http://103.7.193.12:8080/xmlui/handle/123456789/129 2026-04-17T15:36:21Z http://103.7.193.12:8080/xmlui/handle/123456789/822 The Distribution and Decomposition of Organic Phosphorus and Organic Nitrogen in River Ecosystems of Korea Islam, Mohammad Jahidul The 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. Nutrient concentrations often vary seasonally due to influences of anthropogenic inputs, hydrology, and the growing seasons of algae and macrophytes. Major anthropogenic sources causing freshwater eutrophication are animal farming, urban and agricultural runoff, sewage effluents and industrial wastes. As a result, significant increases in the concentration of nutrients (e.g., N, P) and the abundance of primary producers (e.g., phytoplankton, benthic algae and macrophytes) have occurred around the worlds’ freshwater (Harper, 1992; Biggs, 2000; Wetzel, 2001). In Korea, it is now a recognized problem of water quality deterioration (Kim et al., 1998). Phosphorus and nitrogen are the most important parameters that exhibit the current state of water quality. Elevated P concentrations in rivers have been linked to increasing rates of plant growth, changes in species composition and proliferation of planktonic and epiphytic and epibenthic algae, resulting in shading of higher plants (Mainstone and Parr, 2002). 2010-02-01T00:00:00Z http://103.7.193.12:8080/xmlui/handle/123456789/130 MAXIMIZATION OF LAND USE THROUGH AGROFORESTRY PRACTICES IN FLOODPLAIN ECOSYSTEM OF BANGLADESH MIAH, MD. MAIN UDDIN Eight 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. Bangladesh is an agrarian country and agriculture is the driving force for her economic growth (Anon, 2007). Although the share of this sector to its GDP has been decreasing over the last few years due to the multifold expansion of the export oriented garment sector. Yet it dominates the economy accommodating lion share of the labour force living in rural areas. More than 84% of the population living in the rural areas are this or that way dependent on this profession for their livelihoods (MoA, 2007). The economy of the domain is burdened with her increasing population. Note that the present growth rate is 1.5% (BBS, 2006) in the realm. This territory is one of the largest deltas of the orb with a total area of 147570 square kilometer. About 1045 persons live here per square kilometer (CIA, 2007) leading it the densest populated country of the planet. This expanding population is exerting immense pressure on the usable land and ultimately reducing per capita available land in an alarming rate. This availability has been declined from 0.19 in 1961 to 0.101 ha in 1992 (Iqbal et al., 2002) and now the country is claimed to have the lowest per capita arable land of 0.06 hectares. Most of the area of the country is floodplain, covering about 80% of her total land, the rest 20% constitute hills and raised terraces (Abedin et al., 1991). Floodplain and terraces are the major ecosystem of Bangladesh in terms of traditional farm land agroforestry systems (Miah ef al., 2002). 2010-05-01T00:00:00Z