Residue and nitrogen dynamics in suppressed stands Karl Umiker and Jodi Johnson-Maynard University...
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Transcript of Residue and nitrogen dynamics in suppressed stands Karl Umiker and Jodi Johnson-Maynard University...
Residue and nitrogen dynamics Residue and nitrogen dynamics in suppressed standsin suppressed stands
Karl Umiker and Jodi Johnson-MaynardKarl Umiker and Jodi Johnson-MaynardUniversity of IdahoUniversity of Idaho
General research objectives:
1. Determine impacts of residue management strategies on nitrogen cycling.
2. Encourage timely residue decomposition.
What controls decomposition?
1. Organismsmacro to microfauna, microflora
2. Climate
3. Residue status - C:N
Approach: To understand the natural reactions that control residue decomposition.
Residue decomposition:
Residue Carbon Decomposition
• Amount of carbon
• Size of residue
• Type of carbon– % Lignin
• Availability of nitrogen– how fast and how much
C:N Ratio of Materials
Material C:N Ratio
Microbes ~8
Microbial Food ~24
Soil ~12-15
Total Residue – May ~16
Total Residue - August ~55-60
Non-standing residue - June ~22
Standing residue - June ~32
Site Descriptions
Lewis Co. Site• Non-thermal• Alternate Year Fallow• Variety: ‘Quantum Leap’• Treatments:
-Fallow 02/Harvest 03
-Fallow 02/Harvest 03
-Harvest 02/Fallow 03 mow
-Harvest 02/Fallow 03 chem
Lewis Co. – ‘Quantum Leap’ Residue
0.0
1.0
2.0
3.0
4.0
5.0
Res
idue
(ton
s/ac
re)
Fallow 02 / Harvest 03
Fallow 02 / Harvest 03
Harvest 02 / Fallow 03 mow
Harvest 02 / Fallow 03 chem
Winter
Chem/Mow