From Food Production to Food Security - Global Environmental ...

pollutants were then introduced as factors that reduce crop growth, thereby determining the‘actual’ yield. The notions of ‘potential’, ‘attainable’ and ‘actual’ therefore differentiateclearly the factors that define, limit or reduce yield, respectively (Bouman et al., 1996; vanIttersum and Rabbinge, 1997). (‘Available’ was later described in the Report “Realizing thepromise and potential of African agriculture” (InterAcademy Council, 2004) to recognise thata proportion of the actual harvest was lost post-harvest, resulting in a further reduced amountof food that is actually available for human consumption.)This production ecology approach was based on the concept of a single limiting factor which,once overcome, would allow growth to increase until it was restricted by another limitingfactor (the ‘minimum function’). A number of crop, crop-soil and crop-soil-pest modellingapproaches have been developed relating to a range of production situations, i.e. potential,water and/or nutrient-limited (van Ittersum et al., 2003). Differentiating the ‘potential’,‘attainable’ and ‘actual’ concepts is very useful for application in other areas of researchwhere there also is a set of limiting factors. In the case of carbon sequestration in soils, forinstance, soil mineralogy, net primary production and erosion are among major defining,limiting and reducing factors, respectively (Ingram and Fernandes, 2001). A key point aboutthis approach is that interactions between limiting factors are additive not multiplicative.Dalgaard et al. (2003) define agroecology as “the study of the interactions between plants,animals, humans and the environment within agricultural systems”. The general construct ofagroecology is therefore broader than the initial production ecology concept, which wasbased on a single limiting factor. It does however draw on this, but includes also theecological notions of interconnectivity, community behaviour and spatial organisation. Itbuilds on the community ecology notion of Clements (i.e. including “higher hierarchicallevels than the organism [the plant]”), and the worldview of Tansley, which included bothbiotic entities and their environment (Dalgaard et al., 2003). In this regard it is also alignedwith a fuller notion of production ecology (i.e. including the interactions with livestock), butincludes integrative studies not only within agronomy and ecology but also includingenvironmental science more generally. Interdisciplinarity and scaling across spatial levels areboth central tenets and the broad agroecology concept thereby helps move the debate towardsthe needs discussed in Paper 2, and thus towards the broader food security agenda. (Thefurther broadening of both concepts is discussed below.)It is important to note that the ‘eco’ letters in the word ‘agroecology’ do not denote – letalone advocate – a particular approach, as recommended by De Schutter in his SpecialRapporteur report on the right to food, presented to the UN General Assembly in December2010 (De Schutter, 2010). His argument that agroecology “seeks ways to enhance agriculturalsystems by mimicking natural processes” is incorrect; agroecology does not seek to mimic‘natural processes’ but apply ecological principles to help understand how agriculturalsystems operate and can be better managed. While “integrating crops and livestock;diversifying species and genetic resources in agroecosystems over time and space; andfocusing on interactions and productivity across the agricultural system, rather than focusingon individual species” can all be accommodated within agroecological concepts, its “core114