Slow-release Nitrogen Fertilizer Research Articles

Preparation of an Environmental Friendly Slow Release Nitrogen Fertilizer

An environmental friendly slow-release urea fertilizer with double films (SUFDF) was prepared by using dialdehyde starch urea resin (DASU) as inner coating and polylactic acid (PLA) as outer materials. The structural, chemical characteristics and morphology of the SUFDF were characterized by FTIR, element analysis and SEM. Its efficiency in slowing the nitrogen release was examined via soil leaching and pot experiments. The experimental results indicated that the introduction of hydrophobic PLA and DASU reduced the swell ability of the fertilizer, which made it can provide nitrogen persistently at the early farming. After the urea dissolved, the DASU in the fertilizer would continue to release nitrogen due to its good slow-release property. So this fertilizer would have potential applications in modern agriculture and horticulture.

EFFECT OF SLOW-RELEASE NITROGEN FERTILIZERS ON MAIZE PLANTS GROWN ON NEW RECLAIMED SOIL

A field experiment was conducted in summer season of 2009 ata private farm, with loamy sand soil located at El-Sadat district,Minufiya Governorate, Egypt to evaluate the effect of urea+hmic acidas well as ureaform, as a slow release nitrogen fertilizer applied at therates of 60 and 100 kg fed-1 compared to urea at rate of 120 kg fed-1on the yield, some yield components and nutrients uptake by maize(Zea mays L.) (Single-cross 10) grown on a sandy soil.Obtained results indicated that ear length, plant height, shootand grain yields and biological yield were significantly higher withthe application of ureaform at rate of 100 kg N/fed followed by ureaat rate of 100 kg N/fed + humic acid. Application of ureaform at highrate (100 kg/fed) increased the values of nitrogen uptake by shoots,grain and both shoot and grain of maize plant. While urea at high rate+ humic acid induced the influence of the highest values of bothphosphorus and potassium uptake for the same components. Resultsindicated also that, maize plants received urea+humic acid orureaform had the highest values of fertilizer use efficiency, i.e., thehighest ratio of agronomic efficiency (34.67) and physiologicalefficiency (106.07) were obtained the application of 60 kg N/fedurea+humic acid, while ureaform at the rate of 100 kg N/fed resultedin the highest value of apparent N recovery percent (48.34%). Resultsof this work emphasized the beneficial effects of the slow releasefertilizer urea form followed by urea + humic acid in comparison withurea on maize plant growth, yield, yield components and nitrogenrecovery percentage.

Application Research of Slow-Release Fertilizer in Plant Camouflage

Plant camouflage is one of the camouflage methods, which is conducted by using of planting and collecting plant and changing color of plant to conceal targets. It can be used to camouflage relatively big permanent fixed targets in peace time and also to camouflage relatively big permanent fixed targets in peace time and also to camouflage relatively small fixed or moving targets. However, in recent years, with the natural disasters occurring alternately, plant camouflage can be destroyed easily, and it is difficult to rebuild in a short time. To improve the effect of plant camouflage, more fertilizers are required, which may become an environmental hazard, unless adequate technical and socioeconomic impacts are addressed. A multifunctional slow-release nitrogen fertilizer has been developed to improve fertilizer use efficiency and reduce environmental pollution. In this paper, a series of slow-release formulations of nitrogen fertilizer were developed on the basis of natural attapulgite clay, ethylcellulose film, and sodium carboxymethylcellulose/hydroxylethylcellulose hydrogel. The structural of the product were examined. The slow-release profiles of ammonium chloride, ammonium sulfate, and urea as nitrogen fertilizer substrates were determined in soil.

A novel function of controlled-release nitrogen fertilizers.

A novel function of controlled-release nitrogen fertilizers.

Study on Environmentally Friendly Slow-Release Fertilizer for Plant Camouflage

Plant camouflage is conducted by use of planting and collecting plant and changing color of plant to conceal targets. It can be used to camouflage relatively big permanent fixed targets in peace time and also to camouflage relatively big permanent fixed targets in peace time and also to camouflage relatively small fixed or moving targets. However, in recent years, with the natural disasters occurring alternately, plant camouflage can be destroyed easily, and it is difficult to rebuild in a short time. To improve the effect of plant camouflage, more fertilizers are required, which may become an environmental hazard, unless adequate technical and socioeconomic impacts are addressed. A multifunctional slow-release nitrogen fertilizer has been developed to improve fertilizer use efficiency and reduce environmental pollution. In this paper, a series of slow-release formulations of nitrogen fertilizer were developed on the basis of natural attapulgite clay, ethylcellulose film, and sodium carboxymethylcellulose/hydroxylethylcellulose hydrogel. The structural of the product were examined. The slow-release profiles of ammonium chloride, ammonium sulfate, and urea as nitrogen fertilizer substrates were determined in soil.

Effects of Nitrogen Fertilizer Level on Chlorophyll Fluorescence Characteristics in Flag Leaf of Super Hybrid Rice at Late Growth Stage

To compare the effects of slow-release nitrogen fertilizer at six different levels on the flag leaf chlorophyll fluorescence characteristics of super hybrid rice, a field fertilization experiment was conducted with super hybrid rice Y Liangyou 1 as a test material. The photosynthetic electron transport rate (ETR), effective quantum yield (EQY), photochemical quenching coefficient (qP), and non-photochemical quenching coefficient (NPQ) of flag leaves were measured at the initial heading, full heading, 10 d after full heading and 20 d after full heading stages. Results showed that the values of ETR, EQY and qP increased with rice development from initial heading to 20 d after full heading, whereas the NPQ decreased. During the measured stages, ETR, EQY and qP increased initially and then decreased as nitrogen application amount increased, but they peaked at different nitrogen fertilizer levels. The maximum ETR and EQY values appeared at the treatment of 135 kg/hm2 N. In conclusion, the optimum nitrogen amount for chlorophyll fluorescence characteristics of super hybrid rice was 135-180 kg/hm2.

Recovery of Ammonium onto Wheat Straw To Be Reused as a Slow-Release Fertilizer

With the aim of improving fertilizer use efficiency and minimizing the negative impact of nitrogen pollution, a new multifunctional slow-release fertilizer was prepared by recovery of ammonium from aqueous solutions onto a superabsorbent composite. An eco-friendly superabsorbent composite based on wheat straw (WS) was synthesized and used as the carrier to control the release of nutrients. The adsorption studies with NH₄⁺ indicated that the superabsorbent composite showed good affinity for NH₄⁺, with an adsorption capacity of 7.15 mmol g⁻¹ when 20 wt % of WS was incorporated and that the adsorption system can reach equilibrium within 40 min. Afterward, the feasibility of reusing the composite as a multifunctional slow-release nitrogen fertilizer was investigated. The results showed that the product with good water-retention and slow-release capacities could regulate soil acidity and was economical and eco-friendly for application in agriculture and horticulture.

Slow-release nitrogen fertilizer in carrot production on Prince Edward Island

Sanderson, K. R. and Fillmore, S. A. E. 2012. Slow-release nitrogen fertilizer in carrot production on Prince Edward Island. Can. J. Plant Sci. 92: 1223–1228. The impact of nitrogen management using slow-release fertilizers has not been examined for carrot (Daucus carota L.) production in Atlantic Canada. To assess the effects of such products, we evaluated five slow-release fertilizers over a 3-yr period. Treatments consisted of sulphur coated urea (SCU) (42–0–0), isobutylidene diurea (IBDU) (31–0–0), Nutralene® (methylene urea) (40–0–0), Sirflor® (urea formaldehyde) (38–0–0), UFLEXX™ (urea, dicyandiamide, N-(n-butyl) thiophosphoric triamide) (46–0–0) compared with industry standard (ammonium nitrate) (34–0–0). All slow-release fertilizer treatments supplied N at 50 kg N ha–1 pre-plant. Slow-release fertilizer treatments were compared with the industry standard of 50 kg N ha−1 pre-plant plus 50 kg N ha–1 as a top dress. UFLEXX™ increased biological and marketable yield by 7.5 and 18.7%, respectively, compared with the industry standard. Sirflor® produced the lowest yield. GreenSeeker® NDVI reading and LECO N were correlated at the mid-season sample. GreenSeeker® technology has potential as an in-field crop health assessment tool, however, further research is required to develop GreenSeeker® algorithms appropriate for carrot production in Prince Edward Island.

Recent approaches in nitrogen management for sustainable agricultural production and eco-safety

Among plant nutrients, nitrogen (N) is the most important. Its importance as a growth- and yield-determining nutrient has led to large and rapid increases in N application rates, but often with poor use efficiency. Nitrogen management requires special attention in its use so that the large losses can be minimized and the efficiency maximized. Site-specific nutrient management (SSNM) has been found especially useful to achieve the goals of improved productivity and higher N use efficiency (NUE). Leaf color charts and chlorophyll meters assist in the prediction of crop N needs for rice and wheat, leading to greater N-fertilizer efficiency at various yield levels. Crop simulation models can be used in combination with field information and actual weather data to make recommendations to achieve higher NUE. Remote sensing tools are also used to predict crop N demands precisely. At the same time, traditional techniques like balanced fertilization, integrated N management (INM), use of nitrification inhibitors and slow-release nitrogenous fertilizers (SRNF), split application and nutrient budgeting, among others, are also used to supplement recent N management techniques to attain higher productivity and NUE, and reduce environmental pollution through the leakage of fertilizer N.

Synthesis and surfactant modification of clinoptilolite and montmorillonite for the removal of nitrate and preparation of slow release nitrogen fertilizer

This article introduces the synthesis of clinoptilolite and montmorillonite, and their surfactant modification by using solutions of hexadecyltrimethylammonium bromide (CH3(CH2)15N(Br)(CH3)3, HDTMAB) and dioctadecyldimethylammonium bromide ((CH3(CH2)17)2N(Br)(CH3)2, DODMAB). The feasibility of using surfactant modified silicates (SMSs) as a potential adsorbent for nitrate and for slow release of nutrient has been investigated. Adsorption isotherms of NO3− on SMSs have been measured at aqueous concentration of 160–280mgL−1. The SMSs show much higher adsorption capacity than the unmodified materials as determined by Langmuir adsorption isotherm. The surfactant modification and increased surfactant loading concentration enhance the nitrate anion retaining capacity of silicates (montmorillonite (16.05mgg−1)<clinoptilolite (30.58mgg−1)<DODMAB loaded clinoptilolite (75.19mgg−1)<DODMAB loaded montmorillonite (76.92mgg−1)<HDTMAB loaded montmorillonite (80.65mgg−1)<HDTMAB loaded clinoptilolite (125.00mgg−1)). The adsorption data fitted well with the Langmuir and Freundlich isotherms. The slow nutrient release studies have been performed by thin layers-funnel analytical test and soil column percolating system. The obtained results indicate that SMSs are very good adsorbent for NO3− and a slow release of nitrogen is achievable as it releases NO3− still after 15–20 days of leaching study.

New Environment-Friendly Use of Wheat Straw in Slow-Release Fertilizer Formulations with the Function of Superabsorbent

With the aim of improving fertilizer use efficiency and minimizing the negative impact on the environment, a new double-coated slow-release nitrogen and phosphorus fertilizer with water retention was prepared. Wheat straw was introduced into the formulations as the basic coating material. Specifically, poly(acrylic acid-co-N-hydroxymethyl acrylamide)/wheat straw superabsorbent composite was used as the outer coating, and wheat straw/sodium alginate blends was used as the inner coating. The degradation of the superabsorbent composite in the soil solution was studied. The impact of the content of wheat straw on the extent of degradation in cellulase solution was also examined. The superabsorbent composite synthesized under the optimal conditions showed super water absorbency and excellent degradability. The water-retention property and the nutrient slow-release behavior of the product were investigated. The results revealed that the product with water-retention and slow-release capacity, being economical, n...

κ-Carrageenan–Sodium Alginate Beads and Superabsorbent Coated Nitrogen Fertilizer with Slow-Release, Water-Retention, and Anticompaction Properties

A multifunctional slow-release nitrogen fertilizer (SRNF) has been developed to improve fertilizer use efficiency and reduce environmental pollution. κ-Carrageenan–sodium alginate (κC–SA) and cross-linked κC-g-poly(acrylic acid)/Celite superabsorbent were used as inner and outer coating materials, which were coated consecutively on the granule core urea in a pan granulator. Elemental analysis result showed that the product contained 22.6% nitrogen. The water evaporation as well as the nitrogen release behavior of SRNF in soil was explored. In addition, the coated urea had a higher average crushing strength in comparison with uncoated urea. Furthermore, the incorporation of SRNF in soil could effectively prevent the compaction of soil. These studies showed that the product prepared by a simple route with good slow-release and water-retention properties may be expected to have wide potential applications in modern agriculture and horticulture.

不同施氮措施对旱作玉米地土壤酶活性及CO2排放量的影响

对施用速效氮肥(尿素)和缓释氮肥的旱作夏玉米地土壤酶活性及CO₂排放量进行分析。结果表明,与不施肥处理比较,不同氮肥种类和施用量均可显著提高土壤脲酶、蔗糖酶、过氧化氢酶活性和CO₂的排放量。在整个生育期,尿素与缓释氮肥处理土壤酶活性和土壤CO₂排放量表现出相同变化趋势,尿素和缓释氮肥处理土壤CO₂平均排放量分别为459.12 mg·m^-2·h^-1和427.11 mg·m^-2·h^-1,两者达到显著差异水平(<em>P</em><0.5)。相关分析表明,土壤脲酶、蔗糖酶和过氧化氢酶活性与土壤CO₂排放量呈显著或极显著正相关,相关系数分别为0.79、0.64和0.80。说明相同施氮量缓释氮肥较尿素能有效提高土壤酶活性并降低土壤碳排放量。;CO₂ emitted from the arid farming land is an important source of greenhouse gases, nitrogen application is an effective approach to increase production of farming land, soil quality degraded, however, CO₂ emission will be increased by unreasonable fertilization. Therefore,it is an important problem need to be solved urgently now to reduce the greenhouse gas emissions of farming land by reasonable fertilization without crop yield loss. <br> An experiment was conducted in the crop planting station of Northwest A&F University in Yangling Shaanxi, P.R China to explore the effects of different types and dosages of nitrogen fertilizers on soil enzymatic activities and soil CO₂ emission in the arid farming land of summer maize and to elucidate the relationship of soil CO₂ emission and activities of urease, invertase, and catalase, which will provide evidence for carbon emission reduction in the arid farmland management mode of summer maize. <br> Nine treatment levels were set, including four levels each of available nitrogen (urea) and low-release nitrogen, specifically, 80 kg/hm² urea (N1), 160 kg/hm² urea (N2), 240 kg/hm² urea (N3), 320 kg/hm² urea (N4), 80 kg/hm² slow-release fertilizer (SR1), 160 kg/hm² slow-release fertilizer (SR2), 240 kg/hm² slow-release fertilizer (SR3), 320 kg/hm² slow-release fertilizer (SR4), and no-fertilizer treatment served as control (CK). The results showed that CO₂ emission and activities of urease, invertase and catalase in the fertilizer treatments were higher than those in no-fertilizer treatment (<em>P</em><0.5). The averages of urease activity in urea and slow-release nitrogen treatments improved by 66.75% and 67.50% respectively compared with no-fertilizer treatment;The averages of invertase activity in urea and slow-release nitrogen treatments were 45.55% and 62.75% respectively higher than those in no-fertilizer treatment;The averages of catalase activity in urea and slow-release nitrogen improved 45.00% and 46.75% than those in no-fertilizer treatment;The averages of soil CO₂ emission in urea and slow-release nitrogen were higher 42.34% and 32.42% respectively than no-fertilizer treatment. The range of soil CO₂ emissions in slow-release nitrogen was smaller than in urea, which indicated that slow-release nitrogen fertilizer can improve effectively soil enzymatic activities and reduce soil CO₂ emissions. During the whole growth period, the same trends of three enzymes activities and CO₂ emissions were detected between the treatments of available nitrogen and slow-release nitrogen, but maximum values reached at different stage, i.e., at jointing stage for urease activity, at maturity stage for invertase activity, at tasseling stage for catalase activity, and at jointing stage for soil CO₂emission. There were significant differences (<em>P</em><0.5) between the CO₂ emissions of nitrogen and slow-release nitrogen, 459.12 mg·m^-2·h^-1 and 427.11mg·m^-2·h^-1 respectively. Correlation analysis showed that, a highly positive correlation existed between soil CO₂emission and activities of urease, catalase and invertase. Correlation coefficients of soil CO₂emission with activities of urease, catalase, and invertase were 0.79, 0.80, and 0.64, respectively. In conclusion, at the same application levels of available nitrogen, slow-release nitrogen fertilizer can improve effectively soil quality of arid farming land and reduce soil CO₂ emission compared with urease.

Management and Reduction of Chemical Nitrogen Consumption in Agriculture

Nitrogen is an effective material for improving the crop production. There is a big concern about rising chemical nitrogen usage as fertilizer in soil, because some forms of nitrogen absorbs in soil and causes an increase of environment and water pollution and decrease fertilizer efficiency. Composted cow manure is an important resource of organic nitrogen which improves the soil conditions. However, low density of composted cow manure and inconstant nutrient content are two factors that limit the application of composted cow manure. The densification technology is an effective solution for both problems. In this research first the capability of single screw extruder for production of fertilizer pellets including composted cow manure and nitrogen fertilizer was studied and then the effect of fertilizer pellet on the reduction of chemical nitrogen consumption was evaluated. The response of basil plants was determined in three treatments: T1 control (no fertilizer), T2 (nitrogen fertilizer) and T3 (pellet). The results showed that pelletization can be used as a proper method for slow-release nitrogen fertilizer; enhance nitrogen uptake and reducing the chemical nitrogen consumption. The results also showed that all basil responses (chlorophyll content, total weight, leaves weight, root weight and leaf area) were significantly affected by application of N fertilizer and pellet. While maximum recorded parameters were observed with application pellet.

Environmentally Friendly Slow-Release Nitrogen Fertilizer

To sustain the further world population, more fertilizers are required, which may become an environmental hazard, unless adequate technical and socioeconomic impacts are addressed. In the current study, slow-release formulations of nitrogen fertilizer were developed on the basis of natural attapulgite (APT) clay, ethylcellulose (EC) film, and sodium carboxymethylcellulose/hydroxyethylcellulose (CMC/HEC) hydrogel. The structural and chemical characteristics of the product were examined. The release profiles of urea, ammonium sulfate, and ammonium chloride as nitrogen fertilizer substrates were determined in soil. To further compare the release profiles of nitrogen from different fertilizer substrates, a mathematical model for nutrient release from the coated fertilizer was applied to calculate the diffusion coefficient D. The influence of the product on water-holding and water-retention capacities of soil was determined. The experimental data indicated that the product can effectively reduce nutrient loss, improve use efficiency of water, and prolong irrigation cycles in drought-prone environments.

Ammonium nitrate-impregnated woodchips: a slow-release nitrogen fertilizer for plants

Different types of fertilizers are widely used throughout the world for successful crop production. Chemical fertilizers have some adverse effects on the environment if used indiscriminately and are a major source of soil and water pollution. To minimize environmental pollution, use of slow-release fertilizer (SRF) in agricultural practices is an important and effective method. Different materials have been used so far to formulate SRF, but SRF from wood is a unique technique which reflects a new dimension of wood use. In this aspect, present study was designed to develop a slow-release nitrogen fertilizer using three kinds of woodchips: Japanese red pine (Pinus densiflora S. et Z.), eunsasi poplar (Populus tomentiglandulosa T. Lee), and konara oak (Quercus serrata Thunb.). Fertilizers were prepared from woodchips after full-cell treated with a saturated solution (2140 g/l at 25°C) of ammonium nitrate (NH4NO3). The morphology of woodchip fertilizer was investigated by using a field-emission electron microscope (FE-SEM) equipped with an energy-dispersive X-ray (EDX) spectrometer to locate NH4NO3 in woodchips. Deposition of nitrogen in the cell lumen was verified by FE-SEM. Deposition inside the cell wall was confirmed by EDX mapping. This study also evaluated the release pattern of nitrogen from impregnated woodchips in distilled water for 768 h and found that nitrogen was released from poplar, pine, and oak in a slow-release pattern. The encapsulated nutrient in the void volume of wood facilitated the slow release. The above findings confirm that woodchip fertilizers can be used as a slow-release nitrogen source for plants.

Zeolitized tuffs in pedotechniques to improve soil resilience against the impact of treatment by municipal sewage: balance of nutrient and noxious cations

AbstractTwo zeolitized tuffs (ZTs),viz.a Neapolitan yellow tuff (NYT) and a clinoptilolite-bearing tuff (ZCL), were tested as pedotechnical materials to improve soil resilience against the impact of treatment by a ‘dirty’ municipal sewage system (DSW). Soils (surface horizon) were a sandy, alkaline Entisol (Typic Xeropsamment), and a sandy-loam, sub-acidic Alfisol (Ultic Palexeralf). Results showed that the presence of ZTs resulted in several favourable effects. Electrical conductivity (EC) decreased and pH was buffered. Ammonium was selectively taken up from the DSW, making the zeolitized tuffs almost saturated by NH4+, by exchanging both beneficial cations, such as K+and Ca2+, thus improving their potential availability to plants, and undesirable cations such as Na+, thereby hindering the exchangeable sodium percentage (ESP) increase and concurrent soil salinization-alkalinization. At the same time, NH4+was stored as a potentially slow-release nitrogen fertilizer. The mobility of Pb, Cu and Zn dropped off to a large extent. NYT produced the best effects, and the Entisol gained the greatest benefit from treatments.

Effects of Temperature and Soil Type on Ammonia Volatilization from Slow-Release Nitrogen Fertilizers

Ammonia (NH3) volatilization is the major pathway for mineral nitrogen (N) loss from N sources applied to soils. The information on NH3 volatilization from slow-release N fertilizers is limited. Ammonia volatilization, over a 78-d period, from four slow-release N fertilizers with different proportions of urea and urea polymer [Nitamin 30L (liquid) (L30), Nitamin RUAG 521G30 (liquid) (G30), Nitamin 42G (granular) (N42), and Nitroform (granular) (NF)] applied to a sandy loamy soil was evaluated. An increase in temperature from 20 to 30 °C increased cumulative NH3 volatilization loss in the sandy soil by 1.4-, 1.7-, and 1.8-fold for N42, L30, and G30, respectively. Increasing the proportion of urea in the slow-release fertilizer increased NH3 volatilization loss. At 30 °C, the cumulative NH3 volatilization over 78 d from a sandy soil accounted for 45.6%, 43.9%, 22.4%, and <1% of total N applied as N42, L30, G30, and NF, respectively. The corresponding losses in a loamy soil were 9.2%, 3.1%, and 1.7%. There was a significantly positive correlation between NH3 volatilization rate and concentration of NH4-N released from all fertilizers, except for NF (n = 132; r = 0.359, P = 0.017 for N42; r = 0.410, P = 0.006 for L30; and r = 0.377, P < 0.012 for G30). Lower cumulative NH3 volatilization from a loamy soil as compared to that from a sandy soil appeared to be related to rapid nitrification of NH4-N in the former soil than that in the latter soil. These results indicate the composition of slow-release fertilizer, soil temperature, and soil type are main factors to dominate NH3 volatilization from slow- release fertilizers.

Slow-release nitrogen and boron fertilizer from a functional superabsorbent formulation based on wheat straw and attapulgite

To improve fertilizer use efficiency and minimize its negative impact on environment, a slow-release nitrogen and boron fertilizer with water-retention was prepared. Wheat straw was used as skeletal material in copolymerization on which acrylic acid monomer can be grafted to form superabsorbent composite. Urea and borax were introduced to provide nitrogen (N) and boron (B) nutrients, respectively. The product possessed a core/shell structure. Its core was urea in attapulgite and alginate matrix, and the shell was chemically modified wheat straw-g-poly(acrylic acid)/attapulgite (CMWS-g-PAA/APT) superabsorbent composite containing urea and borax. The effects of the amount of cross-linker, initiator, chemically modified wheat straw and attapulgite on water absorbency were investigated and optimized. The water absorbency of superabsorbent synthesized under optimal conditions was 186 g g −1 in tap water. Ammonia-selective electrode and inductively coupled plasma results showed that the contents of the nitrogen and boron of the product were 23.3% and 0.65%, respectively. The water retention capacity and the slow-release behavior of N and B of the product were investigated. The results showed that the product with slow-release and water-retention capacity, being economical, nontoxic in soil and environment-friendly, could be found good application in agriculture and horticultural.

Energy Estimation on CRN Process of Fly Ash as a Slow-Release Nitrogen Fertilizer

Through carbothermal reduction and nitridation (CRN) reaction, nitrogen could be fixed into fly ash up to 28 wt %. Nitrided fly ash has the potential to be a source of slow release nitrogen fertilizer. To further investigate this potential, the energy consumptions were estimated for the nitridation process of fly ash. Reactors such as parallel rotary furnaces were simulated for the heat loss of radiation and convection. Material balance was carried out to determine the dimension of the rotary furnaces. Subsequently, on the basis of the dimension of the rotary furnace, the energy balance was performed from the reaction engineering aspects of the nitridation reaction of fly ash. Ultimately, the total energy was transformed into per unit nitrogen and compared with the energy consumption of the Haber-Bosch process for ammonia synthesis. The energy balance calculation suggested that there is great potential for nitrided fly ash to be slow release nitrogen fertilizer. 1. Introduction Coal fly ash is the incomplete combustion product from a coal-fired power plant. Currently, coal is the major source of fossil energy in mainland China. The electricity generated from coal-fired power plants accounts for 80% of the power nationwide. This situation will remain unchanged over a long period of time. Consequently, the amount of coal fly ash shall continue to increase steadily, accounting for 15-40% of the mass of coal. The proper disposal or utilization of coal fly ash brings a great challenge to the environment. Scientists have long been dedicated to exploiting novel applications of fly ash, such as construction material, 1 flocculant, 2 absorbent, 3 low-value-added ceramics, 3 soil amendment, 4,5 and so on. We had previously demonstrated successful introduction of nitrogen into fly ash via CRN (carbothermal reduction and nitridation) reactions. 6 We had also elaborated the prospect of nitrided fly ash in application as a source of slow-release nitrogen fertilizer from the aspect of reaction kinetics. 7-9 Currently, the most widely used nitrogen fertilizers are mainly based on ammonia synthesized from the Haber-Bosch process. Those commercial nitrogen fertilizers have the drawback of low efficiency due to high solubility in water. In comparison, nitrogen could be incorporated into fly ash as high as 28 wt % 6 and slowly released in the form of ammonia through hydrolysis process. 10 Nevertheless, reasonable energy consumption is essential for any further potential application of fly ash. Accordingly, this study presents the energy estimation for CRN reaction of fly ash. The estimated energy was compared with the energy consumed by the Haber-Bosch process to prepare ammonia. The comparison reveals great potential in application of fly ash as a source of nitrogen fertilizer. From the aspects of reaction engineering, the energy consumption was evaluated by material and energy balance calculations from preliminary design of the rotary furnace reactors. Rotary tube reactors have the advantage that precursor powder or aggregates are continuously replaced at the furnace tube wall, thus providing superior and more uniform heattransfer characteristics relative to fixed bed reactors or moving bed reactors. 11 Residence times are shorter (typically 30 min to a few hours) than in moving beds. In this study on gas-solid reaction in rotary furnaces, a countercurrent flow was chosen. Although many furnaces experience considerable difficulty in achieving uniform product, virtually all of the rotary furnace models are based on an assumption of perfect mixing in an angular direction. The assumption depicts that, at each axial position along the furnace, the bed is well-mixed in the transverse plane; i.e., the bed material is isothermal over any transverse section of furnace. Heat transfer within the bed reactants occurs by the same mechanisms as in any packed bed, i.e., particle-to-particle conduction, radiation, and interstitial gas-to-particle convection. 12 Steady state was assumed throughout the calculation. The nitridation reaction conditions for scaling-up are shown in Table 1 from our previous publications. 6 A more quantitative understanding of the mass balance and heat-transport phenomena within the bed material are presented hereafter.