Agriculture impact on the environment

Agriculture impact on the environment: Agriculture places a serious burden on the environment in the process of providing humanity with food and fibres.

Agriculture impact on the environment

 It is the largest consumer of water and the main source of nitrate pollution of groundwater and surface water, as well as the principal source of ammonia pollution.

It is a major contributor to the phosphate pollution of waterways (OECD, 2001a) and to the release of the powerful greenhouse gases (GHGs) methane and nitrous oxide into the atmosphere (IPCC, 2001a).

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 Increasingly, however, it is recognized that agriculture and forestry can also have positive externalities such as the provision of environmental services and amenities, for example through water storage and purification, carbon sequestration, and the maintenance of rural landscapes.

 Moreover, research-driven intensification is saving vast areas of natural forest and grassland, which would have been developed in the absence of higher crop, meat, and milk yields.

 But conversely, intensification has contributed to the air and water pollution mentioned above (Nelson and Mareida, 2001; Mareida and Pingali, 2001), and in some instances reduced productivity growth because of soil and water degradation (Murgai, Ali and Byerlee, 2001).

Quantification of the agro-environmental impacts is not an exact science.


 there is considerable debate on their spatial extent, and on the magnitude of the current and long-term biophysical effects and economic consequences of the impact of agriculture.
Agriculture impact on the environment

Much of the literature is concerned with land degradation, especially water erosion. Moreover, most of the assessments are of physical damage, although a few attempts have been made to estimate the economic costs of degradation as a proportion of agricultural GDP.

 Scherr (1999) quotes estimates of annual losses in agricultural GDP caused by soil erosion for a number of African countries, which can be considerable.

 Unfortunately, these aggregate estimates can be misleading, and policy priorities for limiting impacts based on physical damage may not truly reflect the costs to the economy at large.


 the relative importance of different impacts may change with time, as point sources of pollution are increasingly brought under control and non-point sources become the major problem.
Agriculture impact on the environment


offsite costs can be considerably greater than the onsite costs. These important analytical limitations are apparent from recent estimates of the external environmental costs of agriculture in various developed countries given in Pretty et al. (2001).

These estimates suggest that in developing countries over.

Agriculture and the environment: changing pressures, solutions 

the next 30 years greater consideration should be given to air pollution and offsite damage because their costs may exceed those of land and water pollution, loss of biodiversity, and onsite damage.

 It should be noted that a large proportion of these environmental costs stems from climate change and its impacts, which are still very uncertain.

 It is generally accepted that most developing countries will increasingly face the type of agro-environmental impacts that have become so serious in developed countries over the past 30 years or more.

The commodity production and input use projections presented in Chapters 3 and 4 provide an overall framework for assessing the likely impacts of agricultural activities on the environment over the next 30 years in developing countries.

 Several large developing countries already have average fertilizer and pesticide application rates exceeding those causing major environmental problems in developed countries.

Agriculture impact on the environment

 Similarly, some developing countries have intensive livestock units as large as those in Europe and North America that are regarded as serious threats to waterbodies (OECD, 2001a).

Moreover, the experience of agro-environmental impacts in developed countries can give advance warning to developing countries where agro-ecological conditions are similar to those in OECD countries.

 Developing countries are likely to face similar problems when adopting similar patterns of intensification.

 They can use the experience of developed countries to identify some of the policy and technological solutions to limit or avoid negative agro-environmental impacts, and to identify the trade-offs.

 They can also estimate the economic costs (externalities) of the agro-environmental impacts of intensive agriculture that are not currently reflected in agricultural commodity prices, and these costs can provide a basis for policy and technology priority setting.

 It will be argued that higher priority than is currently the case should be given to lowering agriculture’s impact on air and water.

The remainder of this chapter assesses the changing pressures on the environment from agriculture, using the projections for land, water, agrochemical input, and technological change given in earlier chapters.

 It examines the main technology and policy options for limiting agriculture’s negative impacts on the
environment and widening its positive ones.

 Finally, it considers the range of situations and trade-offs that may influence the uptake of these options.

The important issue of climate change is examined both here. This chapter examines the role of agriculture as a driving force for climate change,  examines the impact of climate change on agricultural production and food security.

 Major trends and forces It is clear from the crop production projections presented that the key issue for the future is the environmental pressure from the intensification of land use, rather than land cover or land-use changes alone.

 Some 80 percent of the incremental crop production in developing countries will come from intensification and the remainder from arable land expansion.

 Thus the dominant agro-environmental costs and benefits over the projection period will continue to be those stemming from the use of improved cultivars and higher inputs of plant nutrients and livestock feed, together with better nutrient management and tillage practices, pest management, and irrigation.

Nonetheless, extensification of agriculture in environmentally fragile “hot spots” or areas high in biodiversity will also remain of continuing concern.

The positive benefits of these changes will include a slowdown of soil erosion and at least a slower increase in pollution from fertilizers and pesticides.

 Likely outcomes on the negative side are a continuing rise in groundwater nitrate levels from poor fertilizer management, further land and yield losses through salinization, and growing air and water pollution from livestock.

 The main agro-environmental problems fall into two groups. First, there are those that are global in scale such as, for example, the increase in atmospheric concentrations of the GHGs carbon dioxide (CO2) through deforestation, and nitrous oxide (N2O) arising from crop production (Houghton et al., 1995; Mosier and Kroeze, 1998).

The second group of problems is found in discrete locations of the major continents and most countries, but at present has no substantive impact at the global level. Examples are the salinization of irrigated lands and the buildup of nitrate fertilizer residues


in groundwater and surface water. These problems first emerged in the developed countries in the 1970s as a consequence of agricultural intensification.

However, they have become of increasing importance in some developing countries during the past decade or so, and are destined to become more widespread and more intense unless there is a break from current policy and technological trends.

 Most of the negative impacts from agriculture on the environment can be reduced or prevented by an appropriate mix of policies and technological changes (see, for example, UN, 1993; Alexandratos, 1995; Pretty, 1995; and Conway, 1997).

 There is growing public pressure for more environmentally benign agriculture. Countries also have to comply with the WTO Agreement on Agriculture and the UNCED Conventions (particularly the Framework Convention on Climate Change).
Agriculture impact on the environment

 This forces countries to reduce commodity price distortions and input subsidies and encourages them to remove other policy interventions that tend to worsen agro-environmental impacts and to integrate environmental considerations explicitly into agricultural policies.

At the national level, there is now a range of policy options available to correct past agro-environmental mistakes and to prevent or limit future ones. The main problems were first recognized in those developed countries that embarked on agricultural intensification in the 1940s and 1950s, e.g. France, the United Kingdom, and the United States.

 These countries started to formulate corrective measures soon afterward. Their experience can help other countries embarking on intensification to avoid or moderate some of the problems.

 Some developing countries, for example, have introduced institutional mechanisms to promote environmentally benign technologies more rapidly than the developed countries at a comparable point of economic development.

 Moreover, the responses have not been only at the public sector level. Farmers in both developed and developing countries have also made a significant contribution by spontaneously creating or adopting environmentally benign technologies or management practices.

 At the international level, there is now the wide endorsement of the precautionary principle, under which countries accept the need to introduce corrective actions at an early stage and possibly before all of the scientific justification is in place (UN, 1993).

Agriculture impact on the environment International action has also been taken to strengthen research on the biophysical changes that agriculture is causing (Walker and Steffen, 1999), and to monitor the key indicators of agroecosystem health (ICSU/UNEP/FAO/UNESCO/WMO, 1998; OECD, 1991, 2001b) so as to understand and give advance warning of any threats to agricultural sustainability.


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