SUSTAINABLE WATER

In My Spring Garden 7 post I explained what I had learned from reading Back from the Brink by Peter Andrews about how water sinks in soil to the clay or rock level below the surface of the ground. There the salt in the water, being heavier than fresh water, makes the bottom layer of underground water saltier than the water above it. I learned that even fresh rainwater contains salt at 60 parts per million, but after this salt becomes concentrated below the surface the ground water will be at least 5 times saltier by the time it reaches our dams and rivers. I also showed Peter’s preferred farming plan of dividing land into three complementary segments of hilltop forest, agricultural land and flood plain.

In My Spring Garden 8 post I illustrated with flood and drought photographs how we have endeavoured to control and manage flood flows across our land in front of Das Helwig Haus B&B to avoid soil erosion.

This post will be about how to retain more water in streams and dams to how to reduce evaporation.  Peter writes: Even in a pristine landscape, water running into a lake would probably have contained 150 to 200 parts per million of salt. Then, once it was sitting in the lake, the water would start to evaporate. Throughout much of Australia, water evaporates at the rate of around 2.5metres a year – more than the depth of most of our naturally formed lakes.

The book cover

The views of Peter Andrews are controversial because they are opposite to many Australian farming practices of the past two centuries. They are also contrary to the views of Landcare organizations and the purists who do not like to see the introduction of Northern Hemisphere deciduous trees into the Australian landscape.

According to Peter, I am doing the correct thing by planting willow trees and other deciduous trees along my water channels. These bind the soil with their roots, keep the ground or water shaded and cool during the heat of summer and then drop their leaves to create a fertile mulch in autumn. During the usually dry winter months they are dormant, not drawing water from the ground. He maintains that they save more water than they use in transpiration.

Trees for shade

In contrast the eucalyptus trees give poor shade, drop no useful mulch and their roots dry out all surrounding ground preventing the growth of grass. After four dry months the photo below shows green grass beneath the new spring leaves of the Spanish oaks, while the ground under the eucalyptus trees is bare and arid.

Eucalyptus trees dry the ground

In my previous post I wrote that our water channel became eroded by flood water before we could get it grassed and created a headwall. To stop such erosion Peter suggests rocks or other impediments should be placed in the hole under the drop to break up the energy of the water. This would be reasonably easy to do, as our farm has no shortage of rocks.

Keeping the land grassed in this manner also prevents erosion in times of flood. Within my home garden I constructed what is normally a dry watercourse to take the overflow from our rainwater tanks in times of heavy rain. With bigger rocks at the side, I created a broad and shallow drain before planting Mondo grass between smaller stones spread over the base to prevent erosion.

Garden watercourse

This drain not only breaks up the turbulence of any running water, it slows the progress so the water soaks into the ground. The grass cover and small stones mulch the soil to keep it moist by preventing evaporation.

When we constructed this apartment block at the rear of our Das Helwig Haus B&B garden in 1998 I was aware that we possessed an area of underground, water-bearing sand immediately behind them.

I immediately planted this area with deciduous trees and conifers to give a partial windbreak during the winter months and to provide shade on our western side in the summer afternoons. The three upright willow trees were lopped back in August 2008 as they had become too tall. They now shade the Mondo grass in the drain during the hottest part of the day.

Upright willows

When I bought the conifers from a local nursery and commented that I was going to plant them over water, I was warned that they didn’t like wet feet. True, but my underground water was moving and these trees grow in the same manner as hydroponic plants.

Willow, conifer, swamp cypress and evergreen poplar

When I selected the three swamp cypress a bystander remarked that they were slow growing as they needed a lot of water. My three trees have flourished. I established the upright willows, the tortured willows and the evergreen poplars from cuttings. Now these trees are extracting salt and dropping a carpet of leaf mulch every autumn to add fertility to this shallow stream of underground water.

What more should I have done? I planted the deciduous Spanish oaks behind the larger dam. Farmers warned me they would put their roots through the dam wall and steal the water. It became obvious that the ones at the lower corner of this triangle shaped dam were thriving whereas the ones near the two ends were stunted. I wondered why?

Spanish Oaks

In reading Back from the Brink I learned about the pressure a deep volume of water exerts on surrounding soil. The water was moving to the trees, not the trees putting their roots into the dam. The big mistake I made was not to plant weeping willows around the inside of the dam wall. This would have been so easy to accomplish. All I would have needed to do was take cuttings from a mature weeping willow tree and push them into the wet ground just above the water line. They would have struck roots and thrived, shading the water and preventing evaporation.

Book Cover

Das Helwig Haus B&B owned by Eberhard and Fay Helwig is situated at Glen Aplin, near Stanthorpe on the Granite Belt of southern Queensland, Australia.

This is a region noted for Australian wildflowers, four wilderness National Parks and sixty wineries. In 1997 Eberhard and Fay established the Remembrance Field of red Flanders poppies, a European wildflower.

To obtain Fay’s book Wildflowers, wilderness and wine email Fay on helwig@halenet.com.au

Internationally it is available on the Amazon.com website.  http://www.amazon.com/gp/product/B002ACXQ0M/sr=8-1/qid=1244294755/ref=olp_product_details?ie=UTF8&me=&qid=1244294755&sr=8-1&seller=

http://stores.lulu.com/strictlyliterary

http://books.google.co.uk/

Technorati Tags: Australia, Das Helwig Haus B&B, poplars, Queensland, Spanish oaks, swamp cyprus, water, Wildflowers wilderness and wine, willows

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