HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Mamedov, A. I. Articles by Levy, G. J. Search for Related Content PubMed Articles by Mamedov, A. I. Articles by Levy, G. J. Agricola Articles by Mamedov, A. I. Articles by Levy, G. J. Related Collections Fate Soil Salinity Soil Systems Soil Erosion

SOIL & WATER MANAGEMENT & CONSERVATION

Aggregate Stability as Affected by Polyacrylamide Molecular Weight, Soil Texture, and Water Quality

^a USDA-ARS, National Soil Erosion Research Lab., 275 S. Russell St., Purdue Univ., West Lafayette, IN 47907-2077
^b current address: Wind Erosion Research Unit, USDA-ARS-NPA, Manhattan, KS, 66502
^c Univ. of Regensburg, Dep. of Landscape Ecology and Soil Science, Regensburg, Germany
^d Institute of Soil, Water and Environmental Sciences, ARO, The Volcani Center, P.O. Box 6, Bet Dagan 50250, Israel

^* Corresponding author (amirakh.mamedov{at}ars.usda.gov).

The favorable effects of the environmentally friendly, nontoxic, anionic polyacrylamide (PAM) as a soil conditioner have long been established. Some uncertainties exist, however, regarding the effects of PAM molecular weight (MW) on its performance as a soil amendment and its ability to penetrate into aggregates and stabilize interior surfaces. We studied the effects of two anionic polymers, a high-MW (12 x 10⁶ Da) and a medium-MW (2 x 10⁵ Da) PAM, using deionized water (electrical conductivity of 0.004 dS m^–1) or a 15 mmol L^–1 gypsum solution, on the stability of aggregates from four smectitic soils varying in clay content. Penetration of PAM into the aggregates was estimated from treating 0.5- to 1.0- and 1.0- to 2.0-mm aggregates with PAM and thereafter comparing the stability of the small aggregates to that of the large aggregates after the latter had been crushed and sieved to 0.5- to 1.0-mm size. The stability ratio (SR) ranged from 0.090 to 0.900 and tended to (i) increase with the increase in soil clay content, (ii) maintain, in the absence of PAM, a greater level with electrolyte solution than deionized water, and (iii) be greater for the PAM-treated aggregates than the control. In the finer textured soils, the SR of the initially small aggregates was generally greater than that of the initially large aggregates, indicating that most of the PAM was adsorbed on the exterior surfaces and only a small fraction of the PAM added, if any, entered into pores. A significant interaction among the treatments tested (PAM MW, aggregate size, and solution ionic strength), with respect to their effect on the SR, was identified. Consequently, neither of the two PAM polymers tested could have been singled out as preferable.

Abbreviations: DW, deionized water • GS, gypsum solution • MC, moisture content • MW, molecular weight • PAM, polyacrylamide • SR, stability ratio • VDP, volume of drainable pores