Saturday, January 7, 2023

POTD: Row Orientation of Vineyards

From 2022 07 08 Braubach and Rhine

Today's photo-of-the-day is from a vineyard in Germany along the Rhine River. According to Pennsylvania Agricultural History Project, "Contour plowing follows the contours of hills and slopes, rather than orienting crop rows up and down a slope. It is a technique that was popularized during the New Deal and afterwards in response to soil erosion. Contour plowing furrows run crosswise to the slope, slowing runoff and allowing the soil to absorb rainfall rather than wash away."

That's what I learned as a child and always thought was gospel. Then, last summer I noticed the vineyards in Germany along the Rhine River seemed to follow no rhyme or reason. Some went along the hillside, some went straight up and down. I think I found an explanation for this from the USDA's Cooperative Extension Foundation dealing specifically with vineyards.

Row orientation is less critical than row spacing. On level sites, orient rows to maximize length and minimize the number (and cost) of end posts. Most sites are not level, though. Do not contour rows around hills, as the trellises will be structurally weak. Low areas should be used as alleyways rather than for planting.

Sunlight interception by the vine canopies should be maximized. Research studies have shown that rows oriented in a north-south direction receive more sunlight, have better air movement among vines, and produce slightly higher yields than those oriented east to west. Thus, if other factors are equal, align rows as closely as possible to a north-south axis; however, row orientation should be paired with site constraints like topography and erosion potential. In some regions, strong south and southwest winds dictate row orientation more than light interception. In many vineyard locations, it is most important to orient rows across a slope to minimize soil erosion.

In short, light, wind, row length, and soil erosion all need to be considered in deciding optimal row orientation. So now you know.

You might wonder why I'm showing you photos of agricultural fields instead of medieval castles, which this stretch of the Rhine River is famous for. The answer is because I always sit up and take notice when my long-held beliefs are shaken. Besides, it's my blog. I write about what I want, not what I think readers might want.

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