Historically, phosphorus has been considered to be the primary nutrient limiting phytoplankton growth in freshwater ecosystems. We tested this hypothesis in 19 Kansas reservoirs located within the Central Plains region, USA. Bioassay experiments were conducted to assess growth-rate limitation by nitrogen (N), phosphorus (P) and nitrogen and phosphorus (N and P). The addition of P alone rarely i...

The study was conducted to determine the specific chemical constituents of cattle urine and indigenous plant extracts. Chemical analysis revealed that the specific chemical composition i.e., chloride, sulphate, nitrite and phosphorus pentaoxide contents of fresh and fermented cattle urine were 1556, 364, 2.0, 26.8 and 4514, 252, 22.4, 7.49 mg l-1, respectively. The proximate chemical compositio...

Enrichment of surface waters with excess nutrients is associated with increased algal blooms, euthrophication and hypoxic zones, as reported in the northern Gulf of Mexico. A source of nutrients to surface waters results from fertilizer runoff. Management strategies used to maintain turf on golf courses and recreational fields often include aerification and application of fertilizer. Although r...

In response to water quality and quantity issues within the Stroubles Creek watershed in Blacksburg, Virginia, a retrofit bioretention cell (BRC) was installed to collect and treat runoff from an existing parking lot. The BRC was completed in July 2007, and 28 precipitation events were monitored between October 2007 and June 2008. For each storm, inflow and outflow flow-weighted composite sampl...

Prediction of phosphorus (P) availability from soil-applied composts and manure is important for agronomic and environmental reasons. This study utilized chemical properties of eight composted and two non-composted beef cattle (Bos taurus) manures to predict cumulative phosphorus uptake (CPU) during a 363-d controlled environment chamber bioassay. Ten growth cycles of canola (Brassica napus L.)...

BACKGROUND To enable effective management and decision making for the sustainable use of water resources, we successfully integrated factors such as dams, land use and soil properties as well as management factors in the Hanjiang River basin, a subtropical catchment of China, into the SWAT model to simulate water cycles as well as the distribution, movement, and transformations of nutrients. ...

Concerns about manure P and water quality have prompted new regulations imposing P limits on land application of manure. Previous research established that P limits increase land needs for animal feeding operations. We evaluated the effect of N, annual P, and rotation P limits on the feasibility of manure management. A mechanistic model characterized manure management practices on 39 swine oper...

We are using the coupled models in a decision support system, Nest, to evaluate the response of the marine ecosystem to changes in external loads through various management options. The models address all the seven major marine basins and the entire drainage basin of the Baltic Sea. A series of future scenarios have been developed, in close collaboration with the Helsinki Commission, to see the...

The focus of eutrophication research has tended to be upon short-term and experimental studies. However, given the range of factors that can influence eutrophication dynamics, and that these matter over a range of time scales, some discrete, some continuous, eutrophication dynamics may only be fully investigated when long-term, time-series data are available. The present study aims to evaluate ...