Polyacrylamide Effects on Aggregate Stability, Infiltration, Erosion, Off-Site Agrichemical Transport and Yield in Agricultural Settings: Implications for Mid-South Agriculture.

The Mississippi Alluvial River Valley Aquifer (MARVA) has experienced a significant decline in the last 40 years.  Declining aquifer levels are primarily due to an intensification of annual water withdrawals for row-crop production.  A means to improve furrow irrigation application efficiency is required for the mid-south region where 80% of acres are furrow irrigated.

Polyacrylamides (PAMs) are water soluble, long chain synthetic organic polymers that, when applied as a soil amendment, may promote aggregate stability, improve irrigation application efficiency, reduce erosion and decrease off-site nutrient transport.  There is a paucity of data, however, on the effect of PAM applied through polytubing on infiltration, erosion, nutrient transport and crop yield for Mid-South soils.

The objective of this study was to assess PAM effects on furrow irrigation application efficiency, erosion, off-site nutrient transport and corn (Zea mays) yield on a Dundee silt loam soil and a Forestdale silty clay loam soil located in Stoneville and Tribbett, Mississippi, respectively.  For each location, the experimental design was a randomized complete block with four replications of each treatment, anionic PAM applied at 10 mg L^-1 and No PAM (water only).

Independent of soil texture, anionic PAM as an emulsified concentrate (EC) had no effect on infiltration (P ≥ 0.0746) or sediment transport (P = ≥ 0.0601).  Similarly, regardless of soil texture, PAM had no effect on TKN losses (P = ≥ 0.266) or yield (P = ≥0.228).  However, on the Dundee silt loam soil, total P was lower in PAM than Non PAM treatments (P = ≤ 0.05).

Results from year one of a two year study indicate EC PAM applied at 10 mg L^-1 in furrow via polytubing systems does not increase irrigation application efficiency, reduce erosion, affect N transport or corn yield; however, anionic PAM may reduce P transport in furrow irrigated systems.