Soil Fertility as a Contingent Rather than Inherent Characteristic - Principles of Sustainable Soil Management in Agroecosystems - page 161

Both plants and the microbes that inhabit them acquire more implications of agency
in this more biologically shaped view of crop production.
One implication of a less sequential/more interactive understanding of crop pro-
ductivity is that the separation of crop science from soil science becomes less ten-
able. The effects of soil biota on plant gene expression need to be taken into account
since assessments of soil fertility can only be validated in terms of crop productivity.
This makes genetics—and particularly epigenetics—along with soil biology more
directly relevant to soil science than in the present disciplinary division of labor.
Currently, the evaluation of soils under axenic (sterile) conditions is considered not
only acceptable but good science. While there are some issues for which such analy-
sis is appropriate, in general, it places the same kind of limitations on the under-
standing of soil systems as doing all of medical research on cadavers rather than
studying living bodies.

6.10 CONCLUSION
Even more than soil scientists, plant scientists will probably have to make adjust-
ments in their mental models to integrate the roles of microbial symbiotic endo-
phytes into their paradigm. The research findings reported here on the contributions
to crop productivity attributable to soil microorganisms are likely to draw both dis-
ciplinary domains more closely together. It makes sense for them to become more
mutually informative rather than pursue even further the long-standing strategy of
disciplinary specialization. This makes a virtue of knowing more about smaller and
smaller subject areas, in effect to the exclusion of knowledge from other fields. Yet
other fields such as microbiology, soil ecology, and genomics and epigenetics are
becoming more relevant to soil science than before.
Soil fertility could become a bellwether concept for the integration of knowledge
across the agricultural sciences. The emerging understanding of plant-soil-microbial
interactions could lead to a correction of the imbalance among soil chemistry, soil
physics, and soil biology, kindling greater interest in and research on the latter dimen-
sion of soil systems. These are indeed dimensions rather than aspects or domains.
Soil systems should be understood as phenomena that function concurrently in three
dimensions, each affecting and interacting with the other. While the soil biota consti-
tutes only a small percentage of soil volume, it is like “the tail that wags the dog.” We
now are learning that they are also “wagging” the plants that grow in soil systems. Soil
fertility is thus a concept that is due for some revision and expansion.

ABBREVIATIONS
Al: aluminum
BNF: biological nitrogen fixation
CEC: cation exchange capacity
CFU: colony-forming units
CI I FAD: Cornell International Institute for Food, Agriculture and Development
CMEIAS: Center for Microbial Ecology Image Analysis Software
CO 2 :

carbon dioxide