Impact of Cover Crops on Soil Properties and Nutrients in a Coastal Plain Soil.

The effects of cover crops on soil quality and erosion have been widely investigated.  However, research on the consequences of cover crop species and management on structure and nutrient distribution in a Coastal Plain soil is limited.  This study investigated the influence of different cover crops on the macroporosity, bulk density, saturated hydraulic conductivity (Ksat), and total C and N of a sandy loam soil.  Crop treatments were established in two neighboring trials.  The short-term trial had been cropped without cover crops and was newly established in 2013 with the following treatments: fallow, crimson clover (Trifolium incarnatum L.), oat (Avena L.), and an oat/rye (Secale L.) mixture.   The long-term trial had been maintained in a peanut-cotton rotation with cover crop treatments oat, rye, wheat (Triticum L.) and fallow for more than 20 years.  Soil cores were extracted prior to cover crop termination and scanned using X-ray computed tomography to determine bulk density and macroporosity.  Cores were then divided into five interval depths and analyzed for core bulk density and total C and N using automatic dry combustion.   A compact constant-head permeameter was used to evaluate the Ksat at 20 cm in each plot.   Bulk density and macroporosity were not affected by cover crop species at any depth in either trial.  Cover crop treatment had a significant impact on Ksat in the long-term trial only, with the highest Ksat in soil under oat and rye.  Total soil N and C in the long-term trial at the 0- to 5-cm depth was greater in soil under oat, rye, and wheat than under fallow.  These results indicate that long-term cover cropping can affect water movement and N and C content in Coastal Plain soils.