSP was the only fertilizer‐P source that had increased WS P concentrations in the top 6 cm relative to the other fertilizer‐P sources. Results showed that ECST‐derived, WS P had similar soil profile distributions in the top 10 cm, suggesting that ECST will be equally protective of environmental health and leachate quality across multiple soil textures as other common fertilizer‐P sources.

Top dressing of nitrogen and phosphorus fertilizer increases yield and leads to biofortification of a local cowpea genotype

The traditional local genotype, EPACE-10, has a higher grain protein content (GPC) but a lower yield than the commercial genotypes, Gurguéia or Novaera. This study aimed to evaluate whether the GPC and quality or productivity of these different genotypes could be affected by top dressing fertilization with nitrogen (N) or phosphorus (P). In the first experiment, EPACE 10 and Gurguéia were subjected to the following treatments: inoculated with Rhizobium and only inoculated with N fertilization 25 days after sowing (DAS) or at the first flowering stage. In the second experiment, EPACE-10 and Novaera were subjected to the following treatments: inoculated only; inoculated plus mono ammonium phosphate (MAP) or urea applied at the pollination stage. In both experiments, none of the treatments resulted in an increase in GPC for each genotype. However, treatment with N at 25 DAS in the first experiment and with MAP in the second experiment increased methionine and cysteine content in EPACE 10, while treatment with N in the second experiment increased methionine content in Novaera. Therefore, in both trials, the top dressing fertilizer treatments increased the yield of EPACE 10 to the same level as Gurguéia or Novaera. Furthermore, the local genotype EPACE 10 exhibited a positive response to P fertilization, resulting in increased methionine and cysteine content and yield specific to its genotype.