Only 60 Years of Farming Left If Soil Degradation Continueshttp://www.scientificamerican.com/article/only-60-years-of-farming-left-if-soil-degradation-continues/Generating three centimeters of top soil takes 1,000 years, and if current rates of degradation continue all of the world's top soil could be gone within 60 years
"About a third of the world's soil has already been degraded."
"The causes of soil destruction include chemical-heavy farming techniques, deforestation which increases erosion, and global warming. The earth under our feet is too often ignored by policymakers, experts said."
"Unless new approaches are adopted, the global amount of arable and productive land per person in 2050 will be only a quarter of the level in 1960, the FAO reported, due to growing populations and soil degradation."
"Soils play a key role in absorbing carbon and filtering water, the FAO reported. Soil destruction creates a vicious cycle, in which less carbon is stored, the world gets hotter, and the land is further degraded."
[Wikipedia]Soil retrogression and degradationhttps://en.wikipedia.org/wiki/Soil_retrogression_and_degradation
And another article:Soil degradationhttp://www.environment.nsw.gov.au/soildegradation/
"Soil degradation is a serious global environmental problem and may be exacerbated by climate change. It encompasses physical, chemical and biological deterioration. Examples of soil degradation include loss of organic matter, decline in soil fertility, decline in structural condition, erosion, adverse changes in salinity, acidity or alkalinity, and the effects of toxic chemicals, pollutants or excessive flooding."