Transcript Soil Testing and Analysis

Soil Testing and Analysis
Nutrient Management Basics
Sustainable Small Acreage Farming and
Ranching
Slides adapted from the Living on the Land curriculum,
University of Nevada-Reno, Sue Donaldson, et al. 2001
How do I know what to add to
my soil???
Test your soil!
UNCE, Rno, NV
What Information Does a Soil
Test Provide?
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Soil textural analysis
pH and salts
Soil nutrient content
Fertilization
recommendations
A Fertile Soil Has:
• The right kinds and
amount of nutrients
to grow pasture or
crops
• Low salinity and
sodium
• Close to a neutral pH
(about 7)
• Plenty of organic
matter
USDA NRCS Photo Gallery
How Often Should I Take a Soil
Sample?
Prior to seeding a crop in new ground
At least every three years for
established perennial crops
Frequently enough to make good
decisions on fertilization
When it is cost effective
How to take a sample
First select the
site. Your soil
sample should
represent only
one soil type or
soil condition.
OSU Extension Service
How to take a sample
Each sample
should consist of
sub-samples taken
from about 15
locations within
the same soil type
or sampling area.
OSU Extension Service
How to take a sample
Use the “slice”
method for a
representative
sample.
UNCE, Reno, NV
Soil test results
• What do my soil test results
mean?
• What nutrients do plants need?
• How can I supply those
nutrients?
What kind of information does my
soil test report provide?
• Particle size
analysis (texture)
• Soil organic matter
content
• pH
• Soluble salts
• Nutrient content
USDA NRCS
Particle size analysis
• Provides the relative
percentages of sand,
silt, and clay
• Allows determination
of soil textural class
• A loamy texture is
generally best for most
plants
NRCS, Bozeman, MT
Soil organic matter (OM)
• Living or dead
plant and animal
residue
• Measured in
percent
• OM content is
highly variable
• Generally, 3% to
8% OM content is
good for plants
UNCE, Reno, NV
pH
• Indicates relative acidity or alkalinity
• pH 7 = neutral; less than 7 = acid; more
than 7 = alkaline or basic
Adapted from library.thinkquest.org
Soil pH
and
nutrients
Adapted from www.soil.ncsu.edu
Widest part of the bar indicates maximum availability
What makes soils acid?
• Acid soils: pH is below 7
• Soils become acid because of heavy rainfall that
weathers soils quickly
• Basic cations such as calcium, magnesium, and
potassium are leached from the soil profile
• This natural weathering process makes soils acid
Raising the pH of acid soils
• Add lime to raise the pH (making soil less
acid)
• Lime most often consists of calcium
carbonate
• Plant response will be relatively slow,
taking weeks or months
What makes soils alkaline?
• Alkaline soils: pH is above 7
• Soils that have not been greatly weathered or
leached
• Some alkaline soils are high in calcium
• Reduces solubility of all micronutrients
Adapted from library.thinkquest.org
Example of crop in alkaline soil
ag.arizona.edu
Soluble salts
• A measure of inorganic
chemicals that are more
soluble than gypsum, such as
sodium, calcium,
magnesium, chloride, sulfate
and bicarbonate.
• Salty soils are a problem in
arid regions or in poorly
drained soils
USDA NRCS
Managing salt-affected soils
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Select plants that can tolerate salinity
Avoid excess or salty forms of fertilizers
Incorporate organic matter
If appropriate, add sulfur to lower the pH
Nutrient Management
• Meet crop nutrient needs
• Maintain soil quality
• Conserve resources
• Protect water quality -- reduce leaching
and runoff risk
Plant Nutrients
Major Nutrients
Micronutrients
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Nitrogen
Phosphorus
Potassium
Calcium
Magnesium
Sulfur
Boron
Iron
Manganese
Zinc
Copper
Chloride
Molybdenum
Macronutrients
• N = nitrogen
• P = phosphorus
• K = potassium
More macronutrients
• Ca = calcium
• Mg = magnesium
• S = sulfur
Micronutrients
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Fe = iron
Mn = manganese
Zn = zinc
B = boron
Mb = molybdenum
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Ni = nickel
Cu = copper
Co = cobalt
Cl = chlorine
Questions to ask yourself before
you add fertilizer:
1.
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3.
4.
5.
Which elements do I need? (N, P, K, S, Ca)
How much do I apply?
What type of material do I use?
Which application method is best?
When is the best time to apply it?
Types of fertilizers
• Chemical fertilizers
• Organic fertilizers (bone meal, compost,
manure,etc.)
www.farmphoto.com
Organic Materials
• Little or no processing
• Low nutrient content
• Slow release of nutrients
• Plant, animal, or mineral sources
Nutrient uptake
•The forms of nutrients taken
up by plants are the same for
all types of fertilizer -manufactured or organic.
Organic materials:
Fertilizers vs. Soil amendments
• Fertilizer
1. High nutrient content and availability.
2. Main benefit is nutrients.
3. Relatively small amounts applied.
• Soil amendment
1. Low nutrient content and availability.
2. Main benefit is organic matter.
3. Large amounts applied.
How much fertilizer do I need to apply?
• Estimate the amount of fertilizer
needed based on soil test
results, crop needs and area to
receive fertilizer
• Most fertilizer
recommendations are in pounds
per 1000 square feet, or pounds
per acre
Fertilizing with manures
• Good source of
nutrients and
organic matter
• Protects soil from
raindrop impact
and erosion
• Local supply
often available at
no cost
OSU Extension Service
Different sources of manure have different
amounts of nutrients
• Poultry manure is
high in nitrogen
• Beef and horse
manure tends to be
lower in nitrogen
• Sheep manure is
high in potassium
(K)
UNCE, Reno, NV
Cautions for fertilizing with manures
• Watch out for
weeds and
pathogens
• Know the
manure
nutrient content
• Consider the
salt content
N- P- K
OSU Extension Service
Cautions for fertilizing with manures
• Incorporate or
apply evenly to
avoid
smothering
plants
• Don’t apply on
frozen slopes
• Avoid leaching
nutrients into
waterways
UNCE, Reno, NV
What we’ve learned:
• Use soil test results to guide you in
amending your soil
• Nutrient management is more than just
adding fertilizers to meet plant needs
• Chemical fertilizers and natural or organic
soil amendments both have advantages and
disadvantages and must be managed based
on each farms particular cropping system.