Zeroing in on zero till-N-jector allows joint seeding and fertilising

Mr Bob Callow (left), Dalby-based manufacturer of the N-JECTOR tine, and Mr Brian Robotham of DPI Toowoomba, explain the invention at a field day. Bolt-on adapters allow the system to be fitted to most planting machinery. (Photo by Gillian Scott)

N-jector allows joint seeding and fertilising

Growers who have switched to conservation farming practices will be happy to learn of a new seeding machine that allows nitrogen fertiliser to be applied at the same time as seed is sown. At least one Queensland grower who has tried the new strategy is reporting substantial yield increases over earlier methods.

Growers had been finding a number of unexpected problems under no-till conditions, not least being the additional demand for nitrogen when stubble is retained.

Fertiliser nitrogen is often a necessity but existing equipment couldn't apply seed and high rates of fertiliser using the same tine without reducing seedling emergence.

On the other hand a tillage pass to incorporate nitrogen fertiliser is contrary to the whole idea of zero-tillage farming. The alternative of broadcasting urea is not satisfactory when rainfall is uncertain.

New tool

With funding from growers through the GRDC the problem was taken up by researchers from the Queensland Wheat Research Institute and the Department of Primary Industries at Toowoomba.

The outcome : N-JECTOR tine, designed to deliver the fertiliser at a safe distance from the seed so that germination can proceed unhindered by excess nitrogen.

Using the tine, growers can switch completely from reduced to zero tillage. The new tine incorporates a proven, commercially available ground tool, which is easily replaceable. The point is positioned to ensure a positive rake angle, thus preventing smearing of the seed trench. The design of the tine ensures good soil flow around the ground tool while minimising soil inversion and mixing. The tine is compatible with press wheels and their use is recommended for both conventional and conservation sowings. A spokesman for the manufacturers said that his firm was turning out a "fair few" of the implements, and feedback indicated that they were giving good results on no till country. The tines are made by Big Rig Engineering of Dalby, and cost just over $100 each.

Several options are available for various fertiliser types, and they all seemed to be working well. "They will fit almost any implement," the spokesman said. "We are sending the tines as far afield as central NSW and central Queensland."

43 per cent yield increase

One of the first to adopt the tine was Darling Downs grower Ralph Valler. He enjoyed a 43 per cent yield increase in his 1991-92 summer sorghum crop, giving 3.24 t/ha on 45 units of nitrogen in the form of anhydrous ammonia. Mr Valler then zero-tilled wheat in the sorghum stubble, applying seed and fertiliser in the same operation. The wheat was grown under moisture-limiting conditions but was still able to exploit the additional nitrogen to produce Prime Hard wheat.

No other way

"The N-jector was the answer to my problem," Mr Valler said. "There was just no other way I would have been able to put that amount of nitrogen on."We have a sticky clay soil here which builds up on the points of tines, but I have not had this trouble with the Njector," Mr Valler said. He said the equipment is easy to use. "As soon as I can I'll be moving to a bigger machine with more strength on the tine, and I expect even better results from that."

How It works

The fertiliser is released from each tip of a wing that forms a horizontal slot for the fertiliser, slightly above the level of seed replacement. Fertiliser rates of up to 150 kg nitrogen/ha (for a row spacing of 250 mm) can be applied successfully at sowing using the new tine, without impairing seedling establishment. The modified tine can be used in both conventional and conservation cropping systems.

The tines can be fitted to existing equipment without difficulty.

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