Sustainable Soil Management Is More than What and How Crops Are Grown - Principles of Sustainable Soil Management in Agroecosystems - page 354

In addition, we are discovering the importance and significance of the fact that
living organisms including plants and animals each have coevolved with a large
number of symbiotic endophytes and nonendophytes that form mutually beneficial
relationships with plants and animals that can lead to a superior phenotypic perfor-
mance from the same genotype. In other words, the G × E (genotype × environment)
equation can work differently depending on whether certain microorganisms are
present or not in the soil, in the rhizosphere, and within the plants. In some cases,
microorganisms such as the Rhizobia, which are well known for their ability to fix
atmospheric nitrogen in legumes, have recently been shown to behave as a symbiotic
endophyte in rice plants, where it has been shown to penetrate through the root sys-
tem all the way into the leaves, increasing unit leaf photosynthesis rate by some 15%
(Mishra et al. 2006). Similarly, in the case of mobile phosphorus level in the soil,
values as high as 50 to 60 ppm have been recorded in soils with phosphobacteria,
which would otherwise show phosphorus deficiency (Turner and Haygarth 2001).
What is being discovered is that a living soil has a different productive capacity
and resilience when farming practices encourage and facilitate soil life to play its
important role in maintaining soil health and quality. Such soils respond differently
and more efficiently to farming practices that are applied to intensify production, and
there is increasing evidence that the phenomenon of “more from less,” which is often
observed with biologically active soils, is due to the role soil microorganisms play in
the various ecosystem processes and functions in the soil (Uphoff et al. 2006).
14.5 SUSTAINABLE SOIL MANAGEMENT BASED
UPON AGROECOLOGICAL PRINCIPLES
Evidence from different parts of the world suggests that it may not be possible to sep-
arate sustainable soil management from sustainable production system management.
Both are inextricably linked in ways that sustainable crop production systems must
first be ecologically sustainable. This means that any production system that permits
the mechanical disruption of soil life and biology and soil structure and quality, and
therefore ecosystem services, cannot be considered to be sustainable ecologically.
The aim of “sustainable soil management” should be to reverse the trends indicated
by the items listed above, via the inducing of improvements in the quality of the soil
as a rooting environment for plants. Also, an agricultural soil system is of no value
if the crops grown are attacked by weeds, insects, and pathogens. In other words,
sustainable soil management is not enough for sustainable production as an out-
come, and certainly not where sustainable production intensification is the objective
in which crop, soil, nutrient, water, pest, and farm power management in space and
time must be taken care of to remain ecologically and economically viable.
The agroecological principles that underpin sustainable production systems for
small and large farmers from an eco-commercial viewpoint relate to resource con-
servation and efficiency of resource use, both natural and purchased, while profit-
ably managing sustainable production intensification and ecosystem services. At
the core, and based upon large amount of empirical evidence from farmers them-
selves in all continents, we can say that sustainable production derives from a num-
ber of practical principles that can be applied simultaneously through combined