A TOTAL switch to sweet potato growing and newer fertiliser technologies has resulted in operational and input efficiencies as well as improved produce quality for North Coast NSW farming brothers Matthew and Henry Prichard.
After previously growing tomatoes and zucchinis in rotation on their light red volcanic soils near Cudgen, the Prichards moved to a 100 per cent sweet potato program to help simplify their cropping operation, reduce labour requirements and improve returns.
Drawing on their expertise from growing tomatoes and zucchinis, the Beauregard sweet potatoes are grown on drip irrigation following planting from late September through to mid-February.
Harvest occurs from late January through to early November, with another crop planted in May and harvested in January.
Half of their farm is also sown to Jumbo sorghum and sometimes triticale as part of the annual rotation with the sweet potatoes to help suppress parasitic nematodes.
The sorghum land is worked to assist residue breakdown prior to planting of the pathogen-tested sweet potatoes, while any volunteer sorghum is sprayed.
An application of Nemacur is applied at bed forming for further nematode control.
Soil testing is undertaken to assess for nematodes and crop nutritional requirements. Lime and boron are usually applied prior to planting.
The Prichards are also now applying a custom, controlled release fertiliser blend, Ferticote from Barmac, at planting.
The Ferticote blend contains trace elements and has eliminated the need to apply micronutrients separately.
The use of Ferticote has allowed for more even distribution of the micronutrients across paddocks and resulted in better potato quality.
“We know that boron, zinc and manganese are lacking in the soils, but they are difficult to spin out by themselves at 15kg per hectare. “ Matthew said.
He said Ferticote, which uses Haifa’s Multicote controlled release technology, suited the higher rainfall conditions and helped save most of the fertigation requirements later.
“Being controlled release, it eliminates another application of possibly potassium nitrate or potassium sulphate,” he said.
“We just can’t do all the dressings. If controlled release can eliminate all the jobs, like being out at the pumps all the time, it will be much better.
“In considering the cost of a controlled release fertiliser blend, growers just need to weigh up the cost of their base fertiliser plus the trace elements, the applications and all the separate jobs.
“As a value comparison, you just look at the cost of spreading the trace elements separately against a single application of Ferticote.
“With the Ferticote, the fertiliser is in the hill and every row has got exactly the same amount of nutrient.”
Matthew said this had also contributed to improved potato quality.
“Our quality is definitely up. We are getting more potatoes in the premium zone, which is 180-250-millimetre long at 60-75mm diameter,” he said.
“Last year we looked at a compound fertiliser alongside Ferticote and we visually saw more premium potatoes with the Ferticote.”
The Prichard’s custom blend releases nitrogen over two months and potassium nitrate over four months.
“Research has shown that low levels of nitrogen at planting is desirable, which is why we also went away from using standard base fertilisers,” Matthew said.
“Theory suggests there should be less nitrogen at the start to allow better quality at the end.”
He said the accuracy of release of the controlled release fertiliser also meant they could possibly reduce nutrient rates.
The Prichards produce up to 100 tonnes per hectare of the Beauregard sweet potatoes and average about 70t/ha (about 16 cartons per acre).
They are supplied to Woolworths through Hydro Produce in Sydney.