bare patches

 

This is a dramatic visual example of what is happening to our hills under a "conventional cultivation system" of crop production.  Over the 100+ years that this field has been plowed, disc'd, cultivated, weeded, and harrowed, with some of these operations being done repeatedly in any one crop year, the thin mantel of top soil has been removed from the area shown, leaving these bare patches in the winter wheat crop.  The following website gives information on soil and it's value to crop production. <ftp://ftp.fao.org/docrep/fao/009/a0443e/a0443e01.pdf>.   Without the [O and A horizon] crop production is limited.  The "O" horizon is the surface crop residue.  The "A"horizon is  the mineralized organic layer below the "O" horizon.  These two layers, O and A, make up the spongy layer of the soil that is biologically active, and resists the erosive action of rain droplets, and the scouring energy of the wind.  The deeper the layer, the higher the nutrient production capability and water holding capacity.  The "A" horizon is the "engine" that is the future for crop production in a Direct Seed System.  It has the potential to be manipulated, to make and redistribute nutrients for crop production. With todays technology, this erosion process(pic above) can be stopped and the soils rebuilt; however, the rebuilding is a very slow process.  NRCS considers a loss of 10,000 pounds per acre as sustainable.  That is a little less than 3mm depth of soil.  The field above, as an example, receives a number of rain and wind events over the course of a year along with several tillage operations.  It's anyones guess as too the amount of soil that has moved off the surface of this field, but my guess is that it is in excess of 20mm over the course of the two years that it took to raise this crop.  To add insult to injury, that exposed  poor soil ["B"horizon] is eroding down and overlaying the better producing ["A"] soils.   Those soils then, tend to produce at a lower production level.  So, over time, the bare patches enlarge and field yield average shrinks.  These areas will become more prevalent and larger until all tillage stops and residue is considered an asset instead of a liability on the hilltops and hillsides.