NH3 Volatilization Losses Research Articles

Nitrogen Budgets Following Land Application of Composted or Stockpiled Feedlot Manure Containing Wood-Chips or Straw Bedding to Barley Silage for 12 Years

ABSTRACTLand application of composted feedlot manure (CM) instead of stockpiled manure (SM) at increasing application rates to cropland, or use of wood-chip (WD) instead of straw (ST) bedding, may influence the nitrogen (N) balance and cause N surpluses. This could result in environmental losses of N to the atmosphere, surface, or ground waters. We determined the influence of manure type, bedding material, and application rate (13, 39, 77 Mg ha−1 dry wt.) on cumulative N inputs, outputs, and N balance (aboveground system) for a long-term (since 1998) field experiment where manure had been repeatedly applied for 2, 7, and 12 yr. The annual N inputs considered were N in organic amendments or inorganic fertilizer (IN), and N in irrigation water. The annual N outputs considered were N in crop uptake, NH3 volatilization, and N2O gaseous loss. After 12 applications, cumulative N deficits occurred for the unamended control (−1140 kg N ha−1) and IN treatment (−678 kg N ha−1), and cumulative N surpluses were found for the organic amendments (689 to 12,200 kg N ha−1). Manure type, bedding, and application rate influenced the N balance for the three timelines but their effects often involved two- or three-way interactions. The N balance after 7 and 12 applications was significantly lower for CM-WD treatment compared to CM-ST, SM-ST, and SM-WD at the 39 and 77 Mg ha−1 rates, suggesting that composted manure with wood chips might be used to reduce cumulative N surplus at these two higher rates in the longer term.

돈분뇨의 호기적 액비화 과정에서 암모니아 휘산량 평가

BACKGROUND: Composting is the most frequently used waste management process for animal manure in Korea’s livestock industry. In the composting process, a large amount of nitrogen (N) is volatilized to the atmosphere as amonia (NH3). However, quantitative information of NH3 emission from composting of liquid manure is required to obtain emission factors for management of livestock manure in Korea. METHODS AND RESULTS: To evaluate the NH3 emission from composting of liquid manure affected by aeration, we conducted composting of liquid pig manure with three forced aeration systems. The aeration conditions were continuous (A60), cycle of 30 min aeration and 30 min pause (A30S30) and without aeration(A0). All treatments were aerated 12 hour per day with these aeration systems. The total ratio of NH3 volatilization loss to total N content in liquid manure throughout composting period was estimated to 19.9% for A0 treatment, 25.9% for A30S30 treatment and 36.3% for A60 treatment. The A30S30 and A60 aeration systems increased NH3 volatilization by 30.2 and 82.3% compared with systems without forced aeration. CONCLUSION(S): Ammonia emission during liquid pig manure composting was highly affected by forced aeration. The development of liquid pig manure composting systems with forced aeration would be considered both reducing ammonia emission and efficiency of composting.

English

The faster urea hydrolyses process leads to high amount of ammonia gas emission from urea fertilized fields. Coating of urea with various materials is the most successful strategy to control N losses from urea fertilized fields. A laboratory study was conducted to evaluate the effects of uncoated urea, as compare to urea coated with hydroquinone and Cu on NH3 volatilization loss and rate of urea hydrolysis in soil. The coated urea treatments were prepared by using Cu and hydroquinone solutions with a fluidized bed coating machine. Two experiments were carried out to evaluate the coated urea treatments labelled as UCu (Cu coated urea) and UHY (Hydroquinon urea). Both experiments were carried out on a sandy soil named as Serdang series. The soil was characterized for its properties by standard methods. In the first experiment the coated urea was evaluated for ammonia volatilization loss by using closed chamber force draft technique. Simultaneously, an incubation experiment was conducted to evaluate the effect of hydroquinone and Cu coated urea treatments for their hydrolyses rate or mineralization process. It was estimated by the results that ammonia volatilization from Hydroquinon coated urea treated soil reduced 25% however, Cu coated urea showed 30% reduction in ammonia volatilization loss as compare to uncoated urea. In incubation experiment recovery of urea from soil was 50% more in coated urea as compare to uncoated urea. It is concluded that coating of urea with urease inhibitors can reduce successfully the ammonia volatilization loss and increased the recovery of urea either coated by Cu or hydroquinone. Key words: Urease inhibitor, urea, hydroquinone, Cu (Copper).

NH3 volatilization, soil concentration and soil pH following subsurface banding of urea at increasing rates

Rochette, P., Angers, D. A., Chantigny, M. H., Gasser, M.-O., MacDonald, J. D., Pelster, D. E. and Bertrand, N. 2013. NH 3 volatilization, soil [Formula: see text] concentration and soil pH following subsurface banding of urea at increasing rates. Can. J. Soil Sci. 93: 261–268. Subsurface banding of urea can result in large ammonia (NH3) emissions following a local increase in soil ammonium ([Formula: see text]) concentration and pH. We conducted a field experiment to determine how application rates of subsurface banded urea impact NH3 volatilization. Urea was banded at a 5 cm depth to a silty loam soil (pH=5.5) at rates of 0, 6.1, 9.2, 13.3 and 15.3 g N m−1. Ammonia volatilization (wind tunnels), and soil [Formula: see text] concentration and pH (0–10 cm) were monitored for 25 d following urea application. Volatilization losses increased exponentially with urea application rate to 11.6% of applied N for the highest urea rate, indicating that as more urea N was added to the soil a larger fraction was lost as NH3. Cumulative NH3-N emissions were closely related (R 2≥0.85) to maximum increases in soil [Formula: see text] concentration and pH, and their combined influence likely contributed to the nonlinearity of the volatilization response to urea application rate. However, the rapid increase in NH3 losses when soil pH rose above 7 suggests that soil pH was the main factor explaining the nonlinear response of NH3 volatilization. When compared with previous studies, our results suggest that the response of NH3 volatilization losses to urea application rate in acidic soils are controlled by similar factors whether urea is broadcasted at the soil surface or subsurface banded.

Laboratory measurements of ammonia volatilization from five nitrogen-containing fertilizers after surface application at different rates on a neutral to alkaline soil

Volatilization losses of NH3 from five fertilizers, namely (NH4)2SO4, LAN, urea, MAP and DAP were determined. The fertilizers were applied to a Bainsvlei soil of which the pH was adjusted to 6,5; 7,6; 8,3 and 9,1. The application levels were equivalent to 0, 15, 30, 60, 120 and 240 kg N ha−1. After a contact period of three days NH3 losses were determined. Ammonia was lost from all fertilizers under all treatments. The losses increased with increasing pH values and levels of application. These five nitrogen-containing fertilizers differ significantly from each other with regard to volatilization of NH3. They can be ranked in order of increasing NH3 losses as follows: LAN < MAP < (NH4)2SO4 < DAP < urea. These differences can be explained by the composition and properties of the fertilizers.

Polyolefin‐Coated Urea Decreases Ammonia Volatilization in a Double Rice System of Southern China

Field evaluations of slow‐release N fertilizers are needed to improve N use efficiency while reducing NH3 volatilization. Ammonia volatilization losses, floodwater NH4+, and aboveground rice (Oryza sativa L.) tissue N accumulation were compared between non‐coated urea (NCU) and polyolefin‐coated urea (POCU) applications in a double‐rice production system of subtropical China. A factorial treatment design included two urea sources such as POCU and NCU applied at 75 and 150 kg N ha−1, and a no‐N control. For early and late rice seasons, floodwater NH4+ and pH increased significantly within 7 to 10 d after NCU applications and then decreased rapidly. Nitrogen losses through NH3 volatilization accounted for 16 to 30% and 4 to 8% of the total N applied for NCU and POCU, respectively. Applications of POCU significantly increased N accumulation in aboveground rice biomass due to a slower N release and better synchrony between in‐season rice N demand and N supply from this fertilizer. Applications of POCU at a rate of 75 kg N ha−1 provided the optimal amounts of N for early and late rice crops and reduced NH3 volatilization losses. The use of slow release urea fertilizers should increase N use efficiency and maintain the high grain yield in the double rice production systems of subtropical China.

In Vitro Evaluation of Coatings to Control Ammonia Volatilization from Surface‐Applied Urea

Ammonia (NH3) volatilization from surface‐applied N fertilizers containing urea can be substantial if environmental conditions are favorable. Physically coating urea with sulfate salts and urease inhibitor may reduce NH3 volatilization and supply plant available S. The objectives of this study were to quantify in vitro N loss from surface‐applied urea; and measure the rate and total N volatilization loss from urea coated with calcium sulfate, potassium sulfate, alone and in combination with the urease inhibitor, N‐(n‐butyl) thiophosphoric triamide (NBPT). Six trials, lasting 14 d, were conducted using a laboratory system at 26°C, 1.00 L min−1air flow, 44.6 mg N kg−1air‐dried soil, and 100 mL of 0.02 M phosphoric acid to recover volatilized NH3. Cumulative NH3 loss ranged from 33.9 to 37.2% of the applied N in all trials. Initial NH3 volatilization losses were delayed by calcium and potassium sulfate coatings alone. The inhibitor NBPT reduced cumulative NH3 losses to 17.9 to 24.7% of applied N and delayed NH3 volatilization for 96 h after N application when applied at the 0.08% w/w application rate in trials I to IV. In trials V and VI, applying NBPT at 0.02% w/w reduced cumulative NH3 volatilization from 35.6 and 35.1% to 25.4 and 24.1%, respectively. In both trials, no difference in cumulative NH3 loss was observed when NBPT rates exceeded 0.04%. The inhibitor NBPT had the greatest influence on NH3 volatilization losses in these studies, though the K2SO4 coated urea also reduced NH3 volatilization and supplies a small amount of S for crop growth.

Ammonia volatilization losses from surface-applied urea with urease and nitrification inhibitors

Urease inhibitor (UI) and nitrification inhibitor (NI) have the potential to improve N-use efficiency of applied urea and minimize N losses via gaseous emissions of ammonia (NH3) to the atmosphere and nitrate (NO3−) leaching into surface and ground water bodies. There is a growing interest in the formulations of coating chemical fertilizers with both UI and NI. However, limited information is available on the combined use of UI and NI applied with urea fertilizer. Therefore the aim of this study was to investigate the effects of treating urea with both UI and NI to minimize NH3 volatilization. Two experiments were set up in volatilization chambers under controlled conditions to examine this process. In the first experiment, UR was treated with the urease inhibitor NBPT [N-(n-butyl) thiophosphoric acid triamide] at a rate of 1060 mg kg−1 urea and/or with the nitrification inhibitor DCD (dicyandiamide) at rates equivalent to 5 or 10% of the urea N. A randomized experimental design with five treatments and five replicates was used: 1) UR, 2) UR + NBPT, 3) UR + DCD 10%, 4) UR + NBPT + DCD 5%, and 5) UR + NBPT + DCD 10%. The fertilizer treatments were applied to the surface of an acidic Red Latosol soil moistened to 60% of the maximum water retention and placed inside volatilization chambers. Controls chambers were added to allow for NH3 volatilized from unfertilized soil or contained in the air that swept over the soil surface. The second experiment had an additional treatment with surface-applied DCD. The chambers were glass vessels (1.5 L) fit with air inlet and outlet tubings to allow air to pass over the soil. Ammonia volatilized was swept and carried to a flask containing a boric acid solution to trap the gas and then measured daily by titration with a standardized H2SO4 solution. Continuous measurements were recorded for 19 and 23 days for the first and second experiment, respectively. The soil samples were then analyzed for UR–, NH4+–, and NO3−–N. Losses of NH3 by volatilization with unamended UR ranged from 28 to 37% of the applied N, with peak of losses observed the third day after fertilization. NBPT delayed the peak of NH3 losses due to urease inhibition and reduced NH3 volatilization between 54 and 78% when compared with untreated UR. Up to 10 days after the fertilizer application, NH3 losses had not been affected by DCD in the UR or the UR + NBPT treatments; thereafter, NH3 volatilization tended to decrease, but not when DCD was present. As a consequence, the addition of DCD caused a 5–16% increase in NH3 volatilization losses of the fertilizer N applied as UR from both the UR and the UR + NBPT treatments. Because the effectiveness of NBPT to inhibit soil urease activity was strong only in the first week, it could be concluded that DCD did not affect the action of NBPT but rather, enhanced volatilization losses by maintaining higher soil NH4+ concentration and pH for a longer time. Depending on the combination of factors influencing NH3 volatilization, DCD could even offset the beneficial effect of NBPT in reducing NH3 volatilization losses.

Ammonia Volatilization from Urea and Mitigation by NBPT following Surface Application to Cold Soils

Urea is frequently surface applied to winter wheat (Triticum aestivum L.) during cold weather months (October–April) in the semiarid northern Great Plains. This study was conducted to quantify NH3 volatilization loss from surface-applied urea (100 kg N ha−1) and urea amended with N-(n-butyl) thiophosphoric triamide (NBPT) during this period. Ammonia emissions were quantified by a micrometeorological integrated horizontal flux method with samplers placed on a mast in the center of circular plots (20-m radius). Cumulative NH3 losses from urea varied but averaged 20.5% of applied N across 12 trials. The largest losses (30–44% of applied N) occurred after urea was applied to high-water-content soil surfaces, followed by a period of slow drying with little or no precipitation. Emissions occurred for a prolonged period often lasting >42 d. Periods (1–2 wk) of high NH3 flux (>30 g N ha−1 h−1) frequently occurred when mean daily soil temperatures (1-cm depth) were –2 to 5°C. In one trial, 24.3% of applied N was lost after urea was applied to a 140-mm snowpack. Ammonia losses were moderated by applying urea to dry soil surfaces. If precipitation events that followed were light (<8 mm), losses were reduced to 10 to 20% of applied N. If the events were heavy (>18 mm), then losses were <10%. Coating urea with NBPT (1 g kg−1) reduced cumulative NH3 losses by 66%. Volatilization protection lasted 2 to 3 wk on acidic soils, and >7 wk on an alkaline soil. This study demonstrated that significant NH3 losses from surface-applied urea could occur during cold weather months.

English

&nbsp; In agricultural lands, the loss of NH3&nbsp;from surface-applied urea and micronutrient deficiencies are the two most common problems, which can be solved by using coated urea with micronutrients and biodegradable natural materials. These coatings can improve the nutrient status in the soil and simultaneously reduce nitrogen loss from urea. To control ammonia loss and urea&rsquo;s hydrolysis process, two laboratory studies were conducted to compare the effects of using coated urea with that of using only urea. Both studies consisted of consecutive incubation experiments that were conducted on the same Typic Paleudult soil (Serdang Series). Eight treatments (labeled as Urea, UPS1, UPS2, UPS3, UAG1%, UAG2%, UG1% and UG2%) in study 1 and six treatments (labeled U, UPSCu, UAGCu, UGCu, UCu, and UCuZn) in study 2 were prepared and used to determine the effects of various concentrations of natural materials and the inhibitory effects of micronutrients on both ammonia loss and the hydrolysis process. The NH3&nbsp;loss was measured by forced draft techniques; the soil&rsquo;s exchangeable ammonium, available nitrate and urea-N were determined by using standard procedures. The outcomes of the study did not show any significant difference among various concentrations of natural material. Coated urea treatments significantly reduced ammonia loss by 30 to 40% in study 1 and by 40 to 67% in study 2 in comparison to urea alone. The same observation was made with respect to urea hydrolysis. All of the coated urea treatments significantly slowed down the hydrolysis process in comparison to urea. The outcomes of the study may improve urea fertilizer by reducing the loss of NH3&nbsp;volatilization. &nbsp; Key words:&nbsp;Biodegradable polymers, coated urea, CuSO4, NH3&nbsp;volatilization loss, urease inhibitor, urea.

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.

New methods to quantify NH3 volatilization from fertilized surface soil with urea

Gaseous N losses from soil are considerable, resulting mostly from ammonia volatilization linked to agricultural activities such as pasture fertilization. The use of simple and accessible measurement methods of such losses is fundamental in the evaluation of the N cycle in agricultural systems. The purpose of this study was to evaluate quantification methods of NH3 volatilization from fertilized surface soil with urea, with minimal influence on the volatilization processes. The greenhouse experiment was arranged in a completely randomized design with 13 treatments and five replications, with the following treatments: (1) Polyurethane foam (density 20 kg m-3) with phosphoric acid solution absorber (foam absorber), installed 1, 5, 10 and 20 cm above the soil surface; (2) Paper filter with sulfuric acid solution absorber (paper absorber, 1, 5, 10 and 20 cm above the soil surface); (3) Sulfuric acid solution absorber (1, 5 and 10 cm above the soil surface); (4) Semi-open static collector; (5) 15N balance (control). The foam absorber placed 1 cm above the soil surface estimated the real daily rate of loss and accumulated loss of NH3N and proved efficient in capturing NH3 volatized from urea-treated soil. The estimates based on acid absorbers 1, 5 and 10 cm above the soil surface and paper absorbers 1 and 5 cm above the soil surface were only realistic for accumulated N-NH3 losses. Foam absorbers can be indicated to quantify accumulated and daily rates of NH3 volatilization losses similarly to an open static chamber, making calibration equations or correction factors unnecessary.

Design and Validation of a Laboratory System for Measurement of Volatilized Ammonia

The design of laboratory systems for studying ammonia (NH3) released from fertilizers varies widely, and few designs have been tested to determine the accuracy and precision in measuring NH3 loss. A standard volatilization system design is needed for reliable and comparable studies of NH3 volatilization from N fertilizer. The objectives of this study are: (i) to describe the design of a system capable of controlling air flow rate and temperature for laboratory measurement of NH3 volatilized from N fertilizers; and (ii) assess the system's efficiency and variation in recovering NH3 lost from NH4Cl applied to an alkaline sand media. The system is comprised of individual chambers for soil and fertilizer, where temperature can be varied from room temperature to ∼32°C; humidity is maintained near saturation, air flow rate can be varied, and acid traps are used to capture volatilized NH3. Two initial trials (I and II) were conducted at an N rate of 90 kg N ha−1 using air flow rates of 2.00 and 1.00 L min−1 and trapping acid volumes of 50 and 100 mL, respectively. A third trial was conducted at 30°C. A fourth trial (IV) was performed using a range of N application rates (25–250 kg N ha−1). The system recovered 89.3 to 97.1% of the N applied over all four trials and provided accurate and repeatable results under the conditions tested. Rapid, precise comparisons of NH3 volatilization losses from N fertilizers under laboratory conditions can be made with this system.

Grass Forage Response to Broadcast or Surface‐Banded Liquid Dairy Manure and Nitrogen Fertilizer

Manure can provide valuable nutrients, especially N, for grass forage, but N availability is limited because of high NH3 volatilization losses from standard surface‐broadcast application. Field experiments were conducted for 2 yr at two sites in Vermont to evaluate effects of broadcast or banded liquid dairy manure and broadcast N fertilizer on grass yield and N utilization. Treatments were applied to orchardgrass (Dactylis glomerata L.) on a well‐drained silt loam and to reed canarygrass (Phalaris arundinacea L.) on a somewhat poorly drained clay soil. Manure was applied three or four times per year at rates of 25 or 50 m3 ha−1 either by broadcasting or by trailing‐foot spreading in narrow bands. Fertilizer N was broadcast at 0, 28, 56, and 84 kg N ha−1 on separate plots at the same time as each manure application. Fertilizer N increased yields significantly to the medium rate (224 kg ha−1 yr−1) on orchardgrass and the high rate (252 kg ha−1 yr−1) on the reed canarygrass site. The high rate of banded manure produced 80 to 110% of the yields from the high N fertilizer rate. Yields from the trailing‐foot, banded manure application were 6 to 14% higher than those from broadcast manure in the two site‐years where method had a significant effect. Fertilizer N equivalence of manure averaged 44% with banded and 34% with broadcast application. We conclude that surface‐banding manure with a trailing‐foot applicator has the potential to provide benefits over conventional broadcast application by improving N utilization and increasing yield.

Relative Humidity Controls Ammonia Loss from Urea Applied to Loblolly Pine

In the United States, approximately 600,000 ha of pine trees are fertilized with urea each year, with NH3 volatilization losses ranging from &lt;1% to &gt;50% depending on environmental conditions. Previous work showed that the timing of rainfall after urea application plays a significant role in controlling NH3 loss, but the effect of other environmental variables is not well understood. We conducted 10 29‐d studies under different environmental conditions during 2 yr to identify important variables controlling NH3 loss from urea applied to loblolly pine (Pinus taeda L.) at 200 kg N ha−1 Ammonia loss was measured with dynamic chambers that adjusted the rate of air flow through the system based on wind speed at 1 cm above the soil surface. Regression analysis indicated that a variable related to the initial water content of the forest floor and a variable related to the relative humidity (RH) during the study explained 85 to 94% of the observed variability in NH3 loss. Relatively high initial water content followed by consistently high RH led to large NH3 losses. In contrast, low initial water contents resulted in slow rates of NH3 loss, which increased when elevated RH led to an increase in the water content of the forest floor. These results indicate that RH can play a significant role in NH3 loss by accelerating urea dissolution and by increasing or decreasing the water content of the forest floor, which in turn can affect the rate of urea hydrolysis.

On‐Farm Assessment of the Amount and Timing of Nitrogen Fertilizer on Ammonia Volatilization

Ammonia (NH3) volatilization is one of the main pathways through which applied N enters the environment undesirably. A seven site‐year on‐farm field experiment was performed for 3 yr at Ottawa, ON, and 2 yr at Guelph, ON, and Saint‐Valentin, QC, Canada. Our objectives were to (i) quantify the flux and the amount of NH3 volatilization as affected by the rate and time of N fertilizer; (ii) assess the impact of rainfall and soil temperatures on NH3 volatilization; and (iii) determine the threshold level of N fertilizer at which large NH3 volatilization losses occur. Using the static chamber method, NH3 volatilization was monitored after preplant or sidedress N application. Rate of NH3 volatilization peaked at 3 to 7 d and then dropped sharply within next 7 d before leveling off in the following weeks. The amount of NH3 volatilization increased with increasing N levels applied preplant or sidedress at all site‐years. Peak NH3 volatilization ranged from 40 to 8000 g N ha−1 d−1 after preplant fertilization and from about 100 to 2100 g N ha−1 d−1 after sidedress, resulting in NH3 losses of 0.1 to 47 kg N ha−1 and 0.6 to 20 kg N ha−1, respectively, equivalent to 0.1 to 38% and 0.3 to 13% of fertilizer‐induced emission (FIE) within 28 d after preplant or sidedress N fertilization. Our data clearly indicate that sidedress applications enable reduction in N fertilizer for economic crop yields, and may reduce losses simply due to lower total N rates.

Nitrogen Fertilizer Sources and Timing before Flooding Dry‐Seeded, Delayed‐Flood Rice

Urea is the primary N source used for the large preflood N application in delayed‐flood rice (Oryza sativa L.) production in the southern United States. Urea is prone to substantial NH3 volatilization losses, however, if fields are not flooded quickly. Most delayed‐flood rice fields require 5 to 10 d to flood. Consequently, a study was conducted to evaluate the use of less NH3–volatile N sources for the preflood N application. The objectives were to evaluate the NH3 volatilization loss and impact on N uptake and rice yield when urea, urea plus the urease inhibitor N‐(n‐butyl)thiophosphoric triamide (NBPT), (NH4)2SO4, or a urea‐(NH4)2SO4 (UAS) blend were applied preflood and a flood established 1, 5, or 10 d after N application. When flooding was delayed for 5 or 10 d after N application, NH3 volatilization was the least for urea + NBPT (2–10%) and (NH4)2SO4 (4–5%) and they produced the highest rice N uptake and yield. The UAS blend that had NH3 volatilization losses (11–15%) at 5 and 10 d after application that were intermediate between urea (17–24%) and (NH4)2SO4 or urea + NBPT also had N uptake and grain yield intermediate between these N sources. Urea should only be used if ∼2 d are required to flood a field. If 3 to 5 d are required to flood a field, then UAS has some merits but it is not as consistent as (NH4)2SO4 or urea + NBPT. When &gt;5 d are required to flood, (NH4)2SO4 or urea + NBPT should be used.

Model estimation of ammonia volatilization from a paddy rice field after application of a surface film-forming material

SUMMARYThe efficiency of nitrogen fertilizer use is as low as 0·30–0·35 in most agricultural practices due to losses to the natural environment in many ways. Ammonia (NH3) volatilization is important in paddy rice fields. The present study investigated the effect of a surface film-forming material (SFFM) on NH3 volatilization from a paddy rice field, by model estimation using parameters from evaporative pan experiments. The modified Jayaweera–Mikkelsen (J-M) ammonia volatilization model was employed to simulate and elucidate the effect of SFFM in reducing ammonia volatilization from paddy fields. A parameter of kf value in the J–M modified model was introduced to represent the resistance of NH3 volatilization loss from SFFM. The simulated data fitted well with the prediction of the J–M modified model and field observations. The modified J–M model is suitable for screening and verifying the new SFFM, and merits further study.

Ammonia volatilization loss from surface applied livestock manure

Ammonia (NH3) emission from livestock manures used in agriculture reduces N uptake by crops and negatively impacts air quality. This laboratory study was conducted to evaluate NH3emission from different livestock manures applied to two soils: Candler fins sand (CFS; light-textured soil, pH 6.8 and field capacity soil water content of 70 g kg− 1) from Lake Alfred, Florida and Ogeechee loamy sand (OLS; medium-textured soil, pH 5.2 and field capacity soil water content of 140 g kg− 1) from Savannah, Georgia. Poultry litter (PL) collected from a poultry farm near Douglas, Georgia, and fresh solid separate of swine manure (SM) collected from a farm near Clinton, North Carolina were used. Each of the soil was weighed in 100 g sub samples and amended with either PL or SM at rates equivalent to either 0, 2.24, 5.60, 11.20, or 22.40 Mg ha− 1 in 1L Mason jars and incubated in the laboratory at field capacity soil water content for 19 days to monitor NH3 volatilization. Results indicated a greater NH3 loss from soils amended with SM compared to that with PL. The cumulative NH3volatilization loss over 19 days ranged from 4 to 27% and 14 to 32% of total N applied as PL and SM, respectively. Volatilization of NH3 was greater from light-textured CFS than that from medium-textured OLS. Volatilization loss increased with increasing rates of manure application. Ammonia volatilization was lower at night time than that during the day time. Differences in major factors such as soil water content, temperature, soil type and live stock manure type influenced the diurnal variation in volatilization loss of NH3 from soils. A significant portion (> 50%) of cumulative NH3 emission over 19 d occurred during the first 5–7 d following the application of livestock manures. Results of this study demonstrate that application of low rates of livestock manure (≤ 5.60 Mg ha− 1) is recommended to minimize NH3 emissions.

Fertilizer 15N balance in a coffee cropping system: a case study in Brazil

Knowledge about the fate of fertilizer nitrogen in agricultural systems is essential for the improvement of management practices in order to maximize nitrogen (N) recovery by the crop and reduce N losses from the system to a minimum. This study involves fertilizer management practices using the 15N isotope label applied in a single rate to determine the fertilizer-N balance in a particular soil-coffee-atmosphere system and to deepen the understanding of N plant dynamics. Five replicates consisting of plots of about 120 plants each were randomly defined within a 0.2 ha coffee plantation planted in 2001, in Piracicaba, SP, Brazil. Nine plants of each plot were separated in sub-plots for the 15N balance studies and treated with N rates of 280 and 350 kg ha-1 during 2003/2004 and 2004/2005, respectively, both of them as ammonium sulfate enriched to a 15N abundance of 2.072 atom %. Plant shoots were considered as separate parts: the orthotropic central branch, productive branches, leaves of productive branches, vegetative branches, leaves of vegetative branches and fruit. Litter, consisting of dead leaves accumulated below the plant canopy, was measured by the difference between leaves at harvest and at the beginning of the following flowering. Roots and soil were sampled down to a depth of 1.0 at intervals of 0.2 m. Samples from the isotopic sub-plots were used to evaluate total N and 15N, and plants outside sub-plots were used to evaluate dry matter. Volatilization losses of NH3 were estimated using special collectors. Leaching of fertilizer-N was estimated from deep drainage water fluxes and 15N concentrations of the soil solution at 1 m soil depth. At the end of the 2-year evaluation, the recovery of 15N applied as ammonium sulfate was 19.1 % in aerial plant parts, 9.4 % in the roots, 23.8 % in the litter, 26.3 % in the fruit and 12.6 % remaining in the 0_1.0 m soil profile. Annual leaching and volatilization losses were very small (2.0 % and 0.9 %, respectively). After two years, only 6.2 % N were missing in the balance (100 %) which can be attributed to other non-estimated compartments and experimental errors. Results show that an enrichment of only 2 % atom 15N allows the study of the partition of fertilizer-N in a perennial crop such as coffee during a period of two years.