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ARS Home » Midwest Area » Columbia, Missouri » Cropping Systems and Water Quality Research » Research » Publications at this Location » Publication #133235
Title: DEVELOPING WEED SUPPRESSIVE SOILS THROUGH IMPROVED SOIL QUALITY MANAGEMENT

Author
item Kremer, Robert
item LI, JINMEI - UNIV OF MO

Submitted to: Soil & Tillage Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/8/2003
Publication Date: 8/1/2003
Citation: KREMER, R.J., LI, J. DEVELOPING WEED SUPPRESSIVE SOILS THROUGH IMPROVED SOIL QUALITY MANAGEMENT. SOIL AND TILLAGE RESEARCH. 2003. V. 72. P. 193-202.

Interpretive Summary: The soil performs a variety of key functions, many of which are directly related to activities of the resident microbial population. One of the benefits of soil microorganisms is naturally-occurring biological control of pests including weeds. We investigated several biological properties in soils subjected to different agricultural practices to see if these properties might indicate promotion of natural biological control of weeds due to certain management tactics. Soil enzyme activity, an indicator of soil microbial function, was highest in management systems using organic methods or those involving a diversity of crops. These same soil management systems also had the greatest proportion of soil and root bacteria that suppressed growth selected weed seedlings. Soil structure (as stable soil aggregation) and soil organic matter levels were related to high enzyme levels and weed growth suppressive activity. In general, we found that measurements of selected biological activity indicators of soil quality were good predictors of potential weed growth suppression in soil. Potential weed suppression was best in soils managed for high organic matter content under diverse crops and reduced tillage. The results are important to scientists, producers, and extension personnel because relatively simple soil quality assays can be used to identify soil management practices that have potential to promote natural weed suppression and that can be developed further to establish weed suppressive soils and to limit herbicide use.

Technical Abstract: Sustainable agriculture is based in part on efficient management of soil microorganisms for improving soil quality. However, identification of biological indicators of soil quality for predicting weed suppression in soils has received little attention. We investigated differences in soil microbial activity among various crop and soil management systems to assess microbiological characteristics and determine possible relationships to development of weed suppression. Soil enzyme activity, water-stable aggregates, and weed-suppressive bacteria were compared among seven cropping systems and one native prairie ecosystem in mid-Missouri. Assays of soil enzymes revealed that organic and integrated cropping systems and native prairie ecosystems had the highest levels of soil activity. Soils and weed rhizospheres from these ecosystems also had greater proportions of soil bacterial isolates characterized as growth-suppressive to green foxtail and field bindweed, greater than 15 and 10%, respectively. The proportion of water-stable soil aggregates was greatest in soils with the highest organic matter and was similarly related to higher enzyme and weed-suppressive activity. We found that the levels of selected biological indicators of soil quality were related to potential weed suppressive activity in soil when that soil was managed for high organic matter content under reduced tillage systems. This research study provides further evidence that soil quality and sustainable agricultural practices may be linked to integrated weed management systems for the potential biological suppression of weeds.