Ph.D. Thesis
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Item The Distribution and Decomposition of Organic Phosphorus and Organic Nitrogen in River Ecosystems of Korea(Kangwon National University, 2010-02) Islam, Mohammad Jahidul; Bomchul KimThe spatial and temporal distributions of phosphorus and nitrogen and a number of physical, chemical and biological parameters were analyzed to in the Youngsan and the Sumjin River systems, Korea. Substantial amount of P and N was observed in both the rivers all the year round. Mean N:P ratios showed large variations among the sampling sites; highest ratio was observed in most sampling sites during summer. Relative proportions of DOP: TP were fairly constant (0.08-0.09) in both the rivers. In the composition of nitrogen almost all sampling sites of both the rivers were dominated with NO;-N followed by NH3- N and NO>-N. Variations in dissolved nutrients tended to co-vary with particulate forms (PON and POP), implying that dissolved nutrients are primarily released from the decomposition of particulate forms or dissolved forms are in equilibrium with particulate forms. Chlorophyll a levels in the Sumjin River appear to be negatively correlated with the ammonia, implying ammonia is absorbed by algae with preference. While chlorophyll a was positively correlated with TP and DIP in the Sumjin River, negative correlations of these parameters was observed in the Youngsan River. The pattern in concentration of nutrients was found to be related with land use and domestic sewage in the study area. Inter-parameter relationships may be strongly influenced by geographical factors relative to temporal factors.Item MAXIMIZATION OF LAND USE THROUGH AGROFORESTRY PRACTICES IN FLOODPLAIN ECOSYSTEM OF BANGLADESH(HAJEE MOHAMMAD DANESH SCIENCE AND TECHNOLOGY UNIVERSITY, DINAJPUR., 2010-05) MIAH, MD. MAIN UDDIN; Prof. Dr. Musharraf Hossain MianEight field experiments were carried out at the agroforestry research farm of Hajee Mohammad Danesh Science and Technology University (HSTU), Dinajpur during November 2005 to June 2008 to search the suitable agroforestry practices and high productive multistoried agroforestry systems. T’. aman-wheat-mungbean cropping pattern was tested in black siris, guava and mango orchard and multistoried experiment were arranged with goraneem, ipil-ipil, banana, potato and onion. In this experiment, goraneem and ipil-ipil were used as the upper storied tree species and banana was middle storied; where potatoes followed by onion were the lower storied crops. The experiments for T. aman, wheat and mungbean were laid out in a split plot design with three replications. Tree species including one control plot were used as main plot and five (5) varieties of each test crops were assigned in sub plot. Varieties BR 10 (V;), BR 11 (V2), BRRI Dhan 33 (V3), BRRI dhan 39 (V4) and Sorna (local) were used for T. aman; Gourove (Vj), Sourave (V2), Shatabdi (V3), Kanchan (V4) and Protiva (Vs) were used for wheat; BARI Mug 3 (V;), BARI Mug 4 (V2), BARI Mug 5 (V3), BARI Mug 6 (V4) and local varieties (Vs) were used for mungbean. Other experiments for banana, potato and onion in multistoried were arranged in single factor RCBD with three replications.The study showed that various light intensities of different tree species had pronounced effect on the morpho - physiological, yield and yield contributing characters of all tested crop varieties. Considering the yield, yield attributes, HI, LER and BCR values, BR 11 for T.aman, shatabdi for wheat and BARI Mug 6 for mungbean were found superior over other varieties in most of the treatment combinations. Hence, T. amanwheat-mungbean cropping pattern (BR11- Shatabdi - BARI mug 6) in association with mango tree was found highly profitable and sustainable agroforestry practice followed by black siris based T. aman-wheat-mungbean cropping pattern. Guava was not found suitable at all for agroforestry practice especially for tested cropping pattern. Among the different combinations of multistoried systems, goraneem + banana + potato-onion system was found highly productive followed by ipil-ipil + banana + potato-onion, on the basis of LER and BCR. Effect of lower storey crops on the growth performance of MPTs showed that most of the system showed synergistic effect on crops and trees in the first year. In the following years lower storied crop yield reduced due to larger canopy effect but increment of trees enhanced due to lower storied crop management (fertilizer and irrigation) compared to open field. The highest boostering effect was found in goraneem followed by black siris. The soil properties almost remained unchanged. Soil p', calcium and magnesium were slightly increased in the soil of agroforestry systems. The study revealed that Amrapali (mango) based agroforestry using BR 11 — ShatabdiBARI Mug 6 varieties for T. aman, wheat and mungbean, respectively was the best puaatics pe the basis of sustainability evaluation which produced net return of Tk 5.12 lakh hectare” year’! followed by goraneem based ( hana + potato-onion) multistoried production aysteti sata produced Tk 3.21 lakh hectare”! year". The least production (Tk 1.12 lakh hectare’ year") was found from banana grown under ipil-ipil.