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Browsing Presentations by Subject "Deep placement"
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- ItemImpacts of Urea Deep Placement with Intermittent Irrigation on Nitrous Oxide and Nitric Oxide Emissions and Nitrogen Use Efficiency from Lowland Rice Cultivation(2018-10) S.M. Mofijul Islam; Yam Kanta Gaihre; Upendra Singh; Jatish Chandra Biswas; Md. Nayeem Ahmed; Joaquin Sanabria; Bjoern Ole Sander; Mohammad SalequeUrea deep placement (UDP) and alternate wetting and drying (AWD) irrigation method are two promising rice production technologies. However, studies on the impacts of UDP under AWD irrigation on nitrous oxide (N2O) nitric oxide (NO) emissions are still limited. We investigated the effects of UDP on N2O and NO emissions, nitrogen use efficiency (NUE) and rice yields compared with conventional broadcast application of prilled urea (PU) under AWD irrigation. Emissions were measured from three fertilizer treatments — no N, UDP and PU using an automated gas sampling and analysis system continuously for two consecutive Boro (dry) rice seasons in Bangladesh. For UDP, urea briquettes were placed in 7-10 cm below soil surface between four hills of rice at each alternate row after ten days of transplanting, while PU was applied as broadcast in three equal splits. Treatments were arranged in a randomized complete block design with three replications and emissions were measured at every three-hour interval. N2O emissions were irregular and event specific. Fertilizer induced emission peaks were observed after broadcast application of prilled urea (PU), but they were not observed in UDP. However, emissions peaks during dry period were more prominent in UDP compared to PU. Nevertheless, seasonal cumulative N2O emissions were similar between UDP and PU treatments. Across the season, UDP and PU showed yield-scaled N2O emission 96.3 and 88.7 g t–1 grain and emission factors were 0.49 and 0.23%, respectively. In contrast to N2O emission, NO fluxes were small and not affected by either fertilizer or water management. Across the season, UDP significantly increased rice yield, agronomic use efficiency and recovery efficiency of N by 29%, 109% and 167%, respectively compared to broadcast PU. Since UDP significantly increased grain yield and NUE compared to broadcast PU, and maintained similar emissions of N2O with PU, UDP could be equally effective under AWD irrigation as with continuous flooding condition. Therefore, UDP might be considered an eco-friendly technology for improving rice yields and reducing GHG emissions, particularly N2O emissions in both water regimes.
- ItemMovement and Retention of NH4-N in Wetland Rice Soils as Affected by Urea Application Methods(2020) IA Siddique; Abdullah Al Mahmud; M Hossain; MR. Islam; Yam Kanta GaihreThis document presents a study on the movement and retention of ammonium nitrogen (NH4-N) in wetland rice soils, focusing on the impact of different urea application methods. The research was conducted by Imran Ahammad Siddique and his colleagues from the Department of Soil Science at Bangladesh Agricultural University and the International Fertilizer Development Center. The significance of the study lies in the fact that rice is a major crop in Bangladesh, and understanding the behavior of NH4-N in the soil is crucial for optimizing fertilizer application and increasing nitrogen use efficiency. The study investigated the effects of urea deep placement (UDP) and broadcast application methods on NH4-N movement and retention in wetland rice soils. UDP involves placing urea deep into the soil, concentrating NH4-N in the anaerobic layer, and reducing its movement to the soil surface or floodwater. The results showed that deep placement of urea increased NH4-N retention in the soil for a longer period compared to broadcast methods, potentially reducing the need for multiple split applications. Additionally, it was found that UDP could improve nitrogen use efficiency and increase rice production. The characteristics of submerged soil were also examined, including the depletion of oxygen, reduction of certain ions, limited gas exchange, and changes in soil pH. Understanding the nitrogen transformation processes in flooded soils is essential due to the solubility and potential toxicity of inorganic nitrogen. The study aimed to investigate the movement and retention of NH4-N during the rice-growing season using different application methods and nitrogen rates. Pore water samples were collected from UDP and broadcast plots at various depths and time points. The results demonstrated that NH4-N concentration decreased gradually over time, and its horizontal movement was significant up to 10 cm from the placement point. The diffusion area near the rice root zone showed the highest NH4-N concentration, while UDP retained higher NH4-N levels in the soil than broadcast urea.
- ItemQuantifying Adoption of Urea Deep Placement by Rice Growers in Bangladesh(2015) Joaquin Sanabria; Ishrat Jahan; Afzal HossainMore than ten years of experimentation have demonstrated that the use of Urea Deep Placement (UDP) results in significantly higher N Use Efficiency (NUE) than broadcasted prilled urea (PU) for lowland rice in Bangladesh. UDP use increases yields, reduces quantities of urea applied, increases farmers’ returns, and produces national savings due to the reduction of urea imports. Ongoing research indicates that large-scale adoption of UDP also has environmental benefits due to reduced N losses and greenhouse gas emissions. The objectives of this research were to estimate UDP adoptions, compare PU and UDP concerning yield, assess methods used for the diffusion of UDP technology, and identify factors with the potential to constrain UDP adoption. Two-cluster sampling was used. Results show that UDP has been widely adopted across the seasons, albeit to differing degrees. Additionally, diffusion strategies such as farmer training and field demonstrations have proven to be effective in improving yield and NUE compared to PU. However, obstacles like the need for hand application and the scarcity of briquettes prevent wider implementation. Using mechanized techniques, recommendations include extending the UDP application to more fields and enhancing briquette dispersion.