Granular Urea Research Articles

IMPACT OF NITROGEN SOURCES ON THE PERFOMANCE OF LOWLAND RAINFED RICE AT EDOZHIGI IN THE SOUTHERN GUINEA SAVANNA OF NIGERIA

Field trials were conducted at Edozhigi, in the southern Guinea savanna of Nigeria during the 2020 and 2021 cropping seasons to determine the response of lowland rainfed rice to two Nitrogen sources (urea super granule (USG) and granular urea (GU)). There treatments consisted of five levels of USG (80, 90, 100, 110, 120 kg N ha-1) and six levels of GU (40, 80, 90, 100, 110, 120 kg N ha-1) and a control (0). The 12 treatments were laid out in a randomised complete block (RCBD) with three replicates. Result of the physical and chemical analysis of soil of the experimental field revealed that, soil had sandy clay loam texture with slightly acidic soil reaction. The soil organic carbon, total N, available P, exchangeable cataionic nutrients were all low in the soil which make the soil to have low fertility. Result of the study indicated that, plant growth and maturity period were not significantly affected by the application of N. The result further shows a significant response to application of USG, but not to GU. The highest paddy yield of 4.53 Mg ha-1 was recorded for USG at 90 kg N ha-1 which was significantly higher than that of the control and the GU treatments, but statistically similar to most of the other USG treatments. The USG is recommended as a source of N for the enhancement of the paddy yield.

Effects of liquid urea rates on nitrogen dynamics, growth, and yield of corn (Zea mays L.)

Arbitrary use of urea fertilizer reduces nitrogen use efficiency (NUE) and increases the risk of environmental pollution. An experiment was conducted at the Universiti Putra Malaysia from November 2019 to March 2020 to evaluate the application methods and rates of liquid urea (LU) on the yield performance of corn. The treatments were, U0 = control, GU100 = Granular urea (GU) 100%, LU100 = LU 100%, LU50 = LU 50% and LU33 = LU 33%, in two equal splits at 10th and 28th days after sowing (DAS) in randomized completely block design, replicates four. Results showed that plant height (206.99 cm, 216.92 cm, 214.61 cm), ear height (88.13 cm, 88.63 cm, 86.00 cm), days of maturity (88.75, 89.00, 86.75 days), number of grains per kernel row (32.25, 34.50, 33.75), fresh cob weight (10,886.60 kg ha−1, 10,946.60 kg ha−1, 10,927.93 kg ha−1) and 100-grain weight (20.51 g, 22.50 g, 21.39 g) of corn were not different significantly (p ≤ 0.05) in GU100, LU100 and LU50 treatments, respectively. The highest yield of corn was found with LU100 (6249.03 kg ha−1) treatment whereas the yield in LU50 (5666.50 kg ha−1) and GU100 (5746.64 kg ha−1) were not different significantly. Nitrogen (%) in plants was the highest in LU100 followed by LU50 treatment which was significantly higher than GU100 treatment. The total N content was also the highest in LU100 (102.83 kg ha−1) though the total N content was not different significantly in LU50 (77.62 kg ha−1) and GU100 (83.84 kg ha−1) treatments. The NUE was the highest in LU50 (66.92%) treatment followed by LU100 (51.47%) treatment. The results of the study suggested that LU was superior to GU and the LU100 was the best application rate while LU50 treatment was comparable to GU100 in corn cultivation.

Combined applications and Multi-Faceted evaluations of humic acid, seaweed, and vermicompost with chemical and organo-mineral fertilizers on corn, part I: chlorophyll concentration

This study investigated the effects of various fertilizers on the leaf chlorophyll content of the Simpatico (FAO300) silage corn variety under field conditions. Different application combinations were tested, including treatments with and without foliar fertilizers. The foliar fertilizers used were seaweed (SW), humic acid (HA), and vermicompost (VC), combined with granular fertilizers DAP, UREA, OMB, and OMT. Granular fertilizers were applied to the soil, while foliar fertilizers were applied at four different stages: the 4-6 leaf period, 11-13 leaf period, 14-16 leaf period, and at corn tassel. Chlorophyll content in plant leaves was measured using a SPAD-502 device during these periods. The highest SPAD chlorophyll ratios were recorded with OMB-OMT (42.583) and DAP-OMT (42.150) treatments, which did not include foliar fertilizers. Conversely, the lowest SPAD chlorophyll ratio, 28.983, was observed in the DAP-UREA treatment. Treatments with foliar fertilizers resulted in an increase in SPAD chlorophyll by 11.3% to 15.7%, with the greatest improvements observed with vermicompost and humic acid, compared to treatments without foliar fertilizers. Additionally, analysis of periodic effects showed that the highest SPAD chlorophyll ratios were found during the third and second measurement periods, while the lowest ratios were observed in the first measurement period. The use of organo-mineral fertilizers and foliar applications of vermicompost and humic acid were found to enhance the leaf chlorophyll content of corn.

Effect of Sowing Methods and Different Levels of Nitrogen on Yield Attributes and Yield of Maize

The field experiment was carried out at Research Farm, Integral University, Lucknow, Uttar Pradesh, India during Kharif season, 2021. The experiment envisages to study the effect of Sowing methods and different Nitrogen levels on yield and attributes of maize crop. The experiment was laid down in the Split Plot Design and the treatments was replicated three times. Among the sowing methods, the maximum length of a cob (18.52 cm) was obtained in the ridge sowing method (S1) while among nitrogen levels the maximum length of cob (19.51 cm) was obtained with the application of 25% N through granular urea + 75% N through Nano-urea (N5). Among nitrogen levels highest number of grains per row (40.76) were obtained in the application of 25% N through granular urea + 75% N through Nano-urea (N5). Seed Index was achieved to be highest in ridge method of sowing(S1) with the application of 25% N through granular urea + 75% N through Nano-urea (N5). Number of grains per cob were highest (385.55) in the N5 treatment among the nitrogen levels treatments. Among sowing methods, the maximum grain yield of 51.75 q ha-1 was founded in the ridge method of sowing. Among nitrogen levels the highest grain yield of 57.76 q ha-1 was obtained in N5 treatment. However, harvest index was found to be non-significant. Ridge method of sowing was found to be most effective than broadcasted method. Application of Nano-urea alone did not give good results. Granular urea along with nano-urea was found to be more effective in maize crop under this region.

Growth Parameters and Protein Content of Maize as Influenced by Sowing Methods and Different Levels of Nitrogen

The field experiment was carried out at Research Farm, Integral University, Lucknow, Uttar Pradesh, India during Kharif season, 2021. The experiment envisages to study the effect of Sowing methods and different Nitrogen levels on yield and attributes of maize crop. The experiment was laid down in the Split Plot Design and the treatments were replicated three times. The maximum plant height of 56.92 cm, 235.17 cm and 237.16 cm was observed in the ridge method of sowing at knee height stage, tasselling stage and at harvest stage, respectively. Among nitrogen levels, the maximum plant height of 57.61 cm, 235.29 cm and 238.38 cm was observed at knee height stage, tasselling stage and at harvest stage, respectively in the treatment (N5) 25% N through granular urea + 75% N through Nano-urea. Among nitrogen levels, the maximum DMA of 86.30, 425.36 and 1287.73 g sqm-1 day-1 was observed at knee height stage, tasselling stage and at harvest stage, respectively in the treatment (N5) 25% N through granular urea + 75% N through Nano-urea. At harvest stage number of leaves per plant were highest in the S1 (14.33) and N5 (16.13) treatment. Among nitrogen levels, the maximum leaf area index (LAI) of 1.55, 2.49 and 1.9 was observed at knee height stage, tasselling stage and at harvest stage, respectively in the treatment N5. Among sowing methods, highest protein content was found in the ridge method (10.14%) followed by flat method (9.81%) and broadcast method (9.42%) of sowing. The protein yielded maximum of 586.15 kg ha-1 in the N5 treatment. All parameters showed better in granular urea application rather than nano-urea, when used solely.

Electrical conductivity based algorithm for precise application of liquid nitrogenous fertilizers

Precise application of nitrogenous fertilizers mainly urea ammonium nitrate (UAN) and granular urea (both pure and neem-coated) in aqueous form, is critically important for basal and foliar applications. The physicochemical properties of aqueous solution of these nitrogenous fertilizers plays important role in design of any liquid fertilizer application system. The study was carried out during 2019–20 at ICAR-Indian Agricultural Research Institute, New Delhi with an aim to develop algorithms for use in sensors-based systems for real time monitoring of available N concentration in the fertilizer solution before its application. The physicochemical properties like pH, electrical conductivity (EC), specific gravity (SG), dynamic viscosity (DV), surface tension (ST) and percentage light absorbance (LA) of urea ammonium nitrate (UAN-28%), pure urea, and neem coated urea in diluted form (pre-selected N-concentrations i.e. 0.78, 0.9, 1.08, 1.33, 1.75, 2.54 and 4.67% corresponding to the dilution ratios of 1:35, 1:30, 1:25, 1:20, 1:15, 1:10 and 1:05) were measured and analyzed for their significance with N-concentration. Electrical conductivity (EC) alone showed a significant relationship with N-concentrations. Prediction models were developed for diluted UAN and granular urea fertilizers based on the EC and N-concentrations. The regression models in terms of EC to predict N-concentration had coefficients of determination (R2) of 0.998, 0.998, and 0.999 for diluted UAN, pure urea, and neem coated urea with water, respectively showed a great potential for their sensor based precise application. The controlled application of diluted liquid fertilizers with water can be achieved through sensing relevant physicochemical property.

Efficacy of fertilizer nitrogen source, stabilizer, and application timing for corn nitrogen nutrition

AbstractEnhancing fertilizer nitrogen use efficiency (NUE) in corn (Zea mays L.) production is critical for closing yield gaps, increasing producer profitability, and promoting environmental stewardship. In 2014 and 2015, a field experiment was conducted to determine the potential for fertilizer N stabilizer products to improve NUE of granular urea and urea ammonium nitrate (UAN) solution applied to strip‐till corn. A urease inhibitor (UI) or nitrification inhibitor (NI) or both were added at labeled rates to urea or UAN solution for a target rate of 180 kg N ha−1. At V3, a single application of broadcast granular urea and subsurface banded UAN solution with and without fertilizer N stabilizers was made. A split application (50% at V3; 50% at V6) of subsurface banded UAN solution served as a control representing a standard grower practice. Fertilizer N stabilizers improved components of NUE, such as grain N recovery efficiency (GNRE) and partial factor productivity (PFP). A single full rate UAN application did not differ in terms of grain yield each year but did result in less PFP and GNRE in 2015 as compared to the grower standard practice. A timely one‐time full season N rate subsurface banded application of UAN treated with UI and NI to improve NUE could be a viable substitute for the practice of multiple fertilizations. Untreated broadcast urea was inferior to UAN as a N source for corn, but when treated with both a UI and NI, NUE was improved.

UREA TREATMENT OF MATURE WHOLE-CROP CEREAL MIXTURES AS SALVAGE FORAGE FOR SMALL-SCALE DAIRY SYSTEMS IN THE DRY SEASON

<p><strong>Background:</strong> Forage from small-grain cereals is an option to diversify feeding strategies in small-scale dairy systems (SSDS), due to their short cycle and ample adaptation. Mixtures of cereal species may have synergic advantages; however, grazing or ensiling is not always possible due to climatic factors, so forage crops are left to mature and lose quality. Urea treatment of whole-crop mature cereal mixtures may be an option to salvage forage that could not be grazed or ensiled. <strong>Objective:</strong> To evaluate the performance of dairy cows fed urea-treated mature whole-crop forage mixtures of triticale (TRT), rye (RYE), and barley (BLY), in the dry season for SSDS. <strong>Methodology</strong>: Treatment mixtures were TRT+RYE, TRT-BLY, and RYE+BLY. Fully mature cereal mixture crops were treated with 4 - 6% granular urea (plus water) on a fresh basis. Forage variables were analysed with a split-plot design. Whole-crop forage yields were 3.4 ton/ha, with highest yields for RYE-BLY. Crude protein content increased two-fold in treated forages, and dry matter digestibility was moderate with a mean estimated ME content of 7.9 MJ ME/kg DM. Performance was evaluated by an on-farm 3x3 Latin square experimental design repeated 3 times with nine Holstein cows, experimental periods were 14 days, of which 10 days were for adaptation to feeding and 4 days for sampling. Cows were offered daily 9.0 kg DM of urea-treated forage; complemented with 4.4 kg DM of concentrate, day-grazing, and 1.5 kg of cut pasture. <strong>Results: </strong>There were no statistical differences (P>0.05) for any of the animal variables. Urea treatment of whole-crop mature cereal mixtures resulted in a complementary moderate quality salvage forage for the dry season. <strong>Implications:</strong> The present study is presented as an alternative when the crops are in a state of advanced maturation and it is intended to modify the nutritional quality of the forages. <strong>Conclusion:</strong> The use of urea can be an alternative to improve the nutritional quality of forages.</p>

Development and Optimization of an Offset Spiral Tooth Fertilizer Discharge Device

Due to factors such as a small amount of fertilizer application during rice topdressing and slow machine speed, the ordinary fertilizer discharge device fails to distribute the fertilizer uniformly and accurately as required, making it difficult to meet the needs of precise rice topdressing. This research focuses on the development of an offset spiral tooth fertilizer discharge device suitable for rice topdressing. The study analyzes the amount of fertilizer discharged in one cycle, the fertilizer force, and the motion of the fertilizer particles. In order to enhance the uniformity of the fertilizer discharge device at a low speed and small volume, the discrete element method is employed to conduct experimental research on the key structural parameters that affect the one-cycle amount of discharged fertilizer and the dynamics of the fertilizer discharge device. Through single-factor tests, it was found that the angle, height, number of spiral teeth, and diameter of the fertilizer discharge wheel are closely associated with the fertilizer discharge performance. To further investigate the impact of these four parameters on the fertilizer discharge performance, a regression combination test of the four factors is conducted based on the range optimized by the single-factor tests. A multi-objective mathematical model, considering the key parameters of fertilizer uniformity coefficient, one-cycle amount of fertilizer, and fertilizer discharge torque, is established at three speeds: 20, 55, and 90 rpm. The response surface method is utilized to analyze the influence of the interaction factors on the fertilizer discharge performance. The optimal combination of the key structural parameters was determined as follows: spiral tooth angle of 35.42°, tooth height of 9.02 mm, discharge wheel diameter of 57.43 mm, and tooth amount of 9.37. The bench test results of the device, using the optimal parameter combination and a fertilizer discharge speed of 0–90 rpm, were obtained for four commonly used rice fertilizers. The maximum variation coefficient of fertilizer discharge was found to be 10.42%. The one-cycle amount of fertilizer discharge was measured to be 19.82 ± 0.72 (A Kang), 17.20 ± 0.69 (Ba Tian), 20.34 ± 0.54 (Yaran), and 14.51 ± 0.44 (granular urea). The fertilizer discharge torque remained stable. These results indicate that the achieved optimization meets the precise fertilizer application requirements and can provide technical support for precise topdressing operations.

Optimizing Nitrogen Sources in Top Dressing for Wheat: Field Study on Growth, Yield, and Ammonia Volatilization.

In alkaline calcareous soils, ammonia volatilization is the primary nitrogen (N) loss process, resulting in the reduced N use efficiency of crops. This study aimed at assessing the impact of different N sources for top dressing on ammonia volatilization, as well as their effects on wheat growth and yield over two years. In each year, half of the recommended N was applied as a basal dose using diammonium phosphate (DAP) and urea. The remaining half was top-dressed 35 days after sowing with various sources: prilled urea (PU), granular urea (GU), ammonium sulfate (AS), and calcium ammonium nitrate (CAN) in the first year; PU, urea coated with a urease inhibitor from 20 g (VnU-20) and 40 g (VnU-40) leaves of Vachellia nilotica, biochar-coated urea (BU), and urease inhibitor paraphenylenediamine-coated urea (PPDU) in the second year. Ammonia volatilization losses were tracked for up to 12 weeks from sowing. Ammonia losses from basal-applied N remained consistent in both years, comprising around 4% of the applied N. In the first year, top-dressed AS resulted in the highest losses, followed by GU, while losses from urea and CAN were statistically similar. In the second year, coated fertilizers showed lower ammonia losses compared to PU, with VnU-40 displaying the least losses, 48% less than PU. Nitrogen concentration in wheat grain and straw exhibited a negative correlation with ammonia losses. The choice of top-dressed N source influenced tillering, biological, straw, and grain yields of wheat. In the first year, CAN provided maximum yield benefits, and in the second year, VnU-20 exhibited 27% more grain yield than PU. These findings suggest that top dressing with coated urea, especially VnU-20, has the potential to reduce ammonia losses, improve crop nitrogen status, and enhance economic yield compared to other nitrogen sources.

Optimized nitrogen application for maximizing yield and minimizing nitrogen loss in film mulching spring maize production on the Loess Plateau, China

Excessive use of N fertilizers (driven by high-yield goals) and its consequent environmental problems are becoming increasingly acute in agricultural systems. A 2-year field experiment was conducted to investigate the effects of three N application methods (application of solid granular urea once (OF) or twice (TF), application of solid granular urea mixed with controlled-release urea once (MF)), and six N rates (0, 60, 120, 180, 240, and 300 kg N ha−1) on maize yield, economic benefits, N use efficiency, and soil N balance in the maize (Zea mays L.) film mulching system on the Loess Plateau, China. The grain yield and economic return of maize were significantly affected by the N rate and application method. Compared with the OF treatment, the MF treatment not only increased the maize yield (increased by 9.0–16.7%) but also improved the economic return (increased by 10.9–25.8%). The agronomic N use efficiency (NAE), N partial factor productivity (NPFP) and recovery N efficiency (NRE) were significantly improved by 19.3–66.7, 9.0–16.7 and 40.2–71.5%, respectively, compared with the OF treatment. The economic optimal N rate (EONR) of the OF, TF, and MF was 145.6, 147.2, and 144.9 kg ha−1 in 2019, and 206.4, 186.4, and 146.0 kg ha−1 in 2020, respectively. The apparent soil N loss at EONR of the OF, TF, and MF were 97.1–100.5, 78.5–79.3, and 50.5–68.1 kg ha−1, respectively. These results support MF as a one-time N application method for delivering high yields and economic benefits, with low N input requirements within film mulching spring maize system on the Loess Plateau.

Compression Strength and Critical Impact Speed of Typical Fertilizer Grains

The application of fertilizer is necessary for the growth and yield of crops, especially for paddy rice. Precision application is important for the fertilizer utilization rate and sustainable development of agriculture. However, the crushing of fertilizer grains will reduce the quality of fertilization, for the decrease in the size and mass of the fertilizer particles and the degree of crushing mainly depend on the physical and mechanical properties of the fertilizer grains. In this study, the compression strength and critical impact speed of four typical commonly used fertilizer grains, a compound fertilizer of nitrogen, phosphorus, and potassium (NPK compound fertilizer), organic fertilizer, large granular urea, and small granular urea, were measured and analyzed. The static compression test was carried out using a TMS-Pro texture analyzer and the results show that the four kinds of fertilizer grains are brittle materials, and their elastic moduli are 208 MPa, 233 MPa, 140 MPa, and 107 MPa, respectively; the theoretical impact model of fertilizer granules is established based on the compression test result and Hertz elastic contact theory, the theoretical formula for the critical impact speed of fertilizer grains is derived, and the theoretical critical impact strength and speed are worked out. An image capture system for the impact process of fertilizer grains was developed, and the impact test was conducted. The results show that the critical impact speed of the four kinds of fertilizer grains decreases with the increase in granule size, while the variance analysis shows that the effect is not significant. The comparison of the experimental results with the theoretical values shows that the theoretical formula could be used to predict the trends of the critical impact speed of fertilizer grains. The model was optimized with the MATLAB 2018 function fitting tool based on the test and analysis. The goodness of fit of the formula is 0.824, which is 13.43% greater than that of the original theoretical formula, indicating that the modified formula based on the compression test data might estimate the critical impact speed of the granular fertilizer with brittle material properties more accurately. The results may provide a reference for the parameter design of a precision fertilization machine.

Integrating enhanced efficiency fertilizers and nitrogen rates to improve Canada Western Red Spring wheat

Granular urea fertilizer applied at planting is prone to nitrogen (N) losses in certain environments. Enhanced efficiency fertilizers (EEFs) are developed to mitigate losses and optimize plant uptake. To determine the benefits of EEFs in grain yield and quality enhancement in Canada Western Red Spring (CWRS) wheat, an experiment was conducted from 2019 to 2022 at eight sites in Alberta and Saskatchewan, Canada. The effects of five N sources [urea; urea + urease inhibitor, N-( n-butyl)thiophosphoric triamide (NBPT); urea + nitrification inhibitor, nitrapyrin; urea + dual-inhibitor, NBPT + dicyandiamide; and polymer-coated urea, ESN® (Environmentally Smart Nitrogen®)] and four N rates (60, 120, 180, and 240 kg N ha−1) on CWRS wheat production were examined. Results indicated that N source affected grain yield in Dark Brown Chernozem soils but not in Black Chernozem or Dark Grey Luvisol soils. In Dark Brown Chernozem soils, a dual inhibitor increased grain yield by 3.1% and 3.9% relative to urea and polymer-coated urea, respectively, while all other EEFs attained similar results. The use of a dual inhibitor EEF led to greater net returns compared to urea and polymer-coated urea in the Dark Brown Chernozem soils. Grain protein concentration increased linearly with increasing N rate from 60 to 240 kg N ha−1. Generally, a rate of 120 kg N ha−1 was optimal for CWRS wheat grown in Canadian prairie conditions when coupled with EEFs, particularly a dual inhibitor, and grain yield and protein were often responsive.

Enhanced efficiency urea fertilizers and timing effects on N2O emissions from spring wheat production in Manitoba

AbstractOpportunities exist to reduce nitrous oxide (N2O) emissions from nitrogen (N) fertilizers using enhanced efficiency fertilizers (EEFs) and managing application timing. This study examined (1) application timing (fall/spring) and (2) fertilizer N source on N2O emissions, yield, and N uptake of Canadian hard red spring wheat (Triticum aestivum L.) in Southern Manitoba. Fertilizer N sources included granular urea and four EEF products: (1) polymer‐coated urea (environmentally smart nitrogen [ESN]); (2) urea plus nitrification inhibitor (eNtrench); (3) urea plus urease inhibitor (Limus); and (4) urea plus nitrification and urease inhibitor (SuperU). Nitrification‐inhibited products most consistently reduced N2O emissions while maintaining productivity. Compared to urea alone, urea + eNtrench was most effective in reducing cumulative N2O emissions by 47%–64% at four of six site‐years. SuperU reduced N2O emissions by 37%–57% at three of six site‐years. ESN and urea + Limus did not affect emissions in most years. Wheat yield, protein, and N uptake were unaffected by N source in five of six site‐years. Compared to spring, fall application gave greater N2O emissions by 33%–67% at three of six site‐years due to spring‐thaw emissions. Fall was inferior to spring application in wetter site years with lower yield, protein, and N uptake. Overall, nitrification‐inhibited products—either alone or with a urease inhibitor—are a promising tool to reduce N2O emissions while maintaining wheat productivity in Manitoba. However, given that there were few consistent increases in yield or protein, the additional cost of the inhibitors will be a barrier to adoption.

Growth response of corn due to application of simple mixed compound fertilizer derived from urea - azolla (azolla sp.) - coal fly ash

Mixing urea with natural materials that can reduce the rate of urea dissolution is known to increase the N availability replenished by inorganic fertilizers which absorbed by plants for growth and production.This study aimed to examine the effective of application of pellet N fertilizer prepared by coal fly ash- azolla and urea on the response of corn planted in acidic Ultisol. This pot experiment was performed in the greenhouse and soil analysis was conducted in the Laboratory of Chemistry, Biology and Soil Fertility, Soil Science Department, Faculty of Agriculture, Sriwijaya University. The research was arranged using a completely randomized design with nine treatments and three replications. The treatments applied were a mixed composition materials (w/w) of 50% coal fly ash + 50% azolla, and 40% coal fly ash + 60% azolla respectively. Each composition (w/w) of 70% coal fly ash- Azolla mixture was then incorporated by 30% urea and compacted as pellets using a manual screw extruder. In addition, to compare the effect of pellet, it was done the other treatment by granular urea fertilizer only applied by immersing and sowing on the soil surface. The results showed that the application of N slow release using the pellet forms significantly increased N availability, plant N uptake, plant height and dry weight of corn. The N slow release as a pellet can reduce the dose of N inorganic fertilizer as urea by 25%. The response of corn at a dose of 0.75 times is not significantly different from the dose of 1 times the recommended dose of N.

The effect of metal oxide coating of urea on mineralization in two contrasting soils

AbstractUrease inhibitors are used to delay the conversion of N supplied to soil as urea to better match the mineral N supply to crop demand. Using soil in petri dishes, we compared the spatial and temporal mineral N dynamics close to the site of urea addition for two soils of contrasting texture—sandy soil (2% clay) and clay soil (51% clay)—treated with N fertilizer products that had the potential to inhibit urease. The treatments included trace metal oxide coatings (ZnO, NiO, and CuO) of granular urea fertilizer, N‐(n‐butyl)thiophosphoric triamide (NBPT; a commercial urease inhibitor) coated urea and uncoated urea. In the sandy soil, NBPT inhibited urea hydrolysis, whereas the metal oxide–coated urea had little effect. Unlike in the sandy soil, the most striking result for the clay soil was the “disappearance” of mineral N in the latter part of the incubation. However, a delay in the disappearance of mineral N, hence a higher recovery, for the NBPT‐urea and CuO‐urea was observed at day 14 in the clay soil presumably due to the slower hydrolysis of urea compared to other treatments. Overall, the study of both spatial and temporal mineral N dynamics in soils supplied with urea fertilizers suggests that CuO‐coated urea could have properties that delay the hydrolysis of urea in certain soils. Given the strongly contrasting outcomes for the two soils, further experiments with soils that span the range of texture between these two extremes are warranted.

Placement and nitrogen source effects on N2O emissions for canola production in Manitoba

AbstractThis study examined fertilizer nitrous oxide (N2O) emissions and canola (Brassica napus L.) grain yield for two granular urea sources (conventional and a dual urease and nitrification inhibitor [SuperU]) and three at‐planting placement methods (broadcast‐incorporated, shallow banded, and deep banded) on commercial fields in Manitoba. Nitrogen (N) rates were 100% and 70% of what was recommended based on soil test and target yield, with the 100% treatments having N2O emissions monitored. SuperU fertilizer consistently reduced N2O emissions (area‐, N‐applied‐, and yield‐based) compared to urea. Significant reductions in N2O emissions with SuperU occurred in four of six site‐years and coincided with delayed nitrification. Compared to broadcast‐incorporated, subsurface banding of conventional urea reduced N2O emissions in drier site‐years but increased emissions when rainfall was higher (especially in shallow banded urea). Across all six site‐years, shallow banding of urea resulted in significantly higher emission intensities than all other treatments. Nitrogen placement did not affect the emission reduction benefit of SuperU. N source or placement did not greatly affect canola yield within either 100% or 70% N rates. Fertilizer N recovery efficiency was also not greatly impacted by either N source or placement. The results demonstrate that dual inhibited granular urea fairly consistently reduces N2O emissions in canola production in southern Manitoba, whereas nitrogen placement had variable effects depending on growing season rainfall. However, with little agronomic benefit, the added cost of enhanced efficiency fertilizers must be overcome for widespread adoption and to achieve greenhouse gas reduction targets for the Canadian agriculture sector.

Measurement of grass uptake of the urease inhibitor NBPT and of the nitrification inhibitor dicyandiamide co-applied with granular urea.

Grass uptake and phytoaccumulation factors of N-(n-butyl) thiophosphoric triamide (NBPT) and dicyandiamide (DCD) were quantified. Following the application of urea fertilizer treated with the inhibitors in Irish grassland, grass samples were collected at 5, 10, 15, 20, and 30day time intervals following five application cycles. Uptake of NBPT by grass was below the limit of quantitation of the analytical method (0.010mg NBPT kg-1). Dicyandiamide concentrations in grass ranged from 0.004 to 28mgkg-1 with the highest concentrations measured on days 5 and 10. A reducing trend in concentration was found after day 15. The DCD phytoaccumulation factor was ranged from 0.004% to 1.1% showing that DCD can be taken up by grass at low levels when co-applied with granular urea. In contrast, NBPT was not detected indicating that grass uptake is unlikely when co-applied with granular urea fertilizer. The contrasting results are likely due to very different longevity of DCD and NBPT along with the much lower rate of NBPT, which is used compared with DCD.

New trends in sugarcane fertilization: Implications for NH3 volatilization, N2O emissions and crop yields

Recycling nutrients helps to reduce the environmental impact of agriculture and contributes to alleviating the effects of global climate change. A recent trend in sugarcane cultivation is the application of concentrated vinasse (CV) combined with fertilizers into an organo-mineral formulation to improve logistics, reduce costs and foster the circular economy. However, the implications of the application of such organo-mineral formulation in sugarcane fields are unclear. In this study, we evaluated the effects of the organo-mineral formulation containing granular urea (UR), and a nitrification inhibitor (NI) on crop yields, NH3 volatilization, and N2O emissions. Field experiments were conducted during two fertilization seasons, dry and wet, and the treatments were: control; UR; UR + NI; CV; CV + UR; and CV + UR + NI. CV was applied at 7 m3 ha−1. The treatments (except control and CV) were balanced to receive the same amount of N and K. Compared with UR, the organo-mineral formulation of CV + UR decreased NH3 volatilization losses from 7% to 4% in the dry season and from 3.5% to 0.5% in the wet season. Conversely, compared with UR, N2O emissions increased significantly (p ≤ 0.05) in CV + UR in the wet season from 1% to 2% of applied N. In the dry season, no differences were observed. The addition of NI was effective in mitigating N2O emissions in both seasons. Emission reductions ranged from 43 to 48% in the dry season and from 71 to 84%, in the wet season. Fertilization with UR or the organo-mineral formulation influenced sugarcane yield only in the dry season, with the highest yield in CV + UR. NI did not affect crop yield. In general, emission intensities (kg CO2eq Mg−1 of stalk) were highest in CV + UR. We conclude that the organo-mineral formulation reduced NH3 losses and increased N2O emissions compared with regular solid fertilizer and that NI was effective for mitigating N2O emissions.

Nitrogen leaching and groundwater N contamination risk in saffron/wheat intercropping under different irrigation and soil fertilizers regimes

The ever-rising trend of nitrate leaching from the agricultural production systems is a major risk to the contamination of ground- and surface-waters and should be addressed. But so far, there has been no study on the reduction of nitrate leaching from saffron fields through intercropping. Saffron growers can make a sustainable use of the saffron inter-row spaces through the strategy of winter-wheat/saffron base intercropping system to reduce nitrate leaching. During four years of study, in a set of lysimeters, effects of two cropping systems (saffron mono-cropping and saffron–wheat intercropping), application of two sources of nitrogen (organic cow manure and chemical granular urea) and four irrigation regimes [40, 60, 80, and 100% of the standard crop evapotranspiration (ETc)] on plant nitrogen and phosphorus uptake, nitrogen leaching and nitrogen and phosphorus efficiencies were investigated. The optimum irrigation regime was experienced at 60% ETc (with irrigation application efficiency of 60%, equivalent to 100%ETc) where the highest saffron and wheat nutrient (nitrogen and phosphorus) uptake, nutrient (nitrogen and phosphorus) harvest indices, nutrient acquisition and use efficiencies, corm, saffron, and grain yields and lowest nitrogen loss was achieved. Moreover, manure application indicated 12, 42, 50 and 46% lower amounts of drained water, leachate nitrate nitrogen concentration, total leached nitrogen and N losses (other than N leaching), respectively, in comparison to the urea source of nitrogen showing the lower risk of groundwater nitrate pollution. Manure application showed 9, 8 and 9% increase in the concentration of corm nitrogen, phosphorus and protein, respectively, in comparison to urea application treatment. Saffron corm and stigma yields, irrigation and economic water productivities, corm nitrogen use efficiency and saffron-plant-nitrogen-acquisition efficiency in manure application surpassed respectively by 21, 25, 20, 17, 39 and 49% compared with the chemical source of nitrogen. Intercropping showed 10, 11, 23 and 64% lower amounts of drained water, nitrate concentration in drainage water, seasonal leached nitrate and N losses (other than N leaching), respectively compared to saffron sole cropping which reduces the risk of groundwaters nitrate contamination. For all the experimental treatments, empirical regression models were derived for estimation of seasonal leached nitrate based on the seasonal drained water. Intercropping saffron with winter wheat, application of organic cow manure and adopting irrigation regime of 60% ETc is an innovative system of saffron production which mitigates the risk of groundwater nitrate contamination and increases irrigation and economic water productivities. Saffron growers can make sustainable and clean use of the inter-row spaces of the saffron crop to grow winter wheat in order to obtain higher economic water productivity and lower groundwater nitrate pollution, and it is highly recommended to maintain a sustainable environment.