If you're worried about losing soil perhaps you should read this book from Earth Policy News. EPN says the book looks through the ages at the effects of over farming land through a lack of irrigation, over grazing and growing crops in marginal areas... a subject that could become more important as greater volumes of corn are grown for ethanol...
Does the no-till method of growing corn really get round the problems of soil erosion and could it be used in areas where there is currently soil erosion? Is that a question or the basis of a PhD thesis in agronomy? Let me know.,