Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract only
Publication Acceptance Date: 11/7/2005
Publication Date: 11/7/2005
Citation: Sigua, G.C., Coleman, S.W., Williams, M.J., Albano, J.P. 2005. Levels of phosphorus in soils and trophic state of lakes associated with grazed and hayed forage-based pasture systems in florida [abstract]. ASA-CSSA-SSSA Annual Meeting Abstracts. November 6-10, 2005. Salt Lake City, UT. ASA-CSSA-SSSA CD ROM. Interpretive Summary:
Technical Abstract: Forage-based livestock systems have been implicated as major contributors to deteriorating water quality, particularly for phosphorus (P) in fertilizers and manures affecting surface and ground water quality. Little information exists regarding possible magnitudes of nutrient losses from pastures that are managed to both grazing and hay production and how this might be impacting adjacent bodies of water. We examined the changes that have occurred in soil fertility levels of rhizoma peanut- (RP; Arachis glabrata) based beef cattle pastures (n = 4) from 1988 to 2002. These pastures were managed for grazing in spring followed by haying in late summer and were fertilized annually with P (39 kg P2O5/ha) and K (68 kg K2O/ha). Additionally, we investigated trends in water quality parameters and trophic state index (TSI) of lakes (n = 3) associated with beef cattle pastures from 1993 to 2002. Soil fertility levels showed a declining trend for crop nutrient levels, especially soil P (y = 142 - 11.2*years; r2 = 0.52). Overall, there was no spatial and temporal build up of soil P despite the annual application of fertilizers and daily in-field loading of animal waste. Water quality in lakes associated with cattle production was “good” (30-46 TSI) based upon the Florida Water Quality Standard. These findings indicate that properly managed livestock operations might not be major contributors to excess loads of nutrients (especially P) in surface water.