Soil Fertility Management for Forage Crops 25 th Annual FL Cattlemen’s Institute and Allied Trade Show Maria L. Silveira Soil and Water Science University.

Soil Fertility Management for Soil Fertility Management for Forage CropsForage Crops

2525thth Annual FL Cattlemen’s Institute Annual FL Cattlemen’s Institute and Allied Trade Showand Allied Trade Show

Maria L. SilveiraMaria L. SilveiraSoil and Water ScienceSoil and Water Science

University of Florida – Range Cattle RECUniversity of Florida – Range Cattle REC

http://www.ufl.edu/

Essential Elements for Plants

Primary nutrients:

Nitrogen, Phosphorus, Potassium

Secondary nutrients:

Calcium, Magnesium, Sulfur

Micronutrients:

Zinc, Manganese, Iron, Copper, Boron, Molybdenum, Chlorine

Carbon, Hydrogen, and Oxygen

M. Silveira, Soil and Water Science, UF/IFAS Range Cattle REC

Soil Fertility and Forage Production


• Soil fertility management is a continuous process that begins before forages are established

Yield will be limited by the element in shortest supply in relation to plants needs










Soil pH

pH 4.4

pH 5.7


pH 5.6

pH 4.3

Effect of soil pH on fertilizer efficiency

pH N P K

------- Fertilizer Efficiency (%) -------

4.5 21 8 21

5.0 38 10 30

5.5 52 15 45

6.0 63 15 60

7.0 70 30 60


Target pH for different forage crops

grown on mineral soils1 Crop Category Target pH

Bahiagrass 5.5

Bermudagrass, stragrass and limpograss

5.5 – 6.0

Small grains and ryegrass 6.0

Perennial peanut 6.0

Clover 6.5

Alfalfa 7.01C. G. Chambliss, G. Kidder, and R. Mylavarapu. 2003. Liming for Production of Forage Crops in Florida. EDIS SS-AGR-46.

Characteristics of liming materials Lime, calcite, dolomite, calcitic and dolomitic

limestone, aragonite.

ECCE = effective calcium carbonate equivalence


ECCE 100%

ECCE 40%

ECCE 10%

Photo: University of Nebraska

Importance of Soil Test




Soil Test Soil sample collection: representative of the entire area of interest

• Minimum of 15-20 subsamples

• Differences in soil type

• Areas managed or cropped differently

• Areas that clearly have some type of problem


Soil Test Handling and submitting your soil sample

1. Samples are thoroughly mixed

2. Sub-sample should be placed in a clean and properly labeled soil sample bag

3. Samples should be delivered to lab as soon as possible after collection



SOIL TEST RESULTS AND THEIR INTERPRETATION

- Target pH: 5.5

- pH (1:2 sample:water): 5.1

- A-E Buffer Value: 7.3

Mehlich-1 Extractable V Low Low Med High V High

Phosphorus 12

Potassium 4

Magnesium 30

Calcium 112

60”

Tissue Test

Photo: Dr. C. Mackowiak

Tissue Test


Tissue concentration

Def

icie

nt

Low

Suf

ficie

nt

Hig

h

Exc

ess

Cro

p Y

ield

Critical range

Plant Tissue Sampling


• Sample collection and handling

are crucial

• Bahiagrass should be sampled

prior to seed head emergence

• The four uppermost leaf blades

should be sampled

• Critical P concentration for

bahiagrass = 0.15%

Photo: Dr. C. Mackowiak

Changes in Fertilization Recommendations for Established Bahiagrass Pastures

1. Soil sampling is recommended for the entire State

2. Soil pH

• ≥ 5.5 (if pH is below 5.3, lime should be applied)

• When necessary, lime should be applied at least 3 to 6 months prior to fertilization

3. Phosphorus fertilization

• Phosphorus fertilization is recommended when soil test is very low or low in P and tissue concentration is < 0.15%



Low N option (50-60 lb N/A)

- K is not recommended

- Apply 25 lb P2O5/A if soil tests very low or low in P AND tissue concentration is below 0.15%

Medium N option (100 lb N/A)- Apply 50 lb K2O/A if soil tests very low or low in K




High N option (160 lb N/A) - Apply 80 lb K2O/A if soil tests very low or low in K. Apply 40 lb K2O/A if soil tests medium in K.



Summary


Soil Test P Tissue Test Recommendations

Med/High No tissue test

0

Very Low/Low P ≥ 0.15% 0

Very Low/Low P < 0.15% 25 or 40 lb P2O5/A‡

‡ Based on N option

Flow Chart – Bahiagrass Recommendations


Soil Sample Plant Tissue Sample

Soil test P, K, Ca, Mg, lime requirement and tissue test

Soil tested very low or low in P Soil tested medium or high in P

Tissue P < 0.15% Tissue P ≥ 0.15%

P recommendationP recommendation No P fertilizer

No P fertilizer

Soil test P, K, Ca, Mg, lime requirement

Soil pH > 5.3Soil pH < 5.3

No P fertilizer

THANKS


Questions?

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Soil Fertility Management for Forage Crops 25 th Annual FL Cattlemen’s Institute and Allied Trade Show Maria L. Silveira Soil and Water Science University.

Documents

silveira soil

soil ph slide

ufifas range cattle

effect of soil ph

soil test handling

importance of soil test

soil sample bag

ufifas range cattle