Miscanthus shelter boosts farm productivity.

Miscanthus – a giant sterile perennial woody grass – was originally brought into New Zealand to be grown as a renewable energy crop, primarily for boiler fuel.  While this is still a very valid and appropriate use, innovative Kiwis have been taking this almost magical grass and using it for a variety of purposes, some of which have not been even a consideration in international Miscanthus activity.

Lincoln University has led the way in the research of new uses and already has had one PhD completed on the cultivation and benefits of Miscanthus.  Professor Steve Wratten of Lincoln University’s Bio-Protection Research Centre has been the prime mover in this research. Prof Wratten’s research has included the use of Miscanthus to provide shelter on centre pivot irrigated dairy farms.  One of the problems with these farms is that in order to have the irrigator moving freely, there can be no trees anywhere in its path.  This means that pasture is not protected from warm drying winds and stock is not protected from cold winds.

The work done by Wratten and his students has shown that Miscanthus can be successfully used to replace the missing shelter.  The irrigators move through it freely without causing damage to the Miscanthus and without damaging the irrigator in any way.  It appears that this may be a world first use of Miscanthus.

A good summary of this can be seen on a Rural Delivery programme – 2018 Episode 6 – aired on 28 April 2018 https://www.tvnz.co.nz/shows/rural-delivery/episodes/s2018-e6.  In that programme Prof Wratten lists out many of the benefits that can arise from growing Miscanthus, one of which is the increase in productivity of the pasture as a result of the shelter provided by the Miscanthus.  It turns out that the resulting extra pasture growth – which is 18% up to 100m down wind of the shelter – more than makes up for the area taken up by the seven row wide Miscanthus shelter belt.

Managing director of Miscanthus New Zealand Limited (MNZ), Peter Brown, remarked “We have had a lot of interest from many farmers but often they have trouble getting their heads around the idea that although the Miscanthus shelter strips will occupy some of their ‘valuable pasture land’, the farm’s overall productivity will rise.  The Lincoln research makes it clear how this can happen.”

But such farmers are generally used to having narrow strips fenced off for tree shelter.  They often do not seem to appreciate that in most cases the negative impact on pasture growth near the trees – of shading – extends considerably further out than the fenced strip.  This shading does not happen with Miscanthus shelter.

In addition, the Miscanthus provides a whole range of other benefits. One of these is that the farmers can harvest the Miscanthus in winter before it regrows and can then use it for high quality long lasting calf bedding on their own farm.  They can also sell the harvested Miscanthus as bedding to other calf-rearing farmers, to dairy goat farmers, dairy sheep farmers, cow composting barns, or stables. In the case of horses, Miscanthus has for a long time been regarded in the UK as the best horse bedding possible.  But the New Zealand racing industry is extremely conservative and is proving to be very slow to pick up on this.

Prof Wratten has also carried out research on the use of the harvested Miscanthus product for commercial mulch, this research being done on a feijoa orchard in Northland.  It showed that Miscanthus was the best commercial mulch available, that the soil moisture levels under the Miscanthus mulch were generally higher and the number of earthworms was almost twice as many as in the control.  In addition, the orchardist has recently reported to MNZ how delighted he was with the Miscanthus mulch because it lasted for at least two seasons without needing to be replaced.

Miscanthus also makes an excellent feedstock not only for boilers with suitable specifications, but also for use in making renewable diesel.  The technology for this already exists in the USA and has been commercialised there, with the United States EPA certifying this renewable diesel as being able to be sold as a direct substitute for regular diesel.  The scale of the industrial plant required for making this product is nowhere near as large as has been considered by others to be the minimum for other technologies.  As such there is great potential for such renewable diesel plants to be established regionally in NZ to take advantage of locally grown feedstocks and to provide locally produced and used diesel.

So dairy farmers with pivot irrigation can boost their farm’s productivity with confidence by growing Miscanthus, while at the same time producing a useful and saleable product.

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