This Is AuburnElectronic Theses and Dissertations

The Impact of Cover Crops on Soil Microbial Population and Soil Physical and Chemical Properties




Ozdemir, Yunus Emre

Type of Degree

Master's Thesis


Crop Soils and Environmental Sciences

Restriction Status


Restriction Type


Date Available



Conventional farming on Ultisols that are dominant in Southeast US has resulted in the loss of soil organic matter over time. Conservation tillage farming practices that incorporate different cover crops are shown to increase soil organic matter. Soil organic matter is the lifeblood and basis of soil health. Soil microorganisms play a critical role in the breakdown and mineralization of cover crops that are incorporated into soil. Different types of soil microbes are involved in mineralizing different cover crops. Relationships between soil microbes’ diversity and activities in soil are dependent on soluble organic sources. Although the impact of cover crops on soil physical, biological, and chemical properties in general are well established, there are still many gaps in our knowledge on the effects of specific cover crops on soil microbial diversity and populations and, soil physical-chemical properties under specific environmental conditions. Hence, the objectives of our studies were to evaluate three cover crop species, cereal rye (Secale cereale), crimson clover (Trifolium incarnatum), and forage radish (Raphanus sativus L.) and their mixtures in a soybean (Glycine max L.)–corn (Zea mays.) rotation under strip tillage on selected soil properties; investigate the impact of the cover crops on nematode population and phonology, microbial activities, and soil properties at different soil depths. The field experiment was a randomized complete block design with four replications. Treatments were fallow (no cover crop), clover, rye/clover, rye/radish, clover/radish, and rye/clover/radish (3-way mixtures) mixtures. Cover crops had significant impacts on soil respiration, active carbon, labile amino nitrogen, C:N ratio, compaction, bulk density, predator, and bacterial feeding nematodes by soil depths. Cover crops did not significantly affect total organic carbon and nitrogen, organic matter, plant parasitic nematode, fungal feeding nematode, and omnivore in all depths by year. Nematode populations for all feeding groups were considerably high at 0-10 cm depth compared to lower soil depths. This study will contribute to our understanding of the impact of cover crops on Ultisols of Alabama.