Transcript Soil Nutrients

Soil Nutrients/
Sampling
Techniques
Modified by the GA Agricultural Education Curriculum Office
July 2002
The Goal of Soil Sampling
The purpose of soil testing is to identify the
soil fertility that the plants or crop, in a given
area will experience.
Benefits of Soil Sampling
Grow Higher Crop Yields
Produce Higher Quality Crops And
Ornamentals
Use Fertilizer Dollars More Efficiently
What I Need?
Soil Sample Bags
Stainless Steel Soil Probe
Plastic Bucket
A Few Universal Basics
1. Soil samples can be taken with a
professional soil probe, or simply using a
shovel, spade, or garden trowel (see fig. 2).
2. Each sample should be composed of from
10 to 15 cores.
A Few Universal Basics
3. As you take cores of soil, put them into
the plastic bucket. Mix the soil thoroughly in
the bucket (galvanized buckets will
contaminate the sample with zinc), breaking
up all cores. Then, fill the soil bag to the line
(about 1 cup of soil). Discard any extra soil.
A Few Universal Basics
4. The cores should be taken in a random
pattern that is uniform across the area being
sampled (grid sampling may require a
specific pattern).
5. Each sample should represent 10 acres, or
less, per sample(grid samples will represent
from 2.5 to 5 acres per sample).
How Deep Should I Go?
Cultivated Soil (Row Crop)- up to 7” deep
Pastures and permanent grass – 2”-4”
Nutrients Plants Acquire From
Air And Water
Carbon
Hydrogen
Oxygen
The Primary Nutrients
Potassium
Nitrogen
Phosphorus
The Secondary Nutrients
Calcium
Magnesium
Sulfur
The Micronutrients
Boron
Chlorine
Copper
Iron
Manganese
Molybdenum
Zinc
The 16 Essential Nutrients
Boron
Calcium
Carbon
Chlorine
Copper
Hydrogen
Iron
Magnesium
Manganese
Molybdenum
Nitrogen
Oxygen
Phosphorus
Potassium
Sulfur
Zinc
Functions Of Primary Nutrients
And Deficiency Symptoms
Nitrogen (N): most important nutrient besides
water; determines rate of growth
deficiency symptom: yellowing of leaves
Phosphorous (P): required during germination and
fruit/seed formation
Deficiency symptoms: stunted growth; purple-colored
leaves
Potassium (K): regulatory
Deficiency symptoms: stunted growth; mottled leaves
Non-essential Nutrients That Need
To Be Considered
Iodine
Cobalt
Silicon
Why Is A Knowledge Of Soil
Nutrients Necessary?
To maximize yield
To maximize profit
To maintain soil fertility
Determining Soil Fertility
You can use any of the following methods to
determine soil fertility:
soil tests
managing organic matter
fertilizing
What Is Fertilizer Analysis?
The amount of the different nutrients found in
a fertilizer.
It is always listed as a percent.
It is always listed Nitrogen-Phosphorous-Potassium
(N-P-K).
For example, a fertilizer labeled 10-15-10 is 10%
Nitrogen, 15% Phosphorous, and 10% Potassium.
If there is a fourth letter, it designates the nutrient
sulfur.
Example Problem For
Determining The Amount Of A
Nutrient In A Fertilizer
How many pounds of nitrogen are in a 50
pound bag of 10-15-10?
10% of 50# = 5# Nitrogen
Example Problem For Determining
The Amount Of Total Nutrients In A
Fertilizer
How many pounds of actual nutrients are in
a 50 pound bag of 10-15-10?
10+15+10 = 35% nutrients or 17.5#
The other 65% of the bag is inert matter
Another Analysis Problem
A hobby gardener buys a bag of "Scott's
Turfbuilder" for $31.95. The bag weighs 62
pounds and has an analysis of 22-3-10.
How many pounds of actual nutrients does
the bag contain?
21.7# of nutrients in one bag
(22+3+10)=35%
35%*62=21.7
Another Analysis Problem (cont.)
What is the cost per pound of actual
nutrients?
$1.47
$31.95/21.7# nutrients=1.47