The Nexus Approach to Managing Water, Soil and Waste under Changing Climate and Growing Demands on Natural Resources - Governing the Nexus: Water, Soil and Waste Resources Considering Global Change - page 42

Being essential for life, soil-water management is crucial to agricultural pro-
ductivity and ecosystem sustainability (Loucks and Jia 2012 ). With increasing
scarcity of freshwater, the wastewater can be used to enhance soil quality and
improve productivity. Thus, wastewater systems have been considered to assess
emissions of GHGs from both reservoirs and wastewater treatment plants (Hall
et al. 2011 ). When used for irrigation, wastewater application can reduce the C
footprint, earn C credits and enhance crop yields (Hanjra et al. 2012 ). Thus,
wastewater is a valuable resource of irrigation water in arid and semi-arid regions
(Babayan et al. 2012 ). However, risks of environmental and health hazards must be
minimized. Continuous application of wastewater may lead to accumulation of
heavy metals in soils. Thus, rate of application must be assessed in relation to soil
type, crop species, etc.
The runoff water generated from a mixed-farm landscale unit may be enriched in
plant nutrients. There exists a strong relationship between the sources of pollution
(e.g., cows, pigs, poultry) and quality of water runoff (Palhares et al. 2012 ). Under
such conditions, installing a riparian buffer may be useful to mitigating non-point
source pollution. Similar to the municipal wastewater, the winery wastewater can
also be used for irrigation. However, the high salt loading of winery wastewater is
an issue that must be addressed (Laurenson et al. 2012 ). Emission of ammonia
(NH 3 ) from slurry emits bad odours. Thus, separate management of solid and liquid
fractions, covered manure storage and band spread slurry application may be some
mitigation options (Dinuccio et al. 2012 ).
Another rami

cation of WSW nexus is the transport of soluble nutrients in
surface runoff from cropland and grazing lands receiving manure. Technological
options to minimize nutrient losses include (Harmel et al. 2009 ): (1) combining
application of organic and inorganic fertilizers, (2) providing alternate fertilizer
sources, and (3) enhancing understanding of the farming communities. There also
exists a water market and soil salinity nexus, which is an important issue with
regards to secondary salinization risks (Khan et al. 2009 ).
It is widely recognized that linking traditional pedology with soil physics and
hydrology, called hydropedology, can improve soil-water relationships across
spatial and temporal scales (Lin 2003 ; Lin et al. 2005 , 2006 ). Hydropedology is an
intertwined branch of soil science and hydrology that embraces inter-disciplinary
and multi-scale approaches for harnessing the bene ts of linking pedological and

hydrological processes. Societal bene ts of such an approach include those related

to water quality, soil quality, nutrient cycling, denaturing pollutants, waste man-
agement, climate change mitigation and numerous ecosystem functions.
In terms of water, the strategy is to look beyond the watershed, minimize hydro-
centricity (Allan 2006a , b ) and carefully evaluate the importance of hydropedology
(Schoeneberger and Wysocki 2005 ). Soil hydrology is relevant to understanding
transport of water and nutrients over and through the soilscape. The WSW nexus
must be carefully managed, especially in arid and semi-arid regions. Thus, the
importance of integrated management of natural resources, and especially inte-
grated water resource management cannot be over-emphasized (Twomlow et al.
2008 ).