Using Soil Amendments to Improve Infiltration, Reduce Runoff and Soil Erosion

1
Using 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

2
Problem with Intensive Agriculture Water/Air
Entry into the Soil
3
This 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. 
4
Reduced 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.

6
Raindrop 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.
7
Rain 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.

10
Use 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)
13
One 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.
14
This is the source of gypsum shown in the
previous slide - from the scrubbing of high
sulfur coal as required by the Clean Air Act.
15
DeWitt, 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
16
DeWitt, 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
17
This is a corn plant growing in a soil with high
Mg content and poor soil structure in South
Dakota.
18
Control
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).
19
Differences in Soil Structure as affected by
Gypsum Amendment
With Gypsum
Untreated Control
20
With 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.
21
Aerial View of Gypsum-treated field
Fields near Van Wert, Ohio
Untreated fields
No-till field Treated with 1 t/A Gypsum every
other year
22
This 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.
23
This 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.

25
Agricultural Field Study - Silt Loam Soil - 18
lb/A PAM was very effective
PAM Control Control
Up to inflows of 16 Gallons/minute
26
Steep (32) slope study
Untreated Control 71 pounds/acre PAM
PAM 2.2 t/A Gypsum
27
Natural Rainfall Study 45 slope landfill
embankment silt loam soil
PAM 2.2 t/A Gypsum Untreated Control
71 lbs/A PAM
28
Stillwater, 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.