|
Moving from left to right across the bar chart is the equivalent of moving vertically downward through the soil profile. The burgundy colored segment of the chart represents the percentage of the inch of soil sample which is composed of silt sized soil particles. As can be readily seen the second through 4th inch represent zones of silt depletion or where silt has migrated downward or left the original location after last horizontal tillage operation.
The last tillage operation has created the concentration of silt and clay, which is apparent at the top inch of the soil profile. This is the result of the centrifuging action of secondary tillage tools, which separate the soil particles by density in relation to air and each other.
Water performs the same separating function as it percolates downward through the soil. When the water slows the silt drops out. Where this takes place the water continues to slow in the future so that the zone of accumulation of silt sized soil particles becomes more and more restrictive to water movement.
Alfalfa is an excellent indicator of where this zone of accumulation exists. The distance the crown heaving takes place in the early springtime in northern climates is directly proportional to the coefficient of expansion of water when it turns to ice, the amount of water contained above the silt zone of accumulation and the depth of the zone of accumulation.
TILLAGE REDEFINED
The chart and the brief discussion that has followed is the foundation on which we can redefine tillage of soil. If you would read Hosea 10; 11,12 and Jeremiah 4; 3,4 you will see the parallel between the command to till the earth in Genesis and the recurring condition of the iniquitous human heart.
When God breaks up the fallow ground of our hearts he does not destroy us. He sends life and His Word or breath into our spirit. He purges out the old and restores with freshness from Above.
The parallel to how a soil aerator should perform in soil is almost uncanny. Perhaps it is so obvious so that we cannot deny the simplicity of heart or child-likeness of faith that it requires to believe that this form of tillage is entirely adequate to accomplish the command of God to till the earth.
Rather than redistributing the silt zone, soil aeration merely perforates it and restores water movement and diffusion throughout the plow-layer. This naturally results in old air purging and intake of fresh concentrations of above-ground nitrogen and oxygen.
More conventional forms of tillage result in massive changes of soil atmosphere. These result in greater mineralization of soils and/or massive destruction of micro-flora who are adversely affected by sudden and large increases in atmospheric nitrogen concentrations. Using a properly functioning soil aerator is the foundation of building topsoil or humus content.
|
