Prilled Urea Research Articles

Dynamics of dry matter and nitrogen distribution in transplanted rice on mollisols

We studied the dynamics of dry matter (DM) and nitrogen (N) distribution in different plant parts (leaf, stem, and panicle) and grain yield of transplanted rice due to N management practices through neem coated urea (NCU). The results indicated that application of NCU at 125% recommended dose of N (RDN) with 50:25:25 split schedule at basal (B), active tillering (AT), and panicle initiation (PI) stages resulted in higher DM and N distribution to leaf, stem, and panicle at 60 and 90 days after transplanting and harvest than the application of prilled urea at 100% RDN with the same split schedule (existing practice). Further, the increment in grain yield was 10.95% than the existing practice. Hence, we suggest the application of NCU at 125% RDN with 50:25:25 split schedule at B, AT, and PI stages for achieving higher DM and grain yield on Mollisols.

Energy auditing and carbon footprint under long-term conservation agriculture-based intensive maize systems with diverse inorganic nitrogen management options

A greater energy grant in diesel-fed machinery driven farming substantiate the higher GHGs emission along with improper input (fertilizer, pesticide and irrigation) use and intensive soil management. Practicing conservation tillage, residue retention and diversified crop rotations were advocated because of their multiple benefits. Hence we explored the energy requirement and carbon footprint of conservation agriculture (CA) based maize production systems. Coated N fertilizer [sulphur coated urea (SCU) and neem coated urea (NCU)] were compared with unfertilized and uncoated prilled urea (PU) in the scenario of with and without residue retention on permanent beds (PB) under diversified maize systems [MMuMb, maize-mustard-mungbean and MWMb, maize-wheat-mungbean] in search of a sustainable and energy efficient production system with lesser C-footprint. Results of the 4-year study showed that crops planted on permanent bed with crop residue (PB+R) registered 11.7% increase in system productivity compared to PB without residue (PB−R). N management through Neem coated urea (NCU) recorded 2.3 and 10.9% higher system productivity compared with non-coated prilled urea plot under PB−R and PB+R, respectively. MMuMb was marginally superior than MWMb system in terms of cropping sequence yield, profitability, and energy and carbon use efficiency. Crop residue retention in zero tilled PB increased cost of cultivation by 125 and 147 USD/ha in MMuMb and MWMb systems, respectively. The quantified carbon footprint value was higher in MWMb system. In CA-based practices, crop residues management contributed the highest energy input (61.5–68.4%) followed by fertilizer application (17–20%). Among N management practices, neem coated urea (NCU) significantly improved system productivity and profitability in all the residue applied plots compared to un-fertilized and prilled urea (PU) applied plots. Similarly, higher energy output was also observed in NCU treated plots. However, carbon footprint value was higher in PU (268–285 CO2-e kg/Mg) plots than NCU (259–264 CO2-e kg/Mg) treated plots. Thus, the study supports and recommends that the CA-based MMuMb system with efficient N management through NCU is an environmentally safe, clean and energy efficient one, hence can reduce carbon footprint, will ensure food security and will mitigate climate change.

Effect of graded doses of neem coated urea on productivity of low land rice

A field experiment was conducted in the Research field of Regional Research and Technology Transfer Station, Coastal Zone, OUAT to study the efficiency of neem coated urea (NCU) on yield and yield attributing characteristics of low land rice. Results revealed that application of 80 kg N ha -1 as NCU was effective over application of 100 kg N ha-1 as prilled urea (PU). The highest plant height (109.8 cm) panicle length (24 cm) and effective tiller (11.5) was observed with T5 (100 kg N ha-1 as PU) whereas lowest value of 84.5 cm, 20.6 cm and 9.1 cm for plant height, panicle length and effective tillers per hill respectively were recorded with T 1 (control). The highest grain yield of 47.3 q ha -1 was observed in T8 (80 kg N ha-1 as NCU) where as lowest value - of 32.7 q ha-1 was observed in T1 (control). The grain yield of rice under T5 (100 kgN ha-1 as PU) was 47.0 q ha1 which was statistically at par with T8 (80 kg N ha-1 as NCU) indicating the higher efficiency of NCU than that of PU. With the doses at 80 kg N ha-1 the yield advantages was due to application of NCU which had a 5.1% more yield advantages than that of PU. The straw and harvest index followed the same trend as that of grain yield of rice. The highest B: C ratio of 1.44 was observed with application of 80 kg N ha -1 as NCU where as the B: C value of 1.42 was observed with application of 100 kg N ha -1 as PU indicating the efficiency of NCU than that of PU application.

Controlled-release fertilizer enhances rice grain yield and N recovery efficiency in continuous non-flooding plastic film mulching cultivation system

Non-flooding plastic film mulching (PM) cultivation is a promising water-saving technology for rice cultivation. However, because the N fertilizer can only be applied before transplanting due to technical difficulties with later applications, it results in excessive vegetative growth and potential N shortages during the reproductive stages, which may limit grain yield potential. The use of polymer-coated urea (PCU), a slow release N fertilizer, has become one of the best management practices for increasing crop yield and improving N recovery efficiency in traditional flooded rice cultivation (TF), but has not been tested in PM cultivation. The objective of the eight-year (2008–2015) field experiment in the present study was to compare the effects of PCU with a conventional prilled urea fertilizer (PU) and a control (no N fertilizer applied; CK) on grain yield, N recovery efficiency, yield components, and soil nutrients under PM and TF cultivation systems. Within fertilizer treatment, plant N uptake and N recovery efficiency were almost always significantly higher in the PM than the TF cultivation treatments. PCU application significantly increased these parameters in both cultivation systems, but usually by significantly more with PM cultivation. Compared to the PU treatment, PCU significantly increased rice grain yield in both cultivation systems every year (by means of 11% and 15% in the TF and PM, respectively), except for TF in the first year. Within fertilizer treatment, yields of PM and TF were similar. In comparison with PU, the use of PCU had no effect on soil organic matter or alkali-hydrolyzable N. However, PM cultivation decreased these parameters. In conclusion, PCU application increased the N recovery efficiency and N availability in both cultivation systems during the reproductive stages of rice, and thus improved rice grain yield. We demonstrated that the application of PCU is a practical N fertilizer management technique that improves rice grain yield and N recovery efficiency, and is an effective solution to fertilization challenges in PM rice cultivation systems.

Response of broccoli to USG and prilled urea in shallow red-brown terrace soil under Madhupur tract

A field experiment was conducted at Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur during the period from 2012-13 to verify the effectiveness of urea super granule (USG) and prilled urea (PU) on the yield and quality of broccoli, to assess the comparative performance of USG and PU on nutrient uptake and nitrogen use efficiency and to evaluate the effect of USG and PU on post-harvest nutrient status in Shallow Red-Brown Terrace Soil of Madhupur Tract (AEZ-28). The experiment was designed in a randomized complete block with three replications having 5 treatments as T1: Control, T2: USG-N140, T3: USG-N160, T4: USG-N180 and T5: PU-N180. Result showed that USG performed better than PU. The comparative performance of USG in relation to yield, head quality (ascorbic acid, β-carotene and chlorophyll content), SPAD value, nutrient (NPKS) uptake and N use efficiency was found higher as compared to PU. USG treated broccoli plants gave significantly higher yield where the highest yield (13.49 ton ha-1) was recorded with USG-N160 kg ha-1. Moreover, USG showed higher β-carotene and chlorophyll content over PU and those were increased with increasing levels of N. However, ascorbic acid content was slightly decreased with increasing rate of N fertilizer. Nitrogen, phosphorus and potassium uptake increased with increasing N rate upto USGN180 but sulphur uptake was increased upto USG-N160. Nitrogen use efficiency was higher in USG treated plots than that of PU having the highest value of 111.71% with USG-N160 kg ha-1. Post-harvest soil nutrient status was not significantly influenced by the treatments although it was slightly higher in USG as compared to PU. Considering all, USG @ 160 kg N ha-1 (USG-N160) with other recommended fertilizers (@ 53 kg P, 83 kg K, 20 kg S, 2.0 kg Zn, 1 kg B and 0.8 kg Mo ha-1) could be the best USG based fertilizer dose for quality broccoli production in Shallow Red-Brown Terrace Soil of Madhupur Tract.Bangladesh J. Agril. Res. 43(4): 557-574, December 2018

Nitrous oxide and nitric oxide emissions from lowland rice cultivation with urea deep placement and alternate wetting and drying irrigation

Urea deep placement (UDP) and the alternate wetting and drying (AWD) irrigation method are two promising rice production technologies. However, studies on the impact of UDP under AWD irrigation on nitrous oxide (N2O) and nitric oxide (NO) emissions are limited. In this study, the effects of UDP with AWD irrigation on these emissions, nitrogen use efficiency (NUE), and rice yields are investigated, compared to conventional broadcast application. N2O and NO emissions from three fertilizer treatments – no nitrogen, UDP, and broadcast application of prilled urea (PU) – were measured. Measurements were taken using an automated gas sampling and analysis system continuously for two consecutive Boro (dry) rice seasons. N2O emission peaks were observed after broadcast application of PU but not after UDP. In contrast, large spikes in N2O emission were observed after UDP, compared to broadcast application, during dry periods. Despite differences in emission peaks, seasonal cumulative N2O emissions from UDP and broadcast treatments were similar. However, NO emissions were minimal and unaffected by UDP or AWD. UDP increased rice yields by 28% and N recovery efficiency by 167%, compared to broadcast urea. This study demonstrates that UDP with AWD irrigation can increase yields and NUE without increasing N2O and NO emissions.

Determination of economic efficiency of deep placement and foliar application of urea fertilizer through the performance of boro rice cv. BRRI dhan29

Rice is the most extensively cultivated cereal crops in Bangladesh and nitrogenous fertilizer, especially urea is the most pressing fertilizer to supply nutrient in the paddy field. With this view, an experiment was conducted to evaluate the effect of deep placement and foliar application of urea fertilizer on BRRI dhan29 rice cultivar in boro season at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh during December 2015 to May 2016. The experiment was laid out in a randomized complete block design considering twelve treatments with three replications. The treatments were- T0 ( No N application), T1 [140 kg N/ha (as prilled urea)], T2 (1.8 g 1-USG + 5 foliar spray @ 1% N solution), T3 (1.8 g 1-USG + 5foliar spray @ 1.5% N solution), T4 (1.8 g 1-USG + 5 foliar spray @ 2% N solution), T5 (1.8 g 2-USG), T6 (2.7 g 1-USG), T7 (2.7 g 1-USG + 3 foliar spray @ 1% N solution), T8 (2.7 g 1-USG + 3 foliar spray @ 1.5% N solution), T9 (2.7 g 1-USG + 3 foliar spray @ 2% N solution), T10 (1.8 g 2-USG + 3 t/ha cowdung), T11 (2.7 g 1-USG + 3 t/ha cowdung). Results showed that the grain and straw yield of the rice variety responded significantly to the application of prilled urea (PU), deep placement of USG and foliar application of N. The highest grain yield (4.8 t/ha) was recorded in T8 which was identical to the yield (4.7 t/ha) obtained in T3. The highest straw yield (6.0 t/ha) was found in T5. The lowest grain yield (3.7 t/ha) and straw yield (4.5 t/ha) were found in T0. Considering the economic efficiency, the treatment T8 showed the maximum gross margin and marginal gross margin with lowest cost per unit of product. Therefore, to get highest grain yield (4.8 t/ha), 82 kg N/ha as USG and 3 foliar spray of N @1.5% concentration i.e. total 219 Kg urea/ha can be applied to the rice field of BRRI dhan29. This will save an amount of 81 Kg urea per rice growing season per hectare.Res. Agric., Livest. Fish.5(2): 157-164, August 2018

Comparing Closed Chamber Measures of Ammonia Volatilization from Kentucky Bluegrass Fertilized by Granular Urea1

Abstract Easy handling and low unit N cost make prilled urea (46-0-0) a popular fertilizer. While incomplete recovery of granular urea applications by turfgrass is documented, practical guidance for small-plot field assessment of ammonia (NH3) volatilization remains limited. Our objectives were to (i) develop a method for field-implementation of closed flux/dynamic chambers to measure ammonia emission over a 3-day period following granular urea application to turfgrass, and (ii) infer the significance of said measures to levels arising from simultaneous static-chamber measures. A Kentucky bluegrass (Poa pratensis L. ‘Midnight’) lawn was treated with granular urea-N at a rate of 0 or 43 kg.ha−1 (38 lb/A) twice in both 2014 and 2015. Flux chamber measures of mean ammonia volatilization from urea-N fertilizer applied 3 days previous exceeded simultaneous static chamber measures by a factor of 17. Relative to static, the closed dynamic/flux chamber system described affords a more precise and efficient method for measuring ammonia volatilization from small field plots. Furthermore, over a 3-day period of dry conditions and ambient temperatures fluctuating between 10 and 31 C (50 and 88 F), as much as 23.1% of a granular urea application broadcast over a Kentucky bluegrass lawn can be volatilized as ammonia. Index words: flux, gaseous emissions, methods, nitrogen, static, turfgrass. Species used in this study: ‘Midnight' Kentucky bluegrass (Poa pratensis L.).

Nitrogen Recovery and Loss from Kentucky Bluegrass Fertilized by Conventional or Enhanced-Efficiency Urea Granules

Easy handling and low unit N cost make prilled urea (46-0-0) a popular fertilizer. While incomplete recovery of granular urea applications by turfgrass is documented, field evaluations of NH3 volatilization mitigation by coatings or bioinhibitor efficiency enhancements are limited. Meanwhile, NH3 emissions reduce air quality and contribute to nutrient loading of water resources. Our objectives were to quantify 3- and 6-d ammonia emission and 9-week turfgrass recovery of unincorporated granular fertilizer application to turfgrass. In 2014 and 2015, commercial urea-N fertilizers were broadcast over a mature Kentucky bluegrass (Poa pratensis L. ‘Midnight’) lawn at 43 kg ha−1. Treatments included conventional urea and three enhanced-efficiency fertilizers; a blended fertilizer with 25% of its urea-N supplanted by polymer- and polymer-/sulfur-coated prills, or two stabilized urea fertilizers both amended by N-(n-butyl) thiophosphoric triamide (NBPT) and dicyandiamide (DCD) inhibitors. Using a 51% ‘trapping-efficiency’ flux chamber system under the field conditions described, 23.1 or 33.5% of the conventional urea-N was lost as NH3 over the respective 3- or 6-d period following application. Alternatively, dual amendment by NBPT and DCD resulted in approximately 10.3 or 19.6% NH3-N loss over the respective 3- or 6-d periods, and greater fertilizer-N recovery by the turfgrass over the 9-week experiments.

Response of Some Landrace Rice (<i>Oryza sativa</i> L.) Cultivars to Applied Nitrogen in Lowland Ecosystem

An experiment was conducted to determine the effects of nitrogen (N) fertilization on growth and yield of some landrace rice (Oryza sativa L.) cultivars in lowland ecosystem. Three popular landrace rice cultivars: Rajashail, Kutiagni and Sadamota were treated with five times of N application viz. (i) two split applications of prilled urea (PU) at 10 days after transplanting (DAT) and before panicle initiation (PI) stage, (ii) deep placement of urea super granule (DPUSG) at 10 DAT, (iii) DPUSG before PI stage, (iv) PU application before PI stage and (v) control. The results showed that the landrace rice cultivar Kutiagni had the highest number of tillers under PU, while Rajashail gave the highest number of tillers under DPUSG applied before PI stage. Further, Kutiagni produced higher amount of dry matter under two splits of PU, while Rajashail produced higher amount of dry matter under DPUSG applied before PI stage. However, application of PU before PI stage significantly increased leaf area index in all the three landraces. The varieties responded to applied N and produced the highest yield in Kutiagni. The DPUSG at 10 DAT increased straw yield but failed to increase grain yield even over control. The DPUSG before PI stage significantly increased rice yield and economic return. The yield of rice in DPUSG applied before PI stage was comparable to two splits of PU and top dressing of PU before PI stage. Compared to control (2.93 t ha-1), yield increase was 26% in Kutiagni (3.70 t ha-1) under DPUSG before PI stage. These results suggest that Kutiagni was more responsive to added N and this cultivar could be cultivated with DPUSG at PI stage.The Agriculturists 2018; 16(1) 01-12

Enhancing Rice Productivity through integration of Stress Tolerant Rice Varieties and Improved Nutrient Management Practices in Saline Areas of Bangladesh

The study was conducted in two locations of coastal districts Patuakhali and Satkhira during 2012 and 2013 T. Aman season. Stress tolerant rice varieties along with nitrogen application using prilled urea (PU), leaf color chart (LCC), urea super granule (USG), and rice crop manager (RCM) software based nitrogen (N) dose were examined. The objectives of the study were to identify the response of saline tolerant varieties to N fertilization on grain yield and profitability. Among the tested varieties, grain yield of BRRI dhan40, BRRI dhan41 and BRRI dhan54 were higher compared to BRRI dhan52 and BRRI dhan53 irrespective of location. There were no significant difference among the better performed varieties. Interaction effect of yield was significant in 2013 at Patuakhali but insignificant in both the locations in 2012. During 2013 in Patuakhali, the interaction effect of BRRI dhan40 × USG and BRRI dhan41 × USG produced higher grain yield and total N uptake. In Satkhira BRRI dhan54 and BRRI dhan40 performed better and produced higher grain yield and N uptake. Among the N application treatments USG application was the best compared to either LCC or RCM. The combination of BRRI dhan54×USG and BRRI dhan41×USG had more economic gains in both 2012 and 2013 in Patuakhali. The combination of BRRI dhan52×USG and BRRI dhan41×LCC appeared as themost profitable in Satkhira during 2013. Integration of saline tolerant varieties along with USG application could improve the yield of saline tolerant rice in saline environmentBangladesh Rice j. 2017, 21(1): 77-89

Nitrapyrin affects the abundance of ammonia oxidizers rather than community structure in a yellow clay paddy soil

PURPOSE: Yellow clay paddy soil (Oxisols) is a low-yield soil with low nitrogen use efficiency (NUE) in southern China. The nitrification inhibitor nitrapyrin (2-chloro-6- (tricholoromethyl)-pyridine, CP) has been applied to improve NUE and reduce environmental pollution in paddy soil. However, the effects of nitrapyrin combined with nitrogen fertilizers on ammonia oxidizers in yellow clay paddy soil have not been examined. MATERIALS AND METHODS: A randomized complete block design was set with three treatments: (1) without nitrogen fertilizer (CK), (2) common prilled urea (PU), and (3) prilled urea with nitrapyrin (NPU). Soil samples were collected from three treatments where CK, PU, and NPU had been repeatedly applied over 5 years. Soil samples were analyzed by quantitative PCR and 454 high-throughput pyrosequencing of the amoA gene to investigate the influence of nitrapyrin combined with nitrogen on the abundance and community structure of ammonia oxidizers in yellow clay paddy soil. RESULTS AND DISCUSSION: The potential nitrification rate (PNR) of the soil was significantly correlated with the abundances of both ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB). Application of urea significantly stimulated AOA and AOB growth, whereas nitrapyrin exhibited inhibitory effects on AOA. Phylogenetic analysis showed that the most dominant operational taxonomic units (OTUs) of AOA and AOB were affiliated with the Nitrosotalea cluster and Nitrosospira cluster 12, respectively. AOA and AOB community structures were not altered by urea and nitrapyrin application. CONCLUSIONS: Nitrogen fertilization stimulated nitrification and increased the population sizes of AOA and AOB. Nitrapyrin affected the abundance, but not community structure of ammonia oxidizers in yellow clay soil. Our results suggested that nitrapyrin improving NUE and inhibiting PNR was attributable to the inhibition of AOA growth.

Changes in weed community with different types of nitrogen fertilizers during the fallow season

Manipulation of crop fertilization may be an important part of integrated weed management systems. The objective of this study is to investigate the responses of weed community and composition in the fallow season to the different types of nitrogen fertilization. Six treatments were conducted over four consecutive years, including no N fertilizer (N0), conventional prilled urea (PU), polymer coating of sulfur-coated urea (PSCU), urea with nitrification inhibitor (UNI), urea-formaldehyde (UF), and controlled-release bulk blending N fertilizer (70% full dosage of PSCU plus 30% full dosage of prilled urea, BBF). Weed species composition, dominant species biomass, and soil properties were investigated, and indices of weed species diversity were calculated. The results indicated that Mazus japonicus (Thunb.) Kuntze and Alopecurus japonicus Steud. dominated the N0 treatment, whereas Alopecurus japonicus Steud. dominated all N–fertilized treatments. The PSCU treatment produced the greatest shoot biomass (657 g m−2) of Alopecurus japonicus Steud. The N0 treatment had the highest total weed density (365 plants m−2) and Shannon-Wiener index (1.39). Application of PSCU or UF led to significantly lower Shannon-Wiener and higher Simpson indices than did the PU treatment due to high residue soil N contents. The UNI treatment not only produced the highest 4-year average grain yield of double rice, it also maintained a relatively diverse weed community in the fallow season.

Effect of urea super granule and prilled urea on the growth and yield of broccoli

A field experiment was conducted at Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur during the period from 2012-13 to verify the effectiveness of urea super granule (USG) and prilled urea (PU)on growth, yield and yield attributes of broccoli in Shallow Red-Brown Terrace Soil under Madhupur Tract (AEZ-28). The experiment was laid out in a Randomized Complete Block Design with three replications having 5 treatments constituted with different levels of USG and PU as- T1: Control, T2: USG-N140 (140 kg N as USG), T3: USG-N160 (160 kg N as USG), T4: USG-N180 (180 kg N as USG), T5: PU-N180 (180 kg N as PU). Performance of USG was better than PU and the treatment USG-N160 gave the highest yield (13.49 ton ha-1) which was followed by USG-N180 (12.43 ton ha-1) and PU-N180(12.05 ton ha-1) having significant difference among these. Higher but statistically identical number of lateral head 5.103 and 5.38 was produced by USG-N160 and USG-N180 treatments, respectively in comparison with PU-N180 (5.04). But higher lateral head yields (6.05 and 5.03 ton ha-1) were found in USG-N180 treatments followed by PU-N180. All the yield contributing characters and the economic profitability were favorably correlated with these high yield performing treatments with the highest MRR (3336.67%) obtained from USG-N160 which indicated that USG @ 160 kg N ha-1 (USG-N160) is the most economically viable N dose in terms of yield and economics for broccoli production. Therefore, USG @ 160 kg N ha-1 (USG-N160) with other recommended fertilizer could be suggested as USG based fertilizer recommendation for better broccoli production in terms of yield and economics in Silty Clay Loam Soil of Madhupur Tract.Bangladesh J. Agril. Res. 43(1): 53-69, March 2018

Comparative Effects of the Application of Prilled Urea and Urea Supergranules on Flooded Rice in Madagascar

Applying urea supergranules to flooded rice (10 cm deep, 3 weeks after transplantation) is associated with yield increases of 17%, 23%, 22% and 16% (for doses of 27, 54, 81 and 108 units of nitrogen per hectare) compared with prilled urea. Nitrogen-15 can be used to establish the real nitrogen utilization coefficients for the aerial parts of the plant. While the figures are very low for prilled urea (between 4% and 9%), they exceed 25% and 38% for supergranules on the sites studied. The effect of fertilizer form is greater than the dosage factor. The results are discussed in terms of apparent utilization coefficients and mechanism used.

Effect of Different Levels of Urea Super Granule and Prilled Urea on the Crop Quality, Nutrient Uptake and Soil Nutrient Status of Broccoli

A field experiment was conducted at Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur during the period 2010-2011 to assess the effect of urea super granule (USG) and prilled urea (PU) on the quality attributes (Compactness coefficient, Vitamin C, β-carotene and chlorophyll contents) of broccoli, to assess the comparative performance of USG and PU on nutrient uptake and uptake efficiency of broccoli plant, to assess the effect of different forms and levels of urea N on the post harvest soil nutrient status of broccoli field and to select the better doses of USG and PU for quality broccoli production in Shallow Red-Brown Terrace Soil under Madhupur Tract (AEZ-28). The experiment was laid out in a randomized complete block design with three replications having 17 treatments constituted with different levels of urea super granule (USG) and prilled urea (PU) as- T1: N-control, T2: PU-N80, T3: PU-N100, T4: PU-N120, T5: PU-N140, T6: PU-N160, T7: PU-N180, T8: PU-N200, T9: PU-N220, T10: USG-N80, T11: USG-N100, T12: USG-N120, T13: USG-N140, T14: USG-N160, T15: USG-N180, T16: USG-N200, T17 and USG-N220 kg ha-1. Results revealed that the comparative performance of USG in relation to head quality (compactness coefficient, ascorbic acid, β-carotene and chlorophyll content), nutrient (NPKS) uptake and N uptake efficiency was found better as compared to PU. The compactness coefficient, β-carotene and chlorophyll contents were increased with increasing rate of N as well as USG and PU, but ascorbic acid content was slightly decreased with increasing rate of USG and PU. The maximum compactness coefficient (18.61) was found from the treatment USG-N180 that was followed by USG-N160 (18.24) and the highest β-carotene content (0.401 mg/100gFW) was found from USG-N160 followed by PU-N180 (0.40 mg/100gFW). Similarly the highest chlorophyll-a content (0.818 mg/100gFW) was found from USG-N180 followed by USG-N160 (0.814 mg/100gFW) and the highest chlorophyll-b content (1.141mg/100g FW) was recorded from USG-N180. The higher nutrient uptake and N uptake efficiency (108.531%) was obtained from USG treated plots over that of the PU. But N uptake efficiency was decreased with increasing rates of N fertilizer. But post harvest soil nitrogen status did not show any systematic trend although it was found higher in USG over PU. Similarly no remarkable changes were observed in post harvest soil P, K, S and B status for the crop. However, USG @ 160 kg N ha-1 (USG-N160) followed by USG-N140 and PU @ 180 kg N ha-1 (PU-N180) with other recommended doses of fertilizer could be suggested as USG and PU based fertilizer recommendation for a good quality broccoli production in terms of yield and quality in Silty Clay Loam Soil of Madhupur Tract.The Agriculturists 2017; 15(2) 24-39

Effect of Nitrogen and Water Management on Methane Emission of Boro Rice Cultivation in Bangladesh

Water and nitrogen are two key elements required for successful rice cultivation. We examined the responses of nitrogen and water management on methane emission of Boro rice in the field laboratory of Bangladesh Agricultural University research farm, Mymensingh. Three treatments were studied in the field experiment viz, T1: Control plot (no nitrogen fertilizer), T2: Urea super granule (78 kg N/ha), T3: Prilled urea (104 kg N/ha) with three replications under two water management of Continuous Standing Water (CSW) and Alternate Wetting and Drying (AWD). Air samples were collected by the closed-chamber method and methane gas was determined by gas chromatography. The highest CH4 emission was found from CSW plots and the lowest from AWD plots. Under CSW condition, the effects of urea treatments on CH4 emission were not significant. In case of urea treatments, the highest CH4 emission was observed from treatment T3 under CSW condition and T2 under AWD condition and the lowest emission was from the control treatment. The overall results suggest that prilled urea and urea super granule should be applied under AWD and CSW condition, respectively to keep less CH4 emission from irrigated rice agriculture.

Efficacy of Deep Placement of Nitrogen Fertilizers on N Use Efficiency and Yield of Boro Rice (cv. BRRI Dhan29)

The efficiency of nitrogen (N) fertilizers in rice culture is low due to their losses in different ways. An experiment was, therefore, conducted at the Soil Science Field Laboratory of Bangladesh Agricultural University, Mymensingh during boro season of 2016 to evaluate the effect of deep placement of N fertilizers on N use efficiency and yield of BRRI dhan29 under alternate wetting and drying (AWD) condition. The soil was silt loam in texture having pH 6.07, organic matter content 1.10%, total N 0.055%, available P 3.6 ppm, exchangeable K 0.22 me% and available S 11.76 ppm. The experiment was laid out in a randomized complete block design with three replications. There were eight treatment combinations including T1 (Control), T2 (PU, 130 kg N/ha), T3 (USG, 130 kg N/ha), T4 (USG, 104 kg N/ha), T5 (USG, 78 kg N/ha), T6 (NPK briquette, 129 kg N/ha) and T7 (NPK briquette, 102 kg/ha) and T8 (NPK briquette, 78 kg N/ha). All the treatments except T6, T7 and T8 received 25 kg P and 64 kg K /ha as TSP and MoP, respectively. Treatments T6, T7, T8 received NPK briquette fertilizer. Prilled urea (PU) was applied in three equal splits. Urea super granule (USG) and NPK briquettes were applied at 10 day after transplanting (DAT) and the briquettes were placed at 8-10 cm depth in the centre of four hills in alternate rows. The results demonstrate that all the yield components except 1000-grain weight responded significantly to the deep placement of N fertilizers in the form of USG and NPK briquette. The grain and straw yields of BRRI dhan29 were also influenced significantly due to deep placement of N fertilizers under AWD condition. The highest grain yield (6163 kg/ha) was recorded for T3 [USG, 130 kg N/ha) which was statistically similar with T4 (USG, 104 kg N/ha). The highest straw yield (6415 kg /ha) was also found in T3 [USG, 130 kg N/ha]. The lowest grain yield (3266 kg/ha) and straw yield (3637 kg/ha) were found in T1 (Control). The N uptake by BRRI dhan29, N use efficiency and apparent N recovery also showed significant response to the application of PU, USG and NPK briquettes. The maximum N use efficiency of 28.88% was noted in T5 followed by T4 with the value of 26.46% and the minimum value of 17.55% was observed in T2. The results revealed that the deep placement of N fertilizers accelerated the N uptake, N recovery and N use efficiency by BRRI dhan29. Based on grain yield and cost-benefit analysis, it can be concluded that application of 130 kg N/ha as USG is useful for the profitable cultivation of boro rice, BRRI dhan29.

Effect of Nitrogen Sources and Weed Management Options on Weed Growth and Crop Yield of Transplant Aman Rice

A field study was conducted at the Agronomy research field of Bangladesh Agricultural University, Mymensingh, during the period of July to December, 2013 to evaluate the sources of nitrogen and weed management options on weed growth and rice yield. The experiment included four nitrogen sources (100% cowdung, 100% prilled urea, 100% urea super granule, 50% cowdung + 50% prilled urea) and four weed management options (weedy, application of herbicide at 3 DAT, application of herbicide at 3 DAT followed by hand weeding at 21 DAT and weed free). Sources of nitrogen and weed management options had significant effect on tiller number, biomass, SPAD value, panicle number, number of florets panicle-1, grain and straw yield, and weed biomass. The highest grain yield (5.40 t ha-1) was found in the treatment of 50% cowdung + 50% prilled urea with combination of season long weed free. Although 100% prilled urea had significantly similar grain yield to 50% cowdung + 50% prilled urea, however, across the weed management options, 100% urea super granule and 100% cowdung had 15 and 27% lower grain yield. Irrespective of the weed management options, 100% prilled urea had always higher weed biomass and 100% USG, 50% cowdung + 50% prilled urea, and 100% cowdung had 46, 35 and 19% lower weed biomass, respectively, compared with 100% prilled urea. In terms of rice yield and weed management, combined application of organic and inorganic source of nitrogen is better than only chemical or only organic source and pre-emergence herbicide followed by one hand weeding for transplanted aman rice.Bangladesh Agron. J. 2017, 20(1): 85-97

Nitrous oxide and nitric oxide emissions and nitrogen use efficiency as affected by nitrogen placement in lowland rice fields

Urea deep placement (UDP) has demonstrated its benefits of saving N fertilizer and increasing nitrogen use efficiency (NUE) and grain yields. However, studies on its environmental impacts, particularly on nitrous oxide (N2O) and nitric oxide (NO), are limited. We conducted multi-location field experiments in Bangladesh to determine the effects of UDP versus broadcast prilled urea (PU) on N2O and NO emissions, NUE, and rice yields. N2O and NO emissions were measured from three N fertilizer treatments—no N, UDP, and PU—using automated gas sampling and analysis systems continuously for two rice-growing seasons—Aus (May–August) and Aman (August–December). Fertilizer-induced peaks in N2O emissions were observed after broadcast application of PU but were rarely observed after UDP. Total seasonal N2O and NO emissions, yield-scaled emissions, and fertilizer-induced emissions were affected by fertilizer treatments and sites. Though nitrogen fertilizer increased emissions significantly over the control, emissions resulting from UDP and PU were similar. Effects of N placement on grain yields and NUE were site- and season-specific. Of the N placement methods, UDP increased grain yields by 13% (p < 0.05) during the Aman season and gave similar yields in spite of lower N application during the Aus season. UDP increased N recovery from 25 and 16% of broadcast PU to 61 and 73% during the Aus and the Aman seasons, respectively in one site, but was similar in another site. On the other hand, alternate wetting and drying irrigation reduced grain yield and N recovery at the BRRI site during the Aman season.