Authors:
Shankar Ganapathi Shanmugam, Normie W.Buehring
, M. Wayne Ebelhar
, Michael S. Cox
,
James Larry Oldham
, Daniel G. Peterson
and William L. Kingery |
Abstract:
Soil health provides an overall picture of soil functionality that includes chemical, physical and
biological features necessary for long-term, sustainable productivity. Studies have shown that
tillage has profound and complex influence on soil physical, chemical and biological properties.
This study was initiated to evaluate the effects of tillage, crop rotation and residue management
on soil biodiversity in a soybean production system. Soil samples were collected from ongoing
field experiment that studies the effects of tillage and residue on soil quality under soybean-corn
rotation scheme located at North Mississippi Research and Extension Center (non-irrigated) and
Delta Research and Extension Center (irrigated) in Verona and Stoneville, Mississippi,
respectively. Soil samples were collected from existing experimental plots receiving four kinds
of tillage: (1) reduced-tillage on old beds (RT), (2) bed-roller (BR), (3) disk + TerraTill (D+TT)
and (4) TerraTill (in-row-subsoiler-bed-roller, one-pass implement) (TT). Based on the nature
of soil disturbance caused by the tillage treatments they were broadly grouped as conservation
tillage systems (RT and TT) and conventional tillage systems (BR and D+TT). The bacterial
community change at the Reduced-Till (RT) plots was significantly different from the other sites
as explained by the axis of maximum variability from Bray-Curtis ordination (Axis 1= 76 %).
There was no significant difference in the pattern of soil bacterial distribution between other
tillage management practices. However, there was a moderate location effect along the minor
axis of variation (Axis 2= 4 %) and bacterial community composition at Verona was
significantly different from Stoneville plots. Proteobacteria were least abundant in the RT plots when compared to other tillage systems at both the locations. Based on the Simpson's reciprocal
index, the bacterial diversity was considerably higher in RT and Terra-Till plots. Results show
that conservation tillage may create stable environments which favor diverse communities and
slower nutrient turnover. |
