Vegetable BMP Research - 2006-2007 Season: Field Trial
We conducted thirteen trials at
five commercial farms in multiple locations and seasons (fall, winter and
spring) during the 2006-2007 seasons (Table
1). Together the cooperating farms represented 16,000 acres (80%) of staked
tomato production in southern and eastern Florida.
Soils in the area have a sandy surface layer that is prone to leaching, mostly comprised
of Immokalee and EauGallie fine sand).
Growing seasons are defined as fall with planting dates from August to 15 Oct.,
winter from 15 Oct. to 15 Dec. and spring from 15 Dec. to 1 Feb. These seasons differ
in rainfall patterns, temperatures and day length. For example, fall may bring hurricanes,
leaching rains, and wide-ranging temperatures; winter brings cool temperatures and
unpredictable freezes accompanying cold fronts; spring is typically dry with temperatures
cool at the start and warm or hot at the end. Typical growing season lengths are
18, 20, and 16 weeks for fall winter and spring, respectively.
Therefore eight trials were done with seepage, two with drip and three a combination
seepage/drip irrigation. One trial was conducted in the fall 2006, nine in the winter
(2006-07) and four in the spring 2007. Treatments consisted of N fertilizer rates
ranging from 200 to 330 lb/acre N applied to seepage-irrigated tomatoes in a (Table 1), except the multiple
N rate study with eight N rates from 20 to 420 lb/acre at 60 lb/acre increment in
a completely randomized block experimental design with four replications (Table
2). In drip-irrigated
fields, there were two individual zones representing IFAS and growers
N rates. At the seepage-irrigated
fields, the UF-IFAS rates were achieved by changing the rate or composition
of the hot mix and by applying custom-made blends to keep P, K micronutrients rates
constant. Hot-mix N and K fertilizer sources were water soluble nutrients, except
trials 7 and 8 with a 25% slow release fertilizer. The trials represented diverse
growing conditions found in Southwest and East Florida, and also included different
varieties (mostly Florida 47 and Sebring), plant densities (in-row spacing of 18
to 26 inches between plants; 5 or 6 ft bed centers), soil types (described above),
and farm sizes (700 to 5,000 acres). Cooperators prepared beds,
fumigated the soil, applied
bottom and hot mixes
and installed polyethylene
mulch, transplanted,
pruned, staked, irrigated
and provided pest and disease control.
Data collection:
The water table depth
was recorded bi-weekly throughout the growing season. Beginning at first flower
buds and continuing until third harvest, fresh petiole sap NO3-N and K concentrations
were measured bi-weekly using
ion-specific meters (Cardi, Spectrum Technologies, Inc., Plainfield, IL)
(Olson et al., 2005). Harvested plots were 15 to 22-ft long row segments of 10 plants.
They were clearly marked to prevent unscheduled harvest by commercial crews. Marketable
green and color tomatoes were
graded in the field according to USDA specifications of number and weight
of extra-large (5x6), large (6x6), and medium (6x7) fruit (USDA, 1997) of green
and color. Yield data were subjected to analysis of variance (ANOVA) mean separation
using Duncans Multiple Range Test at the 5% level of significance as well as non-parametric
analysis tests like binomial distribution and probability