Split Application Of Prilled Urea Research Articles

Movement and Retention of NH4-N in Wetland Rice Soils as Affected by Urea Application Methods

A field experiment was conducted to investigate the dynamics of ammonium nitrogen (NH4+-N) in the soil during an entire rice-growing season. The NH4+-N dynamics were measured in paddy soils from two N application methods, namely, urea deep placement (UDP) and broadcast prilled urea (PU). The pore water samples from a 10 cm soil depth were collected using a “rhizon sampler.” The samples were collected at 0, 7, 10, 14, 20, and 22 cm from the urea briquette (UB) placement point at 7, 14, 21, 35, 64, and 83 days after transplanting (DAT) of rice. The NH4+-N in the floodwater sample was measured for a week after each split application of PU. UDP retained NH4+-N at the placement site (7–10 cm depth) until 64 DAT. A small amount of NH4+-N moved horizontally up to 14 cm from the placement site. It’s movement to the soil surface and floodwater was very low to negligible. In contrast, PU produced more NH4+-N in both the floodwater and in the soil surface. Therefore, broadcast urea had significantly (p < 0.05) higher ammonia volatilization (~15% of applied N) compared to UDP (<1%). UDP significantly (p < 0.05) increased grain yields, N uptake, and N recovery compared to broadcast urea. These results confirm that a single application of UDP could meet plants’ N demand throughout the rice-growing period, particularly for short- and medium-duration rice varieties.

Medium-term effects of different types of N fertilizer on yield, apparent N recovery, and soil chemical properties of a double rice cropping system

Controlled-release, slow-release and stabilized nitrogen (N) fertilizers can potentially increase crop production and reduce N losses. However, information is limited regarding their medium- and long-term effects on rice productivity and soil chemical properties. Therefore, we investigated the effects of these three types of N fertilizer on rice grain yield, apparent N recovery efficiency (ANR), and soil chemical properties in a double cropped rice system over a 7-year period in Zhejiang Province, China. This study examined six N treatments: no N fertilizer (CK), split application of prilled urea (Urea), a single basal application of polymer-coated sulfur-coated urea (PSCU, formed by coating SCU with a polymer coating), urea with a nitrification inhibitor (UNI), urea formaldehyde (UF), and a mixture of PSCU and prilled urea (Mix). The effect of N treatment varied over the 7 years, but annual grain yields of double cropped rice with UNI, UF, and Mix were significantly higher than with Urea in 6/7, 4/7 and 3/7 years, respectively, and similar to yield with Urea in the other years. Performance of PSCU was variable, with significantly higher yields than Urea in 3/7 years, but lower yields in 2/7 years. Compared to Urea, the UNI treatment increased the grain yield and ANR of early rice by averages of 9.2 and 24%, respectively, and increased the grain yield and ANR of late rice by averages of 8.6 and 22%, respectively.Total N in the topsoil (0–20 cm) of the CK declined gradually during years 2-4. At the end of each of years 4–7, total soil N in all N fertilized treatments exceeded that in the CK. After 7 years, the five N fertilized treatments had 8–17% higher topsoil total N than the initial value, with no significant difference between these treatments. Available P increased over time in all treatments, with higher values in the CK than the five N fertilized treatments after the first year. After 7 years, available P was 387–529% higher in the N fertilized treatments than the initial value, and with no significant differences between these treatments. However, available K declined considerably in the five N fertilizer treatments during the first four years, but then steadily increased during the next three years when the application rate was increased from 120 to 200 kg K ha−1. Soil pH declined over the seven years, more so in PSCU and Mix when pH declined from 5.2 to 4.5, compared with declines to 4.7–4.9 in the other treatments. Although fertilizer for the UNI treatment cost $ 29 ha−1 more than for the Urea treatment, the higher yield/revenue and lower fertilization labor cost of UNI led to increases in net profit of $ 326 and 329 ha−1 year−1 in early and late rice, respectively. Overall, application of UNI was the superior alternative to prilled urea in the double rice cropping system because of consistently higher yield and profitability, while maintaining soil fertility at similar levels to the other N fertilizer options.

Effects of PU, USG and NPK briquette on nitrogen use efficiency and yield of BR22 rice under reduced water condition

An experiment was conducted at the Soil Science Field Laboratory of Bangladesh Agricultural University, Mymensingh during the aman season of 2012 to investigate the effects of prilled urea (PU), urea super granule (USG) and NPK briquette on NH4- N concentration in field water, yield and nitrogen (N) use efficiency (NUE) of BR22 rice under reduced water conditions. The experiment was laid out in a randomized complete block design with three replications. There were altogether eight treatment combinations viz. T1: Control (No N fertilizer), T2: 52 kg N ha-1 from USG, T3: 104 kg N ha-1 from USG, T4: 78 kg N ha-1 from PU, T5: 120 kg N ha-1 from PU, T6: 51 kg N ha-1 from NPK briquette, T7: 78 kg N ha-1 from USG and T8: 78 kg N ha-1 from NPK briquette. Water samples were collected from rice field for seven consecutive days after deep placement of USG and the first split application of PU and the samples were analyzed for NH4-N. The Highest concentration of NH4-N in water was observed at the second day of PU application followed by gradual decrease with time. The yield contributing characters like plant height, panicle length, number of effective tillers hill-1 and grains panicle-1 were significantly influenced by different treatments. The highest grain yield of 3.93 t ha-1 was recorded from 104 kg N ha-1 as USG (T3) and the lowest value of 2.12 t ha-1 was obtained from control. The N use efficiency was increased when the N was applied as USG. The overall results revealed that application of USG and NPK briquette may be practised for obtaining better yields in addition to increasing the efficiency of N fertilizer. DOI: http://dx.doi.org/10.3329/jbau.v11i2.19897 J. Bangladesh Agril. Univ. 11(2): 215-220, 2013

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.

Evaluation of placement methods for urea supergranules in wetland rice (Oryza soil sativa) B.K. MISHRA, A.K. DAS, A.K. DASH, D. JENA , S.K. SWAIN^

-- A field experiment was carried out in a lowland soil, having fine loamy mixed hyperthermic Epiaquept, during winter season of 1994-95 and 1995-96 to evaluate the method of urea supergranule (USG) placement in wetland rice (Oryza sativa L.). The experimental plan was randomized block design with 3 replications. The USG was applied @ 76 kg Nlha either as surface broadcast or as deep placement at soil depths of 2.5, 5 or 7.5 cm by manual or mechanical means along with prilled urea (PU) split. Placement of USG significantly increased both the grain and straw yields of rice in comparison to PU or USG broadcast. The response of rice to nitrogen was more under USG placement than split application of PU. Nitrogen-use efficiency of rice was increased from 18 -, kg grainlkg N applied as PU to as high as 26 kg grainlkg N applied as USG. Similarly, the relative efficiency of USG was increased by 40% over PU. The apparent recovery of N in rice was also increased from 21% in case of PU to 40% for USG.

SEEDING METHODS AND NITROGEN MANAGEMENT PRACTICES FOR IRRIGATED LOWLAND RICE IN CAUVERY DELTA ZONE OF TAMIL NADU

Investigation was carried out at Tamil Nadu Rice Research Institute. Aduthurai from June 1995 to February 1997 to evaluate the efficient N management practices for direct seeded rice raised under irrigated lowland condition. The experiments were carried out both in Kuruvai and thaladi seasons of 1995-96 and 1996-'97. The experiment I consisted of three methods of sowing viz.. transplanting, sowing sprouted seeds in lines manually and using seed drum as main plot treatments and eight N management practices in the sub plots. The experiment II consisted of the same main plot treatments with modified N management practices based on the results of the first experiment. Eventhough the seeding methods had no significant differences among them, the drum seeding recorded numerically higher grain yield and net return than manual sowing and transplanting leading to reduction in crop duration by one week. Application of neem cake blended urea and placement of urea solution at 100 percent recommended N level favourably influenced the growth and yield components. These treatments recorded significantly higher grain and straw yields than conventional split application. Application of 75 per cent recommended N as placement of urea solution and as gypsum and neem cake blended urea gave comparable effect with improved split application of 100 per cent recommended N and integrated application of green manure and urea each supplying 50 percent recommended N in respect of grain yields of rice. These treatments also showed increased net return and return per rupee invested compared to conventional split application of prilled urea.

Long-term Comparison of the Agronomic Efficiency and Residual Benefits of Organic and Inorganic Nitrogen Sources for Tropical Lowland Rice

SUMMARYNitrogen efficiency from Azolla microphylla or Sesbania rostrata green manure, rice straw, and inorganic fertilizer-N was compared in two long-term experiments with irrigated lowland rice (Oryza sativa L.). Treatments included a control and each nitrogen source alone or in combinations that provided 50% of the total applied nitrogen from an organic and inorganic nitrogen source. All nitrogen sources were applied at equivalent nitrogen rates to 19–22 consecutive rice crops. Residual effects were assessed in two subsequent cropping seasons at one site. Lower grain yield, agronomic efficiency (Δgrain per kg total applied nitrogen), and apparent nitrogen uptake were obtained from green manure and rice straw nitrogen as sole or dual nitrogen sources rather than from a standard split application of prilled urea. Compared to prilled urea, residual effects from green manure or rice straw included a significant increase in soil organic carbon and total nitrogen, and greater extractable soil nitrogen in the vegetative growth period. After panicle initiation there was no residual effect on the rate of crop nitrogen accumulation, and final grain yields were similar regardless of previous nitrogen source. Recycling of rice straw appeared to have greater potential for reducing fertilizer-N requirements than use of green manure because rice straw is often a wasted resource in irrigated rice systems of the humid tropics, the efficiency of rice straw nitrogen in combination with prilled urea is comparable to green manure nitrogen, and the increase in soil nitrogen from rice straw was 50–150% greater than from green manure.

Long-term Comparison of the Agronomic Efficiency and Residual Benefits of Organic and Inorganic Nitrogen Sources for Tropical Lowland Rice

SUMMARYNitrogen efficiency from Azolla microphylla or Sesbania rostrata green manure, rice straw, and inorganic fertilizer-N was compared in two long-term experiments with irrigated lowland rice (Oryza sativa L.). Treatments included a control and each nitrogen source alone or in combinations that provided 50% of the total applied nitrogen from an organic and inorganic nitrogen source. All nitrogen sources were applied at equivalent nitrogen rates to 19–22 consecutive rice crops. Residual effects were assessed in two subsequent cropping seasons at one site. Lower grain yield, agronomic efficiency (Δgrain per kg total applied nitrogen), and apparent nitrogen uptake were obtained from green manure and rice straw nitrogen as sole or dual nitrogen sources rather than from a standard split application of prilled urea. Compared to prilled urea, residual effects from green manure or rice straw included a significant increase in soil organic carbon and total nitrogen, and greater extractable soil nitrogen in the vegetative growth period. After panicle initiation there was no residual effect on the rate of crop nitrogen accumulation, and final grain yields were similar regardless of previous nitrogen source. Recycling of rice straw appeared to have greater potential for reducing fertilizer-N requirements than use of green manure because rice straw is often a wasted resource in irrigated rice systems of the humid tropics, the efficiency of rice straw nitrogen in combination with prilled urea is comparable to green manure nitrogen, and the increase in soil nitrogen from rice straw was 50–150% greater than from green manure.

Increasing urea-N efficiency in transplanted lowland rice by urea solution band placement

Alternative N fertiliser management strategies are needed to increase N-use efficiency in wetland rice (Oryza sativa L.). In the wet season of 1993–1994, field experiments were conducted to evaluate the band placement of urea solution in comparison with broadcast prilled urea, neem-coated urea, or point-placement of urea supergranules. Both grain yield and N-use efficiency were higher with band placement of urea solution (50 or 100 kg N ha-1) compared to a conventional split application of prilled urea at 100 kg N ha-1. The total 15N recovery was 58.7 and 51.7% with band placement of urea solution at 50 and 100 kg N ha-1, respectively, compared with 47.8% for neem-coated urea and 28.5% for a conventional split application of prilled urea.

Integrated management of straw and urea nitrogen in lowland rice under a rice-wheat rotation

SUMMARYThe average yields of a 3-year field experiment (1985/86–1987/88) on a mollisol at Pantnagar showed that, at 87 kg N/ha, applying urea supergranules (USG) gave 0·47 t/ha more rice grain than split application of prilled urea (PU). The data also showed that, at this rate of N, one-third (29 kg N/ha) of inorganic N can be substituted by fresh straw (wheat or rice) applied at planting to give similar rice yields. However, at a total of 58 kg N/ha, 29 kg N/ha applied as straw with 29 kg N/ha of PU or USG reduced yield compared with 58 kg N/ha of PU or USG alone, except in 1986/87. Yield differences were attributed to differences in number of panicles/m2, N uptake by the crop and mean wet soil NH4+-N obtained at various stages of crop growth during 1986/87 and 1987/88. Wheat grown after rice in 1985/86 and 1986/87 showed significant residual effects in plots with straw application and these were correlated with the rate of hydrolysable organic N (HN) obtained after rice.

Growth and yield of rice as affected by spacing, time and depth of placement of urea briquettes

A field study was conducted on a sandy clay soil (Entisol) in India to examine urea briquettes (UB) for lowland rice during 1986 and 1987. Grain yield was significantly greater for UB than a split application of prilled urea. At equal rates of N application, a spacing of 30 cm between two UBs was significantly better than 60 to 90 cm spacing. Two applications (10 DAT and at panicle initiation) of UB was no better than a single application (10 DAT). Placement of UB at 3–4 cm depth was significantly better than its surface application or placement at 0–1 cm depth.

Management of fertilizer nitrogen for direct-sown, rainfed lowland rice (Oryza sativa L.)

SummaryField experiments were conducted in wet seasons (June-December) for 4 years on a clay loam Haplaquept, to study the effects of different N management practices on yield, urea and ammonium-N in flood water and N nutrition of an clite rice cv. CR 1009, grown in rainfed lowlands. During the first 3 years of the experiment, fertilizer management practices like band placement of neem-cake-coated urea (NCU), broadcast application of sulphur-coated urea (SCU) at sowing, or point placement of urea supergranules (USG) 3 weeks after germination at 40 kg N/ha gave grain yields of 3·1–3·4 t·ha, which were almost equal to that of split application of prilled urea (PU). In the 4th year of the experiment, besides NCU and USG, single dose applications of PU as band placement, incorporation in the soil at sowing or broadcast incorporation of soil-treated urea at early tillering was also found to have similar effect on grain yield and N uptake as split application of PU. The flood water of the treatment receiving broadcast application of PU at tillering contained some urea and ammonium N, which rapidly decreased to negligible amounts in 3·4 days.The results suggest that, depending upon the feasibility, any one of the single dose application methods at sowing time or 3 weeks after germination may be adopted in this system of rice culture, which avoids top-dressing of PU to surface flowing flood water of greater depths at later stages of crop growth.

Effect of granule size and the placement geometry on the efficiency of urea supergranules for wetland rice grown on a permeable soil

In a laboratory experiment 5 cm depth of water was allowed to percolate daily down through a 15 cm thick soil (Typic Ustipsamment) layer. It was observed that leaching losses of urea supergranules (USG)-N could be decreased by about 20% by the placement of four 0.25 g granules at four points instead of one 1 g granule at one point. In field microplots, the placement of approximately 30 granules of 0.30 g size instead of 9 granules of 1.00 g size resulted in reduced leaching of USG-N and, in turn, increased rice yield. In a follow-up field study, the advantage of more frequently placed USG was confirmed. As compared with 1 g USG placed in the usual manner in the center of four rice hills, increasing the density of placement in soil produced 15% more rice grain. Further increase in rice yield could be obtained by increasing the number of USG placed in the soil and decreasing the size of the granule from 1.00 g to 0.70 or 0.35 g. With USG of 0.35 and 0.70 g yields were equal or sometimes even slightly higher than with split application of prilled urea on a heavily percolating, low-CEC, light-textured soil.

Increasing productivity and protein content using early-maturing rices and efficient nitrogen management

Germplasm with shorter duration than that of the currently grown varieties is being generated to maximize productivity of irrigated rice. However, short-duration varieties often produce yields lower than the medium- and long-duration varieties. Experiments were conducted during the 1980–82 dry and wet seasons to increase productivity through the use of very early-maturing rices and the improved management of nitrogen (N) fertilizers. Results over three years showed that IR58 and IR9729-67-3 (growth duration 100 ± 5 days) yield as well as or higher than IR36 although earlier maturing. They generally had a higher productivity (kg ha−1 day−1) than IR36 (110 ± 5 days). Three years' data suggest that the improved timing of broadcast applications of urea in split doses increased grain yield comparable with the basal incorporation of slow-release sulfur-coated urea (SCU) or deep point-placement of urea supergranules (USG). Results on elite breeding lines showed that the early-maturing IR9729-67-3 produced higher protein yield ha−1 than longer duration varieties such as IR8 and IR42 in the dry season. Furthermore, contrary to earlier results, single basal incorporation of slow-release SCU increased the protein yield of rice by 53 kg ha−1 and deep point-placement of USG by 43 kg ha−1 over split application of prilled urea.

EFFICACY OF UREA FORMS AND MODE OF APPLICATION ON LOWLAND RICE

Field trial was conducted at Tamil Nadu Agricultural University, Coimbatore for four soosana during 1978-80 in a doop clay loam soil, to study the efficiency of different urea forms with split application of prilled urea on lowland rice The grain yield was consistantly higher with granulated compost. Placement of super granules in the reduced zone was next best in efficiency. Neem cake coated uroa, uren oniched FYM and split application of prilled uroa were comparable in their efficiency. The panicles per square metre were greater and mean panicle weight heavier when granulated compost was used as a source of nitrogen.

Efficiency of modified urea fertilizers for tropical irrigated rice

An objective of the International Network on Soil Fertility and Fertilizer Evaluation for Rice (INSFFER) network is to field evaluate deep-point placement (urea supergranules) and slow-release (sulfur coated urea) N fertilizers in irrigated rice. These N sources were compared for performance with split application of prilled urea at 19 sites in Asia in wet season 1981.