Lime Sources
Liming is the application of calcium or calcium-magnesium
compounds that are capable of neutralizing
soil acidity ( raising the soil pH). Two major types of
lime are used for agricultural purposes: calcitic and
dolomitic. Calcitic limestone is composed of calcium
carbonate ( CaCO 3 ) and contains little or no magnesium.
Dolomitic limestone is a mixture of calcium and
magnesium carbonates [ CaMg( CO 3 ) 2 ] and contains, by
state law, 6 percent or more magnesium. Most lime sold
in North Carolina is dolomitic lime. Agricultural grade
lime, or ag lime, must meet specifi cations in fi neness of
grind and guarantee a neutralizing value established by
state law.
Lime Rates
The rate ( tons per acre) of lime recommended on the soil
test report should raise the pH to
• 5.0 for organic ( ORG) soils,
• 5.5 for mineral organic ( M- O) soils and
• 6.0 to 6.2 for mineral ( MIN) soils, depending on the
crop to be grown.
The recommended rate varies depending on the level
of soil acidity and the target pH for each soil type. The
pH obtained with a given rate of lime varies depending
on uniformity of application, particle size, neutralizing
value, method and depth of incorporation, and soil
texture.
When lime is recommended, apply it as early
as possible to allow enough time to neutralize soil
acidity. For best results, use a high- quality ag lime and
incorporate it thoroughly into the top 8 inches of soil.
Apply and incorporate lime prior to beginning reduced
or no- till systems if possible. Maintenance applications
can be surface applied.
A low soil pH is associated with low levels of
calcium and/ or magnesium as well as high soil acidity.
As the level of soil acidity increases, aluminum increases
and becomes toxic to plants. The effi ciency of nutrient
uptake and use decreases as well.
NOTE 3:
Fertilization of
Field Crops
acidity and has a high calcium requirement for quality
lint production. Liming neutralizes soil acidity, supplies
the calcium and magnesium required for plant growth
and fi ber production, and promotes the effi cient use of
other plant nutrients.
Rate and timing of nitrogen applications strongly
infl uence cotton yield. Low nitrogen reduces yield.
Too much causes excessive vegetative growth, makes
pesticide coverage more diffi cult, delays fruiting and
maturity, increases attractiveness to insects and reduces
the effectiveness of defoliants.
The nitrogen rate of 50– 70 lb per acre given on the
soil test report can be adjusted depending on soil type
and expected yield potential. See section Realistic
Yield Expectation ( RYE) N Rates.
On sandy coastal plain soils where nitrogen is subject
to leaching, apply 20– 25 lb per acre at planting with the
remainder side- dressed shortly after formation of squares.
On deeper sandy soils where leaching is extensive,
apply side- dressed nitrogen in split applications. Apply
all nitrogen by mid- June.
In most cases, apply all recommended P 2 O 5 and K 2 O
at planting. High- phosphate starter fertilizer ( 10- 34- 0),
banded at planting, can enhance growth and maturity for
cotton planted early on cool soils. Place banded starter
fertilizer 2 inches to the side and 2 inches below the seed
to avoid salt injury to young seedlings. On deep, sandy-textured
soils where potassium leaches, consider split
applications of K 2 O.
Boron is essential for good bloom set, seed
development, and fi ber production. The boron
recommended on a soil test report ( 1.0 lb per acre) is
for broadcast application during seedbed preparation.
Alternatively, if borated fertilizer is banded, apply 0.2–
0.4 lb actual B per acre. For foliar application, use 0.25
lb B per acre at early bloom followed by another 0.25
lb after two weeks. Select a highly water- soluble boron
source. Monitor the boron status during the season with
plant tissue analysis.
Sulfur defi ciency can occur on sandy coastal plain
soils where the clay is below 16 inches, particularly in
seasons of excessive rainfall. Rates of 20– 25 lb per acre
applied along with the fertilizer safeguard against sulfur
defi ciency under most soil and climatic conditions.
Since sulfur and nitrogen defi ciencies are similar, submit
plant tissue and soil samples for problem analysis and
verifi cation.
The soil test report gives a sulfur recommendation
whenever S- I < 25. Since sulfur leaches readily, it may
be adequate at the time of the report but be limiting later
during the season. To monitor sulfur levels during the
growing season, take plant tissue samples and send them
to the NCDA& CS lab for analysis.
Realistic Yield Expectation ( RYE) N Rates
More specifi c nitrogen rates can be used based on realistic
yield expectations by soil type. These rates are required
for waste and nutrient management plans in some N. C.
river basins. Rates using the RYE approach are available
online at www. soil. ncsu. edu/ nmp/ yields/.
Livestock and Poultry Manures
Farm manures can be valuable sources of N, P 2 O 5 , K 2 O
( Table 1) and, in some cases, the micronutrients zinc
and copper. Since nutrient content varies with rate and
method of application, it is best to have the manures
analyzed for nutrient content near the time of application.
NCDA& CS offers a basic waste analysis for a fee of
$ 5.00 per sample and special tests ( lime equivalence,
heavy metals, nitrogen breakout) for an additional fee of
$ 10 per test per sample.
Repeated applications of animal waste can lead to
high levels of zinc and copper within crops. Excessive
levels can be toxic to plants and cause reproduction
problems in livestock. Test soils regularly to determine
when to discontinue application of manures for a
particular site.
Department of Agriculture
and Consumer Services
Steve Troxler, Commissioner of Agriculture
NCDA& CS Agronomic Division
Dr. Colleen Hudak- Wise, director
www. ncagr. com/ agronomi/
( 919) 733- 2655
Mailing Address
1040 Mail Service Center
Raleigh NC 27699- 1040
Physical Address
4300 Reedy Creek Road
Raleigh NC 27607- 6465
November 2007
20,000 copies of this public document were printed
at a cost of $ 788.99 or $ 0.03 per copy.
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Table 1. Average plant nutrients available
the first year after broadcast application of
animal waste *
N P 2 O 5 K 2 O
-------- lb/ ton --------
Broiler house litter
(> 6,000 samples)
29.0 26.8 40.0
Turkey house litter
(> 2,500 samples)
24.2 28.0 26.6
---- lb/ 1000 gallons ----
Anaerobic swine lagoon
(> 38,000 samples)
1.8 1.0 5.4
Dairy manure slurry
(> 1,500 samples)
4.6 4.2 9.7
* Based on NCDA& CS waste analyses, 1999– 2006.