We evaluated the impacts of natural wetlands and various land uses on stream nitrogen concentration in two grassland-dominated catchments in eastern Hokkaido, Japan. Analyzing land use types in drainage basins, measuring denitrification potential of its soil, and water sampling in all seasons of 2003 were performed. Results showed a highly significant positive correlation between the concentrat...

there is a need to analyze and map rainfall erosivity to assess soil erosion at the regional scale. the objectives of this study were to develop a regional model to estimate seasonal erosivity from seasonal rainfall data and to study temporal and spatial distribution of rainfall erosivity for the gorganrood drainage basin in the northeast of iran. six gauging stations with a high temporal reso...

The lowering of the water table resulting from peatland drainage may dramatically alter C and N cycling in peatland ecosystems, which contain one-third of the total terrestrial C. In this study, tree annual ring width and C (delta(13)C) and N (delta(15)N) isotope ratios in soil and plant tissues (tree foliage, growth rings, and understory foliage) in a black spruce-tamarack (Picea mariana-Larix...

Approximately 50,000 ha of native wet Metrosideros forest on the island of Hawai'i experienced a drastic reduction (dieback) of the tree canopy between 1954 and 1977. Two general hypotheses have previously been suggested to explain this phenomenon: 1) Metrosideros dieback has resulted from recently introduced pathogens, and 2) the dieback has naturally occurred previously in Hawai'i, and is rel...

The Coimbatore varieties Co. 213. 214. '281 are compared with Uba in a soil of poor agricultural qualities. The surface soil is a shallow loam with a very stiff clay subsoil. The field is on a low lying flat and drainage is difficult; the crop is also liable to suffer severely in drought. Further details and a partial chemical analysis of the soil are given in the report on the plant cane results.

In active tectonic regions with large-magnitude storms, it is still difficult to predict stormflow responses by distributed runoff models from the catchment properties without a parameter calibration using observational data. This paper represents an attempt to address the problem. A review of observational studies showed that the stormflow generation mechanism was heterogeneous and complex, bu...

The Root Zone Water Quality Model (RZWQM, V 3.25) was used to simulate the effect of swine manure applications on nitrate-nitrogen (NO3-N) concentrations in subsurface drain water from continuous corn for Iowa soils. Measured values of subsurface drain flow, NO3-N concentrations in drainage water, and residual NO3-N in the soil profile from three chisel plow plots were available for the growing...

Groundwater nitrogen (N) and phosphorus (P) transport from ditch-drained, cultivated fields has not been adequately investigated in the Chesapeake Bay watershed.We monitored hydrology and groundwater Nand P concentrations in 26 shallow (~3 m [10 ft]) wells for 27 months on a heavily ditched, poultry-grain farm on Maryland's Lower Eastern Shore. Water tables fluctuated above and below shallow di...