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United States Department of Agriculture

Agricultural Research Service

Title: The Influence of High Application Rates of Polyacrlyamide on Microbial Diversity in An Agricultural Soil

Authors
item Sojka, Robert
item Entry, James
item Furhmann, Jeffry - UNIVERSITY OF DELAWARE

Submitted to: Applied Soil Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 1, 2005
Publication Date: June 1, 2006
Citation: Sojka, R.E., Entry, J.A., Furhmann, J.J. 2006. The influence of high application rates of polyacrlyamide on microbial diversity in an agricultural soil. Applied Soil Ecology. 32:243-252.

Interpretive Summary: Agricultural runoff is a major source of nutrients, pesticides and enteric microorganisms to surface and ground waters. Water soluble anionic polyacrylamide (PAM) is a highly effective erosion-preventing and infiltration-enhancing polymer, when applied at rates of 1 to 10 grams per square meter in furrow irrigation water. PAM greatly reduces sediment, nutrients, pesticides and coliform bacteria in irrigation runoff. In June, July and August, we measured active soil bacterial and fungal biomass and microbial diversity in soils receiving 0 (control), 2691 and 5382 kilograms of active ingredient PAM per hectare. Active bacterial biomass in soil was 25-40 % greater in the control treatment than in soil treated with 2691 or 5382 kilograms of active ingredient PAM per square hectare in June and August, but not July. Active fungal biomass in soils was 50-200% greater in the control treatment than soil treated with 2691 or 5382 kg active ingredient PAM per square hectare in June and July, but not August. Comparisons of the three sampling times by both whole soil fatty acid and BIOLOG analyses indicated that microbial communities did not differ with regard to PAM treatment but all treatments were different in June compared to July and August. Although PAM application to soil or irrigation water in some cases may reduce active bacterial and fungal biomass it does not seem to appreciably affect the soil microbial diversity.

Technical Abstract: Agricultural runoff is a major source of nutrients, pesticides and enteric microorganisms to surface and ground waters. Water soluble anionic polyacrylamide (PAM) is a highly effective erosion-preventing and infiltration-enhancing polymer, when applied at rates of 1 to 10 grams per square meter in furrow irrigation water. PAM greatly reduces sediment, nutrients, pesticides and coliform bacteria in irrigation runoff. In June, July and August, we measured active soil bacterial and fungal biomass and microbial diversity in soils receiving 0 (control), 2691 and 5382 kilograms of active ingredient PAM per hectare. Active bacterial biomass in soil was 25-40 % greater in the control treatment than in soil treated with 2691 or 5382 kilograms of active ingredient PAM per square hectare in June and August, but not July. Active fungal biomass in soils was 50-200% greater in the control treatment than soil treated with 2691 or 5382 kg active ingredient PAM per square hectare in June and July, but not August. Active microbial biomass in soil was 27-48%greater in the control treatment than soil treated with 2691 or 5382 kilograms of active ingredient PAM per square hectare except in June. Whole soil fatty acid profiles showed no discernible change in the soil microbial community due to either of the PAM treatments at any sampling time. Analysis of nutritional characteristics using BIOLOG GN plates, however, yielded an apparent separation of the non-amended control soils from those plots receiving the high PAM application rate in June, but not in July or August. In contrast, comparisons of the three sampling times by both the fatty acid and BIOLOG analyses indicated that the microbial communities present in June were different from those sampled in July and August. Although PAM application to soil or irrigation water in some cases may reduce active bacterial and fungal biomass it does not seem to appreciably affect the soil microbial diversity.

Last Modified: 7/27/2014
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