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The Florida Lime Study . Rao Mylavarapu, Nancy Wilkinson, William d’Angelo, Jennifer Frey, Cassandra Admire, Alex Bournique, Murthy Kadiyala Soil & Water Science Department, IFAS University of Florida. Objective.

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The florida lime study

The Florida Lime Study

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

Soil & Water Science Department, IFAS

University of Florida


Objective
Objective

  • Screen methods for determination of lime requirement for acid-mineral soils of Florida

  • Methods

    • University of Kentucky - Sikora method

    • Auburn University - Huluka method

    • Clemson University - Sikora-Moore method

    • University of Georgia - Single Titration method


Justification
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 methods
Materials and Methods

  • Collected 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


Materials and methods1
Materials and Methods

  • 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


Preparation
Preparation

  • The experiment was replicated 4 times

    • 200 g of sample was weighed into each cup

    • Labeled with county, Lab, lime rate and replicate

    • 12 counties labeled from A to L

    • 4 Labs were labeled I, II, III, IV

    • Lime rates for a Target pH of 6.5 were labeled as 1 and for a Target pH of 6.8 were labeled as 2


Preparation1
Preparation

  • 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%


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

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


Incubation
Incubation evaporation by weekly weighing

  • All samples were kept in the dark and in a climate-controlled area at 72°F for 63 days for incubation


Post incubation
Post-incubation evaporation by weekly weighing

  • 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 evaporation by weekly weighing








Take home messages methods

  • All 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


Conclusion
Conclusion methods

  • There 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 !


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