Fertigation

I noticed just how much mud had splattered onto the interior of the ute yesterday on driving to work today. No one else at work has twigs, pebbles, off-cuts of tubing and rubble on their tray. No one has a tray. It comes from taking the ute into the orchard maintaining the irrigation system. Its not the sprinklers that have been knocked flat by sheep, its the nozzles that are blocked or chewed that pose the risk of spraying channel water through a partially open window. You cut off the dud nozzle to replace with a fresh one, the tubing slips from your grasp and the thin jet of water escapes onto your driver’s seat.

Irrigation maintenance precedes fertigation. The aim is to direct nutrients to the trees’ roots, not weeds, drains, the corridor between trees or elsewhere. I found an open tap at the end of the poly line in one row. Water had gushed out pooling nearby in the lowest point of the orchard, at maximal risk from inundation.

Our fertigation system is idiosyncratic and getting on. Some of the outflow from the orchard pump is diverted to fill a 1,000 L tank. Another pipe sucks solution from the bottom of the tank to the pump’s intake. Nitrogen and potassium, in powder forms are added to the tank. On thousand litres of water dissolves 150 kg of calcium nitrate in about 25 minutes. It takes up to 90 minutes for that solution to be suctioned through the pump. As solution enters the intake system a flotation device allows more water to flow into the tank to replace that lost. I do the whole orchard with calcium nitrate first. I clean the tank. Then I fertigate with potassium nitrate. Allowing the two chemicals to mix would form a precipitated porridge, that is expensive and difficult to resolve.

Normally, the pump sends water to each station automatically. However, a sheep has chewed one of the wires on a valve in station one. I phoned Chris, our local irrigation expert, who asked ‘How’s it going?’

‘I’m winning this season.’

‘So you’re an optimist’

 

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