No description available.

The total amount of nitrogen and phosphorus in animal manures, and the proportion of this amount that becomes available as dissolved inorganic nitrogen and phosphorus within a month after manures are added to water were examined in the context of fertilization guidelines for pond aquaculture. A literature study was conducted to synthesize information on the dry matter, total nitrogen and total phosphorus contents, and the biochemical oxygen demands of different manures. This information was used to compile a fertilizer database and to examine dry matter-nutrient relationships for different manures. Significantly high correlations between dry matter and total nitrogen, and between dry matter and total phosphorus were observed for poultry manure, and different forms of beef and dairy cattle manures. These relationships can be used to estimate the nutrient contents of manures if the dry matter contents are measured. A laboratory experiment was conducted to determine the amount of nitrogen and phosphorus that becomes available as dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP) over a five week period when poultry, swine and dairy manures are added to water. Mean DIN and DIP concentrations reached highest levels on the 5th day after manure addition for all the manures. These concentrations corresponded to 60.5, 49.5 and 30.1% of the total nitrogen and 78.4, 77.4 and 58% of the total phosphorus supplied by poultry, swine and dairy manures respectively. DIN and DIP concentrations were significantly different among the three manures on all sampling days. Poultry manure supplied the highest amount of nitrogen and phosphorus, followed by swine and dairy manures. Pond fertilization guidelines based on the nitrogen and phosphorus requirements for algae should consider the available portion and not the total nitrogen and phosphorus contents of manures to calculate fertilizer requirements. Another study was conducted to examine the effects of temperature and repeated manure addition on nutrient release patterns from poultry manure. Different temperatures over a three week period did not have a pronounced impact on DIN and DIP levels. Two phases of DIN build-up were observed, whereas DIP levels showed an increasing pattern throughout the temperature experiment. The overall proportion of the total nitrogen and phosphorus supplied by poultry manure that became available as DIN and DIP for all the experimental units considered together amounted to about 64 and 70% respectively, which is consistent with the earlier study. Repeated manure addition resulted in significantly lower DIN and higher DIP concentrations in the interval following the second manure addition compared to the first interval, although nutrient release patterns appeared to be similar. / Graduation date: 1993

Thesis (Ph. D.)--Washington State University, December 2009. / Title from PDF title page (viewed on Feb. 19, 2010). "Department of Biological Systems Engineering." Includes bibliographical references.

No description available.

No description available.

Grazing and no-till management in organic systems have been recently proposed tools to improve nutrient cycling and sustainability. From 2008 to 2012 a series of field experiments were established to identify green manure species and green manure management options to maximize N benefit to following cash crops and explore the opportunities to reduce tillage during the green manure phase of an organic rotation. A total of four green manure systems (double-cropped green manures, relay-cropped green manures, full season green manures, and catch crops after grazed full season green manures), three green manure management options (soil incorporation, grazing and no-till), and 10 green manure species, as well as, three green manure mixtures were tested. Double-cropped pea (Pisum sativum cv. 40-10) and relay-cropped red clover (Trifolium pratense) produced around 900 kg ha-1 and 2000 kg ha-1 of biomass respectively. The greatest biomass producing full season green manures were hairy vetch (Vicia villosa L.), pea/oat (Avena sativa cv. Leggett/Pisum sativum cv. 40-10) and sweet clover (Mellilotus officinalis cv. Norgold). Pea/oat and hairy vetch were the most weed competitive species and on average contained less than 15% weed biomass. Among all the systems and managements tested, nitrogen availability was greatest when full season green manures were grazed. On average grazing increased soil NO3-N by 25% compared to soil incorporation using tillage. Among grazed species, pea/oat mix and hairy vetch green manures resulted in the greatest amount of soil available NO3-N. Catch crops after grazing green manures, regardless of the species, significantly reduced N leaching risk compared to no catch crop treatment, but also reduced wheat productivity the following year. Catch crop biomass productivity and N uptake, soil NO3-N, and wheat productivity were similar in direct seeded and conventionally seeded plots. Grazing may be an effective tool in reducing tillage in organic agriculture because of its ability to accelerate the N mineralization from catch crop biomass. This study was the first study to use grazing as a management tool for green manures in organic systems. Results provide strong evidence that green manures, especially when grazed, can be effective nitrogen suppliers in organic grain based rotations.

Thesis(M.S.)--Auburn University, 2005. / Abstract. Vita. Includes bibliographic references.

Thesis (Ph. D.)--West Virginia University, 2008. / Title from document title page. Document formatted into pages; contains xi, 228 p. : ill. (some col.), col. maps. Vita. Includes abstract. Includes bibliographical references (p. 178-185).

Thesis (M.S. in Soil Science)--Washington State University. / Includes bibliographical references.

Thesis (M.S.)--Rutgers University, 2009. / "Graduate Program in Environmental Sciences." Includes bibliographical references (p. 115-122).