Urea-based Fertilizers Research Articles

CsNIP2;1 is a Plasma Membrane Transporter fromCucumis sativusthat Facilitates Urea Uptake When Expressed inSaccharomyces cerevisiaeandArabidopsis thaliana

Urea is an important source of nitrogen (N) for the growth and development of plants. It occurs naturally in soils, is the major N source in agricultural fertilizers and is an important N metabolite in plants. Therefore, the identification and characterization of urea transporters in higher plants is important for the fundamental understanding of urea-based N nutrition in plants and for designing novel strategies for improving the N-use efficiency of urea based-fertilizers. Progress in this area, however, is hampered due to scarce knowledge of plant urea transporters. From what is known, urea uptake from the soil into plant roots is mediated by two types of transporters: the major intrinsic proteins (MIPs) and the DUR3 orthologs, mediating low- and high-affinity urea transport, respectively. Here we characterized a MIP family member from Cucumis sativus, CsNIP2;1, with regard to its contribution to urea transport. We show that CsNIP2;1 is a plasma membrane transporter that mediates pH-dependent urea uptake when expressed in yeast. We also found that ectopic expression of CsNIP2;1 improves growth of wild-type Arabidopsis thaliana and rescues growth and development of the atdur3-3 mutant on medium with urea as the sole N source. In addition, CsNIP2;1 is transcriptionally up-regulated by N deficiency, urea and NO3 (-). These data and results from the analyses of the pattern of CsNIP2;1 expression in A. thaliana and cucumber suggest that CsNIP2;1 might be involved in multiple steps of urea-based N nutrition, including urea uptake and internal transport during N remobilization throughout seed germination and N delivery to developing tissues.

Urease Inhibitors of Agricultural Interest Inspired by Structures of Plant Phenolic Aldehydes

The plant phenolic natural products (PNPs) protocatechuic aldehyde, syringaldehyde and vanillin were used as platforms for obtaining four urease inhibitors. Urea (urease substrate) or thiourea (urease inhibitor) core was added to the structure of newly synthesized compounds to provide inhibitors up to 230-fold more active than the PNPs they originated from. The PNP derivatives are mixed inhibitors with higher affinity to urease active site. Two compounds were as efficient as N-(butyl)thiophosphoric triamide (NBPT) toward soil. Overall, PNPs derivatives are promising urease inhibitors for use as additive in urea-based fertilizers formulations.

ANALISIS PENGARUH PROGRAM SIMPAN PINJAM PNPM MANDIRI PERDESAAN TERHADAP PRODUKSI DAN PENDAPATAN KELOMPOK IBU TANI PADI SAWAH (Studi Kasus : Desa Pangguran Kecamatan Sumbul Kabupaten Dairi)

This study aims to determine whether there was an effect of Program Simpan Pinjam PNPM Mandiri Perdesaan which given to farmer mothers concerning to increased production and income for rice farming in Pangguran Village, Subdistrict Sumbul, Dairi. The sample of study consisted of 30 samples which selected by stratified random sampling. Data analysis was performed in simple tabulation, regression analysis and analysis of different test average. The results showed, that after obtaining this program, there was an increase in the provision of agricultural inputs whose made by rice farmers, for urea-based fertilizer increased by 44,68 kg ; TSP 23,23 kg ; RJ 27,13 kg dan SS 24,6 kg per hectare. From the results of simple regression analysis, there was no effect from this program due to increase rice production and farmers income. From the results of different test average to production, there was a difference of production number before and after implemented this program, and for the income there was no real difference between the net income of rice farmers before and after this program.

New coating formulation for the slow release of urea using a mixture of gypsum and dolomitic limestone

The use of urea and urea-based fertilizers has increased considerably over the past 15 years. They currently account for approximately 51% of the world's agricultural nitrogen consumption. However, about 20–70% of the applied urea fertilizer is lost to the environment, causing serious pollution and increasing costs. These losses come from leaching, decomposition, and ammonium volatilization in the soil during handling and storage. Controlled release by coating can be used to increase urea fertilizer efficiency. We studied the use of gypsum, sulfur, and ground magnesium lime as cost-effective coating materials. All these coating materials contain nutrients required by plants. The effects of the coating composition and proportion of sealant on the rate of urea release and the crushing strength of the coated urea were investigated. We found that coated urea with the same proportion of gypsum–ground magnesium lime (GML) exhibited low urea release and high crushing strength. The performance was enhanced when using polyols as a sealant on the surface of the coated urea. A surface morphology analysis indicated a uniform and smooth surface on the coated film. The efficiency of the coated urea improved by 34.2% when using gypsum–GML (1:1 ratio) containing 1.1% polyols.

Field-Scale Evaluation of Calcium Ammonium Nitrate, Urea, and Urea Treated with N-(N-Butyl) Thiophosphoric Triamide Applied to Grassland in Ireland

This study investigated the effects of nitrogen (N) source, rate, and timing of application on dry-matter yield (DMY), N responses, N uptake and N-use efficiency (NUE) in a grass crop. The experiment used three fertilizer treatments: calcium ammonium nitrate (CAN), urea, and urea treated with N-(n-butyl) thiophosphoric triamide (NBTPT), applied at 0 (control), 25, 50, and 75 kg ha−1 of N over eighteen application timings. Results showed relatively lower agronomic performance of urea compared with CAN when applied in early spring. Urea reported lower N responses, lower relative DMY (90 percent), and relative N uptake (85 percent), which translated in lower NUE (0.45 kg kg−1) compared with CAN (0.70 kg kg−1). In spring fertilizer applications, urea and NBTPT showed DMY and NUE values comparable to those obtained with CAN. However, NBTPT enhanced overall performance of urea, which was shown with increasing temperatures toward summer or increasing N application rates. For summer applications, the efficiency of urea was less (P < 0.05) than that of CAN or NBTPT in all measured parameters, suggesting greater ammonia volatilization loss in urea-treated grass. Nitrogen saved in volatilization improved uptake and responses in NBTPT-treated grass, and hence DMY was not affected compared with CAN in summer fertilizer applications. The results of this study are supportive of increased usage of urea-based fertilizers treated with NBTPT.

Cuban zeolite as ammonium carrier in urea-based fertilizer pellets: Photoacoustic-based sensor for monitoring N-ammonia losses by volatilization in aqueous solutions

The loss of mineral nitrogen by ammonia volatilization is one of the main drawbacks in modern agriculture. This work proposes the use of a quantum cascade laser-based photoacoustic sensor to continuously monitor ammonia emission rates from fertilizer pellets in aqueous solutions. Pellets were obtained mixing different contents (2.5, 20 and 40wt.%) of Cuban zeolite with urea. The pH of aqueous solutions was also monitored and its maximum value was 9.5 for pellets with 40wt.% of zeolite. Urease obtained from soybean seed extract was added to the solution. Ammonia emission rates were enhanced due to the catalytic action of urease on the urea hydrolysis. The use of Cuban zeolite (40wt.%) reduced the ammonia volatilization from the solutions by approximately 33%. The results give us important clues to reach a better understanding of the kinetics of ammonia release from pellets and the use of zeolite in agriculture as an innovative material to control the retention of mineral nitrogen into soils.

&lt;b&gt;Wheat technological quality as affected by nitrogen fertilization under a no-till system

Wheat is a major cereal crop cultivated worldwide that plays a strategic role in human nutrition. Differently from several other crops, wheat’s technological properties are essential for its commercialization and utilization. Its reserve protein, known as gluten, presents unique rheological properties that can enable the raw material to be used for different industrial uses, mainly for bread making, pasta, cookies and cakes. In the current work, a field trial examined the effects of three urea-based fertilizers and four nitrogen (N) rates on selected physical, physicochemical and rheological characteristics of kernels and flour of wheat grown under a no-till system. The results showed no differences among the three fertilizers but the highest N rates produced changes, decreasing the thousand kernel weight and test weight (PH) and increasing kernel protein content and the gluten content of the flour. Multivariate statistical analysis techniques (principal component analysis and hierarchical cluster analysis) were also effective in differentiating the fertilizers based on the evaluated responses.

Validation for the determination of biuret in water-soluble, urea-based commercial inorganic fertilizer materials, urea solutions, and sulfur-coated urea products by reversed-phase liquid chromatography: single-laboratory validation of an extension of AOAC official methods 2003.14.

A single-laboratory validation (SLV) study for the LC determination of biuret in dry and liquid urea-based commercial fertilizers was conducted. A total of 23 samples were used: 11 commercial dry urea products, two urea ammonium nitrate products, eight liquid urea-based commercial fertilizers, and four sulfur-coated urea samples from different sources. In addition, one biuret standard from Aldrich and one sample from the Magruder check sample program were used as validation samples. The proposed method is an extension of AOAC Official Method 2003.14 and is based on dissolution of the test portion in the LC mobile phase and determination by HPLC. The system is linear over a concentration range of 1.00-4.50 mg/L biuret, with a correlation coefficient > or = 0.9999. The biuret was well- separated from urea in the commercial urea samples, and from other constituents in the commercial liquid fertilizer with no observed interferences. Recoveries were determined by spiking four of the validation materials with a known amount of biuret standard and measuring the biuret level according to the method. The averaged recovery was 97%. Method precision was determined by quadruplicate analyses of four of the liquid and six of the commercially available dry urea validation materials using three and four replicate analyses. For the liquid fertilizer analyses, the RSD ranged from 7.04 to 13.31%. For the dry urea analyses, the RSDs ranged from 5.68 to 14.34%. Instrument precision was evaluated at the test initiation by using seven injections of five biuret standard solutions. SD varied from 0.27 to 1.02%, with RSDs averaging 1.14%. The LOD was determined to be 0.009% biuret in material, while the LOQ was determined to be 0.031% biuret in material. In addition to the intralaboratory study, interlaboratory studies were performed by two other outside laboratories using this method. Over a concentration range of 0.2 to 0.9% biuret, the average SD was 0.11%, the average RSD was 21.16%, and the average HorRat value was 4.73%. Furthermore, comparative studies for biuret using AOAC Official Methods 960.04 and 976.01 with the proposed LC method were performed. The three methods produced very close results; however, the two AOAC methods generate hazardous wastes and are more tedious. On the basis of accuracy and precision of the results for this SLV study, it is recommended that this method be collaboratively studied for the determination of biuret in dry and liquid urea-based commercial fertilizer materials.

Cropping System Affects Polymer-Coated Urea Release and Corn Yield Response in Claypan Soils

Preplant-applied, urea-based fertilizer management in high-residue, no-till (NT) corn (Zea mays L.) is challenging because of potential N loss due to cool, wet conditions in the spring and dry conditions during the summer months. Field research evaluated the effects of polymer-coated urea (PCU) application timing, placement and cropping system on urea release for corn and determined corn yield response to PCU on claypan soils following wheat (Triticum aestivum L.) cropping systems [reduced-till corn following wheat, no-till corn following wheat with double-cropped (DC) soybean [Glycine max (L.) Merr.] and no-till corn following wheat with a frost-seeded red clover (FSC) (Trifolium pratense L.) cover crop]. Urea release from PCU was <35 % from fall through winter (November–January) and <20 % for early preplant (February–March) applications until 1 April. By 1 August, less urea was released in some instances from surface applications of PCU following FSC or DC soybean, but release was generally greater than in the absence of soil. No-till corn following DC soybean or FSC had yields that were 1.01–1.32 Mg ha−1 greater when grown with PCU compared to urea at 168 kg N ha−1. Grain yields were similar within no-till cropping systems with PCU, anhydrous ammonia and sidedressed urea ammonium nitrate (UAN) at 168 kg N ha−1. Farmers should recognize that high yields may not be obtained if PCU rates are reduced by 50 % (84 kg N ha−1) in high-residue (DC soybean or FSC), no-till production systems. Several N sources such as PCU, anhydrous ammonia and sidedressed UAN worked similarly in high-residue, no-till systems, although no differences between N sources were observed in a reduced-tillage system.

Rapid detection of economic adulterants in fresh milk by liquid chromatography–tandem mass spectrometry

A method to aid in the detection of the economically driven adulteration of fresh milk with a range of small, nitrogen containing compounds, including melamine, ammeline, ammelide, cyanuric acid, allantoin, thiourea, urea, biuret, triuret, semicarbazide, aminotriazine, 3- and 4-aminotriazole, cyanamide, dicyandiamide, guanidine, choline, hydroxyproline, nitrate, and a range of amino acids, has been developed. 15N2-Urea is used as an internal standard. The adulteration of milk with exogenous urea has previously been difficult to detect because of the variation in the naturally occurring levels of urea in milk. However, by monitoring the contaminants biuret and triuret, which comprise up to 1% of synthetic urea, the adulteration of milk with urea-based fertilizer can be detected. We estimate that to be economically viable, adulteration of the order of 90–4000ppm of the above adulterants would need to be added to fresh milk. For most of the compounds, an arbitrary detection threshold of 2ppm is therefore more than sufficient. For biuret, a lower detection threshold, better than 0.5ppm, is desirable and the sensitivity for biuret and triuret can be improved by the post-column addition of lithium to create lithium adducts under electrospray ionisation. Sample handling involves a two-step solvent precipitation method that is deployed in a 96-well plate format, and the hydrophilic interaction liquid chromatography uses a rapid gradient (1.2min). Three separate injections, to detect the positively charged compounds, the negatively charged compounds and amino acids and finally the lithium adducts, are used. This rapid and qualitative survey method may be deployed as a second tier screening method to quickly reduce sample numbers indicated as irregular by an FTIR based screening system, and to direct analysis to appropriate quantification methods.

Efficiencies of nitrogen fertilizers for winter cereal production, with implications for greenhouse gas intensities of grain

SUMMARYFertilizer nitrogen (N) accounts for the majority of the greenhouse gas (GHG) emissions associated with intensive wheat production, and the form of fertilizer N affects these emissions. Differences in manufacturing emissions (as represented in the current carbon accounting methodologies) tend to favour urea, even when using the best available manufacturing technologies (BAT), whereas differences in fertilizer N efficiency and emissions of ammonia tend to favour ammonium nitrate (AN). To resolve these differences, data from 47 experiments in two large UK studies conducted from 1982 to 1987 and from 2003 to 2005 were reanalysed, showing that on average urea efficiency was 0·9 of AN (although mean ammonia emissions in 10 subsidiary experiments indicated an efficiency difference of 0·2); treating urea with a urease inhibitor (TU; AGROTAIN®, active ingredient N-(n-butyl) thiophosphoric triamide (n-BTPT)) brought its efficiency almost in line with AN; however, a significantly greater mean optimum N amount for TU (+0·1 of AN) was not fully explained. A standard response function relating wheat yield to applied AN was modified for degrees of relative inefficiency, thus enabling yields and GHG intensities (kg CO2e/tonne (t) grain) to be calculated using a PAS2050 compatible model for GHG emissions for any N amount of any N form. With AN manufactured by average European technology (AET), the estimated GHG intensity of wheat producing 8 t/ha was 451 kg/t; whereas with urea or TU made by AET it was 0.87–0.99 or 0.84–0.86 of this respectively. Using BAT for fertilizer manufacture, the grain's GHG intensity with AN and TU was 368 kg/t, but was 1·03–1·17 of this with untreated urea. The range of effects on GHG intensities arose mainly from remaining uncertainties in the inefficiencies of the N forms. Generally, economic margins and GHG intensities were not much affected by adjustments in N use for relative inefficiencies or different prices of urea-based fertilizers compared with AN. Overall, TU appeared to provide the best combination of economic performance and GHG intensity, unless the price for N as TU exceeded that for N as AN.

Response of turfgrass to urea-based fertilizers formulated to reduce ammonia volatilization and nitrate conversion

Stabilized urea fertilizers are currently being marketed for use in turfgrass, as a more efficient alternative to standard urea that minimizes adverse impacts on the environment. These fertilizers have been evaluated for reducing N losses and increasing grain yield in crop plants, but their effects in turf are not well characterized. The efficacy of two stabilized urea fertilizers containing urease and nitrification inhibitors, N-(n-butyl) thiophosphoric triamide and dicyandiamide or butenedioc-methylenesuccinic acid copolymer, in reducing N losses was studied for a 56-day period in a mixed stand of Kentucky bluegrass (Poa pratensis L.) and perennial ryegrass (Lolium perenne L.) using 15 N-enriched fertilizers. Turf responded to a 49-kg ha−1 N input with increased color, quality, and biomass production. No benefit of nitrification and urease inhibitors compared to urea was observed for clipping production, N use efficiency, or turfgrass color and quality. Though the efficacy of urease and nitrification inhibitors has been demonstrated both in the laboratory and for row crops, inhibitors appear to be of limited value for enhancing N use efficiency in turf.

Impact of land use patterns and agricultural practices on water quality in the Calapooia River Basin of western Oregon

Agricultural practices, including tillage, fertilization, and residue management, can affect surface runoff, soil erosion, and nutrient cycling. These processes, in turn, may adversely affect (1) quality of aquatic resources as habitat for amphibians, fish, and invertebrates, (2) costs of treating surface and ground water to meet drinking water standards, and (3) large-scale biogeochemistry. This study characterized the surface water sources of nitrogen (N) (total, nitrate [NO₃⁻], ammonium [NH₄⁺], and dissolved organic N) and sediment active within 40 subbasins of the Calapooia River Basin in western Oregon in monthly samples over three cropping years. The subbasins included both independent and nested drainages, with wide ranges in tree cover, agricultural practices, slopes, and soils. Sediment and N form concentrations were tested against weather and agricultural practice variables. Subbasin land use ranged from 96% forest to 100% agriculture. Average slopes varied from 1.3% to 18.9%, and surface water quality ranged from 0.5 to 43 mg L⁻¹ (ppm) total N maxima and 29 to 249 mg L⁻¹ suspended sediment maxima. Total N during the winter was positively related to percentage landcover of seven common agricultural crops (nongrass seed summer annuals, established seed crops of perennial ryegrass [<i>Lolium perenne</i> L.], tall fescue [<i>Schedonorus phoenix</i> {Scop.} Holub], orchardgrass [<i>Dactylis glomerata</i> L.], clover [<i>Trifolium</i> spp.], and newly planted stands of perennial ryegrass and clover) and negatively related to cover by trees and one seed crop, Italian (annual) ryegrass (<i>Lolium multiflorum</i>). Results for NO₃⁻ and total N were highly similar. Sediment concentrations were most strongly related to rainfall totals during periods of 4 and 14 days prior to sampling, with smaller effects of soil disturbance. Fourier analysis of total N over time identified four prominent groups of subbasins: those with (1) low, (2) medium, and (3) high impacts of N (up to 2, 8, and 21 mg L⁻¹, respectively) and a strong cyclical signal peaking in December and (4) those with very high impact of N (up to 43 mg L⁻¹) and a weak time series signal. Preponderance of N in streams draining agriculturally dominated subbasins was in the form of the NO₃⁻ ion, implying mineralization of N that had been incorporated within plant tissue following its initial application in the spring as urea-based fertilizer. Since mineralization is driven by seasonal rainfall and temperature patterns, changes in agronomic practices designed to reduce prompt runoff of fertilizer are unlikely to achieve to more than ~24% reduction in N export to streams.

A 3-year record of N2O and CH4 emissions from a sandy loam paddy during rice seasons as affected by different nitrogen application rates

Greenhouse gas fluxes from rice paddies under nitrogen fertilization merit serious attention because nitrogen fertilizer is increasingly used for the intensification of rice cultivation. A 3-year field study was conducted to measure methane (CH4) and nitrous oxide (N2O) fluxes simultaneously in a sandy loam paddy field under three nitrogen application rates (0, 150 and 250kgNha−1) in the Yangtze River Delta from 2005 through 2007. The rice paddies were under a typical Chinese water regime, characterized by intermittent irrigation with midseason drainage. The results revealed a trade-off between CH4 and N2O emissions as influenced by the application of urea-based fertilizers, i.e., the nitrogen fertilization reduced CH4 emissions from rice paddies but increased N2O emissions. The seasonal CH4 emissions averaged 155.9kgCha−1 in the absence of nitrogen amendment. Compared to no nitrogen addition, the seasonal CH4 emissions were decreased by 27% and 53% in the fertilized plots at rates of 150 and 250kgNha−1, respectively. It was most likely that the sandy loam texture combined with the addition of urea-based fertilizers stimulated growth and activity of methane oxidizers. In contrast, nitrogen addition increased N2O emissions 2.5 times for an application rate of 150kgNha−1 and 6.0 times at 250kgNha−1, compared to no nitrogen addition (0.38kgNha−1). The direct emission factor of fertilizer N for N2O was estimated to be 0.39–1.22% for rice fields, with a mean value of 0.77%. The overall emissions of CH4 and N2O, expressed as carbon dioxide equivalents were affected by the nitrogen addition rate, with the minimum emissions occurring at 250kgNha−1. This result indicated that the commonly applied nitrogen rate in this region might be an effective option for mitigating the combined impacts of rice production. Our results also demonstrate the presence of large interannual variations in the CH4 and N2O fluxes. It is probable that these variations resulted from differences in the amount and distribution of precipitation.

Nutrient controls of planktonic cyanobacteria biomass in coastal stormwater detention ponds

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 434:15-27 (2011) - DOI: https://doi.org/10.3354/meps09195 Nutrient controls of planktonic cyanobacteria biomass in coastal stormwater detention ponds Amy Siegel1, Bridget Cotti-Rausch1, Dianne I. Greenfield1,2,4, James L. Pinckney1,3,* 1Marine Science Program, 2Belle W. Baruch Institute for Marine and Coastal Sciences, and 3Department of Biological Sciences, University of South Carolina, Columbia, South Carolina 29208, USA 4Marine Resources Research Institute, 217 Fort Johnson Road, Charleston, South Carolina 29412, USA *Corresponding author. Email: pinckney@sc.edu ABSTRACT: Stormwater detention ponds are a common best management practice (BMP) designed to moderate the impacts of development on surrounding ecosystems. On Kiawah Island, South Carolina, stormwater detention ponds receive high levels of nitrogen (N) and phosphorus (P) loading from non-point sources, which results in eutrophic conditions, recurrent water quality degradation, and problematic cyanobacterial blooms during summer and fall. The purpose of this study was to quantify planktonic cyanobacterial responses to manipulations of the form of N (NO3–, NH4+, urea, or combinations) to determine their relative importance for cyanobacterial blooms. Nutrient addition bioassays were performed monthly (June to September 2009) in 2 brackish water ponds designated as K61 and K67. The 2 study sites were similar in all physical parameters except pond K61 was more brackish (salinity = 14 ± 2, mean ± SD) than pond K67 (6 ± 2). Urea additions resulted in a greater increase in cyanobacterial biomass than other N forms in pond K61 while urea and NH4+ additions promoted growth in pond K67. The bioassays showed a relatively strong cyanobacteria response to the N additions for both ponds (except K67 in July). However, in all cases, the cyanobacterial contribution was always <36% of total phytoplankton biomass. Our results suggest that both NH4+ and urea may preferentially stimulate cyanobacterial growth in brackish stormwater detention ponds on Kiawah Island in the summer months. Although fertilizer application procedures and rates are not known for the areas drained by the stormwater detention ponds on Kiawah Island, our results suggest that the use of urea-based fertilizers, which produce both urea and NH4+ in runoff, could foster the development and maintenance of cyanobacteria blooms. KEY WORDS: Photopigment · Bioassay · Nutrient · Eutrophication · HPLC · Urea · Ammonium · Nitrate · ChemTax Full text in pdf format PreviousNextCite this article as: Siegel A, Cotti-Rausch B, Greenfield DI, Pinckney JL (2011) Nutrient controls of planktonic cyanobacteria biomass in coastal stormwater detention ponds. Mar Ecol Prog Ser 434:15-27. https://doi.org/10.3354/meps09195 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 434. Online publication date: July 28, 2011 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2011 Inter-Research.

Ureic Nitrogen Transformation in Multi-Layer Soil Columns Treated with Urease and Nitrification Inhibitors

The use of N-(n-butyl)thiophosphoric triamide (NBPT), as a urease inhibitor, is one of the most successful strategies utilized to increase the efficiency of urea-based fertilization. To date, NBPT has been added to the soil incorporated in fertilizers containing either urea or the inhibitor at a fixed percentage on the urea weight. The possibility of using NBPT physically separated from urea-based fertilizers could make its use more flexible. In particular, a granulated product containing NBPT could be utilized in soils treated with different urea-based fertilizers including livestock urine, the amount depending on soil characteristics and/or the urea source (e.g., mineral fertilizer, organo-mineral fertilizer, or animal slurry). In this study, a multilayer soil column device was used to investigate the influence of an experimental granular product (RV) containing NBPT and a garlic extract, combining the ability to protect NBPT by oxidation and nitrification inhibition activity, on (a) spatial variability of soil urease and nitrification activities and (b) timing of urea hydrolysis and mineral-N form accumulation (NO(2)(-), NO(3)(-), NH(4)(+)) in soil treated with urea. The results clearly demonstrated that RV can, effectively, inhibit the soil urease activity along the soil column profile up to 8-10 cm soil layer depth and that the inhibition power of RV was dependent on time and soil depth. However, nitrification activity is not significantly influenced by RV addition. In addition, the soil N transformations were clearly affected by RV; in fact, RV retarded urea hydrolysis and reduced the accumulation of NH(4)(+)-N and NO(2)(-)-N ions along the soil profile. The RV product was demonstrated to be an innovative additive able to modify some key ureic N trasformation processes correlated with the efficiency of the urea-based fertilization, in a soil column higher than 10 cm.

CoMFA and CoMSIA 3D-QSAR analysis on hydroxamic acid derivatives as urease inhibitors

Urease (EC 3.5.1.5) serves as a virulence factor in pathogens that are responsible for the development of many diseases in humans and animals. Urease allows soil microorganisms to use urea as a source of nitrogen and aid in the rapid break down of urea-based fertilizers resulting in phytopathiCIT000y. It has been well established that hydroxamic acids are the potent inhibitors of urease activity. The 3D-QSAR studies on thirty five hydroxamic acid derivatives as known urease inhibitors were performed by Comparative Molecular Field Analysis (CoMFA) and Comparative Molecular Similarity Indices Analysis (CoMSIA) methods to determine the factors required for the activity of these compounds. The CoMFA model produced statistically significant results with cross-validated (q2) 0.532 and conventional (r2) correlation coefficients 0.969.The model indicated that the steric field (70.0%) has greater influence on hydroxamic acid inhibitors than the electrostatic field (30.0%). Furthermore, five different fields: steric, electrostatic, hydrophobic, H-bond donor and H-bond acceptor assumed to generate the CoMSIA model, which gave q2 0.665 and r2 0.976.This model showed that steric (43.0%), electrostatic (26.4%) and hydrophobic (20.3%) properties played a major role in urease inhibition. The analysis of CoMFA and CoMSIA contour maps provided insight into the possible modification of the hydroxamic acid derivatives for improved activity.

Natural product based urease inhibitors for the treatment of ulcers

Urease catalyzes the hydrolysis of urea to ammonia and carbamate. The main significance of urease enzyme include (i) its capacity to serve as a virulence factor in human and animal infections of the urinary and gastrointestinal tracts and, (ii) its role in environmental transformation of nitrogenous compounds, including urea-based fertilizers. This has been discovered that bacterial urease plays an important role in the survival of Helicobactror pylori (HP) and manifestation of its adverse effects during peptic and gastric ulcers. Inhibition of urease is therefore considered to be an important intervention in the treatment of ulcers.

Ridge-Till Corn and Urea Hydrolysis Response to NBPT

Ammonia volatilization from surface-applied, urea-based fertilizers can result in reduced fertilizer N availability to the crop, particularly in minimum tillage systems with substantial surface residue. The objective of this study was to evaluate the potential for the urease inhibitor N-(n-butyl)thiophosphoric triamide (NBPT) to minimize ammonia loss and preserve fertilizer N availability of urea and urea-ammonium nitrate (UAN) solution applied to ridge-till, irrigated corn (Zea mays L.). The study was conducted at three sites over 3 yr, 1990 to 1992. The soil for all three site-years was a Crete silt loam (fine, montmorillonitic, mesic Pachic Argiustoll). Urea and UAN solution (28% N) were applied following planting via two methods, broadcast (BR) and surface band (SB), at two N rates, 100 and 200 lb/acre, with and without NBPT at the rate of 1.0 lb/acre. A nonvolatile check of UAN knifed into the soil, with and without NBPT, was applied each year. Grain yield, stover yield, ear leaf N and chlorophyll, basal stalk nitrate, grain N, grain moisture, and stover N were evaluated. A lab incubation study was also conducted to evaluate the effect of subsurface band application of UAN with and without NBPT on the rate of urea hydrolysis and fertilizer N availability to the crop. Nitrogen did not limit yield in 1990. Precipitation soon after fertilization in 1990 and 1991 resulted in little or no benefit from the use of NBPT. Limited precipitation and low humidity for an extended period following fertilization in 1992 resulted in a 56.6 bu/acre increase in yield when NBPT was applied with urea (averaged over rates and application methods), but no yield increase when NBPT was applied with UAN. No differences in yield were observed between BR and SB application methods. Parameters which are indicative of N use efficiency, such as grain N, basal stalk nitrate, leaf N and chlorophyll, responded to source, rate, and application method variables even when grain or stover yield did not. The lab incubation found that urea hydrolysis was reduced when NBPT was added to UAN in a subsurface band, but not slowed to the extent that N availability to the crop would be reduced over the growing season. This study found the yield response of corn to urea or UAN solution containing NBPT to be highly variable, dependent mainly on the climatic conditions following fertilization. The use of NBPT can be an effective management tool to minimize the potential for yield loss due to ammonia volatilization from urea fertilizers applied to high residue conditions in years when climatic conditions are conducive to N loss.

Ammonia loss following surface application of urea fertilizer to undrained and drained forested minerotrophic peatland sites in central Alberta, Canada

Drainage and urea fertilization of forested peatlands in western Canada are being contemplated as means for increasing peatland conifer productivity. Surface application of urea-based fertilizers may result in loss of some N by volatilization of NH 3. The objective of the present study was to assess the loss of NH 3 from undrained and drained peatland sites as affected by various N dosages, i.e. 0 (unfertilized), 200 (N 2) and 400 kg N ha −1 (N 4), following field broadcast application of urea fertilizer. Losses of NH 3 from fertilized plots were higher on the undrained relative to the drained site. Increase in urea-N dosage increased NH 3 volatilization from both sites. Most of the NH 3 volatilization losses occurred during the first 9 days after fertilizer application. The precipitation that occurred on day 9 after fertilizer application decreased NH 3 volatilization to background levels of unfertilized plots for the rest of the study period. Net mean losses of NH 3 from the undrained site were 3% and 4% of applied N for N 2 and N 4, respectively. Corresponding losses on the drained site were 0.7% and 7%. These magnitudes of loss of N appear to be less important from a forest management point of view.