Sustainable Wine Grape Production Using Soil Amendment and Cover Crops.

Increasing interest in developing sustainable horticultural systems has prompted the use of local waste products as soil amendments in conjunction with cover crops. A two-year study on grape yield and soil quality was conducted in Nova Scotia, Canada during the 2011 and 2012 growing seasons in an established vineyard. Soil fertility treatments included woodash (6 Mg ha^-1 dry weight basis), municipal solid food waste compost (MSFW; 13 Mg ha^-1 dry weight basis), mussel sediments (MS; 42,000 L ha^-1, 20% dry matter), nitrogen (N) fertilizer (NF), and N-deficient control (NDF). Nutrients in the amendment treatments were balanced with synthetic fertilizers based on soil test results. Inter-row cover crops included oats/pea/hairy vetch mixture (OPV), oats underseeded with red clover (O/RC), triple mix (TM; 15% RC, 15% alsike clover and 70% timothy grass) and bare soil (BS). To assess the residual effects of amendments, plots were divided into two subplots and soil fertility treatments only applied to one of the subplots in 2012. Soil samples were collected from 0-15 cm depth in spring, at flowering and post-harvest. Soil mineral and total N, total soil organic carbon (C), and soil quality parameters including UV absorbance of NaHCO₃ 0.01 M extract at 205 nm (mineralizable N), and particulate organic matter (POM) C and N were measured. Grape yield was positively (44% in average) affected only by TM and O/RC in 2011, and by application frequency (9%, p<0.06) in 2012. Soil nitrate reached its highest level in mid-season. The nitrate concentration was not affected by cover crops or soil fertility treatments in 2011, but was increased by MSFW and woodash or application frequency for O/RC in 2012. Cover crops improved POMC and POMN in 2011, but only affected POMN in 2012. Moreover, cover crops and MSFW treatment increased total soil N but did not affect total soil organic C in spring 2012. Grape yield was not affected by N fertilization. Amendments resulted in comparable yield to synthetic fertilizers while some of them also contributed to soil quality. Cover crops generally improved yield and soil quality.