2004 Big Rivers Annual CCA MeetingJanuary 21, 2003

Greg Schwab, Ph.D., CPAg.Extension Soil Specialist

UK Department of Agronomy

Nutrient Management: Managing Soil pH and Liming

The effect of soil The effect of soil pH on the activity pH on the activity of soil micro-of soil micro-organisms, organisms, availability of plant availability of plant nutrients, and nutrients, and occurrence of toxic occurrence of toxic elementselements

CornCorn AlfalfaAlfalfa

Mn ToxictyMn Toxicty

• Caused by low soil pH– not enough lime– too much N fertilzer

• Stunts growth• May reduce yield 200

to 300 lbs./A• Soil test and add lime

as needed

Manganese Toxicity, SoybeanManganese Toxicity, Soybean

Photo by: L. MurdockPhoto by: L. Murdock

Low Soil pHLow Soil pH

Wheat yield as affected by soil pHWheat yield as affected by soil pH

NC State

Corn yield as affected by soil pHCorn yield as affected by soil pH

Using Ag lime to correct soil pHUsing Ag lime to correct soil pH

Collect a representative soil sample Collect a representative soil sample and apply recommended rate.and apply recommended rate.

Why didn’t soil pH reach Why didn’t soil pH reach target level after testing and target level after testing and lime application?lime application?

Representative soil sampleRepresentative soil sample330’

330’

xx x

x

x

x x

xx

xx

Determining the Quality of Determining the Quality of Agricultural LimestoneAgricultural Limestone

Purity – The ability of lime to neutralize soil acidity relative to pure CaCO3

CaCO3 = 100%

MgCO3 = 120%

Impurities – sand, iron, other minerals 0 %

Particle Size Determines Reactivity

1”

1”

Surface area = 6 sq. inches

Surface area = 8 sq. inches1”

0.5”

Fineness of GrindFineness of Grind

One cubic inch of limestone ground to pass a 100-mesh One cubic inch of limestone ground to pass a 100-mesh screen would have approximately 600,000 sq. inches screen would have approximately 600,000 sq. inches of surface area.of surface area.

0.25”

Surface area = 20 sq. inches

0. 5”

Particle Size Determines Reactivity

Solubility of limestone based on Solubility of limestone based on particle size particle size

Size of ParticlesSize of Particles Years after Years after applicationapplication

OneOne FourFour

Coarser than 8 MeshCoarser than 8 Mesh 55 1515

8 to 30 Mesh8 to 30 Mesh 2020 4545

30 to 60 Mesh30 to 60 Mesh 5050 100100

Finer than 60 MeshFiner than 60 Mesh 1010 100100

Relative Neutralizing Value Relative Neutralizing Value

Calculation of both purity and fineness used to compare lime from different sources.

CCE % between 10 and 50 % less than 50100 2 +xRNV=

Kentucky state law requires at least Kentucky state law requires at least 80 % CCE80 % CCE90% passing 10 mesh 90% passing 10 mesh 35% through a 50 mesh 35% through a 50 mesh

RNV = 50% with the minimum state requirementsRNV = 50% with the minimum state requirements

Comparing Lime Sources Comparing Lime Sources

Some good quality lime don’t satisfy state lime laws because of fineness of grind – example:

CCE = 90 %Smaller than 10 mesh = 92%Smaller than 50 mesh = 32%RNV= 56%

UK Lime recommendations assume 67% RNVUK Lime recommendations assume 67% RNVOther labs may varyOther labs may vary

** FAILED

http://soils.rs.uky.edu/Lime%20Report%20Spring%202003.pdf

Spring 2003 Ag Lime Test ResultsSpring 2003 Ag Lime Test Results

60

60

60

51

Comparing Lime Price Comparing Lime Price

Source 1 – RNV = 85 % Price = $12/ton

Source 2 – RNV = 65 % Price = $10/ton

UK Recommendation 3 tons/acre

What is cheapest for the farmer??

Source 1 (67/85) x 3 = 2.36 tons per acre = $28.32/acre

Source 2 (67/65) x 3 = 3.09 tons per acre = $30.09/acre

Adjusting Application Rate Adjusting Application Rate Based on Depth of Incorporation Based on Depth of Incorporation

UK Recommendation assume 6 2/3 inches of soil to be neutralized

Dep

th

2

4

6

8

pH5 6 7

Typical reduced tillage profileTypical reduced tillage profile

Dep

th

2

4

6

8

pH5 6 7

Typical conventional tillage profileTypical conventional tillage profile

Adjusting Application Rate Adjusting Application Rate Based on Depth of Incorporation Based on Depth of Incorporation

UK Recommendation assume 6 2/3 inches of soil to be neutralized

Tillage Depth Tillage Depth Multiplying Multiplying FactorFactor

4 inches4 inches 0.600.60

8 inches8 inches 1.201.20

9 inches9 inches 1.351.35

Not adjusting for RNV and depth of Not adjusting for RNV and depth of lime incorporation is the main lime incorporation is the main reasons why recommended lime reasons why recommended lime rates do not achieve the desired rates do not achieve the desired change in soil pH. change in soil pH.

Zinc Deficiency of CornZinc Deficiency of Corn

Liming MaterialsLiming MaterialsByproducts

Suspension Lime 40 – 75

Burned Lime 150 – 185

Hydrated Lime 125 – 145

Ground Oyster Shells 90 – 95

Wood Ash 30 – 70

Reclime® 85 – 90

ByproductsByproducts

Pelletized Lime

Manufactured by bonding together finely ground agricultural lime using lignosulfanates.

How much can the rate be reduced if using pelletized lime?

When calculations are made based on RNV, When calculations are made based on RNV, rates of pelletized lime should not be reduced.rates of pelletized lime should not be reduced.

How much can the rate be reduced if using pelletized lime?

Pelletized Lime

How fast will pelletized lime react?

Pelletizing requires very fine material without any Pelletizing requires very fine material without any course material. One would assume that it course material. One would assume that it reacts more quickly. reacts more quickly.

Actual research result show that pelletized lime Actual research result show that pelletized lime reacts slower than an equal RNV of aglime due reacts slower than an equal RNV of aglime due to bonding agents an distribution across soil to bonding agents an distribution across soil surface. surface.

ConclusionsConclusionsNatural processes continuously reduce soil pH

Soils should be sampled at least every three to four year to assess pH

Relative neutralizing value of lime material should be used to adjust lab lime recommendation

The quality of limestone varies across the state, the least expensive lime might not be the cheapest per ton.