The most important annual activity in the vineyard is dormant pruning – the removal of old wood during the vine dormant season. It’s believed to be the most important and expensive vineyard management practice since the quality and quantity of the later harvested grapes depends on it. Dormant pruning should be performed during the vine dormant period from leaf fall to bud break, while the best time to do the job is late winter to early spring, in order to avoid winter injuries. We are going to cover benefits and techniques of dominant pruning in some other post, while this time we are focusing on vineyard prunings disposal management.
After dormant pruning, vineyards are full of old cut shoots and woods and other pruning residues. Therefore, we looked deeper into the management of vine prunings disposal.
What can winegrowers do with the vine prunings?
According to general practices, most vine growers choose one of the following disposal techniques:
- removing all of the vine prunings from the vineyard and burning them – this is the most widespread method and it’s especially practical in case of infected vines (due to pest and disease issues). In some countries (personally, I have first seen that in France), vine prunings are burned in the vineyard already during the pruning activity. While in some other wine growing countries winegrowers after dormant pruning collect all the prunings on a pile (outside the vineyard) and then open fire the prunings. Either way, open burning pollutes the air with carbon dioxide, soot (carbon particles), Particulate Matter (PM), and other gaseous emissions, which increase the carbon footprint of the wine industry, according to the research from University of Idaho.
- mechanical chopping or mulching in the vineyard – If prunings are not infected with pests and disease, they can represent a good source of nutrients. In order for the winegrowers to return the (vines) nutrients back to the soil, prunings can be crushed or chopped into smaller pieces in the vineyard row middles, and used as a source of nutrients for the cover crops, soil, and grapevines.
- removal of prunings from the vineyard, and chopping or chipping cut material for compost, and then later on, returning that compost into the vineyard – Composting of grape pruning is a great alternative to burning. Not only that composed prunings can, later on, be used as fertilizer in the vineyard, but adding woody wastes from the grape industry to the livestock manures even improves the quality of the livestock manure itself. According to a study from the University of Idaho, adding vines prunings to dairy manures, increases the C:N ratio of dairy manures. Prunings are rich in carbon, they help reduce ammonia emissions, retention of nitrogen in the compost, and the dilution of application limiting components such as P, K, and salts. All that can allow higher application rates of compost.
- removal of the prunings from the vineyard and use for combustion purposes – Another option for sustainable and economical use of vine prunings is to first dry them and then bind the prunings into bundles and use it for combustion purposes. According to Krečič research, the net calorific value of vine prunings is higher if we state it per kilogram than of the tree wood species that are normally used for heating, such as beech wood, European hornbeam, and oak. However, vine prunings have a lower density point and therefore lower calorific value per cubic meter. Thus vine prunings have shown to be a great alternative or complementary source for heating the households in cold days. Who doesn’t like that warm, bright fire in their fireplace, hey?
Dormant pruning of the vines is an important vineyard annual activity which we use to prepare the vines for a new growing season. After pruning, vineyards are usually full of vine prunings. Most of the winegrowers simply choose for open burning the old vine wood wastes although this is not a very sustainable, nor environmentally friendly solution. Namely, prunings are full of nutrients (received during the previous growing season from the soil) and thus represent an excellent fertilizer for the vineyard. Of course, this is useful if they are not infected with vine diseases. Vine prunings can also be used for heating purposes, if the winery has burning stove that can be used for heating.
Winegrowers, what do you do with vine prunings after dormant pruning? Write in the comment below.
M. E. de Haro-Marti, A. Agenbroad, and T. McCammon. 2014. Composting of dairy manure and grape vine prunings using three different composting techniques. University of Idaho
Napa Valley grapegrowers best practices – Vineyard prunings disposal; prepared by Napa Valley Grapegrowers Industry Issues Committee
Principles and Practices of Pruning Grapevines, presentation by B. Bordelon, Purdue University
A. Krečič. 2009. Sušenje odpadnega materiala vinske trte za uporabo v kurilne namene. Ljubljana, Univerza v Ljubljani, Biotehniška fakulteta.