Title

Comparing the effects of farming management strategies on soil nematode communities

Author

Sammi Unangst

Date of Award

2016

Document Type

Thesis

Degree Name

Bachelor of Science

Department

Biology

First Advisor

Dr. Amy Treonis

Abstract

Farming techniques such as organic practices and tillage are used to provide pest control and enhance crop production but the effects of these treatments on soil diversity and functioning are not yet fully understood. Studying soil nematode communities could provide insight because nematodes are very sensitive to the environment that they are in and respond to changes in the ecosystem. I investigated the effects of organic treatment, conventional tillage and no-tillage on soil nematode communities in fields from an ongoing agricultural management experiment at the USDA research center in Beltsville, Maryland. The fields I studied were in a soybean/wheat/corn crop rotation and at the time of sampling the fields contained wheat. I hypothesized that soils under the organic and tillage treatments would have the highest soil quality as indicated by positive impacts on nematode community structure. A DNA-based barcoding approach was combined with a morphological identification method in order to determine nematode community structure and examine the diversity present in the soils. The soils with the most organic matter content were found under no-tillage at the 0-5 cm depth, which is consistent with the goal of no-till practices to enhance soil carbon storage and fertility. In terms of nematode community structure, the no-till samples had significantly increased numbers of plant-root feeding nematodes, which is a negative effect that may offset any improvement in crop production that could have resulted from enhanced soil fertility. The soils under organic treatment had the highest nematode density overall, with significantly reduced numbers of plant-parasites. Organic practices appear to promote a healthy soil food web structure, which should support and sustain crop production. The results of this study provide evidence for the ability of organic farming practices to promote sustainability, biodiversity, and overall soil health.

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