Michael Mulvaney1, Kipling S. Balkcom2, Wes Wood1, Bernard Meso1, and Brenda Wood1. (1) Auburn U. Dept. of Agronomy & Soils, 202 Funchess Hall, Auburn, AL 36849-5412, (2) USDA-ARS, 411 S Donahue Dr, Auburn, AL 36832
An understanding of nitrogen (N)
release patterns from peanut residue under field conditions will help producers
make informed residue management decisions.
This experiment was conducted to assess N release rates from three
peanut varieties at two locations under simulated no tillage and conventional
tillage systems. Three peanut varieties
(NC V-11, GA-02C and Anorden) were placed in nylon
mesh litterbags at two depths (surface and 10 cm deep) and two locations (Rocky Mount, NC and Headland, AL).
Litterbags containing the equivalent of 4.5 Mg ha-1 were
placed in a completely randomized design, blocked by location, with four replications
and retrieved periodically up to 335 days after application for total N
analysis on an ash-free dry weight basis. In Rocky Mount, NC, buried
residue mineralized N at a higher rate than surface-placed residue. Surface and buried residue in NC released N
at the rate %N = 15.7e-1.48(days) + 84.3e-0.00200(days)
and %N = 38.4e-0.183(days) + 61.6e-0.00101(days),
respectively. Additionally, the Virginia type variety
(NC V-11) mineralized N at a higher rate than the two runner type varieties (GA-02C
and Anorden) tested in NC. All treatments released N at the same rate in
Headland, Alabama. Nitrogen is mineralized quickly from peanut
residue. In NC, the higher N
mineralization rate of buried residue is likely due to greater soil microbial
activity acting on the residue. Although
there was no difference between initial C:N ratios among any of the varieties,
the faster rate of N mineralization exhibited by NC V-11 at NC may be due to
different lignin and carbohydrate levels compared to the other two varieties. Warmer and moister climatic conditions in AL are likely
responsible for the lack of treatment differences at this location.
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