Leaching occurs when the air spaces in soil become filled
with water and gravity begins to move water downward. The
percolating water carries any soluble salts that are present in
the soil and is not specific for nitrate.
Fine-textured soils (high clay) are generally less susceptible
to nitrate movement than sandy-textured soils because water
permeability is much lower. However, fine-textured soils are
more prone to denitrification losses of nitrate.
A large portion of water percolation and nitrate leaching occurs
in the large soil pores. These pores develop from shrinking
and swelling of clays, as channels remaining from decomposed
roots, and by insect and animal activity. Water movement
through soil cracks and macropores (preferential flow) can be
as much as twenty times higher than in the same soil without
cracks. This movement can allow nitrate to flush through soil
more rapidly than might be expected.
Examination of the soil texture at the soil surface may not
reflect the soil properties deeper in the profile. Downwardmoving
water will likely encounter many features such as
perched water tables, geologic discontinuities, restrictive layers,
and other barriers to nitrate movement.
Artificially drained fields (tile-drained) allow water to bypass
 
Leaching occurs when the air spaces in soil become filled
with water and gravity begins to move water downward. The
percolating water carries any soluble salts that are present in
the soil and is not specific for nitrate.
Fine-textured soils (high clay) are generally less susceptible
to nitrate movement than sandy-textured soils because water
permeability is much lower. However, fine-textured soils are
more prone to denitrification losses of nitrate.
A large portion of water percolation and nitrate leaching occurs
in the large soil pores. These pores develop from shrinking
and swelling of clays, as channels remaining from decomposed
roots, and by insect and animal activity. Water movement
through soil cracks and macropores (preferential flow) can be
as much as twenty times higher than in the same soil without
cracks. This movement can allow nitrate to flush through soil
more rapidly than might be expected.
Examination of the soil texture at the soil surface may not
reflect the soil properties deeper in the profile. Downwardmoving
water will likely encounter many features such as
perched water tables, geologic discontinuities, restrictive layers,
and other barriers to nitrate movement.
Artificially drained fields (tile-drained) allow water to bypass
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