Our stream bank at my parent’s house has been suffering over the last decade. As a child I had a lot of fun down there with friends over summer. From the bridge we would grab a handful of branches from one of the willow trees nearby and swinging like tarzan and jane. When we get far enough we let go, and plunged down into the cool water. Back then, our stream was rather narrow, but very deep. However, our stream has become so wide, that our bridge has collapsed and disappeared twice now. In fact it has increased in width two or three times at least. Another problem is that the stream is now very shallow, so it is impractical for swimming. If you stand in the stream today you will be lucky if the water reaches your knees – more likely than not it will stop at your ankles. As you can see from the above photo, the willow trees have since died, and the bridge has been replaced with a couple of flat logs.
The bank on either side is slowly but gradually falling into the water. The erosion has been concerning me, but I have no idea what to do about it. A large amount of pumice has been floating down the stream and settling at the bottom of the stream. I had thought we could get rid of the pumice but simpy getting a shovel and digging it out. However I have been told that it would not be a permanent solution as no sooner as it was gone, then more pumice would come along to replace it.
You can just imagine my delight then when Sharon McCarthy told me about the business she is involved in called Vetiver Grass Nurseries Limited. Vetiver (Chrysopogo zizanioides) is a grass with very long roots (growing down to two to four meters in deep). The roots of the grass have many uses, including essential oil, perfume, traditional medicine, weaving mats from the roots, and blocking runoff of surface water. However, the use that was particularly holding my interest was the benefits to controlling erosion in warmer climates. The use of Vetiver grass in water management and soil conservation is often referred to as the Vetiver System. More details on Vetiver can be found on the website for the Vetiver Network International (TVNI).
If you live in New Zealand and would like to purchase a plant or more from the Vetiver Grass Nuseries you can take advantage of nationwide delivery. Individual plants range in price from $6 NZD plus GST or $5 NZD plus GST if you place orders over 100.
There are many places in New Zealand with warm climates, such as Keri keri, and the north of New Zealand, the Cormandel, Gisborne, Tauranga and so on. Unfortunately, I think that Rotorua is not warm enough to be classified as a warm climate. The average temperature of Rotorua is 23 degrees celcius in summer, and 12 degrees celcius in winter. If anyone knows of any grass roots that would be suitable for colder climates, then I would be most grateful to hear from you, so please feel free to leave me a comment.