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.