Environmental Impacts of Modern Agriculture

By R. E. Hester, R. M. Harrison

The Royal Society of Chemistry

Copyright © 2012 The Royal Society of Chemistry
All rights reserved.
ISBN: 978-1-84973-385-4

Contents

Editors, xiii,
List of Contributors, xv,
Modern Agriculture and Implications for Land Use and Management Joe Morris and Paul J. Burgess, 1,
Impacts of Agriculture upon Soil Quality R. Sakrabani, L. D. Deeks, M. G. Kibblewhite and K. Ritz, 35,
Impacts of Agriculture upon Greenhouse Gas Budgets J. M. Cloy, R. M. Rees, K. A. Smith, K. W. T. Goulding, P. Smith, A. Waterhouse and D. Chadwick, 57,
Impacts of Agriculture on Water-borne Pathogens David Kay, John Crowther, Cheryl Davies, Tony Edwards, Lorna Fewtrell, Carol Francis, Chris Kay, Adrian McDonald, Carl Stapleton, John Watkins and Mark Wyer, 83,
Pesticides in Modern Agriculture Dan Osborn, 111,
Balancing the Environmental Consequences of Agriculture with the Need for Food Security Ian Crute, 129,
Positive and Negative Impacts of Agricultural Production of Liquid Biofuels Lucas Reijnders, 150,
Subject Index, 168,

CHAPTER 1

Modern Agriculture and Implications for Land Use and Management

JOE MORRIS AND PAUL J. BURGESS

ABSTRACT

Agriculture is a land-based primary industry that directly depends on natural resources such as land, water, and a diversity of plants and animals. It is supported by the application of human knowledge, both traditional and scientific, and human effort, skills and endeavour. Following the global food and energy crisis in 2007–2008, and growing awareness of the challenges posed by climate change, interest in agriculture, after a period of neglect, has been reinstated as a key area of international and national policies. The performance of agriculture, however, must now be measured not only in terms of food, fibre and bio-energy production, but also a range of other social and environmental outcomes, positive and negative.

An array of technological, environmental, economic, social, and political factors, many of which are very context and spatially specific, shape the characteristics of agricultural systems, and the demand for, supply of and use of agricultural land. The emerging consensus is that agriculture must meet the needs of a growing and potentially more prosperous global population mainly from the existing stock of agricultural land. Otherwise the world’s ecosystems could be irreparably damaged. Harnessing the potential of sustainable agricultural technologies to improve the productivity of farmed land while protecting the natural environment is a key element of this process, especially in regions where agricultural development is the main means of alleviating hunger and poverty.

Following a broad review of issues and challenges facing agriculture at the global scale, the chapter considers the case of modern agriculture in the UK with particular reference to factors affecting land use. It also explores how agricultural technologies can help improve the productivity of farming systems while simultaneously delivering a range of other ecosystem benefits.

1 Introduction and Overview

Agriculture is a human activity carried out primarily to produce food, fibre and bio-energy by the deliberate and controlled use of (mainly terrestrial) plants and animals. This process of crop production uses the process of photosynthesis to capture solar energy and requires land and the associated soil and climate to provide water, nutrients, and anchorage. Animal production in turn is typically based on domesticated animals digesting plant material and producing high value products such as meat, milk and eggs. From a policy perspective, the main aim of modern agriculture is to achieve a stable and affordable food supply for all, whilst reducing climate change and maintaining biodiversity and ecosystem services. From a farmer’s perspective, a principal aim is to secure a stable and rewarding livelihood.

Agricultural activity creates a land-based ecosystem that is focused on the commercial interaction of biotic resources (primarily domesticated crops and animals, but also soil micro-organisms), with abiotic resources such as the atmosphere, soil, water, and energy. It is supported by the application of human knowledge, whether traditional or scientific, and human effort, skills and endeavour. The performance of agriculture can be measured not only in terms of the economic value of agricultural outputs per unit of land ($ ha-1) but also per unit of other inputs such as labour and finance. Increasingly there is awareness that performance also needs to consider a range of wider social and environmental outcomes which can be either positive or negative. Hence performance depends on a range of technological, environmental, economic, social, and political factors, which can be context and spatially specific.

This chapter reviews the characteristics of agricultural systems and the factors operating at the global and regional scale that affect the demand for, supply of and use of agricultural land. The links between modern agriculture and land use are explored with respect to the case of the UK. As the demands on land increase, agricultural activities (at both regional and global scale) will need to combine the challenge of increased food production whilst protecting and enhancing the natural environment and this will also need to be done in the context of the effects of climate change. Harnessing the potential of sustainable agricultural technologies to augment the capacity of the existing stock of agricultural land is critical to this process.

2 Agricultural Systems

Agriculture can be viewed as a system: an organised assembly of components brought together for a purpose (Figure 1). Inputs such as land, genetic resources, labour, energy, water, capital, and human knowledge are combined in a range of farming systems, such as cropping or livestock systems, to produce a diverse array of outputs, some intended and some unintended. Climate, the soil environment, and topography often constrain the particular crops and animals that can be used in a particular area. However agricultural systems are also strongly influenced by political and institutional factors, such as agricultural policy and land tenure arrangements. Whereas, the dominant agricultural purpose is to produce food and biomass for human consumption, increasingly agriculture is charged with (i) contributing to a wider array of beneficial goods and services associated with the occupancy and use of the rural landscape and (ii) controlling the unintended negative consequences of modern farming methods. This requires an understanding of the synergies and tradeoffs between agriculture, the natural environment and human well-being. It also begs a wider question – ‘what is land for?’.

3 Global and Regional Issues

Two recent reviews of world agriculture, the International Assessment of Agricultural Knowledge, Science and Technology for Agricultural Development (IAASTD) and the Foresight review on the Future of Food and Farming examined the key drivers affecting global food and farming systems. They include demand and supply side factors, systems of governance and the effects of climate change.

3.1 Demand Side Factors

Factors affecting the demand for agricultural outputs and hence land use include global population change and changes in the nature of demand for food, fibre and bio-energy. Forecasts for the global human population, predicated on assumptions about GDP growth, income distribution, education and the role of women, predict an increase from the current 7 billion people to a central estimate of 9.3 billion for 2050, with low and high variants ranging from 8.1 to 10.6 billion. The current rate of population growth represents a 1.1% annual increase in the number of people requiring food.

The demand for agricultural products also depends on consumption habits, influenced by tastes, preferences, habits and lifestyles. With rising average global incomes, food consumption per person per year is increasing by about +0.2% per year in terms of weight of food consumed (Figure 2). Dietary changes, such as a switch from starch staples to fats, proteins and sugars, particularly amongst relatively low income groups, could radically affect demand for food and hence land use. For example, the global annual per capita consumption of milk is predicted to increase from 78 kg in 2000 to 115 kg in 2050. Moreover the annual per capita demand for meat is predicted to increase from 37 kg in 2000 to 52 kg in 2050. Each kg increase in milk or meat requires an additional 5 to 8 kg of animal feed. Less than half of global grain production is consumed directly by humans, and this share could decrease as a result of global dietary change.

While increasing food availability is a Millennium Development Goal for the 1 billion people that are currently undernourished, diet-related obesity and ill-health amongst 1 billion of the better off is also a concern. Artificially high market specifications and avoidable food waste can also place further demand pressure on agriculture. For example, it is estimated that between a quarter and a third of all food for human consumption is probably lost in the world food system. Nonetheless, the Food and Agriculture Organisation (FAO) estimates that food production needs to increase by 70% from 2010 to feed 9 billion people in 2050.

Agriculture is also affected by the global energy demand that is predicted to increase by more than 50% in the next 25 years. While agriculture can contribute bio-energy sources, modern agriculture is fossil energy intensive in its use of fertilisers and fuels and is therefore vulnerable to high energy prices.

3.2 Supply Side Factors

On the supply side, agriculture’s ability to meet demand depends on the availability and suitability of land (including associated hydrological and climatic factors), technologies, traditional and modern, that determine the productivity of farming systems, and the logistics, processing and marketing chains that link supply with end users.

Of the estimated 13 400 million ha of land on earth, one third, about 4600 million ha, are used for agriculture. Of the total area, about 3000 million ha is considered suitable for crop production, of which two thirds are moderately suited to cereal production. At present, about half of the potential crop area (1400–1600 million ha) is cultivated for crops, the rest is mainly grassland. In the last 40 years (1967–2007), the total area of land occupied by agriculture has increased by only 8% but this has been mainly at the expense of forests, savannah and natural grasslands. Global yields increased by about 115% over the period, outpacing the 86% increase in world population, except for Africa where production per capita has only recently recovered to 1960 levels. Average agricultural area declined during the period from 1.30 to 0.72 ha per person. Every year, an estimated 12 million hectares of agricultural land are lost to land degradation, adding to the billions of hectares that are already degraded.

There are considerable regional variations in the absolute and relative changes in agricultural land use reflecting, in part, differences in governance, development and population growth (Figure 3). In Europe, for example most of the output has been achieved through increased yields on a declining agricultural area. Following rapid expansion of cropped areas in Asia in the 1960s and 1970s, much of it involving forest clearance, more recent increases in agricultural output have occurred on a declining area. In Africa and Latin America, the agricultural area is increasing, associated with reductions in forest and woodland areas. In Oceania, the large decline in the reported agricultural area (primarily of grazing land) was associated with an increase in designated conservation areas in Australia.

Agriculture is dependent on water supply, whether naturally available ‘green’ water from rainfall or ‘blue’ water artificially extracted from surface and groundwater sources. In drier regions, agriculture can account for up to 70% of blue water withdrawals. Demand for irrigation water could double by 2050, which, combined with declining available water due to climate change and other demands on water resources, could constrain agricultural potential. In addition, agriculture will need to contend with changing levels and distribution of rainfall and temperatures associated with climate change, including increased incidence of extreme drought or flood events. While some areas will experience negative effects, others, particularly in temperate and boreal zones, may derive benefit from warmer climates, especially if soils and water resources are favourable. Agriculture also contributes to climate change and policies to address these impacts, such as control of carbon emissions, also have major implications for agriculture and land use.

Also on the supply side, agricultural commodity markets that induce global land use are now much more internationally integrated, reflecting a reduction in trade barriers, improvements in information technology and the actions of transnational companies operating at the global scale. Emergent economies, such as Brazil, Russia, India, and China now exert stronger influence on agricultural markets, whether as importers or exporters. However, there remains a relatively high degree of protection for the domestic markets of developed countries, although much of this takes the form of indirect producer subsidies rather than direct restrictions on trade. The trade restrictions imposed following the 2008 spikes in global food prices, however, showed a limited commitment to collaboration when national interests are threatened. Protectionist and market distorting policies mean that supplies and prices in residual markets become more volatile with consequences for the poorest nations.

Global food and energy shortages have persuaded many governments to reexamine their approach to food security and the importance of maintaining a strategic capacity in production at a national or regional scale. Estimates of the effect of biofuels on the commodity price spike in 2007 range from 30% to 75%. In future, the additional land required for biofuel production could displace food production, leading to food shortages and higher food prices.

4 Agricultural Land and the Role of Science and Technology

Although the application of science and technology has led to major improvements in agricultural performance, poverty, hunger and environmental degradation are still widespread.

FAO and OECD conclude that while additional agricultural land is available to meet future food and biofuel demand, economic and environmental factors may limit agricultural development. In this context, IAASTD called for a change in approach if agriculture is to meet the needs of the developing world, especially in the face of uncertainties regarding energy, competition for natural resources, climate change and threats to the natural environment. The assessment promoted the concept of ‘multifunctional’ agriculture and land use to provide a range of benefits simultaneously in order to enhance human wellbeing. It explored how traditional knowledge, science and technology could be harnessed to alleviate poverty, achieve food security, and improve environmental sustainability – essentially improving the productivity of farming systems, in the broadest sense.

The concept of sustainable agriculture has been further elaborated by the UK’s Royal Society in a review of the contribution of science and the sustainable intensification of global agriculture. It argues that the needs of the growing population must and can be met from the existing global agricultural land if irreversible damage to the world’s ecosystems is to be avoided. The review calls for a large-scale ‘sustainable intensification’ of global agriculture in which yields are assessed not just per hectare, but also per unit of non- renewable inputs, especially fossil fuel, and impacts upon ecosystem services. The review identifies a key role for agricultural science including new crop varieties and appropriate agro-ecological crop and soil management practices. It argues for an inclusive approach that develops capacity in the governance of sustainable agricultural systems.

These arguments are further reinforced by the Foresight Review of the Future of Food and Farming which concluded that if: (i) there is relatively little new land for agriculture, and (ii) more food needs to be produced, and (iii) achieving sustainability is critical, then sustainable intensification is a priority. The Commission on Sustainable Agriculture and Climate Change also concludes that a ‘business as usual’ approach will not deliver global food security, calling for a commitment to support science-based strategies to improve agricultural production mainly from the existing agricultural land areas whilst operating within safe environmental limits.

(Continues…)Excerpted from Environmental Impacts of Modern Agriculture by R. E. Hester, R. M. Harrison. Copyright © 2012 The Royal Society of Chemistry. Excerpted by permission of The Royal Society of Chemistry.
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