سایت منابع جزوات ارشد دکتری

Impact of polyacrylamide delivery method with lime or gypsum for soil and nutrient stabilization
1. B.J. Lepore,
2. A.M. Thompson and
3. A. Petersen
Applying lime or gypsum as soil conditioners in concert with polyacrylamide (PAM) can reduce soil erosion more than applying the conditioner or the PAM alone, but little is known about the relative impact of different combined application methods. Laboratory rainfall simulations were conducted for 1 hour with runoff collected in 20-minute intervals to compare runoff sediment, sediment-bound P and NH4-N, and dissolved Ca and S loads. Treatments were bare soil, lime, gypsum, PAM-coated lime or gypsum prills, and lime or gypsum prills applied with separate PAM-coated paper mulch granules. All treatments, except gypsum, reduced sediment and sediment-bound P loads compared to bare soil (p < 0.01), and all PAM-conditioner treatments were more effective than the respective conditioner alone. Load reductions compared to bare soil were greatest for PAM-coated lime and PAM-coated gypsum, with sediment reductions of 83% and 69%, respectively (p < 0.01). Sediment P loads followed trends in sediment loads, while sediment NH4-N load reductions were, in general, slightly smaller and statistically less significant. Sediment load reductions were 16% greater for PAM-coated lime than lime applied with separate PAM granules and were 11% greater for the PAM-coated gypsum than gypsum applied with separate PAM granules. However, these differences were not statistically significant (p > 0.05). Runoff dissolved Ca loads (for lime and gypsum) and S loads (for gypsum) were significantly reduced by the PAM-coated conditioner treatments compared to the conditioner applied with separate PAM granules. Dissolution tests indicated that the PAM coating reduces the dissolution rate of the lime and gypsum, suggesting a possible mechanism accounting for differences between the two PAM treatments. This work suggests that the use of PAM in conjunction with lime or gypsum can be an effective erosion control tool, reducing sediment and nutrient losses and that coating lime or gypsum with PAM may have added benefit.
Footnotes
·Brian J. Lepore is a post doctoral research associate, Anita M. Thompson is an assistant professor, and Adam L. Petersen is a former research intern in the University of Wiscsonsin-Madison Biological Systems Engineeering Department, Madison, Wisconsin.
· © 2009 by the Soil and Water Conservation Society