Chandrashekhar Biradar & John G. Lyon 
Remote Sensing of Global Croplands for Food Security [PDF ebook] 

Increases in populations have created an increasing demand for food crops while increases in demand for biofuels have created an increase in demand for fuel crops. What has not increased is the amount of croplands and their productivity. These and many other factors such as decreasing water resources in a changing climate have created a crisis like