Urea Supergranules Research Articles

Evaluation of Urea Super Granule as a Source of Nitrogen in Transplant <i>Aman</i> Rice

An experiment was carried out at Bangladesh Agricultural University, Mymensingh to evaluate the effect of urea super granule (USG) as a source of nitrogen on the yield and yield components of transplant Aman rice cv. BRRI dhan39, BRRI dhan46 and BINA dhan7. Five levels of N (viz., 0, 60, 120 kg ha-1 as prilled urea and 60 and 120 kg ha-1 as USG) were taken as experimental treatments. The experiment was laid out in a randomized complete block design with three replications. Plant height, effective tillers hill-1, grains panicle-1 and grain yield varied significantly due to different cultivars. All the yield and yield components except 1000-grain weight were influenced significantly by the levels of nitrogen fertilizer. The highest grain yield (4.82 t ha-1) was recorded in BINA dhan7 and the lowest one (4.30 t ha-1) was recorded in BRRI dhan39. Nitrogen @ 120 kg ha-1 as USG performed the best among the treatments in respect of yield and yield components of rice. The highest grain yield (5.46t ha-1) was obtained from BINA dhan7 with 120 kg N ha-1 as USG which was statistically identical with 60 kg N ha-1 as USG. A considerable amount (31.25%) of prilled urea (PU) nitrogen could be saved by using USG. It may be concluded that USG could be used as N management to achieve better nitrogen use efficiency in reducing N loss than the PU.DOI: http://dx.doi.org/10.3329/pa.v24i1-2.19095 Progress. Agric. 24(1&2): 29 - 37, 2013

Effect of fertilizer management on growth and yield of fragrant fine rice varieties in rainfed condition

A field experiment was carried out at the Banglasesh Institute of Nuclear Agriculture (BINA) farm, Mymensingh during July to December 2010, to find out optimum variety and optimum fertility management of aromatic fine rice grown in transplant rainfed condition. The experiment was laid out in split-plot design with three replications assigning the variety in the main plot and different fertilizer management in the sub-plot. Results indicated that the effect of aromatic fine rice varieties and fertilizer management showed significant variation in respect of yield contributing characters and yield. At harvest, maximum number of effective tillers/hill (12.7 and 12.5), number of grains/panicle (105.6 and 115.2), 1000 grain weight (13.25 and 19.97 g), grain yield (3.29 and 3.30 t/ha) and straw yield (5.0 and 5.7 t/ha) were obtained from the application of T6 (NPKSZn; RD BARC, 2005) @ 126.9, 19.81, 65, 43.3 and 1.8 kg/ha+Cow dung at 5.0 t/ha) and T9 (Urea super granules (USG) @ 1 (1.8 g) granules/spot) + PKSZn; (RD BARC, 2005 @19.81, 65, 43.3 and 1.8 kg/ha). The fertilizer management T6 (NPKSZn; RD BARC, 2005) @ 126.9, 19.81, 65, 43.3 and 1.8 kg/ha+Cow dung at 5.0 t/ha) and T9 (Urea super granules (USG) @ 1 (1.8 g) granules/spot)+PKSZn; (RD BARC,2005 @ 19.81, 65, 43.3 and 1.8 kg/ha) produced the highest grain yield of Ukunimadhu (2.95 t/ha) and Kataribhog (3.96 t/ha).

Integrating best management practices for rice with farmers’ crop management techniques: A potential option for minimizing rice yield gap

The major cereal cropping system in Bangladesh is rice (Oryza sativa L.) in the dry season (Boro) – rice in the wet season (Aman). The average productivity (7tha−1) of this system is far below attainable yields (14tha−1) in farmers’ fields, resulting in a large yield gap mainly due to farmers’ traditional management practices. We evaluated a set of selected best management practices (BMP) along with two N management options in the farmers’ crop management practices for rice in numerous farmers’ fields across 24 villages over 5 contiguous seasons during 2006–2008. Across years, BMP and two N management options increased grain yields compared with the farmers’ practice (FP) by 0.73tha−1 in both Aman and Boro seasons. The higher yield response (24.6% in Aman and 8.6% in Boro season) occurred with BMP in combination with leaf color chart (LCC) aided N management (BMP–LCC) than BMP with Urea Super Granule as N source (BMP–USG). Best management practices and two N management options reduced the yield gap of FP by 45%, with an average of 1.5Mgha−1. The average added net returns with BMP were US$22 to US$120ha−1 in the wet season and US$93 to US$115ha−1 in the dry season. Our study shows that the integration of BMP and either LCC-aided N management or USG as an N source with the farmers’ management techniques and its adoption has the potential to boost rice yield and profit and total rice production in Bangladesh.

An Effect of Fertilizer Management Practices on the Yield of T. Aman Rice under Tidal Ecosystem

The experiment was carried out at the field laboratory of Department of Agronomy, Patuakhali Science & Technology University, Dumki, during the period from July 2011 to December 2011 to assess the comparative advantages of using Urea Super Granule (USG) and NPK briquette over normal urea, Triple super phosphate and Muriate of Potash and also predict the better performing T. aman rice. The effect of different levels of fertilizer was studied on growth, yield and yield attributing character of T. aman. Six fertilizer Treatments (F0= Control(No urea), F1 = Total urea (150 kg ha-1)during land preparation at available tide free time, F2 = Urea (75 kg ha-1)at 2 split, F3 = Urea (50 kg ha-1)at 3 split, F4 = Urea Super Granule (54 kg N ha-1) at 10 days after transplanting and F5 = NPK briquette ( 42Kg N ha-1 9 Kg P ha-1 12 Kg K ha-1)at 10 days after transplanting of T. aman rice). Besides, TSP, MOP , zinc sulphate and Gypsum were applied @100, 70, 50 and 12 kg ha-1 respectively as basal dose. The experiment was laid out in a Split plot design with 3 replications. The analysis revealed that different fertilizer management practices with a few exceptions significantly influenced the growth, yield and yield attributes of the T. aman rice. Plant height, number of effective tillers hill-1, number of non-effective tillers hill-1, panicle length (cm), number of grains panicle-1, number of sterile spikelet’s panicle-1, nitrogen use efficiency (%), straw yield(t ha-1) and grain yield (t ha-1) were found highest when NPK briquette was applied and all the characters showed lowest value when control. Highest number of effective tillers hill-1 (13.00) and grain yield (6.60 t ha-1) was obtained from NPK briquette and where lowest number of effective tillers hill-1 (5.66) and grain yield (4.48 t ha-1).The NPK briquettes showed higher agronomic efficiency than Prilled urea(PU) and Urea super granule(USG). The small size briquettes (2.4 g) could save 33 kg N ha-1 compared to recommended PU. There was no residual effect of NPK briquettes on soil chemical properties.The NPK briquettes were found beneficial to the farmers in tidal ecosystem.

Impact of rice husk charcoal application on soil properties and growth and yield of rice

Fertilizer application in rice farming is an indispensable requirement. Most of the high yielding varieties which are extensively grown throughout the country require recommended levels of fertilizers in order to obtain their potential yields. Therefore, effective and efficient ways of fertilizer application are important. Coated fertilizers are used to improve the efficiency of fertilizer. However, the conventional coated fertilizers such as sulphur coated urea and urea super granules are not popular among the rice farmers in Sri Lanka owing to high cost of the coated fertilizers. One of the most sustainable solutions is application of paddy husk charcoal as a coating material to absorb N fertilizer which release nitrogenous compounds and making them available for plants. Objective of this study was to evaluate paddy husk charcoal coated urea as a slow releasing fertilizer and compare the total N and organic matter in soil and yield of paddy production. A pot experiment was carried out at Meewathura Research field in Yala 2010. Five treatments were used for twenty pots each replicated 4 times, chemical fertilizer only (Treatment 1), paddy husk charcoal coated urea only (Treatment 2), chemical fertilizer with paddy straw compost only (Treatment 3), rice husk charcoal urea with rice straw compost (Treatment 4) and no fertilizer as the control (Treatment 5). One third of urea from the recommended fertilizer was used for the treatment 2 and 4. The soil sampling was done once a week for three months period. The mean total dry biomass for treatment 4 was significantly higher than the means for all other treatments. Considering treatment 2 and 4, rice grain yield was significantly greater in treatments 4 (charcoal coated urea with rice straw compost). Therefore, using charcoal coated urea reduce the two third of urea usage and save 70% fertilizer cost.rice husk charcoal coated urea can potentially be used as a slow releasing nitrogen fertilizer which reduces leaching losses of urea. Key words: Charcoal, slow releasing N fertilizer, coated fertilizers, compost

Urea Super Granule: A Good Source of Nitrogen on Growth Yield and Profitability of Cabbage in Sylhet

An experiment was conducted in Sylhet under AEZ-20 (Eastern Surma-Kushiyara Floodplain) during 2007-08 and 2008-09 to find out the effect of Urea Super Granule (USG) on cabbage. There were five treatments viz. T1: recommended nitrogen (N) dose as prilled urea (PU), T2: recommended N dose as USG, T3: 10% less than recommended dose of N as USG, T4: 20% less than recommended dose of N as USG, and T5: farmers practice (average of 20 farmers N dose used as PU) used in the experiment. Results revealed that yield of cabbage increased significantly due to application of USG over PU. The highest head yield of cabbage 92.04 and 91.36 t ha-1 were obtained from the USG (recommended dose) in 2007-08 and 2008-09, respectively which was statistically similar with USG 10% less than recommended dose (84.78 t ha-1) instead of traditional PU. The treatments T3 and T4 were found more effective over PU, and N loss was also minimum than that of prilled urea where 10-20% N fertilizer could be saved by using USG instead of traditional PU. Regarding economic analysis, the higher returns were also obtained from the treatment T2 which was more profitable in terms of higher gross returns as well as Benefit Cost Ratio (BCR). DOI: http://dx.doi.org/10.3329/jesnr.v5i1.11595 J. Environ. Sci. & Natural Resources, 5(1): 295-299, 2012

Yield of Fine Rice Varieties as Influenced by Integrated Management of Poultry Manure Urea Super Granules and Prilled Urea

Higher grain yield (2.45 t ha-1) was obtained in BRRI dhan34 than that of Kalizira (2.23 t ha-1). Fertilizer application @ 1.8g USG and other inorganic fertilizer ( full dose for T. aman + PM at 3.5 tha-1) gave the highest grain yield (2.85 t ha-1) and lowest grain yield (1.52 t ha-1) was found at control (no PM and NPKS). Grain yields were affected by the interaction of variety and nutrient management. The highest grain yield (2.88 t ha-1) was found in BRRI dhan34 coupled with 1.8g USG and other inorganic fertilizer(full dose for T. aman) + PM at 3.5 t ha-1 and the lowest grain yield (1.24 t ha-1) was found in Kalizira coupled with control (no PM and NPKS). The combination of fine rice BRRI dhan34 and 1.8g USG and other inorganic fertilizer (full dose for T. aman) + PM at 3.5t ha-1 appeared as the best treatment combination for the highest grain yield. DOI: http://dx.doi.org/10.3329/jesnr.v5i1.11567 J. Environ. Sci. & Natural Resources, 5(1): 129 - 132, 2012

Farmers’ attitude towards the use of USG in rice cultivation in three selected villages of Netrakona district

The study was conducted to determine the attitude of farmers towards the use of urea super granule (USG) in rice cultivation and explore relationship between the selected characteristics of the farmers. Data were collected through personal interview from 84 randomly selected USG users in rice cultivation of the three villages under Sadar Upazila of Netrakona district during October to December 2008. A five point Likert scale was used to determine the attitude of farmers. The majority (73.81%) of the farmers had moderately favourable, 21.43% slightly favourable and 4.76% highly favourable attitude towards use of USG in rice cultivation. Level of education, farm size, annual income, farming information, agricultural training exposure and rice farming knowledge of the farmers’ had significant positive relationship but family subsistence pressure had significant negative relationship with their attitude towards the use of USG. DOI: http://dx.doi.org/10.3329/jbau.v9i2.10983 J. Bangladesh Agril. Univ. 9(2): 179–185, 2011

Effect of Variety and Urea Super Granule on Growth and Yield of Wheat

The experiment was carried out at Agronomy Field Lab of Bangladesh Agricultural University (BAU), Mymensingh during the period from November 2009 to March 2010 with a view of finding out the effect of appropriate dose of USG on growth and yield of wheat. Three wheat varieties viz. Shatabdi, Bijoy and Prodip and 6 levels of nitrogen (T0, T1, T2, T3, T4 and T5) were applied as treatments in this study. Among the application of USG on morpho-physiological and growth characters of wheat, the maximum plant height (98.33 cm), number of spikelet (21.33) and sterile spieklet (19.87) were found from V3T5. Similarly, V2T3 produced the highest no. of spikelet spile-1 (11.50) and grain yield (2.75 t ha-1) whereas similar treatment also showed the maximum no of non effective tiller (1.07) with V1T3.The treatment combination of V2T2 were recorded the highest on 1000-grain yield (51.98 g), no of non sterile spike (2.07) and no of grains spike-1 (48.87). The highest no of total tiller hill-1 (5.13) and effective tiller (4.33) were taken from the treatment combinations of V1T5. The highest straw yield (4.67 tha-1) was recorded in V2T4.DOI: http://dx.doi.org/10.3329/jesnr.v4i2.10134J. Environ. Sci. & Natural Resources, 4(2): 51-54, 2011

Effect of Urea Super Granule on Growth and Yield of Wheat

A field experiment was carried out at Agronomy Field, Bangladesh Agricultural University (BAU), Mymensingh during the period from November 2009 to March 2010 with a view to finding out the effect of appropriate dose of USG on growth and yield of wheat. Six levels of nitrogen (T0, T1, T2, T3, T4 and T5) were applied as treatments for growth and yield of wheat var. Bijoy for this study. Among the application of USG, treatment T5 produced the superior results on morpho-physiological and growth characters of wheat except number of non sterile spikelet where USG treatment T2 performs the best (1.82). As results, T5 produced the highest plant height (95.77 cm), number of total tiller hill-1 (4.96), no. of effective tiller (4.13), no of non effective tiller (1.00), number of total spikelet (20.22), no of spikelet spile-1 (10.92), sterile spieklet (18.70), no of grains spike-1 (46.27), 1000-grain yield (51.39 g), grain yield (2.42 t ha-1) and straw yield (4.06 tha-1).DOI: http://dx.doi.org/10.3329/jesnr.v4i2.10164 J. Environ. Sci. & Natural Resources, 4(2): 143-146, 2011

COMPARATIVE EFFICACY OF UREA FERTILIZATION VIA SUPERGRANULES VERSUS PRILLS ON NITROGEN DISTRIBUTION, YIELD RESPONSE AND NITROGEN USE EFFICIENCY OF SPRING WHEAT

The impact of urea prills (1–2 mm) versus urea supergranules (USGs, ∼10 mm), placed at different depths, on the growth and nitrogen (N) use efficiency of spring wheat was investigated under greenhouse conditions. The amount of fertilizer 15N derived from either form was 50% greater in the top soil than at lower depths. The comparatively slower release and distribution of USG-N resulted in enhanced dry matter production and fertilizer-N uptake during the later growth stages that were also associated with a higher translocation of fertilizer-15N into the grain (34.9% versus 28.7% for the prills). Deeper placements of USGs (5.0–7.5 cm) resulted in greater fertilizer-N recovery in the crop (70.5–78.0%) compared to the use of prills (56.6%). Our results strongly suggest that the proper application of USGs can increase yields and fertilizer-N utilization of wheat and simultaneously decrease N losses compared to equivalent use of prills, and therefore presents important agronomic advantages.

The kinetics of ammonia disappearance from deep-placed urea supergranules (USG) in transplanted rice: the effects of split USG application and PK fertiliser

Deep placement of urea supergranules (USG) in transplanted rice cultivation can protect nitrogen from losses. In the 20 × 20 cm plant geometry, the 4 g urea application corresponds to 116 kg N ha−1. However, the ammoniacal nitrogen concentration at the placement sites increases as the mass of the USG increases, and with the 4 g USG it takes too long for the ammonia concentration to decrease to 10 mM, the concentration at which root uptake commences. Therefore, split applications (two applications of 2 g USG) were studied regarding the change of ammoniacal nitrogen concentration at the point of application. The first application was always at transplanting, at a depth of 10 cm; the second application was made 41 days after transplanting (DAT) (tillering stage) or 62 DAT (panicle initiation). These times correspond to the beginning or the end of ammonia disappearance (plant uptake) from the site of placement, respectively. Ammonia disappearance from the placement site is faster for the second application, and it appears that the rice roots took up ammonia at a higher concentration: 20 mM for the second application versus 10 mM for the first application. The kinetics of ammonia disappearance from a single application of 2 g granules at transplanting was also influenced by the PK application rate. The rate of ammonia disappearance, the number of tillers per hill, and grain yield all increased with PK rate. The constant which characterizes the first order rate of ammonia disappearance below 10 mM also increased with PK level, proportionally to the number of tillers.

EFFECT OF NEEM-OIL COATED PRILLED UREA WITH VARYING THICKNESS OF NEEM-OIL COATING AND NITROGEN RATES ON PRODUCTIVITY AND NITROGEN-USE EFFICIENCY OF LOWLAND IRRIGATED RICE UNDER INDO-GANGETIC PLAINS

The nitrogen (N) fertilizer-use efficiency (20–50%) is low in rice fields in India. The neem-oil coated urea can increase N-use efficiency in lowland rice, but the desirable thickness of neem-oil coating onto urea is not known yet. Therefore, field experiments were conducted during kharif (rainy) season years 2004 and 2005 at the Research Farm of Indian Agricultural Research Institute, New Delhi to know the suitable thickness of neem-oil coating on prilled urea (PU) for increased N-use efficiency and yield. The treatments comprised of twelve combinations of four N sources (PU coated with neem-oil thickness of 0, 500, 1000 and 2000 mg kg−1 PU) and three N levels (50, 100, and 150 kg N ha−1) plus a no-N control. Prilled urea (PU) refers to the common urea available commercially in prills, which is different from urea super granules. Application of urea coated with neem-oil thickness of 1000 mg kg−1 PU resulted in significantly higher growth, yield parameters, grain yield, N uptake, and efficiency of aromatic rice (Oryza sativa L.) over uncoated PU. Nitrogen application at 122 kg ha−1 was optimum for increased yield of rice. Nitrogen-use efficiency decreased significantly and substantially with each successive increase in levels of N from 50 to 150 kg ha−1.

Effects of urease and nitrification inhibitors added to urea on nitrous oxide emissions from a loess soil

AbstractUrea fertilizer‐induced N2O emissions from soils might be reduced by the addition of urease and nitrification inhibitors. Here, we investigated the effect of urea granule (2–3 mm) added with a new urease inhibitor, a nitrification inhibitor, and with a combined urease inhibitor and nitrification inhibitor on N2O emissions. For comparison, the urea granules supplied with or without inhibitors were also used to prepare corresponding supergranules. The pot experiments without vegetation were conducted with a loess soil at (20 ± 2)°C and 67% water‐filled pore space. Urea was added at a dose of 86 kg N ha–1 by surface application, by soil mixing of prills (<1 mm) and granules, and by point‐placement of supergranules (10 mm) at 5 cm soil depth. A second experiment was conducted with spring wheat grown for 70 d in a greenhouse. The second experiment included the application of urea prills and granules mixed with soil, the point‐placement of supergranules and the addition of the urease inhibitor, and the combined urease plus nitrification inhibitors at 88 kg N ha–1. In both experiments, maximum emissions of N2O appeared within 2 weeks after fertilization. In the pot experiments, N2O emissions after surface application of urea were less (0.45% to 0.48% of total fertilization) than from the application followed by mixing of the soil (0.54% to 1.14%). The N2O emissions from the point‐placed‐supergranule treatment amounted to 0.64% of total fertilization. In the pot experiment, the addition of the combined urease plus nitrification inhibitors, nitrification inhibitor, and urease inhibitor reduced N2O emissions by 79% to 87%, 81% to 83%, and 15% to 46%, respectively, at any size of urea application. Also, the N2O emissions from the surface application of the urease‐inhibitor treatment exceeded those of the granules mixed with soil and the point‐placed‐supergranule treatments receiving no inhibitors by 32% to 40%. In the wheat growth experiment, the N2O losses were generally smaller, ranging from 0.16% to 0.27% of the total fertilization, than in the pot experiment, and the application of the urease inhibitor and the combined urease plus nitrification inhibitors decreased N2O emissions by 23% to 59%. The point‐placed urea supergranule without inhibitors delayed N2O emissions up to 7 weeks but resulted in slightly higher emissions than application of the urease inhibitor and the urease plus nitrification inhibitors under cropped conditions. Our results imply that the application of urea fertilizer added with the combined urease and nitrification inhibitors can substantially reduce N2O emissions.

Gaseous Nitrogen Losses from a Cambisol Cropped to Spring Wheat with Urea Sizes and Placement Depths

Globally identifying mitigation options for the emission of reactive N gases from agricultural soils is a research priority. We investigated the effect of urea size and placement depth on sources and emissions of N gases from a Cambisol cropped to spring wheat (Triticum aestivum L.). In Exp. 1, wheat received either prilled urea (PU) mixed within the soil, urea super granule (USG; diam. 10.1 mm) point‐placed at a soil‐depth of 7.5 cm, or no N fertilizer. In Exp. 2, wheat received either USG (diam. 10.2 mm) point‐placed at 2.5‐, 5.0‐, and 7.5‐cm soil depths, or no N fertilizer. In both experiments, maximum peaks for nitrous oxide (N2O) fluxes and nitrification were delayed by 2 to 3 wk in the USG compared with the PU treatment. The added 15N‐urea lost as 15N‐N2O over 116 d was only 0.01% for both PU and USG treatments in Exp. 1. This loss for USGs was higher in Exp. 2 (0.02–0.15%) measured over 70 d, mainly related to higher moisture‐induced denitrification. Temporal N2O fluxes were significantly related to changes in soil NO3−–N, water‐filled pore space and NH4+–N (R2 = 0.50, P < 0.05). However, the previous predictive model of Khalil et al. (2006) could best estimate its cumulative fluxes over time. The relative losses of ammonia (0.07–1.17%) and nitrogen oxides (0.19–1.54%) measured in Exp. 2 over 43 d decreased with increasing depths of USG placement. The USG point‐placed at the 5.0‐ and 7.5‐cm depths decreased the pooled gaseous N losses by 35 and 77%, respectively, over the shallower placement. The 15N results imply that soil N could be the major source of N2O emissions (79–97%). Field studies are suggested to validate our findings that the deeper placement of USG can decrease N emissions under arable cropping.

Emissions of Nitrous Oxide, Ammonia, and Carbon Dioxide from a Cambisol at Two Contrasting Soil Water Regimes and Urea Granular Sizes

The superiority of mixing and deep placement of prilled urea (PU) or urea supergranules (USG) over surface‐broadcast application for reducing nitrogen (N) loss from lowland rice is well established. In upland agricultural systems, rainfall and/or the application and loss of irrigation water from soil systems may regulate urea N transformations and gaseous losses, depending on the method of fertilizer application and the particle size. To develop further insights into these processes, experiments were carried out in a silt loam soil mixed with PU or amended with point‐placed USG at a depth of 7.5 cm. Two soil water regimes were used: around field capacity (AFC) with low evaporative conditions (depletion: 77 to 69% water‐filled pore space, WFPS) and below field capacity (BFC) with high evaporative conditions following two irrigations (depletion: 70 to 55% WFPS). The nitrous oxide (N2O) emission was greater at AFC than at BFC, where nitrification was more rapid. The N2O peaks appeared mostly after the disappearance of nitrite (NO2 −), presumably dominated by nitrifier and/or chemodenitrification and the degree of emissions probably depended on the stability period and the reduction of NO2 − induced by the soil water regimes. The relative N2O losses from the added N were small (⩽0.20%) for all treatments after 21 days. The point at which 50% of its emissions (t½) occurred was delayed up to 6 days longer than found from the application of PU. The differences between PU and USG application were likely linked with the concentrations of ammonium (NH4 +), NO2 −, and pH. These high concentrations continued longer at AFC than at BFC and were limited to a distance of <5.0 cm from the application zone. Similarly, the relative losses of the added N ranged from 0.19 to 0.56% at AFC and 0.08 to 0.37% at BFC, the highest being with USG application. Based on the areas receiving equal N, the N2O and ammonia (NH3) emissions from USG differed marginally with PU. Carbon dioxide (CO2) release was higher at AFC than BFC, in which the USG application probably limited microbial respiration preferentially to methane oxidation. A correlation study showed that the N2O flux was best explained together with CO2, nitrate (NO3 −), NO2 −, and WFPS (R 2 = 0.67***). This indicates the influence of both auto‐ and heterotrophic microbial activities toward N2O emission, with soil water being an important regulatory factor.

Influence of nitrogen and weed management on the productivity of upland rice

AbstractNitrogen and weeds are two important factors that influence the productivity of rainfed upland rice (Oryza sativa L.) in tropical Asia. A low recovery of applied fertilizer N in rainfed uplands is generally associated with high nitrate leaching losses and weed interferences. Field experiments were conducted during the wet seasons of 2002 and 2003 at the research farm of Central Rainfed Upland Rice Research Station, Hazaribag, Jharkhand, India, to determine the response of upland rice to nitrogen applied at 60 kg N ha–1 as different forms of urea (single pre‐plant application of controlled‐release urea, single pre‐plant application of urea supergranules, and split application of prilled urea with or without basal N) against no N application under three weed‐control regimes (unweeded, pre‐emergence application of butachlor at 1.5 kg a.i. ha–1 supplemented with one single hand weeding or two hand weedings). The response of rice to applied N varied greatly among the three weed‐control regimes. Across the different N treatments, the application of 60 kg N ha–1 resulted in a grain‐yield increase above the unfertilized control of only 0.24 Mg ha–1 in unweeded treatments, whereas yields increased by 1.07 Mg ha–1 when butachlor application was supplemented with a single hand weeding and by 1.28 Mg ha–1 with two hand weedings. Among the weed‐control measures, hand weeding twice produced highest grain yield in both years. The comparison of different forms of urea showed that a single pre‐plant application of controlled‐release urea resulted in average grain yields of 1.57 and 1.87 Mg ha–1 compared to 1.32 and 1.30 Mg ha–1 in the case of the recommended practice of split‐applied prilled urea in the years 2002 and 2003, respectively. The highest agronomic N use efficiency of 15–20 kg grain per kg N applied and the highest apparent N recovery of 39%–45% were attained with controlled‐release urea, suggesting that this N form is particularly beneficial for upland‐rice cultivation under variable rainfall conditions, provided weeds are controlled.

Effect of different times and depths of USG application on the growth and yield of cabbage

An experiment was conducted for two consecutive years in the farmers' field of Palima, Tangail to evaluate the effect of time and depth of placement of urea super granule (USG) on the yield and yield attributes of cabbage during 2003-04 and 2004-05, respectively. USG @ 330 kg per hectare was applied at 0, 10, 15, and 20 days after planting each at 4, 8, and 12 cm depth. The result showed that application of USG at 10 days after transplanting at a depth of 8 cm gave the highest yield of 74.92 and 117.60 t/ha in 2003-04 and 2004-05, respectively. The yield variation was observed due to change of variety (i. e., Atlas 70 in 2003-04 and Autumn Queen in 2004-05). Placement of USG either at 4 cm or 12 cm depth slightly reduced yield than obtained with point placement at 8 cm. USG application later than 10 days of transplanting decreased cabbage yield in both the varieties. Bangladesh J. Agril. Res. 32(2) 2007: 301-306.

Efficiency of urea super granule point placement on potato

Efficiency of urea super granule point placement on potato

Effects of Urea Super Granule as a Source of Nitrogen on the Growth and Yield of Tomato

Effects of Urea Super Granule as a Source of Nitrogen on the Growth and Yield of Tomato