TERRECO WP 2-09
Effect of PAM, biopolymers and biochar on runoff, erosion, soil properties, and plant growthFrom 03/2009
Project manager: Yong Sik Ok
Coworkers: Sang Soo Lee
Grant: IRTG 1565 WP II TERRECO - Complex Terrain and Ecological Heterogeneity - Evaluating ecosystem services in production versus water yield and water quality in mountainous landscapes
Anionic polyacrylamide (PAM) can reduce soil erosion. Slope is an important factor determining erosion rate; however, PAM guidelines have not been well developed for different slopes. The objective of this study was to evaluate the extent which 20-kg ha-1 (18-lb ac-1) PAM (20P) and 40-kg ha-1 (36-lb ac-1) PAM (40P) increase the time to initial runoff (TRO), decrease cumulative runoff (RO), and decrease cumulative sediment loss (SL) on a Mexico silt loam soil adjusted to slopes of 10%, 20%, and 40%. Soils were packed to a bulk density of 1.3 Mg m-3 (81 lb ft-3) in test beds 0.3 m x 0.3 m x 0.15 m (12 in x 12 in x 6 in) and were subjected to a 61-mm h-1 (2.4-in hr-1) simulated rainfall with a kinetic energy (KE) of 1.5 kJ m-2 h-1 (103 ft lb ft-2 hr-1) for 1 h. Differences in TRO and SL for all slopes and PAM rates were all highly significant, as were all two-way interactions (p < 0.01). Applications of 20P and 40P increased TRO at slopes of 20% and 40% compared to the untreated control (0P); however, no difference in TRO was found for soils having 20P and 40P. Values of TRO with 20P and 40P were not increased at a 10% slope compared to 0P. Slope was not a factor in reducing RO. Applications of 40P for all tested slopes had greater RO than 20P. Polyacrylamide reduced SL for all tested slopes. A higher rate of PAM (40P) had less SL than a lower rate of PAM (20P) at slopes of 20% and 40%. With 40P, the reduction in SL was 72% greater than 0P at 40% slope. Therefore, slope is a critical factor in determining a proper PAM rate for reducing soil erosion. Future work on PAM applications for differing rainfall intensities and plot length would be beneficial in developing improved guidelines for PAM use.Doctoral stipend financed by KOSEF (Korea).