Seep damage reduced by better water use

Insights gained from spaded seep plot at Lameroo


Cropping
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A small seep management trial near Lameroo has given an insight into what may help address the ever-growing problem in the Mallee.

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A small seep management trial set-up on the Pocock property near Lameroo has given an insight into what may help address the ever-growing problem in the Mallee.

Robert Pocock hosted a Mallee Sustainable Farming spring field day in early September, where seeding systems, edge-row seed placement and novel nutrition of the Sandy Soils project were observed and discussed.

The site was also home to a 50-metre long, 5m wide seep.

“(MSF project manager) Michael Moodie had his plot-sized spader there, which had a small airseeder on it, so we decided to spade and sow the seep with barley and budgie feed (a mix of sorghum, sunflower, safflower, maize and barley),” Mr Pocock said.

“We used a mix as we wanted to see what grew best.”

Research by Juliet Creek Consulting principal consultant James Hall showed the main cause of Mallee seep formation was excess water draining through sandy dune soils, which is then held up when it reaches the low-permeability layer known as Blanchetown clay.

This ‘seepage’ of perched water along restrictive layers can cause perennial waterlogging or ‘seeps’ at ‘discharge’ sites, resulting in lost production on some of the best Mallee soils, he said.

Mr Pocock said seeps were an increasing issue in the region because of better summer weed management.

“More water is available in the sand hills,” he said.

“We are lucky to not have it as a major problem because we grow perennial pastures and they use a lot of water.

“But those that just crop have a lot of issues because annual crops only use that water from April to October. The aim will be to better use that water before it evaporates and brings salts to the surface.”

Mr Pocock said their seep plot was only trafficable to sow because it had been a dry winter and spring.

“Most of the time we can’t establish a crop in it because it is too wet, stagnant or salty,” he said.

The crop had emerged well by mid-September and the plan was to graze the crop to continue utilising the moisture available.

“Hopefully now we have taken moisture out of the seep, we will be able to sow through it next year and introduce it back into the winter system,” Mr Pocock said.

“Questions remain however, as to whether our airseeder or combine will get through it, or whether the spader is better for sowing as it breaks the saline layer up and dilutes the saltiness of the surface back through the profile, making for easier crop establishment.

“There isn’t any science in my observations, but it’s an option. It makes me think I should target some of our other soaks in the same manner.”

YIELDS SURPRISING IN DROUGHT YEAR

THE 2018-19 cropping season will be classed as a “successful drought” by the Pocock family.

Robert Pocock, who farms with wife Courtney and parents Bruce and Gaylia near Lameroo, said they had 147 millimetres growing season rainfall and about 200mm for the year.

“It’s 3mm less than the 2002 drought, but yields are about five times better,” he said. “We really owe a lot to modern farming systems.”

The Pococks sow about 2200 hectares of cereals, legumes, pastures and hay, which includes contract seeding.

The 25mm of rain in late December inspired the family to grow a 60ha summer crop of sorghum and millet.

“If we can get one graze out of it, it’d be good or we may cut it for silage,” Robert said.

He said last year was good for sheep producers.

“We were lucky we made the decision to cut our cropping back 30 per cent this year to make room for more sheep,” he said. “We went from 1600 breeding ewes to 2050.”

Their cereals also yielded about 1t/ha, which Robert was thankful for.

“Where prices are at, it has worked out pretty well.”

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