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Careful management of nitrogen fertilizer usage is required to ensure world food security while limiting environmental degradation; an analysis of historical nitrogen use efficiency reveals socio-economic factors and technological innovations that have influenced a range of past national trends and that suggest ways to improve global food production and environmental stewardship by 2050.
Instead of containing stable and chemically unique ‘humic substances’, as has been widely accepted, soil organic matter is a mixture of progressively decomposing organic compounds; this has broad implications for soil science and its applications.
Formal criteria must be met to define a new human-driven epoch; the geological evidence appears to do so, with 1610 and 1964 both likely to satisfy the requirements for the start of the Anthropocene.
