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Number of Sheep Increased to Boost Weeding Efficiency at Solar Plant (page 4)

Herbicide used proactively in areas with no sheep

2019/06/17 17:01
Shinichi Kato, Nikkei BP Intelligence Group, CleanTech Labo
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Herbicide utilized for weeding in areas without sheep

Including for the additional sheep, Nikke has reportedly needed to undertake more work at a higher cost than it initially estimated. The company radically changed the measures against weeds in the areas where no sheep graze. Initially, Nikke was planning to cut the grass as it grew taller than a certain height. However, this method cost more every time the company weeded.

The areas with and without sheep are clearly different (Fig. 6). The area where the sheep graze is green, whereas the area without sheep is covered by crushed stones.

Fig. 6: Areas where sheep graze (right in top photo) and herbicide is used (left in top photo). No herbicide used around observatory (right in bottom photo) (source: Nikkei BP)

Laid under the crushed stones were weed barrier sheets. Even so, the effect was limited, and more weeds than expected grew. Given the circumstances, the company switched the weeding method and has effectively used herbicide for the past three years. Spraying herbicide three times a year, Nikke has succeeded in reducing manual weeding by limiting weed growth to a certain extent.

First, the company sprays herbicide in March before grass starts growing. This reportedly has a distinctive effect and limits growth when the grass starts growing. Then, the company sprays herbicide in July and between September and October. Since it began to use herbicide, it no longer needs to weed the site until July. After cutting grass around July, the company considers whether it implements weeding again according to the circumstances.

According to Nikke, over the last three years, it has gradually established an environment where weeds do not easily grow.