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66 P R A C T I C A L W I N E R Y & V I N E YA R D September 2015 G R A P E G R O W I N G organic matter have small, closely packed aggregates, and many have very small pores. When wetted, any poorly struc- tured large aggregates break down, or slake, into micro-aggregates. When dry, the micro-aggregates block pores that are too small for water to move through, causing the soil to become poorly aerated when wet and very hard when dry. Earthworms and other fauna move through the soil in search of food (organic residues), hence their populations are increased when organic residues are added to soil. The fauna produce stable tunnels that enable water and roots to move through soil. How to increase organic matter As you prepare the soil in summer and fall before you plant vines, till (rip and/ or cultivate) the soil, then grow ryegrass, but kill it in winter. Once the grapevines are planted, till the soil as little as possible, as repeated tillage oxidizes (burns) organic mat- ter and decreases activity of beneficial organisms, worsening the soil structure and the supply of water, air and nutrients. It is not wise to incorporate cover crops in the soil, as discussed above, as this will decrease the supply of nitrogen for the grapevines. However, you may need to till the soil occasionally to remove rodents and ruts in the tractor row. It is best to apply herbicides to remove weeds. Each year, manage the soil carefully with a cover crop or organic mulch to: • Add organic residues, • Protect the surface of the soil from heavy rain, • Increase activity of beneficial biota in soil. In winter, allow weeds to grow. Throw the green residues of the weeds onto the vine row when you slash. In spring and summer, apply herbicides to kill weeds in the vine row, so that the weeds do not compete with the vines for water and nutrients. The green and dead weeds on the soil surface protect the soil surface from heavy rain, and the dead roots add organic matter and maintain a soft, sta- ble and porous surface soil. PWV Dr. Judith Tisdall is a soil scientist and a former senior lecturer in soil science at La Trobe University, Melbourne, Australia. Bas Van den Ende is a tree fruit consultant in Australia's Goulburn Valley. This text was edited from first publication in the Good Fruit Grower, March 15, 2015, with the publisher's permission. The Wine Business With New Rules 24th Annual Wine Industry Financial Symposium September 21 & 22, 2015 Napa Valley Marrio Connect. Collaborate. Network. Learn. Wine Execu ve Survey Results Congressman Mike Thompson Ian Harris, Chief Execu ve The Wine & Spirits Educa on Trust Wine Vision UK Ted Baseler, President & CEO Ste. Michelle Wine Estates Damien Wilson, PhD, Wine Business Chair Sonoma State University Produced by the Wine Industry Symposium Group Register Online At WineSymposium.com • 707.666.2525 Visit us at www.miovigneto.com Email dwightb@miovigneto.com Call Dwight Busalacchi at (415) 531-6450 Custom Tanks, Fermentors, and Winery Equipment Slovenian Oak barrels, Fermentors, Round and Oval Casks to 2,600 gallons Open and Closed Top Tanks, Oval Tanks and Fermentors from 26 to 5,000 gallons "Excellent quality at reasonable prices with exceptional customer service built around an understanding of vintners' needs." ~ Jim Schultz, Windy Oaks Winery Mio Vigneto Products, Inc. Outstanding Tanks for Outstanding Wines Presses to 100 hl Semi Auto Fillers Semi Auto Corkers Semi Auto Cappers