Cultivated soils that have been put into sod experience an improvement
in soil structural properties. This study was conducted to determine
the effect of tillage systems on maintaining the infiltration characte
ristics of sod sad and the effect of tillage systems on water runoff a
nd soil erosion. An alfalfa (Medicago sativa L.)-smooth bromegrass (Br
omus inermis Leyss.) sad established in 1984 was converted back to cro
pland beginning in the spring of 1990. Tillage treatments established
were moldboard plow, chisel plow, and no-till. Additional no-till trea
tments were established in 1991, 1992, and 1993. A grass sod treatment
was also maintained for comparison. After planting in 1993, two rainf
all simulation runs with an average rainfall application rates of 70 m
m hr(-1) were conducted on selected treatments. Time of each run was o
ne hour; the second run was conducted a minimum of six hours after the
first run but most commonly the next day. Water runoff from the moldb
oard plowed treatments averaged 24 and 66% of the applied rainfall res
ulting in soil loss levels of 6.7 and 18.2 t ha(-1) for the two runs,
respectively. Maximum observed water runoff for the no-till treatments
was 3% of the applied rainfall resulting in a soil loss of 0.2 t ha(-
1). No water runoff or soil loss was measured from the grass rod. Thes
e results show that soil characteristics developed under sad that were
beneficial to a reduction in water runoff and soil erosion rapidly di
sappear with tillage, but can be maintained with no-till.