Nutrient management through irrigation tubes involves precise scheduling
of N and K applications. Application rates are determined by crop growth
and resulting nutrient demand. Demand early in the season is small and
thus rates of application are small, usually on the order of ½ to ¾ lb of N or
K2O per acre per day. As the crop grows, nutrient demand increases rapidly
so that for some vegetable crops such as tomato the demand might be as
high as 2 lb of N or K2O per day. Schedules of N and K application have
been developed for most vegetables produced with drip irrigation in Florida
(Table 7).
FOLIAR FERTILIZATION
Foliar fertilization should be used as the last resort for correcting a nu-
for micronutrients but not appropriate for macronutrients such as N, P, and
corrected by foliar application. For example, micronutrients should be foliar
applied in such situations (1) In winter when soils are cool and roots cannot
extract adequate micronutrients and (2) In high pH soils (marl and Rockdale
adequate and toxic amounts of micronutrients. Indiscriminate application of
micronutrients may reduce plant growth and yields because of the toxicity.
The micronutrients can accumulate in the soil and may cause yield and
economic losses in vegetable production. If you are not sure if your crop
requires micronutrients or how much you should apply, contact your UF/
IFAS Extension county agent.
The 5th R, RIGHT IRRIGATION
Fertilization and irrigation go hand-in-hand, with fertilizers included in
irrigation schedules and systems. Water is the solvent of all nutrients and
the carrier of almost every pollutant. Keeping moisture and fertilizer primarily
in the root zone by managing irrigation inputs and drainage minimizes nutrient
related impacts. Irrigating in excess of the soil’s water-holding capacity
or excessive drainage leads to increased runoff or leaching, and may result
in higher production costs or lower marketable yields.
Table 2.9. Phosphorus (P; expressed as P2O5) and potassium (K; expressed as K2O) fertilization recommendations for selected vegetable crops in mineral soils of Florida,
using MEHLICH 1 SOIL EXTRACTANT METHOD. VL, L, M, H, and VH = very low, low, medium, high, and very high, respectively.
P2O5 K2O
VL L M H VH VL L M H VH
(lb/A/crop season) (lb/A/crop season)
Celery
200 150 100 0 0 250 150 100 0 0
Eggplant
160 130 100 0 0 160 130 100 0 0
watermelon, pepper, sweet corn, crisphead lettuce, endive, escarole, strawberry, and romaine lettuce
150 120 100 0 0 150 120 100 0 0
Tomato
150 120 100 0 0 225 150 100 0 0
Cucumber, squash, pumpkin, snapbean, lima bean, pole bean, beet, radish, spinach, and sweetpotato
120 100 80 0 0 120 100 80 0 0
Bunching onion and leek
120 100 100 0 0 120 100 100 0 0
Potato
120 120 60 0 0 150 -- -- -- --
Southern pea, snowpea, and English pea
80 80 60 0 0 80 80 60 0 0
Table 2.10. Interpretations of Mehlich-1 soil tests for micronutrients.
Soil pH (mineral soils only)
5.5–5.9 6.0–6.4 6.5–7.0
(parts per million)
Test level below which there may be a crop
response to applied copper. 0.1–0.3 0.3–0.5 0.5
Test level above which copper toxicity may
occur. 2.0–3.0 3.0–5.0 5.0
Test level below which there may be a crop
response to applied manganese. 3.0–5.0 5.0–7.0 7.0–9.0
Test level below which there may be a crop
response to applied zinc. 0.5 0.5–1.0 1.0–3.0
2 lbs Zn, 4 lbs Fe, 3 lb Cu and 1.5 lbs B (higher rate needed for cole crops).
Table 2.11. Some nutrients and fertilizer management for vegetable production in Florida.
Nutrient Source
Foliar application
(lb product/A)
Boron Borax1
Solubor
2 to 5
1 to 1.5
Copper Copper sulfate 2 to 5
Iron Ferrous sulfate
Chelated iron
2 to 3
0.75 to 1
Manganese Manganous sulfate 2 to 4
Molybdenum Sodium molybdate 0.25 to 0.50
Zinc Zinc sulfate
Chelated zinc
2 to 4
0.75 to 1
Calcium Calcium chloride
Calcium nitrate
5 to 10
5 to 10
Magnesium Magnesium sulfate 10 to 15
1 Mention of a trade name does not imply a recommendation over similar materials.
2019 Vegetable Production Handbook of Florida 9