Agriculture Reference
In-Depth Information
countervailing the powerful trend toward monoculture (Friedrich et  al. 2009; www.
fao.org/ag/ca) , has met with some similar resistance (Giller et al. 2009; Andersson and
Giller 2012). So SRI should not be considered as an isolated case.
In analytical terms, agroecologically informed methods aim to optimize the environ-
mental conditions ( E ) that affect the expression and realization of the genetic endow-
ments for a particular plant (or animal). The latter is referred to as a phenotype ( P ),
the actual biological phenomenon. This will diverge from the initial genetic potential
(the genotype, G ) according to the organism's history of development. Plant and animal
breeders summarize the relationship among E, G and P in this notional equation:
()
[
]
P = f G + E + G x E,
where any crop (or animal) being produced ( P ) is seen as a result of its genotype ( G ) and
its environment ( E ), and of continuous interaction between the genotype and all relevant
environmental factors [ G x E ].
Paradigms for agricultural development can be distinguished analytically as follows.
Biotechnology and genetic engineering focus on how to change and improve the G fac-
tor in this equation, seeking to achieve greater productivity of crops (or livestock) in a
specific environment or for many environments by making changes in the genome. The
environments ( E ) in which a crop (or an animal) is grown are expected to be managed
to suit the given G , by providing inorganic nutrients from fertilizer, agrochemical means
of protection, water inputs through irrigation, or other mechanisms. Everything pivots
around G . With agroecology, in contrast, the primary concern is with making modifica-
tions in E so as to achieve, by promoting more productive and sustainable G x E interac-
tions, the greatest productivity from any given G in the present and/or over time.
This equation makes clear that both G and E are important, indeed essential. Genetic
potentials are the starting point for all organisms, from microbes to mammals. All liv-
ing organisms (phenotypes) are the outcome of myriad environmental inputs and
influences that affect the expression of their genetic endowment (genotype). In agro-
ecological practice, there is particular concern with engaging the services of beneficial
microbes (bacteria and fungi), other soil organisms, and the ubiquitous earthworms and
other soil-system enrichers that function both above- and belowground (Wardle 2002;
Wolfe 2001). To the extent that modifying management can produce cost-effective and
more profitable results, a breeding strategy for agricultural improvement that focuses
primarily on G and gives short shrift to G x E interactions will become less attractive.
This observation could have significant implications for the future of what is now called
“modern agriculture.”
The chapter reviews, first, the opportunities that SRI methods are opening up
compared to current agricultural practices, even “best management practices” now
recommended by crop scientists. SRI is presented here as an example of agroecologi-
cal management that is convergent with other production strategies, such as agrofor-
estry, conservation tillage, and integrated pest management. These have been grouped
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