The Impact of Cover Crop Management on Rooting Profiles, Mycorrhizal Colonization and Mycorrhizal Community Structure of Young Grapevines

The purpose of this project is to better understand how cover crops and management of their residue affect the development of vine root systems and arbuscular mycorrhizal fungi (AMF) in a young vineyard. This project is an extension of ongoing work, where we are monitoring the impact of winter annual cover crop use and management of the above-ground mowed residue (simulating ?a mow & blow? approach) on vine growth and development, vine mineral nutrition, water stress, weed suppression, soil moisture conservation and other soil quality attributes. Work on the root and AMF aspect of the project has just begun, since the graduate student who will be working on this project was not available until the spring term of 2011 and because funds did not arrive at OSU until January of 2011. However, soil samples were collected from the research plots as planned (from the vine row and alleyway at three depths within each location), and preliminary root data has been collected and partially analyzed. We examined more plots than originally proposed by including the 3X mulch residue treatment in our analysis. Fine roots were collected from the plots and samples were safely stored for future analysis. These will be used to assess AMF colonization of roots and to amplify AMF in order to identify the specific fungi forming mycorrhizas. Analysis of the root fresh mass data collected to date indicates that the use of cover crop residue as an in-row mulch has already altered the spatial distribution of roots in this vineyard. The density of total root mass (woody + fine roots) in both the 1X and 3X mulched plots was greater in-row (under the mulch) than in the alleyway, but this was not true in the mowed-in-place or in unplanted control plots. In addition, total root mass was greater in the 3X mulched treatment rows than in either the mowed-in-place or control treatment rows, and the 1X mulched plots being intermediate between these divergent groups. The higher density of in-row roots of the mulched plots was associated with greater soil moisture and reduced soil compaction in the mulched plots compared to the control and mowed-in-place treatments. Vine shoot lengths and leaf SPAD values were also greater in both the 1X and 3X mulched plots. These early results indicate that the use of cover crop residue as an in-row mulch will have a dramatic impact on the growth potential and rooting patterns of young vines and may lead to a more sustainable approach to establish vines on dry-land sites.