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 38

yields may not feed the human world, what is next for agriculture (Beddington et al.
2012 )? There is a strong need to explore innovative options towards sustainable
intensi

cation of agroecosystems. The strategy is to understand the linkages and
inter-connectivity among resources and the underlying mechanisms governing
critical processes, which are determinants of principal functions and ecosystem
services.

1.1 Natural Resources and Human Wellbeing

Food security remains a major among global issues of the twenty- rst century.

Principal determinants of food security are the availability and quality of soil
resources, and their interactions with water resources and vegetation (crop species)
through energy-based inputs using managerial skills for optimizing the net primary
productivity or NPP (Fig. 1 ). The latter is speci

cally affected by critical linkages

that govern speci c functions of nexuses between: (1) soil and water for the plant,

available water capacity by in

uencing water retention and transmission, conver-
sion of blue and grey into green water, and moderating the effects of pedologic and
agronomic droughts, (2) soil and vegetation for biogeochemical cycling, which
determines elemental budgets (C, N, P, S), nutrient use efficiency, root distribution
and turnover and soil/root respiration, (3) vegetation and energy for energy/mass
transformation and in uencing energy productivity, ecosystem C budget, and

biomass feedstocks for biofuel production, and (4) energy and water affecting the
hydrological cycle with speci c impacts on water and energy balance on a land-

scape, energy use in irrigated systems, and moderation of the hydrological/mete-
orological droughts (Fig. 1 ). These nexuses affect and are affected by climate
change and variability on the one hand and anthropogenic perturbations (human
demands) on the other (Fig. 1 ).
The importance of nexuses and inter-connectivity is also documented by a close
relationship between soil security, climate security, water security, energy security,
economic security and political security (Fig. 2 ). Indeed, an important rami

cation
of the strong nexuses among natural resources is the human wellbeing based on
speci uent

lifestyle. For example, the food security (availability, access, nutritional quality,
retention) strongly depends on soil security (quality, resilience), water security
(renewability, availability, quality), energy security (supply, price, dependability),
climate security (optimal temperature and moisture regimes, and low frequency of
extreme events), economic security (income and access to resources), and political
stability (peace and harmony) (Fig. 2 ).
Indeed, both economic and political securities are closely linked with food
security on the one hand and security of natural resources on the other (Fig. 2 ).
Therefore, the co-productivity generated by the anthropogenic use of primary
resources (soil, water, climate) and secondary inputs (fertilizers, amendments,
irrigation, tillage) must be optimized. Understanding and judiciously managing the

c needs, which are increasing because of the growing population and af