Dr Marcellous le Roux
Department of Agronomy (Faculty of AgriSciences)
I
t is often reflected that the
only constant in life is change.
Change implies that things are
dynamic and therefore always
in a state of transition. It would
appear that agriculture, globally,
also finds itself in some state of
fluidity, with a radical shift urged
by the demands of the day and an
eye on future generations. With
these dynamics at play, agricultural
systems are under pressure to sustain productivity within narrow environmental confines. ‘Soil health’
has been compromised through
inappropriate farming practices,
including continuous mono cropping, which have led to declines in
soil fertility, accelerated soil erosion, and degradation of arable
lands. It is evident that soil management influences soil microorganisms and soil microbial processes through changes in the quantity
and quality of plant residues enter-
ing the soil, their seasonal and spatial distribution, the ratio between
above- and belowground inputs,
and changes in nutrient inputs. Despite this, soil ‘quality’ as it pertains
to biological fertility has been neglected.
There is a resurgence of interest in
environmentally prudent, sustainable agricultural practices. Inherent
in the concept of best management
practices (BMP) is the ideal to improve resource use efficiency, to
mitigate environmental impact and/
or increase farm profitability. In
light of the aforementioned argument, such an approach inevitably
needs to be intricately linked to the
activity of soil biota, especially microbial communities that are largely
responsible for the nutrient decomposition processes and the subsequent nutrient cycling that ensue.
Conservation agriculture (CA) has
emerged as a potential means to
improve soil organic matter (SOM)
and is widely endorsed to pave the
way for systems change in many
agrarian societies, to whom agriculture is the bloodline of their livelihoods. CA prioritises protection of
soils from degradation processes
and is underpinned by three major
principles – (reduced) tillage, crop
rotation, and residue management
to advance agricultural intensification on a sustainable trajectory.
Minimum soil disturbance and
maintaining permanent soil cover
are two of the foremost approaches
that can mitigate the effects of soil
degradation (see Figure 1). It does
this through moderating soil surface conditions, which could translate into crop yield improvements
and increase net farm benefits due
to reduced production costs. In addition, permanent soil cover moderates soil temperature variations,