World’s Soil Resources

The land sparing, land sharing approach can also been framed in terms of resilience (sharing) and efficiency
(sparing). Efficient systems by their very nature will prioritise the performance of one function over that of
others. The degree to which others are affected will depend on whether they perform well under similar
management or not. Currently, the data in 3 indicate that the choice lies between efficiency and redundancy.
We can have an efficient carbon storage system, e.g. peat development, which may also perform well as a
climate thermal buffer because the conditions for peat accumulation require lots of water, but it will not be
productive for crops in that state, nor will the arable system have high biodiversity as this is inefficient.
Choices need to be made as to what types of systems we wish to promote. In light of this, the focus of this
chapter is to assess the global scientific literature and understand how soil change discussed in Chapters 5
and 6 is likely to impact soil functions and the likely consequences for ecosystem service delivery. Each section
of this chapter outlines key soil processes involved with the delivery of goods and services and how these are
changing or - where evidence permits - may change. Each section then reviews how this change impacts soil
function and affects ecosystem service delivery. Some soil change does not produce an ecosystem service, but
does impact it; these impacts are considered when assessed as important and adverse. The focus is on the
local, regional and global scales and follows the general reporting categories of the MA (2005) modified by
TEEB (2014) to provisioning, regulating and cultural services. Towards the end of the section there is a focus on
the links with policy, institutions and management.
7.2 | Soil change and food security
Keating et al. (2014) provide a useful frame for examining the main roles of soils in food supply through their
development of the food wedge concept. The food wedge is the triangular area between the level of food
demand in 2010 and the upper bound of food demand in 2050 (suggested by Keating and Carberry (2010) as a
wedge equal to approximately 127 x 1015 kcal). The food wedge presented by Keating et al. (2014) assumes that
food supply and demand were broadly in balance in 2010. Increases in food supply (through, for example, the
strategies suggested by Foley et al., 2011) would increase the supply to meet the rising demand for food.
Either the incremental loss of productivity from current agricultural land or the total loss of agricultural
land due to degradation in the future would cause the lower boundary of the wedge to decrease and hence
increase the gap between food supply and demand (Figure 7.4). This decrease (or total loss) could occur if the
services for plant production supplied by the soil decreased due to a significant impairment of one or more
of the soil functions. Alternatively the restoration of productivity to previously degraded land would increase
plant production in addition to addressing the yield gap or increases in food delivery. Therefore a key soilfocused
strategy is to reduce future productivity loss from agricultural soils due to degradation to a minimum
and to restore productivity to soils that have previously experienced productivity losses.
Status of the World’s Soil Resources | Main Report The impact of soil change on ecosystem services
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