Figure 1. Source: Conti, FD. “Conservation Agriculture and Soil Fauna: Only Benefits or also Potential
Threats? A review”. EC Agriculture 2.5 (2015): 473-482.
controls surface runoff, slows soil
drying and enhances root exploration. Thus, biological tillage (i.e.,
soil microorganisms, roots and soil
fauna taking over the tillage functions through implemented crop
rotations) is opted in place of mechanical tillage. For this reason, CA
is prompted as an ecological sound
alternative to more conventional
approaches. Although CA is proposed as a system based on integrated management of available
soil, water and biological resources,
combined with as little external inputs as feasible, as currently practised, it is still a very high input system that depends too heavily on
agrochemical inputs that is not ideal.
Another pillar of CA is the use of
crop rotations, which arose as one
of the earliest sustainable agricultural practices. It has been argued
quite eloquently that without the
use of crop rotations the distribution of profit now favours agricultural-related industries (e.g. fertilizers, pesticides, seeds) and not the
farmers. Crop rotation may reduce
pathogen carry-over on crop residues in the soil. Yield declines in
crop monoculture systems is being
attributed to the fact that the soil
biological balance may be skewed
in favor of pathogenic soil microbiota that can lie dormant for many
years. Even a short rotation cycle
can offer significant relief from pest
pressures because of rotationinduced changes in the composition
of the soil biota. Crop rotations,
however, have to be economically
viable to be adopted by farmers
and may still require a fallow period
to be effective for some diseases,
like Pythium and Rhizoctonia that
have a wide host range. In addition,
it is known that pests can also
adapt to crop rotation.
A lot of emphasis of CA is on soil
improvements (and rightly so given
the state of arable soils), but an
often-neglected aspect of CA pertains to its usefulness in mitigating
the effects of carbon dioxide (CO2)
emissions into the atmosphere that
contributes to climate change. It is
widely acknowledged that reducing
CO2 emissions is necessary to alleviate the projected negative impacts
of climate change. With the emergence of crop residue management
in CA practices as a strategy to improve soil productivity it has inadvertently lend itself as a means to
reduce CO2 release to the atmosphere as well. The build up of SOM
serves to sequester C in soils. It is
estimated that agricultural soils
have the capacity to significantly
capture C in excess of that by terrestrial plants, with the potential
for expanded C sequestration. Currently, agriculture and other forms
of land use contribute about a third