FRUIT GROWERS LABORATORY, INC.
Chad Lessard
Certified Crop Advisor
Director of Agricultural Services
Talking points for
interpreting your soil and tissue
analysis reports
• Primary Nutrients and Macronutrients
– N, P, K, Ca, Mg, S
• Secondary Nutrients and Micronutrients
– Fe, Zn, Mn, Cu, B, Cl, Mo
• Other Chemical Properties
– pH, cation exchange capacity, soil salinity, limestone
• Quality Control
• Database Management Systems
First
Understanding
Your
Soil Analysis
Report
Soil Rpt
Start w/ N
Common Nitrogen Questions
Q. Why is nitrate-nitrogen only analyzed in the soil and not ammonium and/or total
nitrogen?
A. Under conditions favoring plant growth, most forms of
soil nitrogen are rapidly converted to nitrate.
2 NH4+ + 3 O2  2 NO3- + 2 H20 + 4H+
Q. Why is the nitrate bar blue?
A. The blue bar indicates there really is no “optimum
range.” Soil nitrate requirements are primarily
dependant on the growth stage of your crop and soil
temperature.
On to N Avail
Nitrogen Availability
• Nitrogen uptake efficiency during critical stages
– 25% when applied to the soil in a single annual
application
– 50 – 60% when applied to the soil in 3 to 4
increments
- Fertigation may be the easiest way to accomplish these
incremental applications
Closer look at soil N avail
Nitrogen Availability
• Soil application
– Average nitrogen losses = 20 – 50 percent
• Leaching losses - apply nitrogen in short irrigation runs or at the end
of a normal run
• Volatilization - urea and ammonium sources should not be applied
at high pH, high temperature, or on the soil surface
• Immobilization: significant for organic growers
–
–
–
–
High soil carbon content = Immobilization
C:N Greater than 30:1 = N immobilization
C:N 20:1 to 30:1 = about equal mineralization to immobilization
C:N Less than 20:1 C:N = more rapid N mineralization
OM mtrl to use
Properties of Different Organic Materials
Material
Undisturbed top soil
Alfalfa
Manure
Corn stalks
Green waste
Coal and shale oil
Oak
Spruce
C:N ratio
10:1
13:1
20:1
60:1
80:1
124:1
200:1
1000:1
*When using the high carbon content materials be sure to
apply 15 – 25 pounds of extra nitrogen fertilizer to facilitate mineralization
Next is P
Common Phosphorus Questions
Q. Why is phosphorus reported as P2O5?
A. Phosphorus fertilizer is sold as P2O5 equivalent
To convert from P2O5 to P multiply by 0.436.
Q. Why are there two different methods for soil P analysis?
A. Depending on the pH, phosphorus exists as two
different ions so there are two different extraction
solutions to mimic actual P available to your crop.
Dif P forms available
Phosphorus Availability
• Different precipitates of P
– Important to monitor pH for P
Some K ?s
Common Potassium Questions
Q. Why are there two different potassium results?
A. Potassium is measured in two ways.
1. Exchangeable (Exch)
The exchangeable portion is the potassium
available as a reserve in your soil. This moves
into solution as the soluble K is taken up.
2. Soluble (Sol)
The soluble portion is the potassium most
readily available.
So just because
Potassium Availability
• Just because your soil has a high
exchangeable potassium content, doesn’t
mean its all available
– 4 general forms of K in the soil
•
•
•
•
Mineral or structural = 5,000 - 25,000 ppm
Fixed or difficultly available = 50 - 750 ppm
Exchangeable = 40 - 600 ppm
Soil Solution = 1 - 10 ppm
K avail issues
Potassium Availability
• Potassium in the soil is mostly available by mass
flow…so…
– Leaching is possible
• Soluble potassium may leach in sandy soils with high rainfall
– Foliar applied K is an option for most crops
• If foliar application use KNO3
– Some crops can’t absorb foliar applications thus,
water soluble forms of K should be applied to the soil
• Potassium Thiosulfate appears to be the most available
source
Lets look @ few more K avail issues
Potassium Availability
• Potassium and crop yields
– Most directly related nutrient to high crop yield
– High N and P increases yields as well but also
increases the total demand for K to support that yield
– K released from the exchangeable sites in the soil is
often too slow to supply ample amounts in a high
yield system
On to the secondary nutrnts
Calcium, Magnesium, Sodium and Sulfur
Q. Why are these nutrients considered secondary?
A. This just means they are not normally needed in as large of
of quantities as the primary nutrients.
-Secondary nutrient deficiencies can depress
plant growth just as much as
primary nutrient deficiencies.
-Sometimes, plants can even require
more S and Ca than P.
Next section Chem Props
Cation Exchange Capacity, pH, % Base
Saturation, and the Lyotropic Series
The “Easy” Definitions:
•Cation Exchange Capacity – The total amount of cations a soil can hold
on its negatively charged particles (the clay and humus)
•Percent Base Saturation – The percent of a certain cation that is
held on the CEC in comparisons to the other cations
•pH – A measurement estimating the “active” hydrogen ions
•Lyotropic Series – The order in which cations will bond with the negative
charges in your soil
Al3+ > Ca2+ > Mg2+ > K+ = NH4+ > Na+ Percent Base Sat
Percent Base Saturation
•No relationship to crop yields
•Sufficiency levels of each nutrient should be used to make
fertilization recommendations
•However percent base saturation is still important
•Predicting soil structure
•In a typical soil, the percent base saturation
is directly related to the lyotropic series
Next prop to look at is pH
Adjusting the soil pH changes more than just the pH
___________________________
Another ? on Micros
Metal Micronutrient Availability
• If my soil pH is between 5.5 and 7 and I still
have micronutrient deficiencies?
– Chelated micronutrients are the way to go for soil
applications
– Chelated micronutrients are 6 – 10 times more
effective than non-chelated micronutrients
– Chelates prevent micronutrients from precipitating
with other ions in the soil and allow them to move with
water to the root.
How they work
Metal Micronutrient Availability
• How chelates work
– Apply to the soil
and irrigate
*Chelate is derived from the Greek word meaning crab claw
*May suppress the growth of plant pathogens by iron deprivation
On to plant tissue rpts
Understanding
Your
Plant Tissue Analysis
Report
Tissue reports show
How to use your tissue analysis
report
• A tissue analysis report shows
– The sufficiency of nutrients in your trees
– Indicates the plants ability to extract nutrients
from the soil
Tissue exmpl
Tissue Analysis
Your Fertilization Management Report Card
*Your tissue analysis report should be used along with your soil analysis data to
optimize your nutrient management plan
How to use this
How to use your tissue analysis
report
• If nutrient levels are optimal, then your nutrient
management program is well balanced
• If not, your tissue report will indicate which
changes are necessary to your nutrient
management program
• Compensation must be made for crop nutrient
removal
A freq asked question
How to use your tissue analysis
report with your soils report
• A frequently asked question
– Q. Why does my soil report show ample
nutrient levels and my leaf tissue report
shows deficiencies?
– A. Because crops are not always capable of
taking up the necessary amounts of nutrients
to support their rate of growth and yield.
Transition to QA / QC
Quality Assurance / Quality Control
• Quality Assurance….is the overall
process used to ensure accurate and
precise results
• Quality Control…. is the actual steps
taken such as blanks, standards, spikes,
and duplicates used in the above process
A visual example
Quality Assurance / Quality Control
• We need to use QA / QC because you need to know
your data is precise and accurate
Imprecise
and
inaccurate
Accurate
but
imprecise
Inaccurate
but precise
Precise and
accurate
(Valid Data)
Reporting options
Reporting of Testing Results
• Color graphic reports by mail
• E-mail
• Web reporting on FGL’s password
protected website
• Alternatively............
Trans to database mgmt
Database Management
Systems
These systems catalog and organize
information making it easily accessible to assist
with decisions regarding fertilization and
amendment programs
•
What else?
Database Management
Systems
• Provides tools for making comparisons
between previous years’ performances,
different blocks / properties and
different management practices
• Parameters can be tailored to specific
crops, crop growth stages, or even
specific growers
Supported dbms
Fruit Growers Laboratory, Inc.
Supports
• SureHarvest
• AgCode
• Most Company Specific Reporting
Formats
End
Questions?
For more info:
Chad Lessard
www.fglinc.com
chadle@fglinc.com
Fruit Growers Laboratory, Inc.