Soil Samples

1
Soil Samples

• Analyses
• and
• Interpretation

2
PPM

• parts per million
• average weight of 6 inch soil 2 million pounds
• 1 ppm 2 pounds / acre

3
pH

• measure of soil acidity or alkalinity
• tells if you need lime, not how much
• active acidity 0 - 14
• 7 neutral
• rice lt 5 can add lime
• 5.2 - 6.5 good
• above 7 may cause Zn deficiency

4
Buffer pH

• measure of total acidity
• used to determine lime requirements of soil

5
Effects Salt May Have On pH

• if high soluble salts are present, pH may appear
  lower than actual
• if you suspect a problem, then you should notify
  lab

6
CEC

• Cation Exchange Capacity
• measure of soils ability to retain and exchange
  cations
• determined by the amount of soil colloids that
  are present

7
Whats A Cation?

• positively charged ion
• common soil cations include
• aluminum (Al), calcium (Ca), magnesium (Mg),
  potassium (K), and sodium (Na)
• held to colloids in that order
• Al tightest
• Na weakest

8
Soil Colloids

• clay
• organic matter - humus
• colloids - not small enough to form true
  solution, too small to settle out
• negatively charged

9
Different Labs/Businesses Different
Recommendations?

• extraction techniques
• interpretation
• philosophy
• replacement
• maintenance
• base saturation