Many semiarid and arid soils are prone to irrigation-induced erosion.
Polyacrylamide (PAM) greatly reduces erosion from furrow
irrigation. We hypothesized that PAM applied via sprinklers will
provide erosion control and benefit water infiltration and aggregate
stability. Screened (6.4 mm) Rad silt loam (coarse silty, mixed, superactive
mesic Durinodic Xeric Haplocambid) was placed in 1.5 by 1.2
by 0.2 m steel boxes with 2.4% slope. An oscillating nozzle, 3 m above
the soil, produced a median drop size of 1.2 mm diameter. We applied
0, 1, 2, 4, and 6 kg ha-1 PAM in 20 mm of water in the first irrigation,
followed by two 20-mm water-only irrigations. In a second test, we
applied 0, 2, and 4 kg ha-1 PAM in 8 mm of water in the first irrigation,
followed by two 20-mm water-only irrigations. Two kilograms per
hectare PAM in the first 20-mm irrigation reduced runoff 70% and
soil loss 75% compared to control. Polyacrylamide in 8 mm of water
was less effective. Polyacrylamide in the 20-mm irrigation did not
affect tension infiltration; PAM in the 8-mm irrigation doubled tension
infiltration following the third irrigation. Wet aggregate stability following
the first irrigation was greater in all PAM treatments than on
the check. With 2 kg ha-1 PAM in the 20-mm irrigation, it was 55%;
in 8 mm, 77%. Polyacrylamide applied in the first irrigation at low rates
effectively reduced runoff and erosion. Erosion was more effectively
controlled than runoff
