Irrigation

Supplying water to any garden area, regardless of what it grows is a time consuming and tedious job without a decent, well thought out irrigation system. Rainfall is the best form of irrigation but, as we do not always get enough rain or get it at the right time we have to resort to other methods of delivering water to the plants.

I have tried several methods of automatic watering of the vegetable beds with no great success. In the climate we have here we cannot afford to waste water so I now prefer to hand water all of the vegetables. To make this easier I have installed enough taps so that no part of the vegetable beds are more than five metres away from one.

This growing season (2006/2007) we are experiencing the worst drought in our area for nearly a thousand years so getting the water to where it is most needed is critical. I have also mulched areas of the vegetable garden that I will plant nearer the end of 2006 with straw to help conserve moisture and this has worked better than expected.

To deliver water to the fruit trees and vines we use drippers or under tree sprays. These are connected to a gravity system fed by a 22,250 litre tank on the highest point on the property. We use two drippers per fruit tree. One about 400mm either side of the trunk so that the area of irrigated ground around each trees has a better chance of feeding its root system. Each time the water is turned on the drippers are all checked to see if they are going as one never knows when a blockage may occur.

The trees in what we call the bottom orchard are watered with sprays and these are very successful but the variable drippers in the top orchard are a waste of time and will be replaced in time for the next growing season. The grape vines are watered by drippers that have had their regulator removed and they work great. It takes about fifteen minutes to get 20 litres of water to each vine.

Because of the drought and the fact that it is too easy to forget that a tap is running I have purchased two parking meter timers that I set every time I turn on a tap that runs drippers or sprays. The timers have eliminated a lot of over watering and in doing so our water supply should last us for this growing season.

The trees and vines are planted in swales (depressions) so that there is a better chance of the water staying in the vicinity of the root zone.

The biggest problem with any irrigation system is making sure that enough water is given to each plant without wastage. I have tried to source a moisture meter so that I can test to see if the trees and vines have enough water but the only ones suitable cost more than I am prepared to spend.

An easy way to check that the drippers are delivering enough water is to put a container under one of the drippers and measure how much it delivers in a given amount of time.