What is changing is how we deal with fertility in soils. "In Defence of Food" ( by Michael Pollan - published 2008) says that food quality is going down and that this is largely attributed to soil quality going down over time as land is used and reused with traditional farming techniques. Does a plant really know where it's nitrogen source originates? No - but in soils kept growing with only the use of chemical fertilizers the lesser known nutrients are also diminishing and not being replaced. In an organically managed soil, the micro-organisms provide a lot of the nitrogen to plants and in doing so provide many other little know benefits.
If you have time for any late spring reading pick up a copy of Teaming with Microbes, by Jeff Lowenfels (Timber Press) and learn how to manage your soils better and more naturally.
Stay tuned here as I report back from the Sustainable Soils conference being held March 23-24, 2009.