Soybean: Evaluation of Inoculation
Soybean: Evaluation of Inoculation
T. M. Albuquerque 0
O. Ortez 0
G. I. Carmona 0
I. A. Ciampitti 0
0 Kansas State University , USA
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Abstract
Most of the nitrogen (N) required by a soybean plant is supplied via biological nitrogen fixation (BNF).
When BNF is adequately established in the soil, soybean can obtain up to 50 to 75% of its N from the air. This
project aims to quantify the response to inoculation for soybean in its second year in a field without previous
history of this crop. Due to this objective, a field study was conducted during the 2015 and 2016 growing
seasons at Ottawa, KS (East Central experiment field location). The treatments consisted of five different
Nmanagement approaches: non-inoculated (NI), inoculated ×1 (I×1), inoculated ×2 (I×2), inoculated ×3
(I×3), and non-inoculated but fertilized with 300 lb N/a (NF) as the main N source. In 2015, yields among
treatments did not differ significantly from one another. In 2016, yields ranged from 36 to 59 bushels per acre.
Greater yields were recorded when fertilized with 300 lb N/a, while lowest yield was related to the
noninoculated scenario. Treatments presented significant yield difference; however, the scenario with 300 lb N/a
did not differ from the inoculated ×3; while the inoculated treatments were not different for the yield factor. In
summary, further research should be pursued to be more conclusive as to the best management approach for
N in soybeans in an area without history of this crop.
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This Soybean article is available in Kansas Agricultural Experiment Station Research Reports: https://newprairiepress.org/kaesrr/
vol3/iss6/20
Kansas Field
Research 2017
Soybean: Evaluation of Inoculation
Summary
Most of the nitrogen (N) required by a soybean plant is supplied via biological nitrogen
fixation (BNF). When BNF is adequately established in the soil, soybean can obtain up
to 50 to 75% of its N from the air. This project aims to quantify the response to
inoculation for soybean in its second year in a field without previous history of this crop. Due
to this objective, a field study was conducted during the 2015 and 2016 growing seasons
at Ottawa, KS (East Central experiment field location). The treatments consisted of
five different N-management approaches: non-inoculated (NI), inoculated ×1 (I×1),
inoculated ×2 (I×2), inoculated ×3 (I×3), and non-inoculated but fertilized with 300
lb N/a (NF) as the main N source. In 2015, yields among treatments did not differ
significantly from one another. In 2016, yields ranged from 36 to 59 bushels per acre.
Greater yields were recorded when fertilized with 300 lb N/a, while lowest yield was
related to the non-inoculated scenario. Treatments presented significant yield difference;
however, the scenario with 300 lb N/a did not differ from the inoculated ×3; while
the inoculated treatments were not different for the yield factor. In summary, further
research should be pursued to be more conclusive as to the best management approach
for N in soybeans in an area without history of this crop.
Introduction
Soybean crop, as a legume species, has the characteristic of N fixation or can convert
from the atmosphere when the proper symbiotic relationship with specific bacteria is
established. The success of an effective symbiotic process depends on the existence of
the bacteria in the soil. Thus, if the bacteria are not present in the soil, the “inoculation”
practice can establish the specific rhizobia in the field, providing a successful N fixation.
Based on previous information, inoculation is usually effective when: 1) soybean was
never planted before or in the past 3 to 5 years; 2) soil pH is below 6.0 units; 3) soil has
a high sand content; 4) in anaerobic conditions, field has been flooded for more than a
week when nodulation was supposed to become established; and 5) early-season stress
conditions (e.g. heat) affects plant-bacteria establishment. The inoculation has become
a standard practice in soybean fields due to the critical supply of N coming from BNF
and the high (...truncated)