Time to embrace irrigation culture

Those of you who built larger effluent ponds will have managed to keep some life in your effluent block pasture at least. Dead pasture only gets back to full performance after a couple of years following its re-sowing, so not letting it die off in the first place is important.

 It may save the cost of re-sowing, and diminish the subsequent pasture related losses. If climate change factors are already having an impact on your farm, then think about capturing water. Not all of you will be able to build dams to do this. Some farms are too flat, in which case you build a bigger effluent pond and conserve whatever comes from the yards and shed roof. 

We can show that 1mm of extra rain on 100ha is worth about $1000, so think what would happen if you could apply 20mm twice over the whole farm in summer (40,000m³). In ‘good’ years it would add to production, in ‘bad’ years – like this one – it would keep your farm alive, at least.

This leads me to suggest that your effluent irrigation equipment should not be designed just to spread manure but to irrigate it. Design it to be able to deliver proper water irrigation, even if the amounts are small. 

The same equipment can then be used to water irrigate from the dam later on. Bear this in mind when you buy new effluent plant, especially if you also have a gully that might eventually become a useful dam.

We have recently asked the Waikato Regional Council whether they would frame policy on this because it may be the next pressure point for policy makers.

 This year we have had more enquiries about dam construction as a consequence of the drought and changing climatic conditions. You appear to be warming to the idea of some form of drought insurance schemes, and these are usually water-based. 

You might also start planning to put money aside for capital projects. Consider the farmer who had built a dam and had it filled by November 2012.  He will have invested quite heavily in the project, but his losses in this year’s drought will be far less than yours, partly because his farm will recover quickly, while yours will have taken a two-year knock and next year’s drought might double your problem. His early investment will have reduced his losses in bad years, but will have added to production even in good years. Why? Because that extra water even in good years will still assist in growing more grass.

There may be some cases where a number of you can get together to construct a pond you can all use – a mini-scheme, if you like. It’s happening in Canterbury and Otago quite regularly, but then they have an irrigation culture which the rest of you have yet to buy into.

So remember this – about half the rainwater that arrives on your farm runs straight off. The other half (the stuff that wets the 200 mm layer of soil on your farm) is the stuff responsible for your entire income. 

• Stuart Reid is a professional engineer at Revolution Technologies, marketing integrated water and effluent irrigation systems.