Polymer-coated Urea Research Articles

Soil solution and plant nitrogen on irrigated rice under controlled release nitrogen fertilizers

ABSTRACT: A study was conducted to evaluate the solubilization and nitrogen (N) use efficiency (NUE) of controlled release nitrogen fertilizers in irrigated rice, compared to urea. It was developed under semi-controlled conditions, including five treatments: Control, Splitted Urea (pre-sowing and topdressing), Pre-sowing urea, and Polymer Coated Urea (PCU) with 60-day and 90-day release. PCUs did not maintain high NH4 + and NO3 - levels in solution over a longer period than urea. NUE of PCUs was similar to uncoated urea, not increasing nutrient release in irrigated rice field.

Nitrogen Sources and Rates Affect Soybean Seed Composition in Mississippi

Soybean (Glycine max L.) seed is a major source of protein, oil, carbohydrates and other nutrients that are important for human and animal nutrition. Producers have considered applying nitrogen (N) fertilizer to soybean crop to maximize seed yield; however, its effect on seed composition is not well understood. The objective of this two-year (2015 and 2016) study was to evaluate the effects of N fertilizer sources and application rates (45, 90, 135 and 179 kg N ha−1) on soybean seed composition on two soil textures (clay and silt-loam) in Mississippi. The three fertilizer sources included in this study were urea with N-(n butyl) thiophosphoric triamide (Urea+NBPT), polymer-coated urea (PCU), and ammonium sulfate (AMS). Nitrogen application at 179 kg ha−1 on clay soil reduced seed protein by 1.05% compared to unfertilized soybeans in 2016. However, N application at 179 kg ha−1 increased oil content by 0.7% on clay soil compared to the unfertilized soybeans only in 2016. Nitrogen applications reduced stachyose content on both soil textures in 2015. The fatty acids showed variable response to N applications. Since, seed quality is not a trait from which growers receive an economic incentive, they are unlikely to adopt this practice for standard soybean production.

Irrigated Corn Productivity as Influenced by Nitrogen Source, Rate, and Climatic Conditions

Core Ideas Polymer coated N fertilizer was effective in improving crop yields. Chemical inhibitors used in the study was not effective in reducing environmental N losses. Varieties of available different chemical inhibitors may act differently and need to be compared and contrasted. Nitrogen fertilizer modifications such as coating or chemical additives are designed to either slow or inhibit N transformation, thereby to improve grain yield (GY) and reduce N losses. Effectiveness of these specialized products depend on various factors including climate. This field trial compared effects of various fertilizer modifications in irrigated corn (Zea mays L.) in loamy sand in Nebraska. Urea–ammonia–nitrate (UAN), UAN with 30% methylene–urea (UAN–MU), split‐applied UAN‐MU (UAN–MU–SP) and polymer‐coated urea (PCU) were evaluated in 2009. In 2010 and 2011, UAN with nitrapyrin (UAN–IN) and nutrisphere (UAN‐NS) and PCU were evaluated. The PCU treatment consistently improved GY compared to other N treatments in all 3 yr irrespective of inter‐annual climatic variations. In 2009, a dry year, UAN–MU and UAN were not different but UAN–MU–SP increased GY, grain and total N uptake (GNU, TNU) compared to UAN and UAN–MU. In dry (2009) and wet (2011) years, residual N did not differ by N rate while it was the greatest in the highest N rate in 2010, a normal year. The UAN–IN and UAN–NS improved GY, GNU, and TNU compared to UAN in 2010. These treatments performed as well or better than UAN, even when the UAN rate was higher. In 2011 that had high potential for N leaching, UAN–IN and UAN–NS did not increase GY compared to UAN. In extreme weather conditions, chemical additives failed to improve performance of UAN, when N was all applied after corn emergence.

Nitrogen losses, use efficiency, and productivity of early rice under controlled-release urea

Ammonia (NH3) volatilization and nitrogen (N) surface runoff from rice (Oryza sativa L.) paddies contribute to air and water pollution in China and everywhere else. The purposes of this study were to assess N losses through NH3 volatilization and surface runoff and to determine the grain yield and N use efficiency (NUE) of early rice in double rice cropping system in southern China. We implemented six treatments viz., control with 0kgNha−1 (CK), basal application and split application (1/2 at transplanting, 1/4 at tillering, and 1/4 at panicle stages) of urea (U), and basal applications of three controlled-release urea (CRU) sources (polyurethane-coated urea [CRU-1], degradable polymer-coated urea [CRU-2], and water-based polymer-coated urea [CRU-3]) all applied at 165kgNha−1. Results showed that CRU-1 and CRU-2 significantly reduced NH3 volatilization (23 to 62%) and N surface runoff losses (8 to 58%) compared with U. Precipitation and ammonium-nitrogen (NH4-N) concentration in surface water from rice paddy were predominant factors defining N losses through NH3 volatilization and surface runoff. Application of CRU reduced NH4-N concentration and pH of surface water and N losses through surface runoff. The CRU produced similar (−3 to 4%) or higher (5–16%) rice grain yields and increased NUE (3 to 34%) and N uptake (3–55%) compared with U. Polymer-coated urea can reduce environmental risks of N losses through volatilization and surface runoff while maintaining rice yield and N uptake, it also enhances NUE compared with urea in double rice cropping system in southern China.

Nitrogen nutrition in cotton and control strategies for greenhouse gas emissions: a review

Cotton (Gossypium hirustum L.) is grown globally as a major source of natural fiber. Nitrogen (N) management is cumbersome in cotton production systems; it has more impacts on yield, maturity, and lint quality of a cotton crop than other primary plant nutrient. Application and production of N fertilizers consume large amounts of energy, and excess application can cause environmental concerns, i.e., nitrate in ground water, and the production of nitrous oxide a highly potent greenhouse gas (GHG) to the atmosphere, which is a global concern. Therefore, improving nitrogen use efficiency (NUE) of cotton plant is critical in this context. Slow-release fertilizers (e.g., polymer-coated urea) have the potential to increase cotton yield and reduce environmental pollution due to more efficient use of nutrients. Limited literature is available on the mitigation of GHG emissions for cotton production. Therefore, this review focuses on the role of N fertilization, in cotton growth and GHG emission management strategies, and will assess, justify, and organize the researchable priorities. Nitrate and ammonium nitrogen are essential nutrients for successful crop production. Ammonia (NH3) is a central intermediate in plant N metabolism. NH3 is assimilated in cotton by the mediation of glutamine synthetase, glutamine (z-) oxoglutarate amino-transferase enzyme systems in two steps: the first step requires adenosine triphosphate (ATP) to add NH3 to glutamate to form glutamine (Gln), and the second step transfers the NH3 from glutamine (Gln) to α-ketoglutarate to form two glutamates. Once NH3 has been incorporated into glutamate, it can be transferred to other carbon skeletons by various transaminases to form additional amino acids. The glutamate and glutamine formed can rapidly be used for the synthesis of low-molecular-weight organic N compounds (LMWONCs) such as amides, amino acids, ureides, amines, and peptides that are further synthesized into high-molecular-weight organic N compounds (HMWONCs) such as proteins and nucleic acids.

Rice responses to single application of coated urea on yield, dry matter accumulation, and nitrogen uptake in Southern China

ABSTRACTNitrogen is the most important element for rice (Oryza sativa L.) growth. However, excessive use of conventional urea leads to serious environmental problems in China. The objective of this study was to evaluate the release patterns of coated urea and response of rice to coated urea on dry matter accumulation, nitrogen uptake, and nitrogen use efficiencies on a clay soil. A two single-year experiment was carried out in southern China to evaluate two coated urea, polymer-coated urea (PCU) and polymer-sulfur coated urea (PSCU). Nitrogen (N) release patterns of PCU and PSCU were determined in the laboratory and in the field. The release rate of PSCU in the field was much higher than that in the laboratory. And PCU had a similar release pattern both in the field and laboratory. Compared with urea, rice fertilized with PCU and PSCU had similar dry matter accumulation, but higher grain yield and N use efficiencies. Recovery efficiency of PCU treatment reached 50% in 2012 and 60% in 2013, around 40% for PSCU, which was only 16% for single application of urea.

Effect of Non-flooded Plastic Film Mulching Cultivation for Rice in Southeast China

The effects of non-flooded plastic film mulching cultivation (PM) and polymer-coated urea (PCU) on rice yield, soil properties, and weed diversity were investigated in experimental plots of rice monoculture in Lanxi, China. The combination of PM and PCU increased rice yield. Compared with traditional flooded cultivation, under PM, soil pH remained higher, but decreased soil organic matter, total nitrogen, available phosphorus, and exchangeable potassium in the 0- to 10-cm soil layer. Soil fertility influenced winter weed communities, with hairy bittercress, Asian mazus, and shortawn foxtail being the most abundant species. Multivariate analysis indicated that changes in the winter weed species diversity were primarily due to exchangeable potassium. PCU had no significant influence on weed diversity, while plots without nitrogen fertilizer had higher spring-germinating weed density.

Effect of controlled-release urea on heavy metal mobility in a multimetal-contaminated soil

Controlled-release N fertilizers can affect the availability of heavy metals in the contaminated paddy soil. A soil incubation experiment was conducted to investigate the effects of prilled urea (PU), S-coated urea (SCU), and polymer-coated urea (PCU) on the solubility and availability of heavy metals Cd, Pb, Cu, and Zn in a multimetal-contaminated soil. The results showed that the application of different coated urea significantly affected the solubility and availability of heavy metals. At 5 d of incubation, the application of PU, SCU, and PCU had significantly decreased the concentrations of water-soluble and available Cd, Pb, Cu, and Zn, when compared with the control. At 60 d of incubation, the depletory effects of PU on water-soluble and available heavy metals had reduced, and the initial decrease in the concentrations of water-soluble Cd, Pb, Cu, and Zn caused by SCU had changed to an increase. The concentrations of water-soluble Pb, Cu, and Zn in the SCU-treated soil were higher than those in the control. Application with PCU led to a higher water-soluble Cu than that in the control, while the available Cd, Pb, and Zn were lower than those in the control. The effect of different coated urea was much stronger on the water solubility of the heavy metals than on their availability. The effects of controlled-release urea on the transformation of heavy metals resulted in changes in the concentrations of NH+4, water-soluble SO2−4, and soil pH. The results further suggested that PCU could be used in dry farming operations in multimetal-contaminated acid soils.

Effects of Polymer Coated Urea and Irrigation Rates on Lantana Growth and Nitrogen Leaching

Core Ideas Polymer‐coated urea reduced N leaching as compared with conventional urea. Climatic conditions during the lantana growth affected the N uptake and N‐use efficiency. These results can be used for water and fertilizer management for ornamental plants. This study can be used to minimize environmental impact caused by N leaching. Lantana (Lantana camara L.) is a popular ornamental plant in seaside communities and an annual plant in hanging baskets. This species cultivated as an annual plant in containers needs to receive fertilizers. The nutrient management in containers can be made using conventional or controlled release fertilizers. The effects of ratios among conventional urea (CU) and polymer‐coated urea (PCU), and irrigation water rates applied by evapotranspiration (ET)‐based irrigation were studied on dry weight of biomass and N uptake of lantana, N leaching, water‐use efficiency (WUE), and N‐use efficiency (NUE). Six ratios between CU and PCU (expressed in percentages) and two irrigation rates were evaluated: 0:100, 25:75, 50:50, 75:25, 100:0, and 0:0 of CU/PCU; and water volume applied by 150% of reference evapotranspiration (ETo) and 200% of ETo‐based irrigation. Two trials were conducted with environmental conditions varying between them. With greater temperatures, the cumulative number of inflorescences increased with 100% of PCU as compared with 100% of CU applied in the trial. Polymer‐coated urea (100%) as compared with CU (100%) also reduced N leaching by 64.5 and 61.5% in the first and second trial, respectively. High water volume applied (200% of ETo) increased the dry weight of biomass, N uptake, and NUE. Water volume applied by 150% of ETo‐based irrigation resulted in a reduction of 53.5 and 58.5% of N leaching in the first and second trial, respectively. The response of WUE to ratios among CU and PCU and irrigation rates was not consistent, and was influenced by climatic conditions since WUE increased 26.6% in the second trial characterized for lower temperatures.

Reducing nitrogen losses through ammonia volatilization and surface runoff to improve apparent nitrogen recovery of double cropping of late rice using controlled release urea.

Controlled release fertilizer can reduce nitrogen losses to the environment while increasing grain yield and improving apparent nitrogen recovery (ANR) of rice. However, few studies have evaluated the comparative efficacy of different polymer-coated urea products on nitrogen (N) losses, ANR, and N uptake of rice. A 2-year field experiment was conducted to compare the effects of three different types of polymer-coated urea fertilizer on nitrogen losses through NH3 volatilization and surface runoff to the environment, ANR, grain yield, and N uptake as compared to conventional urea of rice. Six treatments including (1) control with 0kg N ha-1 (CK), (2) basal application of urea (Ub), (3) split application (Us) of urea (50% at transplanting, 25% at tillering, and 25% at panicle stages), (4) CRU-1 (polyurethane-coated urea), (5) CRU-2 (degradable polymer-coated urea), and (6) CRU-3 (water-based polymer-coated urea) all applied at 165kg N ha-1. It was found that CRU-2 resulted in the highest grain yield and panicle numbers among the N fertilization treatments in 2013 and 2014. Applying CRU could help increase N uptake in rice, reduce N losses through NH3 volatilization and surface runoff, and hence improve ANR. Its single dose can meet the nutrient demand of the rice plant. Controlled release urea could be adopted as an effective mitigation alternative to retard N losses through NH3 volatilization and surface runoff while improving ANR of double cropping of late rice.

Effects of two slow-release nitrogen fertilizers and irrigation on yield, quality, and water-fertilizer productivity of greenhouse tomato

Technical research on efficient water and nitrogen use is crucial for sustainable agricultural development. A field experiment was conducted to investigate the combined effects of two slow-release nitrogen fertilizers (polymer-coated urea (PU) and carbon-based urea (CU)) and two different irrigation water levels (conventional irrigation, CI; 90% of conventional irrigation, RI) on tomato yield, quality, and water-fertilizer productivity. Tomato yield and irrigation water productivity improved when nitrogen fertilizer was applied. Compared with U application, CU application increased tomato fruit diameter, volume, single-fruit weight, yield, and water-fertilizer productivity, therefore increasing yield by 4600kgha−1 and net income from tomato cultivation by 6313yuanha−1. Treatment with the two slow-release nitrogen fertilizers increased soluble sugar and lycopene contents and reduced nitrate content in fruits. Compared with U treatment, PU and CU treatments decreased total nitrate nitrogen residue in the 0–100cm soil layer. Compared with CI, RI significantly reduced tomato yield and net incomes under PU treatment, whereas RI did not significantly reduce tomato yield and net income under CU treatment. RI increased fruit Vc (vitamin C) and lycopene contents. Results of the study indicated that polymer-coated slow-release fertilizers may have great potential for widespread use because they improved tomato fruit quality while reducing the environmental risks caused by soil nitrogen. In addition, carbon-based, slow-release nitrogen fertilizers promise to improve fruit quality, yield, water-fertilizer productivity, and benefits associated with tomato cultivation. These fertilizers also reduce environmental risks caused by soil nitrogen and help reduce irrigation water consumption while sustaining normal tomato growth and fruit yield, making their promotion extremely beneficial.

Ammonia and greenhouse gas emissions from a subtropical wheat field under different nitrogen fertilization strategies

Minimizing soil ammonia (NH3) and nitrous oxide (N2O) emission factors (EFs) has significant implications in regional air quality and greenhouse gas (GHG) emissions besides nitrogen (N) nutrient loss. The aim of this study was to investigate the impacts of different N fertilizer treatments of conventional urea, polymer-coated urea, ammonia sulfate, urease inhibitor (NBPT, N-(n-butyl) thiophosphoric triamide)-treated urea, and nitrification inhibitor (DCD, dicyandiamide)-treated urea on emissions of NH3 and GHGs from subtropical wheat cultivation. A field study was established in a Cancienne silt loam soil. During growth season, NH3 emission following N fertilization was characterized using active chamber method whereas GHG emissions of N2O, carbon dioxide (CO2), and methane (CH4) were by passive chamber method. The results showed that coated urea exhibited the largest reduction (49%) in the EF of NH3-N followed by NBPT-treated urea (39%) and DCD-treated urea (24%) over conventional urea, whereas DCD-treated urea had the greatest suppression on N2O-N (87%) followed by coated urea (76%) and NBPT-treated urea (69%). Split fertilization of ammonium sulfate-urea significantly lowered both NH3-N and N2O-N EF values but split urea treatment had no impact over one-time application of urea. Both NBPT and DCD-treated urea treatments lowered CO2-C flux but had no effect on CH4-C flux. Overall, application of coated urea or urea with NPBT or DCD could be used as a mitigation strategy for reducing NH3 and N2O emissions in subtropical wheat production in Southern USA.

Effect of Polymer-Coated Urea and Ammonium Nitrate Application on Nitrogen Behaviour in Sandy Soil and Yield Productivity

Effect of Polymer-Coated Urea and Ammonium Nitrate Application on Nitrogen Behaviour in Sandy Soil and Yield Productivity

Optimizing Weight Method to Evaluate Nitrogen Release Characters of Polymer-Coated Urea in Paddy Soil under Field Conditions

ABSTRACTPolymer-coated urea can improve nitrogen (N) use efficiency of rice. But, the nitrogen release characters from flooded paddy soil are lacking. Traditional weight methods use a vacuum oven to dry. Depending on the coating, some polymer-coated urea still retain water after drying. A new weight method was proposed: washing fertilizer granules in the buried bags with distilled water, and transferring to a plastic bag, then placing it at −80°C for 2 h, and then transferring to the lyophilizer to dry for 24 h. The method was compared with chemical analyses. This result indicated that the weight method can be used for determining N release characteristics in paddy soil. In the whole growing season, over 75% of N was released. Different amounts of granules in the bag can influence the result. The release rate of 10.0 g in bags was higher than 3.0 g. Surface applied polymer-coated urea has a higher rate than deep application.

Buffalograss Divot Recovery as Affected by Nitrogen Source and Rate

Core Ideas Buffalograss treated with urea to provide 1 lb N/1,000 ft2 achieved 50% divot recovery 6.3 days faster than untreated turf. Polymer‐coated urea applications did not improve divot recovery rates compared with the 0 lb N treatment. Under limited irrigation situations and with minimal fertilization, buffalograss exhibits improved divot recovery and, thus, playability in low input turfgrass management systems. Divots occur when a golfer's club impacts the surface and removes turf. No published research has been conducted to explore the influence of nitrogen (N) fertility on divot recovery in buffalograss [Buchloë dactyloides (Nutt.) Engelm]. The objective of this study was to determine if nitrogen source and rate influence divot recovery in buffalograss. Research trials were initiated in 2014 at the Rocky Ford Research Center (RF) in Manhattan, KS and Council Grove Country Club (CG) in Council Grove, KS. Three divots were created per plot using a modified edger. Urea (46–0‐0) served as the quick‐release N source, and polymer‐coated urea (PCU) (43–0‐0) was the controlled release N source; each was applied to provide 0, 1, 2, and 3 lb N/1,000 ft2/yr. Buffalograss treated with urea to provide 1 lb N/1,000 ft2 achieved 50% divot recovery 6.3 d faster than untreated turf; however, the 3 lb N/1,000 ft2 rate did not enhance divot recovery in comparison. Polymer‐coated urea applied the day of divoting did not improve divot recovery rates compared to the 0 lb N treatment. Acceptable divot recovery is possible in buffalograss with a quick‐release N source and N fertility levels as low as 1 lb N/1,000 ft2/yr.

Effects of different controlled-release nitrogen fertilisers on ammonia volatilisation, nitrogen use efficiency and yield of blanket-seedling machine-transplanted rice

Recently, a novel controlled-release N fertiliser (CRNF) application method using basal CRNF combined with urea top-dressing at the tillering stage has been proposed to enhance rice yield and N use efficiency (NUE). However, its effect on ammonia volatilisation (AV) loss and the yield and NUE of blanket-seedling machine-transplanted rice are unknown. A field experiment was performed to investigate the effect of three types of CRNF (slow-release blending fertiliser (BSRB), polymer-coated urea (PCU) and sulphur-coated urea (SCU)) and two fertilisation regimes (a single basal application (B) and a basal CRNF application combined with urea top-dressing at the tillering stage (BT)) on grain yield, NUE and AV loss from paddy soil of blanket-seedling machine-transplanted rice. Conventional high-yield fertilisation (four split applications of urea at 270kgNha−1 (CK)) and 0-N treatments were established as controls. The results demonstrated that the AV flux values from paddy soil varied in distinct patterns for the different CRNF treatments. The cumulative AV loss in the urea treatment during the basal (the first week) and tillering fertiliser (the second week) comprised the majority of the total AV loss, both accounting for 87.2% in each year. Compared with CK, B-BSRB significantly reduced AV loss during the first two weeks and the total AV loss by 24.7% and 27.9% in 2013 and 2014, respectively. B-SCU and B-PCU generally showed no benefits for reducing AV loss relative to urea. Compared with B-PCU and B-SCU, B-BSRB met the N demand of rice, substantially mitigated N loss via AV in paddy fields, and improved yield and NUE of Blanket-seedling Machine-Transplanted rice. The effect of BT for each CRNF on AV loss was not consistent. The BT-BSRB and the BT-SCU correspondingly mitigated AV loss to a certain extent in each year, mostly due to the relatively lower AV loss during the first week, and no significant increase in AV loss at the second week. The BT-BSRB incurred not only the lowest AV loss of 39.7kgNha−1 and 37.8kgNha−1 but also the highest yield of 11.6tha−1 and 10.1tha−1 and an NRF of 48.8% and 52.4% in 2013 and 2014, respectively. Our results suggested that combining BSRB and BT optimised rice yield and nitrogen use efficiency while decreasing ammonia volatilization from paddy soil of blanket-seedling machine-transplanted rice.

Soil Waterlogging and Nitrogen Fertilizer Management Effects on Corn and Soybean Yields

Core Ideas Excessive soil moisture resulting from extreme precipitation events during early spring can often cause decreases in corn grain yields in the midwestern United States. Each day of waterlogging resulted in an average corn grain yield loss of 0.42 Mg ha−1 and 0.72 Mg ha−1 in 2013 and 2014, respectively. Pre‐plant N fertilizer applications of non‐coated urea; polymer coated urea, and non‐coated urea+nitrification inhibitor resulted in 19% higher yields compared to the non‐treated control in 2014. Effects of rescue N fertilizer were seen on soybean yields in the succeeding year after corn, while rescue N affected corn yields only in 2014. Climatic conditions including rainfall and air temperature had a significant role in crop response to waterlogging and N fertilizer treatments. In the midwestern United States, excessive soil moisture resulting from extreme precipitation events during early spring can often cause decreases in corn (Zea mays L.) grain yields and escalate N loss. A field trial was conducted from 2013 to 2015 in Northeast Missouri to determine the effects of soil waterlogging duration, pre‐plant N and rescue N fertilizer applications on corn and succeeding soybean [Glycine max (L.) Merr] production. Plots were either non‐flooded or flooded for durations of 1, 3, or 7 d when corn was at V6 growth stage. Pre‐plant N fertilizer treatments included non‐treated control (CO), urea (NCU), urea plus nitrapyrin (NCU+NI), and polymer coated urea (PCU) applied at 168 kg N ha−1. A rescue N fertilizer application of 0 or 84 kg N ha−1 of urea plus N‐(n‐butyl) thiophosphoric triamide (NBPT) (NCU+UI) was applied at V10 growth stage. Each day of waterlogging resulted in an average corn grain yield loss of 0.42 and 0.72 Mg ha−1 in 2013 and 2014, respectively. Pre‐plant N fertilizer applications of NCU, PCU, and NCU+NI resulted in 19% higher yields compared to CO in 2014. Effects of rescue N fertilizer were seen on soybean yields in the succeeding year after corn, while rescue N positively affected corn yields only in 2014. These results indicated that rescue N fertilizer applications are not effective if drought conditions occur after its application in corn. Climatic conditions including rainfall and air temperature had a significant role in crop response to waterlogging and N fertilizer treatments.

Enhanced Efficiency Nitrogen Products Influence Ammonia Volatilization and Nitrous Oxide Emission from Two Contrasting Soils

Core IdeasAmmonia volatilization and N2O emissions from N‐sources were assessed in two soils.The N‐(n‐butyl) thiophosphoric triamide reduced NH3volatilization losses from both sandy loam and silty clay soils.Nitrapyrin and SuperU reduced N2O emissions from sandy loam soil only.Polymer coated urea was effective in reducing both NH3and N2O emissions from sandy loam soil.Right N‐source could mitigate gaseous N losses from agroecosystems.Potentials of enhanced efficiency nitrogen (EEN) products to control N losses can vary with soil pH, cation exchange capacity, organic matter, water, temperature, and management. A laboratory experiment was conducted to quantify and compare ammonia (NH3) volatilization and nitrous oxide (N2O) losses with (i) control, (ii) urea, urea treated with (iii) urease inhibitor, NBPT [N‐(n‐butyl) thiophosphoric triamide], (iv) nitrification inhibitor, nitrapyrin (NP) [2‐chloro‐6‐trichloro methyl pyridine], (v) urea stabilized with NBPT and nitrification inhibitor dicyandiamide (SuperU), and (vi) slow release N fertilizer polymer coated urea (PCU) amendments from Ulen sandy loam and Fargo silty clay soils. Across N amendments, cumulative NH3–N losses from sandy loam soil ranged from 0.7 to 4.3% of applied N, and were higher than those from silty clay soil (0.1–0.4% of applied N). In sandy loam, compared to urea, NBPT and PCU reduced NH3–N volatilization by 32.3 and 84.2%, respectively, whereas NP and SuperU increased NH3–N losses by 98.7 and 20.3%, respectively. However, in silty clay soil, only NBPT exhibited significant reduction in NH3–N losses of 71.4%, relative to urea. Cumulative N2O emissions did not differ between soil textures and ranged from 3.7 to 7.4% of applied N across N sources. However, soil N2O emissions differed among N sources in sandy loam soil. In sandy loam soil, NP, SuperU, and PCU treatments significantly reduced N2O‐N emissions by 23.5, 43.8, and 51.1%, respectively, compared to urea. Applicability of using EEN products to mitigate NH3and N2O emission losses varies with soil texture.

Cumulative release characteristics of controlled-release nitrogen and potassium fertilizers and their effects on soil fertility, and cotton growth.

To investigate the interacting effects of polymer coated urea (PCU) and polymer coated potassium chloride (PCPC) on cotton growth, an experiment was conducted with containerized plants in 2014 and 2015. There were two kinds of nitrogen fertilizer, PCU and urea, which were combined with PCPC at three application rates (40, 80 and 120 kg ha−1). The kinds of nitrogen fertilizer formed the main plot, while individual rates of PCPC were the subplots. The results suggested N and K release patterns for PCU and PCPC in the soil were closely matched to the N and K requirements by cotton. Soil inorganic nitrogen contents significantly increased by using PCU instead of urea, and the same trend was observed with soil available potassium contents, which also had increased rates. Meanwhile, the number of bolls and lint yields of cotton in the PCU treatments were 4.9–35.3% and 2.9–40.7% higher than from urea treatments. Lint yields also increased by 9.1–12.7% with PCPC80 and PCPC120 treatments compared with PCPC40 treatment at the same nitrogen type. Hence, application of PCU combined with 80 kg ha−1 of PCPC fertilizer on cotton increased the yields and fertilizer use efficiencies in addition to improving fiber quality and delaying leaf senescence.

Effects of enhanced-efficiency nitrogen fertilizers on nitrous oxide emissions from cotton field under plastic mulched drip irrigation in Xinjiang,China

The effect of enhanced-efficiency nitrogen (N) fertilizers on emissions of nitrous oxide (N2O) from the grey desert agricultural soils of Xinjiang is uncertain. In this study, the enhanced-efficiency fertilizers, polymer-coated urea (ESN), and stabilized urea with urease and nitrification inhibitors (U+I) were compared to conventional urea (U) for N2O emissions from cotton under plastic mulch drip irrigation near Urumqi, Xinjiang. ESN was added once at planting but the other treatments were added multiple times with drip irrigation during the growing season. Gas samples were collected and analyzed twice per week during the growing season, using the static chamber-chromatography methodology. The results showed that generally, ESN significantly increased soil cumulative N2O emissions during the growing season by 47%-73% compared to other treatments. In the first four months after fertilization, soil ammonium (NH4+-N) and nitrate (NO3--N) concentrations under ESN treatment were generally higher than under other treatments. Thereafter, NH4+-N and NO3--N concentrations under all treatments gradually decreased to similar levels. ESN all added at planting was likely responsible for high NH4+-N and NO3--N concentrations and highest N2O emissions. The U+I treatment reduced soil N2O emission by 9.9% in comparison with U, whereas the difference was not statistically significant. In addition, soil NO3--N contents of the U+I treatments were generally lower than those of the ESN and the U treatments. The cumulative N2O emissionsover the growing season ranged from 300 to 500 g N2O-N·hm-2, generally lower than emissions reported for other agricultural ecosystems. Drip irrigation successfully kept moisture conditions below levels for appreciable N2O emissions. Multiple applications of N via drip irrigation seemed to be effective to lower emissions than all N applied at planting. Therefore, for cotton field under plastic mulch drip irrigation in arid land of Northwest China, the benefit of enhanced efficiency N ferti-lizers on N2O mitigation is limited.