Title: Using%20Soil%20Amendments%20to%20Improve%20Infiltration,%20Reduce%20Runoff%20and%20Soil%20Erosion
1Using Soil Amendments to Improve Infiltration,
Reduce Runoff and Soil Erosion
- Dennis C. Flanagan
- Agricultural Engineer
- USDA-Agricultural Research Service
- National Soil Erosion Research Laboratory
- West Lafayette, Indiana
2Problem with Intensive Agriculture Water/Air
Entry into the Soil
3This is a typical midwest landscape showing the
crop damage from ponding and runoff. Yield
variation can be large, and there can be a great
loss of production.Â
4Reduced Water/Air Entry into soils by surface
sealing results in reduced infiltration,
increased runoff, and increased soil erosion.
5- Soil Tilth is Often Poor Due to
- Intensive Cultivation over past 200 years,
depleting Organic Matter from soils. - Lower Organic Matter can result in smaller and
weaker soil aggregate particles, soils with
poorer structure, and reduced water holding
capacity. - Soils with low Organic Matter can more easily
seal and crust. - Frequent cultivation will reduce or eliminate
large permanent pores in soil. - Shift in cation exchange complex from Calcium to
more dispersive Mg or K.
6Raindrop impact can destroy aggregates and
contributes to surface sealing. However, there
is also a chemical effect of the rainwater that
disperses soil and enhances aggregate destruction
and surface sealing.
7Rain is derived from a natural distilling process
and is low in electrolytes
8- Approaches are needed to control
- Physical destruction of soil aggregates by
raindrop impact - Chemical dispersion of soil particles because of
low electrolyte concentrations in the rainfall
and ponded surface water. - Slaking and destruction of soil aggregate
particles due to rapid wetting and explosion of
air out of micro-pore spaces in peds.
9- Physical Destruction of Soil Aggregates can be
reduced by - Use of mulches to protect the soil from raindrop
impact. - Reduced-tillage or no-tillage systems that can
leave the soil in an aggregated and/or more
porous state with crop residues to minimize
raindrop impact directly on soil - Use of soil surface amendments (organic
polymers) to strengthen the soil aggregates.
10Use of Residues in No-till to Reduce Physical
Destruction by Raindrop Impact
11- Chemical Dispersion of Soil Particles can be
reduced by - Use of soil amendments that can rapidly produce
large amounts of electrolytes (multivalent
cations Ca) in the surface water solution,
which enhances flocculation and minimizes
dispersion. - Balancing of the Calcium/Magnesium ratio in
soils, towards higher Calcium. - Use of soil surface amendments (organic
polymers) to strengthen the soil aggregates.
12(No Transcript)
13One way to prevent dispersion of the soil surface
is to add a source of electrolytes such as
gypsum. This is a cheap source of pure gypsum
from the IPL power plant in Petersburg, Indiana.
14This is the source of gypsum shown in the
previous slide - from the scrubbing of high
sulfur coal as required by the Clean Air Act.
15DeWitt, Iowa Site Fayette silty clay loam Control
0.40
80
0.35
Rainfall
0.30
60
0.25
Runoff
mm/h
Soil Loss
0.20
40
Soil loss g/m2/s
0.15
0.10
20
0.05
Infiltration
0.00
0
5
10
15
20
25
30
35
40
45
50
55
60
Duration min
16DeWitt, Iowa Site Fayette silty clay loam PAM
By-Product Gypsum Treatment
0.40
80
0.35
Rainfall
0.30
60
0.25
mm/h
0.20
40
Soil loss g/m2/s
Runoff
0.15
0.10
20
Infiltration
0.05
Soil Loss
0
0.00
5
10
15
20
25
30
35
40
45
50
55
60
Duration min
17This is a corn plant growing in a soil with high
Mg content and poor soil structure in South
Dakota.
18Control
With Gypsum
This shows the difference in production within
100 feet, between the existing high Mg soil
control (left) and the same soil treated with
Gypsum (right).
19Differences in Soil Structure as affected by
Gypsum Amendment
With Gypsum
Untreated Control
20With Gypsum Amendment
Control
These corn ears are from a similar on-farm
treatment in Colorado. The 3 ears on the left
were from an area treated with Gypsum.
21Aerial View of Gypsum-treated field
Fields near Van Wert, Ohio
Untreated fields
No-till field Treated with 1 t/A Gypsum every
other year
22This is a photo from a farm near Van Wert, Ohio
on a Hoytville soil. There is a lot of crusting
visible in this untreated Control.
23This picture was taken just 10 ft away where
Gypsum has been applied, and there is no crusting
visible.
24- Slaking and Destruction of Aggregates by Rapid
Wetting can be reduced by - Use of mulches or residues that absorb part of
the rainwater and slow the wetting process. - Use of soil surface amendments (organic
polymers) that strengthen the soil aggregates and
also strengthen the entire soil surface.
25Agricultural Field Study - Silt Loam Soil - 18
lb/A PAM was very effective
PAM Control Control
Up to inflows of 16 Gallons/minute
26Steep (32) slope study
Untreated Control 71 pounds/acre PAM
PAM 2.2 t/A Gypsum
27Natural Rainfall Study 45 slope landfill
embankment silt loam soil
PAM 2.2 t/A Gypsum Untreated Control
71 lbs/A PAM
28Stillwater, OK large flume study
Inflows of Water up to 200 gallons per minute
Control PAM
Untreated Control 71 lbs/A PAM
29- Anionic Polyacrylamide (PAM) use
- Has been shown to be very effective at
controlling soil erosion on a range of soils and
slopes. - Current cost of the material (3.00/lb) would
make it impractical for general agricultural use
for erosion control. - For certain types of applications, PAM may be a
practical soil amendment, such as - embankments
- construction sites
- critically-eroding regions
- newly-seeded grass waterways or other channels
30- Summary
- Soil amendments that act at the soil surface can
have dramatic effects on water infiltration,
runoff and soil loss. - These amendment effects can also subsequently
improve crop stands and yields. - On many Midwest US soils that are subject to
sealing and crusting, use of Gypsum or a
Gypsiferous amendment may be of benefit. - Anionic Polyacrylamide may also be of benefit,
especially in controlling erosion on critical
areas during establishment of permanent
vegetation.