The incorporation of cover crops in orchards and vineyards can increase soil organic carbon (OC) and improve nitrogen (N) availability. This study compared how three herbaceous under-vine cover crop assemblages affected OC and N pools in four edaphically distinct vineyard agroecosystems. Using physical fractionation and soil spectral analysis we: 1) compared effects of grass and legume mono- and poly-cultures on total, coarse (≥50 µm) and fine (<50 µm) pools of OC and total N (TN), as well as extractable N (ExN), and 2) assessed predictions of OC and TN pools by infrared spectroscopy (IRS) and partial least squares regression analyses (PLSR). Compared with the control treatment, total, coarse and fine fraction OC were greater in the presence of grasses and legumes; ExN was increased 38% by legumes, and 78% in legume-grass mixture. With initial calibration, we used one soil spectral analysis to successfully derive models predicting contents of OC in the whole soil, and the allocation of OC to coarse and fine fractions. In addition to demonstrating the efficacy of incorporating grass and legume cover crops into vineyard cropping systems to improve OC and the storage and availability of N across diverse soil types, this study confirms the ability of IRS/PLSR to predict changes in OC concentrations related to differential ground cover management. IRS/PLSR is an important and practical approach for the rapid quantification of short-term management impacts on SOM pools, contributing significantly towards improved understanding of soil C and N dynamics in vineyard agroecosystems.
The authors wish to acknowledge the traditional owners of the lands
on which these studies were conducted: The Ngarrindjeri and others, the Ngadjuri Nation, and The First Peoples of the Murray River and Mallee Region. We wish to acknowledge technical support provided by Janine McGowan and Dr Thomas Carter @ CSIRO Waite campus whose assistance was invaluable in obtaining accurate IRS measurements and results from C and N analyses. We wish to acknowledge the University of Adelaide and Wine Australia for the development of the under-vine cover cropping trial on which this study was conducted, in addition to the growers at CMV Farms, Eden Hall Wines, SARDI Research Station and Oxford Landing in South Australia for their care in providing and maintaining the commercial field sites. We also wish to acknowledge internal reviewer J. Li and two anonymous reviewers who assisted in refining the manuscript for publication. The authors also wish to thank Johanna Pihlblad at Western Sydney University for producing the study site map for the publication. Funding for this project was provided by a joint University of Western Sydney and University of Aberdeen postgraduate award to KB.
- Soil health
- Particulate organic matter
- Mineral-associated organic matter
- GREENHOUSE-GAS EMISSIONS
- PLANT FUNCTIONAL COMPOSITION
- MICROBIAL CARBON
- DIFFUSE-REFLECTANCE SPECTROSCOPY
- ECOSYSTEM SERVICES
- MICROBIOLOGICAL FUNCTION
- AUSTRALIAN SOILS
- CROPPING SYSTEMS
- PARTIAL LEAST-SQUARES