<p>The purpose of this research was to measure P losses in runoff from agricultural land in the Piedmont region of the southeastern U.S. with varying soil P levels and receiving broiler litter and inorganic P fertilizers. The experimental results will be helpful for the development of the P Loss Assessment Tool in North Carolina and other P Index approaches in states with similar soil characteristics and crop management practices. A net influx of P into many areas due to high animal populations has resulted in increased potential P losses to sensitive surface waters. A typical North Carolina broiler farm and dairy farm were found to have annual P surpluses of 65 kg P/ha and 20 kg P/ha respectively. The use of low phytic acid corn varieties and phytase enzyme has the potential to reduce the P surplus on broiler farms by 25 to 58%. Phosphorus losses in runoff from Piedmont conventional till (CT) and no-till (NT) soils with varying soil P concentrations and from soils currently receiving broiler litter and fertilizer P applications were assessed. In these studies, rainfall simulation at rates of 6 and 7.6 cm/hr were utilized to collect runoff samples from crop land with a range of initial P concentrations and from plots with varying fertilizer P and broiler litter application rates, both incorporated and broadcast. Runoff samples were collected at 5-min intervals for 30 min and analyzed for reactive P (RP), algal-available (AAP), and total P (TP). Concentration of RP in runoff from CT and NT plots was positively correlated with Mehlich-3 extractable P (r2 = 0.61 and 0.7 respectively) and oxalate extractable degree of P saturation (DPS) (r2 = 0.6 and 0.61 respectively). However, only TP mass loss (kg TP/ha) in runoff from CT was correlated with DPS (r2 = 0.57). A Mehlich 3 extractable P concentration of 350 mg P/kg and a DPS of 84% corresponded to 1 mg RP/L in runoff. Incorporation of broiler litter and inorganic P fertilizer into the soil at all P application rates virtually eliminated P runoff loses and had similar P losses in runoff as the unfertilized control. Surface application of broiler litter resulted in runoff containing between 2.9 and 24.5 mg RP/L for application rates of 8 to 82 kg P/ha respectively. Mass loss of TP in runoff from surface-applied broiler litter ranged from 1.3 to 8.5 kg P/ha over the same application rates. There was no significant relationship between surface applied inorganic P application rate and RP concentrations or TP mass losses in runoff. However, there was a trend for increased RP concentrations and TP mass losses in runoff with increasing application rate. Concentration of RP and mass loss of TP in runoff from surface applied inorganic P averaged 4.9 mg RP/L and 1.1 kg P/ha over all application rates. There was no significant difference between P losses in runoff from plots receiving surface applied conventional broiler litter and broiler litter derived from birds fed a low phytic acid corn (High Available P corn). <P>
| Identifer | oai:union.ndltd.org:NCSU/oai:NCSU:etd-20010926-002603 |
| Date | 26 September 2001 |
| Creators | Tarkalson, David Dale |
| Contributors | Robert L. Mikkelsen, J. Wendell Gilliam, John E. Parsons, Eugene J. Kamprath |
| Publisher | NCSU |
| Source Sets | North Carolina State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://www.lib.ncsu.edu/theses/available/etd-20010926-002603 |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to NC State University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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