Many tomato growers in Southwest Florida believe that
they would incur significant financial losses if they limited N
fertilization rates to 200 lb N/acre. They believe that a 50 percent
increase in the N-rate would support higher production levels and allow
them to fully take advantage of favorable market prices. In other words,
they view higher N-rates as a form of insurance. Most prices presented
in the price history of US#1 tomatoes corresponding to all the harvest
dates during the 2004-05 N trials (Table 1) were
higher for the larger sizes (5x6s). Under high price market conditions,
the price difference between 5x6s and 6x7s increased. When the market
prices fell to low levels, there was no price difference between extra
large and medium sized tomatoes. Most of the fall trials were harvested
during January 2005, a time when the market was at historic low prices.
Between the end of December and mid-March, tomato prices were below an
estimated break-even price of $9.50 per 25-lb box. More importantly, a
price of $4 per 25-lb box or below does not even cover harvest, packing,
and marketing costs. Consequently, many fields were picked once for the
5x6 size and then abandoned. For the purpose of data collection,
grower-cooperators allowed field trials to be picked three times
regardless of the commercial market conditions. By the latter part of
March, prices rebounded and the market for southwest growers remained
strong for the rest of the spring season. Abandoning fields for
economical reasons may result in increased residual fertilizer levels
left in the field at the end of the season. This may not be an
environmental concern for N as it may be denitrified during the summer
flooding of the fields.
Table 2 summarizes for each trial
the impact of N rate differences within a trial on 5x6 yields and total
revenue. In trial one, four N rates were evaluated. On the remaining
farm sites, only two N rates were considered, the “grower-standard” and
an IFAS rate of 200 lb N/acre. For example, the “grower-standard” on
trial three was 300 lb N/acres, or a difference of 100 lb N/acres
between “grower-standard” and UF-IFAS rate. A monetary value of yield
differences was calculated on the basis of the projected yield
differences between N rate treatments and prices listed in Table 4 that
corresponded to the actual harvest dates of a given trial.
Yield and financial impacts varied across trials. In
all trials except trial six, total production of extra larges (5x6)
boxes was greater under the higher grower fertilization rate. Total
revenue was greater on all experiment sites, even in trial six. Since
treatment plots were harvested regardless of market prices, it must be
noted that revenue differences for the fall trials were overstated. When
prices fall below $5 per box, growers will often choose either to
abandon the crop, or direct harvesting crews to pick only the extra
large sizes (5x6s). Trial six illustrated an important lesson of market
timing. While the UF-IFAS rate on trial six produced more total cartons
of 5x6s, 5x6 yields from the grower standard plots were greater during
the third harvest date – April 19 when the market price exceeded $19 per
box.
