Sustainable Intensification of Agriculture
All
commentators agree that food production will have to increase
substantially. But there are very different views about how this should
best be achieved. Some still say agriculture will have to expand into
new lands. Others say food production growth must come through redoubled
efforts to repeat the approaches of the Green Revolution; or that
agricultural systems should become organic. Traditionally agricultural
intensification has been defined in three ways: increasing yields per
hectare, increasing cropping intensity (i.e. two or more crops) per unit
of land or other inputs (water), and changing land-use from low-value
crops or commodities to those that receive higher market prices.
It is now
understood that agriculture can negatively affect the environment
through overuse of natural resources as inputs or through their use as a
sink for pollution. Such effects are called negative externalities
because they are usually non-market effects and therefore their costs
are not part of market prices. What has also become clear in recent
years is that the success of some modern agricultural systems has masked
significant negative externalities, with environmental and health
problems documented and recently costed for many countries. These
environmental costs change conclusions about which agricultural systems
are the most efficient, and suggest that alternatives which reduce
externalities should be sought.
Sustainable agricultural intensification is defined as producing more
output from the same area of land while reducing the negative
environmental impacts and at the same time increasing contributions to
natural capital and the flow of environmental services (Royal
Society, 2009;
Godfray et al., 2010).
A
sustainable production system would thus exhibit most of the following
attributes:
i.
Utilising crop varieties and livestock breeds with a high
ratio of productivity to use of externally-derived inputs;
ii.
Avoiding the unnecessary use of external inputs;
iii.
Harnessing agro-ecological processes such as nutrient
cycling, biological nitrogen fixation, allelopathy, predation and
parasitism;
iv.
Minimising use of technologies or practices that have
adverse impacts on the environment and human health;
v.
Making productive use of human capital in the form of
knowledge and capacity to adapt and innovate and social capital to
resolve common landscape-scale problems;
vi.
Quantifying and minimising the impacts of system
management on externalities such as greenhouse gas emissions, clean
water availability, carbon sequestration, conservation of biodiversity,
and dispersal of pests, pathogens and weeds.
As agricultural and environmental outcomes are
pre-eminent, sustainable agricultural systems cannot be defined by the
acceptability of any particular technologies or practices (there are no
blueprints). If a technology assists in efficient conversion of solar
energy without adverse ecological consequences, then it is likely to
contribute to the system’s sustainability. Sustainable agricultural
systems also contribute to the delivery and maintenance of a range of
valued public goods, such as clean water, carbon sequestration, flood
protection, groundwater recharge, and landscape amenity value. By
definition, sustainable agricultural systems are less vulnerable to
shocks and stresses. In terms of technologies, therefore, productive and
sustainable agricultural systems make the best of both crop varieties
and livestock breeds and their agro-ecological and agronomic management.
The pioneering
rice breeder, Peter Jennings, who led early advancements in high
yielding rice varieties during the first green revolution, has argued
for an “agronomic revolution”: “It is now widely recognized that rice
yield gaps result from agronomic failings, and that future yield
increases depend heavily on this science. Agronomy’s time has come to
lift farm productivity out of stagnancy”. Agronomy refers to the
management of crops and livestock in their specific circumstances, and
matches with the emergence of the term agro-ecology to indicate that
there is a need to invest in science and practice that gives farmers a
combination of the best possible seeds and breeds and their management
in local ecological contexts.
This suggests that
sustainable intensification will very often involve more complex mixes
of domesticated plant and animal species and associated management
techniques, requiring greater skills and knowledge by farmers. To
increase production efficiently and sustainably, farmers need to
understand under what conditions agricultural inputs (seeds, fertilizers
and pesticides) can either complement or contradict biological processes
and ecosystem services that inherently support agriculture. In all cases
farmers need to see for themselves that added complexity and increased
efforts can result in substantial net benefits to productivity, but they
need also to be assured that increasing production actually leads to
increases in income. Too many successful efforts in raising production
yields have ended in failure when farmers were unable to market the
increased outputs. Understanding how to access rural credit, or how to
develop warehouse receipt systems and especially, how to sell any
increased output, becomes as important as learning how to maximize input
efficiencies or build fertile soils.
