Southeastern U.S. Vegetable Crop Handbook - 2022 - 20

pensions (liquid lime) can be convenient and fast-acting, but are
usually considerably more expensive than ground limestones.
Industrial by-product liming materials can be useful soil amendments
capable of reducing soil acidity and supply a variety of
nutrients including calcium, magnesium, potassium, phosphorus,
and micronutrients. Each lot of such materials should be
analyzed as considerable variation in CCE, fineness, and nutrient
composition may occur.
Within a one to three year time-period, lime moves little
in the soil and neutralizes acidity only in the zone where it is
applied. To be most effective, lime must be uniformly spread
and thoroughly incorporated. In practice, rates are adjusted after
checking the spreader pattern and making appropriate corrections.
If the application is not correct, strips of under-limed soil
could result, possibly reducing crop yields. The most commonly
used lime incorporation tool is the disk. It will not incorporate
lime as well as offset disks that throw the soil more vigorously.
The best incorporation implement is a heavy-duty rotary tiller
that mixes the soil throughout the root zone.
Overall, it is imperative that a soil is limed properly before
soil is covered in vegetable systems; i.e. installing polyethylene
mulch, as lime additions through drip irrigation or overhead are
not practical or possible.
Lime and Fertilizer. Lime and fertilizer work together synergistically
to produce high yields and better crops. Lime is not a substitute
for fertilizer, and fertilizer is not a substitute for lime.
How to Use Plant Nutrient Recommendation Table #1 and #2.
Use Table 1 to determine the relative levels of phos phorus and
potassium in the soil based on the soil test report from the laboratory.
Use Table 2 as a guide in conjunction with specific soil
test results. Plant nutrient recom mendations listed in Table 2 are
expressed in terms of nitrogen (N), phosphate (P2
(K2
O5
O5) and potash (K2
), and potash
O), rather than in specific grades and amounts of fertilizer.
The phosphate (P2
O) needs for each cropping
situation can be determined by selecting the appropriate values
under the relative soil test levels for phosphorus and potassium:
very low, low, medium, high, or very high.
The cropping and manuring history of the field must be
known before a fertilization program can be planned (see Table
3). This history is very important in planning a nitrogen fertilization
program because a reliable soil test for nitrogen is not available.
Plant
nutrient recommendations listed in Table 2 were developed
for fields where no manure was applied and where no
Relative Yield
Medium
High
Very high*
75-100
100
100
Low
without Nutrient (%) Recommendations
50-75
legume crop is being turned under prior to the planting of a new
crop. If manure and/or legume crops are used, the plant nutrient
recommenda tions listed in Table 2 should be reduced by the
amounts of nitrogen (N), phosphate (P2
O5), and potash (K2
O)
being contributed from these sources. See Tables 3 and 3A for
nutrient values of various products.
Once the final fertilizer-plant nutrient needs are known, determine
the grade and rate of fertilizer needed to fulfill these requirements.
For ex ample, if the final plant nutrient requirements
that need to be added as a commercial fertilizer are 50 pounds of
nitrogen (N), 100 pounds of phosphate (P2
of potash (K2
O5
), and 150 pounds
O), a fertilizer with a 1-2-3 ratio, such as 5-1015,
6-12-18, 7-14-21, is needed. Once the grade of fertilizer is
selected, the quantity needed to fulfill the plant nutrient requirements
can be deter mined by dividing the percentage of N, P2
or K2
O5
,
O con tained in the fertilizer into the quantity of the respective
plant nutrient needed per acre and multiplying the answer by
100.
For example, if a 5-10-15 fertilizer grade is chosen to supply
the 50 pounds of N, 100 pounds of P2
K2
O5
, and 150 pounds of
O needed, calculate the amount of 5-10-15 fertilizer needed as
follows: Divide the amount of nitrogen (N) needed per acre (50
pounds) by the percentage of N in the 5-10-15 fertilizer (5 percent),
and multiply the answer (10) by 100, which equals 1,000
pounds. This same system can be used for converting any plant
nutrient recommendations into grades and amounts.
NUTRIENT MANAGEMENT AND
MAXIMIZING PRODUCTION
Nitrogen Management. Nitrogen is one of the most difficult
nutrients to manage in vegetable production systems. Nitrogen is
readily leached in sandy textured soils that dominate vegetable
production regions of the southeastern US. Nitrogen can be immobilized
by soil microbes, volatilized if not quickly incorporated,
or lost via denitrification under water-saturated soil conditions.
Nitrogen recommendations are based on years of fertilizer
trials and yield potential. Nitrogen application timings, application
methods, and sources are also commonly tested in state
university fertilizer trials and have resulted in recommendations
for splitting nitrogen fertilizer application for increased fertilizer
use efficiency.
Heavy rainfall, higher than normal yields, and production
following non-legume cover crops are a few examples where nitrogen
fertilizer may be immobilized or lost from the production
TABLE 1. SOIL TEST INTERPRETATIONS AND RECOMMENDATIONS BASED ON SOIL TEST RESULTS
Soil Test Rating
Annual application to produce maximum response and increase soil fertility.
Normal annual application to produce maximum yields.
Small applications to maintain soil level to replace nutrients removed by crop. Amount suggested may be doubled and
applied in alternate years.
Depending on crop and state, none until level drops back into high range. This rating permits growers, without risk of loss in
yields, to benefit economically from high levels added in previous years. Where no P or K is applied, soils should be resampled
in 2 years. When phosphorus is extremely high, further additions may limit the availability of Fe and/or Zn.
* Some states recommend that no fertilizer P or K be added when the soil test rating is " Very High " in order to minimize losses in nutrient-sensitive watersheds.
Some crops may still benefit by additions of starter fertilizer for P and K and state guidelines should be followed.
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2022 Vegetable Crop Handbook for Southeastern United States

Southeastern U.S. Vegetable Crop Handbook - 2022

Table of Contents for the Digital Edition of Southeastern U.S. Vegetable Crop Handbook - 2022