Agricultural sustainability: concepts, principles and evidence

Abstract

Concerns about sustainability in agricultural systems centre on the need to develop technologies and practices that do not have adverse effects on environmental goods and services, are accessible to and effective for farmers, and lead to improvements in food productivity. Despite great progress in agricultural productivity in the past half-century, with crop and livestock productivity strongly driven by increased use of fertilizers, irrigation water, agricultural machinery, pesticides and land, it would be over-optimistic to assume that these relationships will remain linear in the future. New approaches are needed that will integrate biological and ecological processes into food production, minimize the use of those non-renewable inputs that cause harm to the environment or to the health of farmers and consumers, make productive use of the knowledge and skills of farmers, so substituting human capital for costly external inputs, and make productive use of people's collective capacities to work together to solve common agricultural and natural resource problems, such as for pest, watershed, irrigation, forest and credit management. These principles help to build important capital assets for agricultural systems: natural; social; human; physical; and financial capital. Improving natural capital is a central aim, and dividends can come from making the best use of the genotypes of crops and animals and the ecological conditions under which they are grown or raised. Agricultural sustainability suggests a focus on both genotype improvements through the full range of modern biological approaches and improved understanding of the benefits of ecological and agronomic management, manipulation and redesign. The ecological management of agroecosystems that addresses energy flows, nutrient cycling, population-regulating mechanisms and system resilience can lead to the redesign of agriculture at a landscape scale. Sustainable agriculture outcomes can be positive for food productivity, reduced pesticide use and carbon balances. Significant challenges, however, remain to develop national and international policies to support the wider emergence of more sustainable forms of agricultural production across both industrialized and developing countries.

Figure 1

Rural and urban world population (1950–2030; from UN (2005)).

Figure 2

(a) Agricultural area (1961–2002; from FAO (2005)). (b) Head of livestock, world (1961–2004; from FAO (2005)). (c) Irrigated area and agricultural machinery, world (1961–2002; from FAO (2005)). (d) World fertilizer consumption (1961–2002; from FAO (2005)).

Figure 3

(a) Relationship between all fertilizers applied and world plant food production (1961–2002; from FAO (2005)). (b) Relationship between world agricultural machinery and world plant food production (1961–2002; from FAO (2005)). (c) Relationship between world irrigation area and world plant food production (1961–2002; from FAO (2005)). (d) Relationship between world agricultural land area and world plant food production (1961–2002; from FAO (2005)).

Figure 4

World population 1950–2300 (from UN, 2005).

Figure 5

Histogram of change in crop yield after or with project, compared with before or without project (n=360, mean =1.79, s.d.=0.91, median=1.50, geometric mean=1.64).

Figure 6

(a) Mean changes in crop yield after or with project, compared with before or without project. Vertical lines indicate ±s.e.m. ‘Other’ group consists of sugar cane (n=2), quinoa (1), oats (2). (b) Relationship between relative changes in crop yield after (or with project) to yield before (or without project). Only field crops with n>9 shown.

Figure 7

(a) Association between pesticide use and crop yields (data from 80 crop combinations, 62 projects, 26 countries). (b) Changes in pesticide use and yields in 62 projects (A: n=10; C: n=5; D: n=47).