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Title: ASSESSING SOIL QUALITY IN A RIPARIAN BUFFER STRIP SYSTEM BY TESTING ORGANIC MATTER FRACTIONS

Author
item MARQUEZ, C - IOWA STATE UNIVERSITY
item Cambardella, Cynthia
item ISENHART, T - IOWA STATE UNIVERSITY
item SCHULTZ, R - IOWA STATE UNIVERSITY

Submitted to: Agroforestry Systems
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/15/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Landscape buffers are needed to keep potential non-point source pollutants out of surface water systems. Nationwide, the goal is to establish two million miles of conservation buffers by the year 2002, yet the long-term benefits to soil and water quality are largely unknown. This study examined the changes in soil quality that occurred after establishment of a multispecies riparian buffer strip on previously cultivated soil in central Iowa. In particular, we wanted to know if we could detect increases in biologically active soil organic matter within 7 years after establishment of the buffer strip. After six growing seasons, we found that particulate organic matter (POM) carbon had increased by 23% under the section of the strip with poplar trees and more than 30% under the switchgrass portion of the strip. Our results show that relatively rapid and significant improvements in soil quality occur in soils of the multispecies riparian buffer strip. This means that farmers and conservationists may expect an improvement in soil quality in these kinds of buffers.

Technical Abstract: Particulate organic matter (POM) has been shown to be very responsive to changes in agricultural management and thus is considered a good indicator of soil quality. This study evaluates POM in soils within different vegetation zones of a multispecies riparian buffer strip seven years after establishment on previously cultivated or grazed soil. Improvements in soil quality are considered to be an indication of the potential of the buffer strip to serve as an environmental buffer. Soil organic matter fractions were assessed within the tree and native grass zones of the buffer strip, within a corn and a soybean field, and within an abandoned cool season grass pasture. POM was isolated by dispersing soil in 5 g L**-1 metaphosphate and passing the dispersed soil samples through a 53 um sieve. Light POM fraction material was extracted densiometrically in sodium polytungstate solution (specific gravity 1.85 g cm**-3). Total organic C, light POM C, and total POM C were all significantly greater in the perennial vegetation plots than in cultivated systems. This effect was most pronounced for total POM C. After six growing seasons, total organic C increased 23% under poplar and more than 30% under switchgrass. The results suggest that relatively rapid and significant improvements in soil quality can be attained through the use of multispecies riparian buffer strips.