Residue May Be Key Infiltration Factor
John Church, Extension Educator Natural Resources,
Rockford Extension Center, 815-397-7714, email@example.com
During and after planting can be a good time to compare the impact
of various tillage and conservation practices on soil erosion
and water infiltration in fields. Residue left on the soil surface
from no-till and other high-residue tillage systems helps protect
the soil from raindrops, which reduces the breaking apart of soil
particles and ultimately the erosion of soil. Residue's impact
on protecting the soil surface from erosion is well accepted.
However, there is also growing interest in the impact of residue
and less tillage on increasing water infiltration, which can reduce
runoff as well as maintain moisture supplies.
Purdue studies have shown that fields with no residue on the
surface similar to conventional tillage can have a 45 percent runoff
rate as compared to no-till fields with high residue that have
runoff rates as low as 0.5 percent of the rainfall. At about 40 percent
residue cover, which is comparable to many mulch tillage systems,
the runoff rate was about 40 percent. The same study shows about 12 tons
per acre soil loss with no surface residue as compared to 3.2
tons at 40 percent residue and 0.3 tons at 93 percent residue levels. Runoff
velocity rates for the same three residue levels were 26, 14,
and 7 ft./min., respectively. Less runoff means less soil erosion
and more water infiltration, which can enhance groundwater supplies,
reduce stream volumes and velocities, and reduce streambank erosion
and lessen sedimentation. Increased infiltration also is a good
indicator that soil structure is improving for better rooting,
less compaction and better air, water and nutrient movement.
While evaluating the field residue for sheet erosion and water
infiltration, be sure to check other erosion structures for necessary
maintenance or need for new construction to reduce gully erosion
or streambank erosion.