|Authors: ||E. Simonne, M. Dukes, R. Hochmuth, G. Hochmuth, D. Studstill, W. Davis|
|Keywords: ||Citrullus lanatus, Best Management Practices, BMP|
The Surface Water Improvement Management (SWIM)
Act of 1987 declared that several water bodies in Florida were at risk of
becoming degraded from point and non-point sources of pollution (including
agriculture, and vegetable production). With approximately 142,000 ha, the vegetable industry in Florida has an
estimated value of $1.2 billion.
Consequently state agencies, water management
districts, and the University of Florida are developing and testing Best
Management Practices (BMPs) aimed at reducing alleged non-point source
The philosophy and purpose of BMPs is to produce economical yields
of vegetables while minimizing the impact of production on ground water nitrate
nitrogen (NO3-N) levels.
were grown in the spring between 1998 and 2002, following the recommendations
of the Institute of Food and Agricultural Sciences (IFAS). Nitrate levels in
the soil water at the 1.6-m and 7-m depths were monitored every three weeks
with suction cup lysimeters and wells, respectively.
yields ranged between 43,680 and 72,280 kg/ha, and were comparable to current
Nitrate-N in the lysimeters ranged from 20 to 150 mg/L NO3-N
except when rye cover crops were grown between vegetable crops.
Under rye cover
crops, NO3-N levels in the lysimeter samples ranged between 5 and 20
mg/L NO3-N. Those in the monitoring well samples were always below
20 mg/L NO3-N. It was concluded that economical yields of watermelon
may be produced with current recommendations, and that under these growing
conditions, NO3-N levels at the 1.6-m depth may range between 0 and 90 mg/L NO3-N. These
results suggest that it is not possible to maintain NO3-N levels in
the soil water or the shallow groundwater below the EPA drinking water
standard, when current recommendations are followed.
fertilizer rates to reduce nitrate levels to or below 10 mg/L NO3-N
is likely to reduce yield.
This research was
supported by the Florida Agricultural Experiment Station and approved for
publication as Journal Series No.N-02292
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