ABSTRACT
Soil health encompasses the ability of soil to provide ecosystem services that humans require. In most cases, the predominant service is the supply of forage for livestock. Although livestock produce comprises predominantly meat and dairy, it also includes other products on which humans are also dependent, such as leather and hides, wool and fibre, or deer velvet. These principles can also be extended to non-productive livestock, such as those used for recreational purposes (horses) or pets (rabbits, llamas or alpacas). There are numerous other services provided by grasslands, and although most land owners are not remunerated for those services, this provision is increasingly being valued in the society. The ecosystem services provided by grassland include:
i Forage for livestock (either direct consumption or conserved as hay or silage) ii Reservoir of nutrients (including a trap for nutrients prevented from reaching
waterways) iii Host for pollinators iv Erosion control (soil stability, slowed movement of surface water) v Water reservoir (infiltration), water harvesting (surface-collected municipal water and
quality water for streams and rivers)
Managing soil health for grassland
vi Biodiversity (host for rare and native plant and animal species) vii Medium for soil biodiversity (including macro-fauna, such as earthworms) viii Carbon (C) sequestration (including absorption of CH4 and nitrous oxide) ix Aesthetic purposes (including agri-tourism, landscape appearance, etc) x Host for wildlife (including nesting birds, grazing mammals, insects within the food
chain) xi Bioremediation (trap for particulate air-borne C, etc)
Many of the topics in this list are covered in greater detail in other chapters, and thus this chapter will focus on fertility management for soil health. Low fertility is most easily managed by fertilizer application. However, losses of nutrients from grassland are among the most significant non-point sources of environmental impact from grassland systems. One strategy for fertility management is the principle of ‘The Three Rs’: applying the right nutrient, in the right place, at the right time. In many cases, managing grassland fertility for high livestock production can be beneficial to other ecosystem services. For example, high forage production from use of a nitrogen (N) fertilizer can also promote vigorous root growth and enhance C-sequestration. Conversely, that N-fertilization can suppress N-fixation and might result in N leaching into surface waters. These conflicts are the focus of much of the social debate in many countries today, as we attempt to balance production and environmental impacts. Soil health is not a fixed condition, but dependent upon the context in which that soil is being used. Soil health is thus defined by the stakeholders, and a soil that is suitable for one purpose may be unsuitable for a different purpose. The analogy with human health is a good example; an average person might be considered to be in good health, but in comparison to an Olympic athlete, who is also considered healthy, has a vastly different level of performance.
