What are the impacts of soil depletion?

Answer 1

Although there is evidence that our fruits and vegetables contain lesser amounts of nutrients and minerals than they did 20 years and 50 years ago, it is not clear whether this is solely from soil depletion or from some other cause such as non-organic farming practices and green harvesting as well. Some people would have us believe that because commercial farming practices often do not allow for fallow periods of the same duration as in the past - or any fallow at all - then our soils are depleted. Those who argue that our soils are not depleted say farmers enrich the soil, but in fact, for many farmers the only thing they put back is NPK.

With this plants will grow, but the vital micro and macronutrients will be missing. On an organic farm, soil quality is maintained through the use of organic matter like manure and field waste. These products are turned into useable nutrients by worms, nematodes, bacteria, mycorrhizal fungi and other organism in the soil. In contrast, soils on non-organic farms are often lacking in soil biota. Many of the beneficial micronutrients in the produce fall into the class of 'phenolics'. Plants make phenolics to repell pests and if the plants are sprayed with pesticides they have little need to produce phenolics and so produce far fewer, resulting in less nutritious food for us. A report in the Journal of Agricultural and Food Chemistry confirmed that for several plant species there are fewer phenolics produced when chemical pesticides are used.