AGRICULTURE AND ENVIRONMENT - Science for Agriculture and Rural Development in Low-income Countries - page 64

Chemical pollution of soil and water
Food production increase has more than kept pace with global population growth
over the last decades. This has mainly been achieved through intensification. The
irrigated area has increased, and the use of purchased inputs (e.g., fertilizers, crop
protection agents) and new technologies has grown, leading to increased production
per hectare (Hengsdijk et al. 2005; Fang et al. 2005; Roetter et al. 2007a). Several
environmental problems are related to high input levels that result in nutrient and
pesticide leaching. The combination of high inputs and advanced technologies
clearly has consequences for the sustainability of agro-ecosystems. Overuse and
misuse of agro-chemicals works in two ways, it pollutes soil and water needed to
sustain production and it directly and indirectly undermines human health.
The North-South programme addressed the issue of pesticide and fertilizer use in
intensive aquaculture and vegetable production in Asia via the projects MAMAS
and VEGSYS and, in the Pujiang case study of the IRMLA project (Roetter et al.,
2007b). Asia is in the process of rapid changes in agricultural production. The fast
adoption of high-yielding varieties (Van Keulen 2007; Roetter et al. 2007c) was
directly associated with an increase in the use of agro-chemicals. The rapid transition
from traditional farming systems to intensive industrialized farming systems as we
currently see in parts of Asia has similarities with the transition of agriculture witnessed
in Western Europe, following the introduction of the Common Agricultural Policy
(Van Keulen 2007). Unfortunately, also the environmental effects of intensive agricul-
ture bear similarities in the emissions of agro-chemicals to the environment, and
these problems require immediate action.
The fuel of the development engine is the increased demand for vegetables in
urbanized regions in Asia, which provides strong incentives for farmers to change
production systems and increase inputs. Lack of knowledge at farm level and lack of
awareness at government level result in lack of action, leading to accumulation of
negative environmental effects. Hence, the risks related to pesticide use for human
health and the environment are clear. Understanding and minimizing the risks related to
the use of agro-chemicals requires active participation of a range of stakeholders and
a systems approach to research. In both, the MAMAS and VEGSYS project a com-
bination of participatory research and modeling was used to quantitatively assess
risk in different production systems. A decision support tool to assess the risks has
been developed (Van den Brink 2005).
The negative environmental impact of fertilizers has been subject of research and
both, scientific and public debate for several decades, concentrating mainly on
intensive farming systems in the developed world (especially Western Europe and
North America) and started much more recently in tropical regions. Also in this
research, a systems approach was followed. Initially starting with understanding of
the effect of the biophysical environment and the role of management at plot and
field scale, the analyses moved up to the farm and regional scales, to include socio-
economic aspects of farm level decision-making. Following this approach, trade-offs
and possible synergies of management and policy options can be identified.