Ammonium Phosphate Fertilizer Research Articles

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 <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 (<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.

Zinc in ammoniated phosphate fertilizers: Solid‐phase speciation, solubility, and use of barrier coatings to enhance zinc availability

AbstractZinc (Zn) is the micronutrient commonly found deficient in agricultural soils worldwide, limiting crop yield and reducing food quality. Zinc‐enriched fertilizers have been successfully used to tackle crop Zn deficiency. However, Zn solubility is reduced after addition to phosphate fertilizers due to the formation of sparingly soluble precipitates, decreasing Zn availability to crops. We hypothesized that the availability of Zn in the fertilizer to plants is related to its speciation in the fertilizer. We evaluated a range of ammonium phosphate fertilizers using X‐ray absorption near‐edge structure and assessed the water‐solubility of Zn in the formulations. Four Zn species were identified in these fertilizers, with zinc ammonium phosphate the most abundant one. The speciation of Zn in the fertilizer had little relationship with the water solubility of Zn in the final product. Zinc solubility was driven by fertilizer pH, with lower pH resulting in higher solubility. We concluded that added Zn reacts with the fertilizer matrix to form mainly zinc (ammonium) phosphates, and when the fertilizer is dissolved in water, hopeite controls the solubility. Based on these findings, we tested whether a barrier coating between the P granule and the Zn compound could prevent reaction between Zn and P and thus enhance Zn availability. Indeed, higher Zn uptake was observed in an isotopically labeled fertilizer growth trial when a barrier coating physically separated Zn and P in the fertilizer. In summary, Zn availability to crops can be maximized by decreasing fertilizer pH and separating P and Zn in the granule.

Micronutrients in coated phosphate fertilizer improve precision distribution and nutrient use efficiency of soybean

AbstractChallenges regarding uniform micronutrient distribution and P‐use efficiency in agricultural soils are common. Micronutrients can be added as coated P fertilizers, creating multi‐nutrient fertilizers for crops to address this issue. The objective of this study was to quantify the diffusion and availability of P, B, Cu, Mn, and Zn in coated P fertilizers. Another objective was to evaluate the nutrient uptake, partitioning, and yield of soybeans. Treatments were monoammonium phosphate and NPS (nitrogen, phosphorus, sulfur) fertilizer coated with Maxxi‐Phós and either Wolftrax, Microsol, or MIB Precise. Applied concentrations of B and Cu varied between 0.15% and 0.05%. The Mn and Zn ranged from 0.45% to 0.15%. Nutrient accumulation and recovery were assessed in the greenhouse and field trials. P diffusion ranged from 5.58 to 18.88 mm in 336 h. Micronutrient use efficiencies varied according to the soybean (Glycine max) phenological stages, with emphasis on the V4 stage, which resulted in the following values: B (0.65% to 13.89%), Cu (6.73% to 62.84%), Mn (0.73% to 3.36%), and Zn (0.01% to 2.34%). Nutrient exports were: 55.7 kg of P2O5 ha−1, 209.6 g of B ha−1, 109 g of Mn ha−1, 216.7 g of Zn ha−1, and 64.3 g of Cu ha−1. There was significant absorption (p ≤ 0.05) of B, Mn, and Zn at stages R1–R5.1 in the field trial, whereas it was from V4 to R1 for Cu. As a multi‐nutrient fertilizer for soybeans, micronutrient‐coated P fertilizers could replace exported nutrients.

The fate of nitrogen of ammonium phosphate fertilizers: A blind spot

AbstractAmmonium phosphate fertilizers are a common phosphorus (P) source for crops, namely monoammonium phosphate, diammonium phosphate, and ammonium polyphosphate. Despite containing appreciable nitrogen (N), ammonium phosphate fertilizers are generally considered P fertilizers. However, the approximately 8.5 million Mg N co‐applied with P annually as ammonium phosphate fertilizers represents 8% of global N fertilizer input flux to agroecosystems. Despite this, a systematic review of the literature revealed only one direct assessment of N losses from ammonium phosphate fertilizers. An additional five studies reported NO3‐N leaching and N2O‐N emissions from soils fertilized with ammonium phosphates, but inadvertently as observations from failed or control treatments that are confounded (e.g., not accounting for non‐fertilizer contributions to N losses). The magnitude and fate of N co‐applied with P in ammonium phosphate fertilizers is a blind spot in agroecosystem N budgets and environmental footprints that necessitates quantification.

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.

Influences of Permeate Solution and Feed pH on Enhancement of Ammonia Recovery from Wastewater by Negatively Charged PTFE Membranes in Direct Contact Membrane Distillation Operation.

This research investigated the feasibility of enhancing ammonia recovery from wastewater using a negatively charged poly(tetrafluoroethylene) (PTFE) membrane in a direct contact membrane distillation (DCMD) system. The influences of phosphate solution types (as the permeate solutions) and feed pH on ammonia recovery were analyzed. Three types of permeate solutions—DI water and two types of phosphate solutions (H3PO4 and KH2PO4)—were investigated for recovery of ammonia gas on the permeate side. From the obtained results, the H3PO4 solution was found to be the most suitable permeate solution to recover ammonia gas in the DCMD operation with the highest overall ammonia mass transfer coefficient of 7.4 × 10–5 m/s, compared to values of 1.2 × 10–5 and 2.4 × 10–5 m/s for DI water and KH2PO4 solution, respectively. Moreover, an increase in the H3PO4 concentration from 0.3 to 0.5 M in the permeate solution also could significantly enhance ammonia recovery. With an increase in the feed pH from 10.0 to 11.8, the ammonia recovery could be enhanced to 92.98% at a pH of 11.8. Liquid ammonium phosphate fertilizer could be produced by the DCMD system with the use of 0.5 M H3PO4 solution. Therefore, the DCMD process using a negatively charged PTFE membrane with an appropriate permeate solution is one of the challenging processes for ammonia recovery from wastewater to promote the circular economy concept.

The development road of ammonium phosphate fertilizer in China

Ammonium phosphate fertilizer is the compounds containing nitrogen and phosphorus that are usually produced through the neutralization reaction of phosphoric acid and ammonia. At present, there are a variety of products, such as slurry monoammonium phosphate (MAP), diammonium phosphate (DAP), industrial grade MAP, water soluble MAP, water soluble ammonium polyphosphate (APP) and so on. After more than 60 years of development, China’s ammonium phosphate fertilizer industry has experienced the road of from scratch and from weak to strong. The successful development of the slurry MAP technology ended the history that the high concentration phosphate fertilizer cannot be produced by using the medium and low grade phosphate ore. The continuous, stable and large-scale production of DAP plant provides sufficient guarantee for DAP products in China. The development of new ammonium phosphate fertilizer products, such as industrial grade MAP, water soluble MAP, water soluble APP, provides technical support for the transformation and upgrading of phosphorus chemical enterprises. In this paper, the production methods, the development history and the latest research progress of ammonium phosphate fertilizers were reviewed.

Vibrio and Heterotrophic Marine Bacteria Composition and Abundance in Nutrient-enriched Kappaphycus striatus

Inorganic nutrient application in Kappaphycus seaweed farming has been a practice in the southern Philippines for the past years. To investigate the inorganic nutrient’s influence on the number and assemblage of Vibrio and heterotrophic marine bacteria and on the presence of ice-ice disease-inducing bacteria in Kappaphycus striatus, a field experiment was conducted using ammonium phosphate (16-20-0) fertilizer at high concentration (HC, 8.82 g L–1), low concentration (LC, 0.01 g L–1), and control (C, 0.00 g L–1). Vibrio (VCs) and heterotrophic marine bacterial counts (HMBCs) were found similar among treatments. Based on 16S rRNA gene sequencing, isolates from source K. striatus, nutrient-enriched K. striatus (HC, LC, and C), farm seawater, and fertilizer solutions were identified as Vibrio alginolyticus (three strains), V. parahaemolyticus, V. brasiliensis, V. harveyi, Gilvimarinus chinensis, and species related to Bacillus sp. ST7, Psychrobacter sp. ST8, Enterococcus sp. ST5, Oceanobacillus sp. ST9, and Paracoccus sp. ST10. Bacillus sp. ST7 and Oceanobacillus sp. ST9 were unique and only present in HC and LC. The agarolytic activity of G. chinensis, isolated from all samples, suggests that it is an ice-ice disease-causing bacterium. The microbial community dynamics of farmed K. striatus, when enriched with inorganic nutrients, may pave way in addressing the occurrence of ice-ice disease.

Maize and soybean response to phosphorus fertilization with blends of struvite and monoammonium phosphate

Struvite (MgNH4PO4·6H2O), a low water solubility (<3%) mineral that is increasingly recovered from wastewater treatment plants, has potential to be used as a slow release ammonium phosphate fertilizer, especially when blended with highly water soluble phosphorus (P) fertilizers such as monoammonium phosphate (MAP). Maize and soybean were fertilized using a gradient of struvite substitution for MAP, entailing five struvite: MAP blends in a factorial combination with struvite granule size (1.5, 3.0 mm diameter) and fertilizer placement (incorporation, banding). Crop biomass, and P and N uptake (total, concentration) were used to evaluate crop response, and post-harvest soil Mehlich-3 P was measured to assess soluble P loss risk. Maize biomass response was similar using up to 50% struvite and similar in soybean using up to 25% struvite. Total P uptake by maize was similar across 0–75% struvite blends, but significantly lower for 100% struvite. Maize apparent fertilizer P uptake and apparent fertilizer P uptake efficiency was greatest for 100% MAP. Despite differences in biomass, soybean apparent fertilizer P uptake and apparent P use efficiency were similar across struvite blends. Soybean P uptake was significantly greater when fertilized with 100% struvite than with 25 and 50% struvite. Inverse correlation of plant P and N concentrations with biomass indicated a biomass dilution effect. Residual soil Mehlich-3 P decreased with increasing struvite substitution of MAP. Struvite:MAP blends (25–50% struvite) appear to lower soluble P loss risk compared to MAP without restricting early season (vegetative) growth of maize and soybean, and this can differ by crop species.

ВЛИЯНИЕ КОМПЛЕКСНЫХ МИНЕРАЛЬНЫХ УДОБРЕНИЙ НА УРОЖАЙНОСТЬ И КАЧЕСТВО ЗЕРНА ЯРОВОЙ ПШЕНИЦЫ В УСЛОВИЯХ ЛЕСОСТЕПНОЙ ЗОНЫ АЛТАЙСКОГО КРАЯ

he effect of sowing multiple-nutrient mineral fertilizerapplication on spring wheat crops of the Astrid variety on gray forest soils of the forest-steppe zone was found. The study of the weather conditions of the growing season showed that the total amount of precipitation during the growing season was significantly lower than the average annual -158 mm as compared to 220 mm of the normal. The monthly rainfalls sharply differed from long-term ones; this had a significant impact on the formation of yield and grain quality. The application of NPK fertilizer and ammoni-um-phosphate-sulfate at a rate of 100 kg ha and ammoni-um phosphate fertilizer at a rate of 50 kg ha increased the yield of spring wheat grain by 8-66%, and the gluten con-tent in the variant with ammonium phosphate fertilizer at the level of 26-31% ascompared to 28% in the control. The payback of 1 kg of the primary nutrient of the fertilizers by grain yield gain was the highest against the background of NPK fertilizer and ammonium-phosphate-sulfate -55.0 and 40.8 kg, respectively. The protein content in wheat grain for in all fertilization variants ranged within 13.1-15.2% as compared to 13.7% in the unfertilized variant. The thou-sand-kernel weight as a result of obtaining high gains in the variants of sowing application ranged within 31.1-38.3 g; TKW below the control was in the variants with ammonium phosphate fertilizer and ammonium-phosphate-sulfate -31.1 and 33.4 g. The grain-unit belonged to Class 3 (no less than 730). It has been found that it is agronomically efficient when cultivating soft spring wheat in a temperately moist zone, on more arid years, on gray forest soils, when sowing, to apply NPK fertilizer and ammonium-phosphate-sulfate at a rate of 100 kg ha.

ПРОДУКТИВНОСТЬ И КАЧЕСТВО КОРМА СЕНОКОСНЫХ УГОДИЙ В ЗАВИСИМОСТИ ОТ СОВМЕСТНОГО ВНЕСЕНИЯ АММОФОСА И АММИАЧНОЙ СЕЛИТРЫ

This paper discusses the effect of a multiple-nutrient fertilizer and a mixture of simple mineral fertilizers on yield increase and forage quality improvement of hayfields under the conditions of the mid-mountain zone of the Republic of Altai. The natural forage lands of the mid-mountain zone of the Republic of Altai are characterized by the predomi-nance of the motley grass-grasses type of vegetation. The soils are deficient in available phosphorus and have in-creased exchangeable potassium content, so it is advisa-ble to apply mineral fertilizers containing nitrogen and phosphorus. The research was conducted from 2018 through 2020 on the farm of the KFK “Yegarmina M.M.” in the Shebalinskiy District of the Republic of Altai. In the var-iants of ammonium phosphate fertilizer application and its combination with ammonium nitrate in the rates of 20 and 40 kg ha (primary nutrient basis), yield increase of 24.1-85.9% (0.72-2.56 t ha) was obtained. The mineral fertilizers not only increase the yields, but also improve the nutritional value and forage quality. Digestible protein content in one fodder unit increased by 15-35 g as compared to that of the control. The maximum value of this indicator (116 g) was recorded in the variant with N12P52. Thus, the application of mineral fertilizers made it possible to obtain forages that met animal nutrition requirements.

4R Management of Phosphorus Fertilizer in the Northern Great Plains.

Phosphorus (P) fertilizer has played a vital role in increasing the productivity of crop production in the northern Great Plains for approximately 100 years. Throughout this period, agricultural production practices have changed dramatically, while our knowledge of P behavior and beneficial management practices has improved. Some of the more recent and substantial changes in farming practices on the northern Great Plains include widespread adoption of reduced tillage systems, introduction of new crops and high-yielding cultivars, intensification and extension of crop rotations, development of new fertilizer products, increased appreciation of the role of microbial interactions in P dynamics, and growing concern for the effects of P on water quality. As cropping systems, technology, and societal demands evolve over time, nutrient management practices must also evolve to address concerns and take advantage of emerging opportunities. Classic principles and new P fertilizer technologies and management practices must be integrated into packages of 4R practices that optimize crop yield and agronomic efficiency while minimizing negative environmental impact and conserving P resources. Although a wide range of products and practices can be combined for this approach, placing ammonium phosphate fertilizer in a band, in or near the seed-row, at the time of seeding and at a rate that matches P removal by the crop generally provides the greatest P efficiency, long-term sustainability, and environmental protection for small grain, oilseed, and pulse crop production in the northern Great Plains.

Quantitative analysis of nitrogen in ammonium phosphate fertilizers using laser-induced breakdown spectroscopy.

Laser-induced breakdown spectroscopy (LIBS) coupled with the linear multivariate calibration method was applied to analyze nitrogen (N) quantitatively in ammonium phosphate fertilizers. The intensity of lines N (NI:742.4, 744.2, 746.8, 856.7, 859.4, 862.9, 870.3, 871.2, 871.8nm) and O (OI:777.2, 844.6, 882.0nm) were used as independent variables for the models. To verify the accuracy of the models, the unary, binary, ternary, and quaternary variables were chosen to establish the linear regression equations. The results of the linear models showed that the quaternary model was better than the other three models. The correlation coefficient of the quaternary linear model was 0.981 and the maximum relative error of the validation samples was 4.32%.

Statistical Study and Modeling of the Effect of Phosphoric Acid Impurities on the Physical Quality of Ammonium Phosphate Determined from the Production Data Using Artificial Neural Network

The monitoring of the physical properties of fertilizers presents a lot of interest at different levels. All the problems related to the behavior of the granules (segregation, spreading, granulation, hardness…) need a better characterization of the fertilizers in order to understand and/or predict them. The scientific community is led to develop a variety of modeling approaches for, on the one hand, the understanding of the dynamics of impurities originating from phosphoric acid during the manufacture of fertilizers, and on the other hand, the evaluation of the effectiveness of measurements and data monitoring from production and the fluctuations in the physical quality of the fertilizers that follow. In this investigation of the influence of elements such as Fe, Al, Mg, F-, Si, Na, K and Cl on fertilizer quality, we gathered and followed-up data from production lines of Ammonium phosphate fertilizers for several months. The aim of the current work is the statistical study and modeling of the phosphoric acid impurities effect on the physical quality of fertilizers such as granulation yield, grain size, and the average diameter of granules D50, based on the analysis of data from different production lines by applying the Artificial Neural Network (ANN) approach. In addition models, were constructed using Multiple Linear Regression (MLR) and Principal Components Analysis (PCA).

Uptake of elemental or sulfate-S from fall- or spring-applied co-granulated fertilizer by corn—A stable isotope and modeling study

Sulfur deficiency has become more common in the last decades and the demand for S fertilizers has increased. Commercial fertilizers containing elemental S (S0 or ES) are usually in granular form, but their efficiency under field conditions has rarely been studied. A field trial with stable isotope (34S) as tracer was carried out to assess the uptake of ES and SO4-S applied as S-fortified ammonium phosphate fertilizer. The fertilizer, which contained 5% ES and 5% SO4-S, was broadcast applied in spring or in fall and the contribution of fertilizer S was assessed over two years, by analyzing the corn plants at early stage and at maturity. In the first year, near equal amounts (12–14%) of S in the plant were derived from fertilizer ES and SO4-S for the spring applied fertilizer, while more S was derived from fertilizer ES (12%) than from fertilizer SO4-S (5%) with fall-applied fertilizer. In the second year, the contribution of fertilizer S decreased and was greater for ES than for SO4-S in all cases. As demonstrated through modeling, the results could be explained based on leaching of applied SO4-S, particularly when fall-applied, cycling in organic matter, and oxidation of ES with an estimated rate of 0.005d−1 at 20°C. This study demonstrates the benefit of ES as a slow release S fertilizer in high-rainfall environments.

Analysis of the Supply Trend and Response of Onion in the Ilocos and Central Luzon Regions in the Philippines, 1991-2014

This paper examined the nature of supply response of onion in the key onion-producing regions in the Philippines using price, rainfall, and production volume regional time series data for onion. From 1990 to 2014, onion showed positive growth rates in production and area harvested, with the Central Luzon region exhibiting larger growth rates than the Ilocos region. Using Prais-Winsten regression analysis, the study found that in the Ilocos Region, onion area negatively responds to higher rice prices while responding positively to higher squash prices. Moreover, onion supply responds positively to the increase in the prices of ammonium phosphate fertilizer (16-20-0) and technological improvement while responding negatively to higher complete fertilizer (14-14-14) prices. In the Central Luzon region, higher wage rate and prices of complete fertilizer restricted onion supply increases. Furthermore, the price of rice positively affects supply. The paper attributes the varying nature of supply response in the regions to the differences in the cropping patterns, which define the relationships of onion with related goods such as rice and squash. These findings suggest that development interventions should improve, not only the onion industry, but also the productivity and profitability of relay crops in each region.

Effects of fertilizers on plant diversity, density, and uniformity in Golestan rangelands

ABSTRACTOne of the management operations in rangeland ecosystems for pastures restoration and improvement is fertilizer application. This study was designed to investigate the effect of fertilizer (50 kg/ha urea and ammonium phosphate fertilizers) on species diversity changes in a 100-ha experimental field of Salmechal Rangeland, Golestan Province. Plant species mean canopy cover was recorded using a 50-m2 sampling plot. Statistical analysis was performed using Excel 2007 and PAST software. Fertilizer application increased the number of species present in the region from 21 to 51 and the plant families from 11 to 23. The forbs had the highest proportion (54.91%) and bushes and shrubs had the lowest percentage in the region. Fertilizer application increased plant diversity, uniformity, and coverage of the grasses. There was a significant difference (p < 0.01) between the grass and forbs coverage before and after fertilizer treatments. The results showed that the biological and physiological growth periods of the annual and perennial plants were significantly different before and after fertilizer application (p < 0.01). Also, their proportion in rangeland plant species composition significantly increased after fertilizer application.

Agronomic Effectiveness of Granular and Fluid Phosphorus Fertilizers in Andisols and Oxisols

Fluid phosphorus (P) fertilizers are more efficient than granular fertilizers in calcareous soils, but their potential to improve P use efficiency in strongly P-sorbing acidic soils is not known. We therefore evaluated P uptake by wheat (Triticum aestivum) from granular (calcium phosphate and ammonium phosphate) and fluid (ammonium phosphate) fertilizers in two Andisols from Chile and New Zealand, two Oxisols and a calcareous soil from Australia, by using an isotope (33P) dilution technique. All fertilizers were applied at a rate of 150 mg kg−1 soil. The availability of soil P was very low in the Oxisols and Andisols, and most P (>71%) was derived from the seed in the control treatment. Addition of P fertilizer increased dry matter yield up to sevenfold compared with the control, except with ammonium phosphates in the Chile soil, likely due to Ca deficiency limiting plant growth, and with triple superphosphate in the Oxisol with the highest pH, likely due to precipitation of fertilizer P. The percentage of P in the shoots derived from the fertilizer (%Pdff) in the P-amended Andisols and Oxisols ranged from 65 to 88%. No significant difference in %Pdff between granular and fluid sources was observed in these soils, except for the calcareous soil, in which significantly more P was derived from fertilizer with fluid than with granular MAP (as found previously). We conclude there is no agronomic benefit of fluid over granular P fertilizer sources in soils in which P availability is controlled by strong adsorption, that is, Andisols and Oxisols.

Appraisal of Varieties and Fertilizer Use in Rice at Farmers’ Field in District Kapurthala

A survey was conducted to collect the information from the farmers of the district regarding input use and yield of rice varieties obtained during kharif 2014. It was noticed that farmers were growing many varieties of rice including basmati rice and some of the un-recommended varieties. Basmati variety, Pusa Punjab Basmati 1509 and non basmati variety, PR 121 was most popular however, basmati rice variety Punjab Basmati 3 resulted in the maximum gross returns during kharif 2014. Regarding urea application, it was noticed that maximum number of farmers applied urea in the range of 187.5 to 250 kg/ha to the variety Pusa Punjab Basmati 1509 and up to 250 kg/ha in case of Pusa Basmati 1121. Maximum productivity of Pusa Punjab Basmati 1509 was obtained without the application of Di Ammonium Phosphate (DAP) fertilizer, while Pusa Basmati 1121 responded to application of DAP. Non basmati varieties of rice responded positively to urea up to a range of 250 to 312.5 kg/ha.

Soil Stabilisation Using Phosphogypsum and Flyash

Since ancient times, a number of stabilization methods are being used to improve soil properties. Various studies have been carried out on expansive soil after stabilization with additives such as cement, lime, cement kiln dust, rice husk ash etc. which shown promising results. Now-a-days easily available industrial by-products are used for the enrichment of soil properties. In present study, effects of stabilizing agents like Phosphogypsum (PG) and Flyash (FA) have been studied for strength improvement in varying percentages. This paper describes a study carried out to check the improvements in the properties of soil with phosphogypsum in various percentages (i.e., 2, 4 and 6%) with fixed quantity of flyash (5%). The unconfined compression test (UCC) and microstructure analysis of the soil with different percentage of additives were determined separately after curing the specimens for 3 days and 7 days. Strength of stabilised soil is increase with increased amount of stabiliser and curing periods. Expansive soils were been a tough task for Civil Engineers in the design and construction of Infrastructure projects. The major problems with clays, including low strength and high compressibility, can cause severe damage to civil engineering structures and can lead to very serious economic loss and environmental hazards. Therefore, these soils must be treated before commencing the construction operation to achieve desired properties. This has led to the development of soil stabilization techniques. Since the nature and properties of natural soil vary widely, a suitable stabilization technique has to be adopted for a particular situation after considering the soil properties. The chemical technique is a common soil stabilization approach, since it produces a better quality soil with higher strength and durability than mechanical and physical techniques. In many countries of the world, stabilization of soils is especially done if locally available natural/industrial resources are available. The use of Phosphogypsum (PG) and Flyash (FA) in soil stabilization can lead to low-cost construction and can provide an environmentally friendly means of their disposal and also enhance the engineering properties of soil. Phosphogypsum is a by-product in the wet process for manufacture of phosphoric acid (ammonium phosphate fertilizer) by the action of sulphuric acid on the rock phosphate. Flyash is one of the residues generated during the combustion of pulverized coal and is transported from the combustion chamber by exhaust gases. Flyash is mainly used as stabilizer considering its construction potential as a pozzolanic material. In this paper, the study is aimed to investigate the strength and the microstructure of treated clay using unconfined compressive strength test and scanning electron microscope (SEM) analysis. II. LITERATURE REVIEW