No till moisture model walks the walk

Every millimetre of stored soil moisture after flowering is worth about one per cent in yield, according to Department of Agriculture and Food WA (DAFWA) researcher Bill Bowden.

At the WANTFA Post Seeding Field Walk last week, Mr Bowden spoke to growers about how the Practice for Profit yield determination model simulated how much yield would come from certain inputs.

“The model runs on rainfall and uses stored soil moisture as a soil type discriminate, ” he said.

“Stored soil moisture is what gets your crop from one rain to the next, at this time of year you are probably losing about one millimetre a day.

“The major time when you want to use up your soil moisture is at the end of the season.

“For every millimetre of stored soil moisture after flowering and beyond is worth about one per cent in yield. If you can operate to get more stored moisture to the crop, you are looking at increasing yield by that amount.”

Mr Bowden said there were two methods that could increase the amount of soil moisture available to a crop.

“Remove a subsoil constraint such as a resistance pan which stops roots penetrating deeper, by deep ripping it up once every 10 to 15 years, ” he said. “And remove the acidity pan by applying lime.

“The man-made traffic pan occurs at about 10 to 20cm below the surface and the acidity pan is deeper.”