Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/15/2003
Publication Date: 1/1/2004
Citation: Wallace-Cochrane, B.H., Reichert, J.M., Eltz, F.L., Norton, L.D. 2004. Controlling soil erosion and runoff with polyacrylamide and phosphogypsum on subtropical soil. Transactions of the American Society of Agricultural Engineers. Vo. 48(1):149-154. Interpretive Summary: Soil erosion by water is a global problem causing environmental damage and threatens potential to grow food. This is a particularly severe problem in the humid semitropical areas of the world. We conducted a field study with a rainfall simulator to study two types of soil amendments on controlling soil erosion. The treatments included no-treatment and a surface application of phosphogypsum (PG) and an anionic polyacrylamide (PAM) and both together to compare to no treatment at recommended rates. Rainfall was applied and water and soil loss measured. We found PG performed better than PAM or PG+PAM at controlling erosion and all were greatly less than the untreated soil. All reduced erosion more than 90% and reduced water loss by more than 35%. The impact of this research is that the use of these amendments can be as a easily applied soil conservation tool for areas where tillage is necessary.
Technical Abstract: Sandy soil, prone to intense soil erosion, is used for agriculture in the subtropics of Brazil. This study was conducted to determine whether soil amendments are effective for conserving topsoil by preventing water-induced erosion on a Brazilian sandy Alfisol soil (coarse-loamy, mixed, thermic Typic Paleudalf). A programmable rainfall simulator was used at the experimental station of the Federal University of Santa Maria, in a newly harvested black oat (Avena estrigosa L.) field that was moldboard plowed and disked twice. Plots were on bare tilled soil with 8-12% slopes. The soil treatments consisted on a single 5 Mg ha-1 surface applied cation of by-product phosphogypsum (PG), a single 20 kg ha-1 surface applied anionic polyacrylamides (PAM), a combined amendment (PAM+PG) with the same rates as above, and an unamended soil (control). Simulated rainfall average intensity was 25mm h-1 with a 2 h duration. Sediment and runoff samples were collected at intervals during the experiment, and soil surface samples inside the plot were taken after the rain for surface crusting analysis. Total soil loss was significantly lower for the treatments than the control and averaged 197, 278, 217, 218l kg ha-1, respectively for PG, PAM, PAM+PG and control treatments. PAM and PAM+PG had steady-state runoff rates significantly less than the control. All of the amendments reduced soil sediment erosion (average 90% reduction) more than final runoff (average 35% reduction). Using amendments to reduce precipitation induced erosion is a possible alternative conservation practice in this region.