Managing soils for a warming earth in a food-insecure and energy-starved world


  • Keynote Lecture at the DBG symposium on the occasion of the World Soil Day, December 4, 2008, Berlin, Germany.


World energy consumption increased from 11.5 EJ in 1860 to 463 EJ in 2005, and is projected to be 691 EJ in 2030 and 850 EJ in 2050. The principal driver of such a drastic surge in energy demand is the increase in world population which was merely 1 billion in 1800, 1.6 billion in 1900, 6.0 billion in 2000, and is projected to be 7.5 billion in 2030 and 9.2 billion in 2050 before stabilizing at ≈10 billion by 2100. Heavy reliance on fossil-fuel consumption has increased atmospheric CO2 abundance from 280 ppm in 1750 to 383 ppm in 2008 and is increasing at ≈2 ppm (4.2 Pg) per year along with the attendant threat of climate disruption. Similar to the close link between energy use and atmospheric chemistry, there also exists a close link between food insecurity and climate change through degradation of soils and desertification of the ecosystems. Global annual per capita cereal consumption increased from 267 kg in 1950, peaked at 339 kg in 1985, and decreased to 303 kg by 2000. In the quest for identifying alternate sources of energy, world production of bioethanol (mostly from corn grains in USA and sugarcane in Brazil) was 65 billion L, and that of biodiesel was 13 million Mg (t) (55% in EU countries) in 2008. Conversion of lignocellulosic biomass, using crop residues or establishing energy plantations, has severe constraints of the additional requirements for land area, water, and plant nutrients. Removal of crop residues for energy and other uses has severe adverse impacts on soil quality and agronomic productivity. Yet, globally average crop yields must be increased by 60% to 120% between 2000 and 2050 for meeting the needs of increase in population and change in dietary habits. Meeting demands of the growing world population and rising aspirations necessitate serious and objective considerations of change in food habits (to a more vegan diet), improvement in energy-use efficiency, increase in crop yield per unit area and input, restoration of degraded soils and ecosystems, widespread adoption of recommended soil and crop practices, and identification of non-C fuel sources.