Can grapes be grown in Taiwan, China using the dry farming water-saving method?
In California, USA, a Mediterranean-climate region, severe drought in recent years has led some farmers to abandon artificial irrigation systems and switch to completely dry farming, growing grapes without giving them water, and they unexpectedly found that grape quality and yield were better. Last year Taiwan suffered its worst drought in ten years, causing about 44,000 hectares of farmland to have irrigation suspended at the time, and this summer's heatwave was astonishing, even soaring to a high of 38.7 degrees. As extreme weather occurs frequently, could Taiwan also possibly launch a dry-farming model in response?
Close-up of the fruit cluster of Taichung No. 4 wine grape, with smaller berries than ordinary grapes (photo provided by Taichung District Agricultural Research and Extension Station)
Moderate dry farming and pinching can increase fruit quality
Zheng Zhengyong explained that, aside from variety selection, grape quality can actually be promoted through moderate dry farming and pinching. In dry-farming practice, during the grape's small-fruit stage, the soil can be turned together with the weeds to a depth of 10 to 20 cm below the surface. Although the grape root system is cut off for a time, the weeds are also suppressed at the same time; and the cut sections of the grape root system will grow many fine roots within a short time, making it easier to absorb water and nutrients from the loosened soil.
As for pinching, it means removing excess leaves. Zheng Zhengyong said that scientific experiments have confirmed that too many leaves do not help improve grape quality. It is now known that the grape's "leaf-to-fruit ratio" is 5 square cm of healthy leaf surface for every gram of grapes; converted, every kilogram of high-quality grapes requires about 20 leaves, so excess leaves must be removed, which is called "pinching." However, pinching also requires attention: it means removing the tips of the leaves and leaving one leaf on each node.
Dry farming cultivation must be adapted to local conditions
But is Taiwan suitable for dry farming with no watering at all? Zheng Zhengyong believes it must depend on field management needs and cannot be generalized; crops such as rice cannot be adapted to it.
The Taichung District Agricultural Research and Extension Station, which provides guidance for grapes in Taiwan, believes that Taiwan currently does not have conditions suitable for dry farming, and there has also been no dedicated research on dry farming in the past. Ye Wenbin, host of the fruit tree research laboratory, said that even under extreme drought climate, it will rain again after 1 or 2 months, so it is instead impossible to maintain a completely dry, rainless cultivation method.
However, grapes have deep root systems, and the groundwater level in the central region is high, with water sources within 1 meter, so surface drought does not easily affect the grapes' water absorption; if an extreme drought situation is unfortunately encountered, water use can then be reduced further by reducing leaves, covering with plastic sheeting, and replacing water-saving equipment.
But there are still farmers in Taiwan who cultivate crops in a way that relies completely on no artificial irrigation water. Farmer Lin Yilong, who operates Shumei Natural Agriculture in Taitung, has a 7-fen-sized carambola orchard; apart from 8,000 Taiwan catties in the first year 8 years ago, yields have ranged from 880 to more than 2,000 Taiwan catties, and the drought at the end of 2014 reduced it further to 300 Taiwan catties, but last year's harvest returned to 7,500 Taiwan catties, and the quality was highly accepted by the market, "all sold out completely."
Overall, he believes that a cultivation method relying completely on rainwater must still be adapted to local conditions. For example, his farm has a gentle slope and drains easily, but other farms may easily accumulate water, so it cannot be generalized and must still depend on individual farmland conditions.