Soil quality response to cover crops and amendments in a vineyard in Nova Scotia, Canada

The effects of cover crop mixtures combined with organic and industrial wastes on selected soil properties were assessed in a vineyard in Eastern Canada. The experimental treatments were randomly arranged in a nested design with three replicates. Four alleyway cover crop mixtures [control with no cover crop (CONT), oats+pea+hairy vetch (OPV), oats underseeded with red clover (ORCl), and timothy+alsike+red clover (TM)] were applied to main plots. Five fertility treatments [fertilizer without N (NDEF), full synthetic fertilizer (FERT), wood ash (WA), municipal solid food waste (MSFW), and mussel sediment (MS)] were assigned to sub-plots. Changes in selected soil quality (0-15cm) were assessed at the beginning of the growing season (May 9, 2011 and April 28, 2012), at bloom in early-July (July 06, 2011 and 2012), and at harvest in late-October (October 31, 2011 and October 20, 2012). At bloom, soil mineral N was 23.56kgha^-1 for OPV and 20.68kgha^-1 for ORCl, but only 16.38 kg ha^-1 for CONT and 12.53 kg ha^-1 for TM. At harvest, soil mineral N was 21.95kgha^-1 for ORCl, but only 15.43 kg ha^-1 for OPV and TM and 9.10kgha^-1 for CONT. Soil mineral N was mainly in the form of NO<inf>3</inf>^--N until bloom, but at harvest majority of soil mineral N was consisted of NH<inf>4</inf>⁺-N. After one year of experiment, the three organic and industrial amendments maintained greater soil pH (7.34 for MSFW and 7.35 for WA) and Mehlich-3 extractable P (399kgP<inf>M3</inf>ha^-1 for MSFW and 333 kg P<inf>M3</inf>ha^-1 for WA) compared with FERT (pH 7.17; 306 kg P<inf>M3</inf>ha^-1) and NDEF (pH 7.12; 288kgP<inf>M3</inf>ha^-1) treatments. After two years of experiment, the combination of cover crop×amendment improved soil organic-C by 8.8% and 10.6% and -N by 8.1% and 9.8% compared with amendment alone and cover crop×FERT treatment, respectively. Potentially mineralizable N estimated by UV-absorbance of NaHCO<inf>3</inf> extraction was greater under ORCl (0.79 abs) compared with the other cover crops (0.69 abs). The microbial biomass C was 205kgha^-1 under MSFW and 212kgha^-1 under WA, but only 168 kg ha^-1 under NDEF, 125 kg ha^-1 under FERT. The combination of cover crops and organic or industrial wastes provide comparable soil mineral N supply and available P with fertilized treatments while improving soil physical and biological properties and overall soil quality in this vineyard production system.