Rao Mylavarapu, Nancy Wilkinson, William d’Angelo, Jennifer Frey, Cassandra Admire, Alex Bournique,

Murthy KadiyalaSoil & Water Science Department, IFAS

University of Florida

ObjectiveScreen methods for determination of lime

requirement for acid-mineral soils of Florida

MethodsUniversity of Kentucky - Sikora method Auburn University - Huluka method Clemson University - Sikora-Moore methodUniversity of Georgia - Single Titration

method

Justification

The current Adams-Evans Buffer method involves p-Nitrophenol, an environmentally hazardous chemical

An environmentally friendly alternative method is needed

Primary need, however, is to identify a method that will be effective for acid-mineral soils of Florida

Materials and MethodsCollected 12 soil samples from 10 different counties-

Bradford, Clay, Columbia, Highlands, Hendry, Lake,Marion, Sumter, Putnam (3 samples) and Jackson counties

Samples were dried, sieved through 2.0mm mesh

The 4 methods were replicated 4 times

Water pH (1:2) was determined on all samples

Soil pH ranged from 4.0 to 5.4

AE-Buffer pH was determined and the Target pHs were identified as 6.5 and 6.8

Four replicates of each sample, weighing 200 grams, were sent to each state Lab

Each Lab ran their preferred method and determined the lime requirement and returned the data

Calcitic lime was added to all cups as per the recommendation from each of the state labs and the cups were incubated in the dark for a total of 63 days

Materials and Methods

PreparationThe experiment was replicated 4 times

200 g of sample was weighed into each cupLabeled with county, Lab, lime rate and replicate12 counties labeled from A to L4 Labs were labeled I, II, III, IVLime rates for a Target pH of 6.5 were labeled as 1 and for

a Target pH of 6.8 were labeled as 2

Pure CaCO3 was added to the cups as prescribed by each Lab for Target pHs of 6.5 and 6.8, after converting from Lb Acre-1 to g cup-1

Soils was stirred well for homogeneity

All the sample cups were maintained at 30% moisture content for the entire duration of incubation by estimating the bulk density and pore space

The samples were weighed regularly and water was added using syringe inserted into a straw, which stayed inserted thru the incubation period, to bring the moisture content back to 30%

Preparation

Water was injected slowly into the incubating cups by a syringe inserted into a straw reaching the bottom of the cups to replace the moisture

Incubating cups were checked for any moisture loss through evaporation by weekly weighing

IncubationAll samples were kept in the dark and in a climate-controlled

area at 72°F for 63 days for incubation

Post-incubation

All the straws were removed and the soils were stirred and let them dry for a couple of days

Determined the water pH (1:2) by subsampling the cups for 20 grams of soil and adding 40 ml of water.

Results

Sikora (Kentuky)

Huluka (Auburn)

Sikora-Moore

(Clemson)

Single titration (Georgia)

Adams-Evans (UF)

pH LR (lb/acre) pH LR

(lb/acre) pH LR (lb/acre) pH LR

(lb/acre) pH LR (lb/acre)

Bradford 5.44 1940 5.22 2258 5.21 3360 4.63 2625 5.00 2049

Clay 4.58 6099 4.30 8549 4.43 9000 3.74 12681 5.40 1570

Columbia 5.01 6007 4.98 1575 5.07 3660 4.18 2130 4.90 1845

Highlands 5.08 6007 5.00 3772 5.11 5660 4.32 4477 5.40 1698

Immokalee 4.49 6129 4.44 2312 4.56 3552 3.54 3886 5.40 2498

Lake 4.67 6007 4.49 1849 4.59 3600 3.74 2926 4.50 12652

Marion 4.83 6050 4.70 1903 4.79 3460 4.04 2014 5.25 2511

Sumter 5.04 1850 4.88 3611 5.00 5660 4.11 4736 4.95 1853

Putnam 1 3.77 1756 3.76 5373 3.83 8204 2.87 10971 4.06 4913

Putnam 2 3.89 1698 3.77 3055 3.76 5660 2.90 7126 4.09 2581

Putnam 3 4.78 1743 4.70 1950 4.78 3360 4.05 2411 4.86 1514

Jackson 4.79 1760 4.44 2204 4.51 3860 4.05 2891 4.63 1794

Lime requirement calculated for 6.5 target pH by different methods

Sikora (Kentuky)

Huluka (Auburn)

Sikora-Moore

(Clemson)

Single titration (Georgia)

Adams-Evans (UF)

pH LR (lb/acre) pH LR

(lb/acre) pH LR (lb/acre) pH LR

(lb/acre) pH LR (lb/acre)

Bradford 5.44 2292 5.22 2613 5.21 4100 4.63 3247 5.00 2353

Clay 4.58 6589 4.30 9286 4.43 9000 3.74 14445 5.40 1919

Columbia 5.01 6479 4.98 1782 5.07 4400 4.18 2501 4.90 2094

Highlands 5.08 6479 5.00 4275 5.11 6400 4.32 5327 5.40 2076

Immokalee 4.49 6612 4.44 2519 4.56 4000 3.54 4380 5.40 3055

Lake 4.67 5809 4.49 2017 4.59 4100 3.74 3332 4.50 13772

Marion 4.83 6393 4.70 2097 4.79 4200 4.04 2338 5.25 2988

Sumter 5.04 2135 4.88 4054 5.00 6400 4.11 5529 4.95 2115

Putnam 1 3.77 2024 3.76 5829 3.83 8700 2.87 12056 4.06 5251

Putnam 2 3.89 1981 3.77 3317 3.76 6300 2.90 7839 4.09 2727

Putnam 3 4.78 2015 4.70 2151 4.78 4100 4.05 2800 4.86 1709

Jackson 4.79 2048 4.44 2399 4.51 4600 4.05 3350 4.63 1979

Lime requirement calculated for 6.8 target pH by various methods

Measured pH after application of lime for target pH of 6.5

Measured pH after application of lime for target pH of 6.8

S.No Lime requirement

method

pH measured

Target 6.5 Target 6.8

1 Sikora 7.38 7.49

2 Huluka 7.49 7.55

3 Sikora-Moore 7.64 7.68

4 Single Titration 7.56 7.60

LSD (P=0.05) NS NS

Average pH values measured after lime application

County pH measured Soil texture Target 6.5 Target 6.8 OC (%) Sand (%) Silt (%) Clay(%)

Bradford 7.03 7.12 3.04 96.86 1 2.14

Clay 6.78 6.87 10.35 98.36 0 1.64

Columbia 7.82 7.83 1.43 97.36 0.5 2.14

Highlands 7.71 7.73 4.73 98.36 0 1.64

Immokalee 7.87 7.87 1.73 98.36 0 1.64

Lake 7.65 7.65 1.66 98.36 0 1.64

Marion 7.82 7.88 1.76 98.36 0 1.64

Sumter 7.37 7.5 3.78 98.36 0 1.64

Putnam 1 7.37 7.49 5.20 98.36 0 1.64

Putnam 2 7.67 7.71 1.86 98.36 0 1.64

Putnam 3 7.38 7.52 1.35 98.36 0 1.64

Jackson 7.71 7.75 1.94 89.36 7 3.64

LSD (0.05%) 0.95 0.78

Average target pH values measured in various county samples

Take home messagesAll the methods have over-estimated the lime requirements

as indicated by the increase in pH beyond the Target pH at the end of the incubation period

Differentials in Target pHs were not realized even with different lime recommendation amounts, for any of the methods

Soil pH determinations showed a high amount of variation, with possible statistical significance in certain cases

Other soil physical and chemical parameters may be influencing the lime efficacy

Field calibrations may further increase the variability

ConclusionThere is a method that Florida can use……

OR

There is no method that can be clearly identified as suitable

AND

Repeat the study with a few modifications !