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Title: ASSESSING THE LEVELS OF NUTRIENTS IN SOILS AND WATER ASSOCIATED WITH FORAGE BASED PASTURE SYSTEM IN SUBTROPICS

Author
item Sigua, Gilbert
item Coleman, Samuel
item Albano, Joseph

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 1/18/2005
Publication Date: 2/9/2005
Citation: Sigua, G.C., Coleman, S.W., Albano, J.P. 2005. Assessing the levels of nutrients in soils and water associated with forage based pasture system in subtropics. Meeting Abstract.Abstracts of the 69th Annual Meeting of the Florida Academy of Sciences. page 6, AGR-22

Interpretive Summary:

Technical Abstract: Forage-based livestock systems have been implicated as major contributors to deteriorating water quality, particularly for phosphorous in fertilizers and manures impacting surface and ground water quality. For this reason, we investigated the historical water quality parameters and trophic state index (TSI) in three lakes associated with beef cattle pastures adjacent to or within about 8- to 16-km radius from the USDA-ARS, Subtropical Agricultural Research Station from 1993 to 2003. We also examined the changes that have occurred in soil fertility levels in beef cattle pastures over a 15-year period. Soil fertility levels over a 15-year period showed a declining trend for the levels of P and other crop nutrients from 1988 to 2003. Overall, there was no spatial and temporal build up of soil P and other crop nutrients in rhizoma perennial peanut fields harvested for hay despite the annual application of P-containing fertilizers. In addition, grazed bahiagrass pastures declined in P despite daily in-field loading of animal waste. Water quality in Lake Lindsey (TSI of 35) was "good". Measures of current water chemistry in Lake Lindsey were similar to what was found in the 1960s. Water quality in Spring Lake (TSI of 30) and Bystre Lake (TSI of 46) were also "good" with low concentration of total nitrogen and total phosphorus. Based upon the Florida Water Quality Standard, TSI of 0-59 is "good"; TSI of 60 to 69 is "fair"; and TSI of 70 to 100 is "poor". These findings indicate that properly managed livestock operations might not be major contributors to excess loads of nutrients (especially P) in surface water.