fertilizing pastures gene pirelli oregon state university
Post on 21-Dec-2015
218 views
TRANSCRIPT
Fertilizing Pastures
Gene Pirelli
Oregon State University
Mixed Species grazing in New Zealand
Disadvantages:
(1) Increased facility costs
(2) Size of scale (3) Potential labor
conflicts(4) Management/skill
requirements
Pasture is the Most Economical Feed Source
Eighty Percent of the Cost of a Livestock Operation is FEED
Management and Fertility
• The two “Keys” to increasing the available feed from a pasture
• Pasture forage is significantly cheaper than purchased feed
Important Nutrients in Soil Fertility
• Nitrogen, Phosphorus, Potassium
• Sulfur, Boron, Molybdenum
• Calcium, Magnesium
Major Soil Nutrients
• Nitrogen
• Phosphorus
• Potassium
• Sulfur
Is a Key Nutrient for Pasture Production
Apply to Match Feed Needs and to Supplement the
System
Grazing Animals Can Remove a Significant Amount of
Nitrogen Fertilizer, in many cases, supplies
only part of the total N consumed as plant protein
Nitrogen is a Component of Protein
• Crude protein of forages are measured by Nitrogen x 6.25
• Vegetative grasses and legumes contain high amounts of crude protein
• The nitrogen that is removed from the soil as plant protein must be replaced
NitrogenNitrogen
• Application Rate Depends on Use
• For Grazing, Apply Fall, Late Winter and Spring
• Base Late Winter Application on T-Sum 200 dates
• Example: 40 lbs N/A Fall, 40-60 Lbs N/A in Late Winter and 40-60 Lbs N/A in Early April
PhosphorusPhosphorus
• Apply in Fall
• Stable, Does Not Move
• Soil Test to Determine if Soil Levels are Rising
PotassiumPotassium
• Depletes Rapidly with Haying and/or Intensive Grazing
• Apply in Fall
• Low Levels Reduce Grass and Clover Vigor
Other Nutrients to ConsiderOther Nutrients to Consider
• Lime
• Boron
• Molybdenum
OSU’S FG 63
• Includes recommendations for major nutrients
• Helps to interpret soil test results
• Provides guidelines for pounds of nutrients to apply
Fertilizer Nutrients
• Are calculated as “pounds of the nutrient per acre”
• For example: 60 pounds of N/Acre means 60 pounds of actual nitrogen, not 60 pounds of total fertilizer
• It does not matter if we are applying commercial or organic fertilizer
Fertilizer Mixes
• Listed as N - P - K
• Numbers are %
• Example:– Fifty pound bag of 16-16-16 contains how
much nitrogen, phosphorus and potassium?
Organic Material
• Can be manures or natural fertilizer sources
• You need to have an idea of the concentration of nutrients
• Book values can be helpful
• Lab Testing (if the material is consistent) is the best method
Availability
• Remember that organic materials take time to break down and become available
• Commercial fertilizers are rapidly available but the duration of response is less
Application Times
• Manure or commercial fertilizer should not be applied when there is a risk of surface water moving the material
• Manure is a greater risk since it takes time to break down
Nitrogen Fertilizer
• Can be used as a tool to increase early spring forage.
• Split the usual amount applied into an early and mid-season application.
• Nitrogen is available when plant growth initiates.
Spring Pasture Growth
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
1 2 3 4 5 6 7 8 9 10 11 12 13
Weeks
Po
un
ds
of
Dry
Mat
ter
Series1
Series2
Spring Pasture Growth
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
1 2 3 4 5 6 7 8 9 10 11 12 13
Weeks
Poun
ds o
f Dry
Mat
ter
Series1
Series2
T-Sum 200
A method of calculating the appropriate time for the first N
application
T-Sum 200
A method of calculating the appropriate time for the first N
application
T-Sum 200
• A method of tracking heat units starting on January 1
• Apply N when heat units reach 200
• System was developed in Scotland, used in the United Kingdom and Western Canada
Heat Units
Average of the maximum and minimum temperature of the day
in degrees centigrade
T-Sum Example
17.33.11.05.2Jan 4
14.24.72.27.2Jan 3
9.53.907.8Jan 2
5.65.62.88.3Jan 1
TOTALHEAT UNITS
MIN CMAX CDATE
