Presentations

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Browsing Presentations by Author " Abdullah Al Mahmud"

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    Influence of Organic and Inorganic Nitrogen on Rice Grain Yields and Nitrogen Use Efficiency in the Non-Calcareous Soils of Bangladesh
    (2018) M.R. Islam ; Halima Akter; M.A. Ali; Yam Kanta Gaihre; Abdullah Al Mahmud; Md. Moyeed Hasan Talukder
    Increasing use of nitrogen fertilizers along with its inappropriate application method resulting in higher N losses and low N use efficiency (NUE), is an important concern to sustain soil fertility and crop productivity in Bangladesh. Urea Deep Placement (UDP) technology, which reduces fertilizer use, increase NUE and crop productivity, is a proven technology in lowland rice cultivation. Moreover, use of organic fertilizer combined with chemical fertilizer helps to increase soil organic matter and increase crop yield. Therefore, cropping pattern-based field experiments were conducted at Bangladesh Agricultural University farm to determine the effects of different forms of nitrogen fertilizer in combination with organic manures on rice yield and NUE in Non-Calcareous soils (AEZ 9). Eight fertilizer treatments including broadcast urea, deep placement of granular urea and urea briquette and combined use of organic manure with broadcast urea were laid out in randomized complete block design with three replications. Results show that deep placement either urea or urea briquette increased grain yields and NUE significantly compared to broadcast PU. Moreover, addition of organic manure with broadcasted urea significantly increased both grain and straw yields compared to without organic manure. No significant grain yields difference observed among the deep placement and organic manure with broadcasted urea treated plot, but addition of organic manure improves and sustains the physical, chemical and biological functioning of soil. The NUE among the fertilizer treatments decreased with increasing N rates. The highest NUE observed at deep placed treatment (65-72%), which was significantly higher than broadcast PU (28-45%), suggesting an effective technology to attain food and environmental security.
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    Movement 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 Gaihre
    This 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.