# Presentation: 893654

## 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

## Problem with Intensive Agriculture:  Water/Air Entry into the Soil

**Problem with Intensive Agriculture:  Water/Air Entry into the Soil**

## 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. 

**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. **

## Reduced Water/Air Entry into soils by surface sealing results in reduced infiltration, increased runoff, and increased soil erosion.

## 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.**

## 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.

**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.**

## Rain is derived from a natural distilling process and is low in electrolytes

**Rain is derived from a natural distilling process and is low in electrolytes**

## 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.**

## 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.**

## Use of Residues in No-till to Reduce Physical Destruction by Raindrop Impact

## 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.**

## Slide 12

## 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.

**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.**

## 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.

**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.**

## DeWitt, Iowa Site

**Fayette silty clay loam**
**Control**

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**Infiltration**

**Soil Loss**

## DeWitt, Iowa Site

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**DeWitt, Iowa Site**
**Fayette silty clay loam**
**PAM + By-Product Gypsum Treatment**

**Runoff**

**Infiltration**

**Rainfall**

**Soil Loss**

## This is a corn plant growing in a soil with high Mg content and poor soil structure in South Dakota.

**This is a corn plant growing in a soil with high Mg content and poor soil structure in South Dakota.**

## Control

**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).**

**Control**

**With Gypsum**

**Differences in Soil Structure as affected by Gypsum** **Amendment**

**With Gypsum**

**Untreated Control**

## 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.**

**With Gypsum Amendment**

**Control**

## Aerial View of Gypsum-treated field

**Aerial View of Gypsum-treated field**

**No-till field Treated with 1 t/A Gypsum every other year**

**Fields near Van Wert, Ohio**

**Untreated fields**

## 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.

**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.**

## This picture was taken just 10 ft away where Gypsum has been applied, and there is no crusting visible.

**This picture was taken just 10 ft away where Gypsum has been applied, and there is no crusting visible.**

## 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.**

## Agricultural Field Study - Silt Loam Soil -  18 lb/A PAM was very effective

**Up to inflows of 16 Gallons/minute**

**PAM****    ****Control****  ****Control**

## Steep (32%) slope study

**Untreated Control              71 pounds/acre PAM      PAM + 2.2 t/A Gypsum**

## Natural Rainfall Study – 45% slope landfill embankment – silt loam soil

**PAM + 2.2 t/A Gypsum         Untreated Control              71 lbs/A PAM**

## Stillwater, OK large flume study

**Untreated Control    71 lbs/A PAM**

**Control                 PAM**

**Inflows of Water up to 200 gallons per minute**

## 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**

## 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.**