wAbstract
@In tracking nutrients that enter the Gulf of Mexico via the Suwannee
Basin, a disproportionate amount of the nitrate-nitrogen (NO3-N) has been shown to originate in the Santa
Fe River Watershed (SFRW). This study investigated soil NO3-N distributions across the range of land-use
and soil order combinations that exist in the SFRW with a focus
on comparing NO3-N levels in forested versus
non-forested land-uses. The SFRW consists of 52 forested land-uses
(i.e. pine plantation, forest regeneration, upland forest, and
forested wetland), 47 non-forested land-uses (i.e. agriculture,
rangeland, and urban), and 1 water. Soil samples were collected
from four depth intervals (0-30, 30-60, 60-120, 120-180 cm) at
101 to 141 sites with a stratified-random design in six sampling
events (Sept. 2003, Jan. 2004, May 2004, Jan. 2005, May 2005,
and Sept. 2005). No samples were collected in Sept. 2004 due to
flooding associated with two hurricane. Nitrate-nitrogen was significantly
lower in forested than non-forested land-uses across all sampling
events, depth intervals, and for profile average data. Within
the non-forested land-use category, NO3-N
levels were highest in row crop agriculture and improved pasture
sites. In terms of soil order, NO3-N values
were generally highest in Ultisols and Spodosols, but soil order
explained less of the variation in the NO3-N
data than did land-use or sampling date. Nitrate-N concentrations
were considerably altered by Hurricanes Frances and Jeanne which
passed over the SFRW in late summer of 2004. In the post-hurricane
sampling events, NO3-N was significantly
lower in both forested and non-forested sites. A year later, however,
NO3-N concentrations in forested sites remained
quite low, while concentrations in non-forested sites had begun
to increase.
Keywords: Florida; Land-use; Nitrate-nitrogen; Soil; Watershedx
1. Introduction
2. Materials and methods
@2.1. Study area
@2.2. Land-use reclassification
@2.3. Field data collection
@2.4. Laboratory analyses
@2.5. Statistical analyses
3. Results and discussion
@3.1. Forested versus non-forested sites across all dates
@3.2. Specific land-uses across all dates
@3.3. Soil orders across all dates
4. Conclusions
Acknowledgements
References