Why CSA's do what we do.......We have hundreds of reasons why, and here are a few of them!  I, like many other csa farmers use low inputs to achieve the greatest outputs.  For example we use organic/natural methods to manage the soil in which the food is grown.  The belief of feeding the soil instead of the plant has tremendous value to the nutritional elements  of the produce grown.  As quoted from the book Real Food Fake Food  "Soil bacteria, which are essential to the creation of topsoil (the only natural material plants can grow in), and which make soil nutrients available to plants, cannot feed on unnatural chemical fertilizers: they must have organic material.  Without organic material, their soil factories shut down, and instead of being a living source of  nutrients and usually  none of the trace elements, which more and more we are discovering to be essential to human growth.". 
As far as the health of the soil and how it impacts our mmediate environment, we have an obligation to be consious of what we are doing in and around our production of food.  Only in the last 100 or so years has food been grown for profit margin purposes which for that reason only has encourage the large agribusiness producers to increase unnatural chemical inputs in order to get the most  number of any produce item, the special size or transportable form of those items to increase the bottom line.  This way of growing food has become such an obsession with our culture that many folks do not realize the impact this type of food production has on our land and what it is doing to our bodies. We are natural beings that did not derive from  blue water of WWII  era.  As a small scale multi crop producer I am the last one to dictate to other farmers that do not share my views that what they do are bad.  It is only to state that if we all just try some natural methods it can make a difference on some level.      

Before the industrialization of our food production, people ate seasonally. Growing and eating crops that were adapted to their climates was their mainstay.  Food preservation technics were a common practice handed down by generations. There are many populations around the world that are genetically attuned to gain the needed nutrition from their region's food varieties.  For an example-did you know that many of the trace elements and nutrition values that our society here in the US can obtain from what is grown in the areas they live?  Did you know that there is just as much Vitamin C in a spinach variety as it would be from any citrus only grown elsewhere?