Polyacrylamide Effects on Infiltration, Erosion, Nutrient Transport and Yield in Furrow Irrigated Systems in the Mississippi Delta.

The Mississippi Alluvial River Valley Aquifer has significantly declined in the last 40 years.  Declining aquifer levels are primarily due to an increase in the number of irrigated acres 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 PAM effects when 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 and a Forestdale silty clay loam soil located in Stoneville and Tribbett, Mississippi, respectively.  The experimental design was a randomized complete block with four replications of each treatment, anionic PAM applied at 10 mg L^-1 and water only.

EC PAM applications of 10 mg L^-1 in furrow via polytubing systems reduced surface runoff and increased infiltration by at least 7% (P ≤ 0.0040).  For total solids, the year x site x treatment interaction was significant (P ≤ 0.0023).  PAM had no effect total solids transport in 2014.  Conversely, in 2015, PAM reduced total solids transport on the Forestdale silty clay loam by 59% but had no effect on the Dundee silt loam.  PAM did not reduce cumulative N or P transport, or consistently reduce specific N and P species transport. 

The site specific nature of PAM with regards to infiltration, erosion, and off-site nutrient transport indicates the need to evaluate this amendment on an array of soil textures and production systems.