Thursday, 25 August 2016
Mechanisation is everywhere. It has stolen the romance of the vineyards where once merry bands of pickers chatted and sang, drinking water spouting from a botijo, while they laboured under the blistering sun. Now, since the 1960s, the roar and clatter of diesel engines has taken over as the machines have evolved into an efficient and economical means of collecting the harvest. They are very expensive though; similar in price to a mid-range Ferrari, so most are hired since they are only needed for two or three weeks a year.
It is not only the machines which have evolved, however; the vineyards themselves have had to be altered to suit them. They can’t be too steep or the top-heavy machines could topple, and excessive mud can immobilise them. Vine rows need to be planted at a suitable distance apart to allow room for the machine to pass, say 2.5 metres, and while the machines are adjustable, the vines themselves need to be allowed to grow to a suitable height so the bunches hang 60-100 cm from the ground. This requires training the vines on an espalier system rather than the traditional vara y pulgar of Jerez.
Harvesting machines straddle the rows of vines and use a series of floating, oscillating, soft-faced finger-like rods which shake the grapes from their stems into a tray which catches them, and a cup-conveyor takes them up to a collection hopper, where a powerful fan blows away any leaves. There is also a magnet which picks out any metallic objects such as bits of wire or clips from the espalier. When the hopper is full the grapes are discharged into a waiting trailer and taken to the bodega.
The machines move slowly, at about 3.5 km/hour. This is the optimum speed as moving faster or slower can cause damage to the vines, but it is much faster than hand picking with secateurs or knives. Machines can pick about 200 tons per day, where an experienced picker can pick perhaps 2 tons, and the machine is equally efficient at night, when humans have difficulty seeing. With hand picking, whole bunches are picked, and when they get to the bodega they need to go through a “despalilladora” or de-stemmer to remove the stems, which would otherwise make the wine more tannic.
Advantages of machine harvesting:
The latest machines are pretty sophisticated, and their sheer speed outweighs their disadvantages. Once the grapes are ripe enough for harvesting, machines can pick them much more quickly and thus avoid over-ripe grapes, giving a more homogeneous crop. If for example heavy rain is forecast, a machine can bring in the grapes quickly before they become diluted. The machine’s driver usually comes with the machine and is much less likely than the hand-pickers to go on strike, which has happened before. Then there is cost; machines work out much cheaper than hand pickers, especially in very big vineyards.
These machines are very heavy and have a tendency to compact the soil. They can’t differentiate between rotten grapes and healthy ones, they just pick everything. There is a risk of yeast build-up on machinery setting off premature fermentation, so careful and regular cleaning is necessary. The mechanical nature of the machine can potentially cause damage to the vines and the espalier system.
So there is no doubt that machines are here to stay, so long as the vineyards are suitable, as they are in the Marco de Jerez, and where nearly all the grapes are already picked by machine. It will be a long time, however, before vineyards in, say, the Douro, Mosel or Málaga’s Axarquía will be picked mechanically, and I for one am pleased about that.