Comparing pulses: Some fix a lot more nitrogen by Tony Fay*

Collaborative project: Birchip farmers visiting the laboratory at the University of Western Australia in Perth, where plant samples from their paddocks are analysed. Left to right: David Smith (Birchip farmer), John Ferrier (Birchip farmer), Murray Unkovich (CLIMA research scientist) and Ian McLelland (Birchip farmer).

We all know that legumes fix nitrogen, but some species may be far better at it than others, according to early results from recent trials in Victoria and Western Australia.

A partnership of growers and scientists is starting to discover that some pulses might fix more than twice as much nitrogen as others. For example, faba beans and lentils fix more nitrogen than chickpeas and field peas.

Grain yields from all the crops were generally close to district averages in the year when these data were collected.

To make it even more interesting, the nitrogen is not released at the same time after different legumes. Vetch, field peas and pasture legumes produced a flush of nitrogen during the following autumn.

On the other hand, where lentils and, in particular, chickpeas were grown, much of the nitrogen became available later in the next year, closer to the time of grain filling.

Major collaboration

The project, now in its third year, involves growers in Victoria and Western Australia, and scientists from five organisations: the Cooperative Research Centre for Legumes in Mediterranean Agriculture (CLIMA), Victoria's Department of Natural Resources and Environment, the Birchip Cropping Group, Agriculture WA and Lamond Burgess and Associates.

The aim is to measure how much nitrogen is fixed in the paddock by a range of legumes currently grown on alkaline soils in southern Australia.

Samples of pasture legumes or pulses from more than 40 paddocks at Birchip in the southern Mallee region of Victoria have been analysed, together with samples from subsequent cereal crops.

Grain species under the microscope include faba beans, chickpeas, lentils, vetch, lupins and field peas. The pasture species are lucerne and medic.

Farmers' comments

The close collaboration between scientists and graingrowers has been beneficial for John, Robyn, Peter and Sue Ferrier, who farm three of the sites located at Birchip.

"This work allows us to see research in action," says Mr John Ferrier. "We're confident that we will be able to use the results quickly."

This year extra trials have been established to investigate some of the patterns observed in the field by the scientists. For example, at one site, scientists are studying the effects on root nodulation of various rates of calcium (applied as gypsum). Other work is investigating possible effects on nodulation of particular herbicides.

Program 3.5.3 Contact: Dr Murray Unkovich 08 9380 2209 Dr Ann McNeill 08 8303 7879 Ms Jo Slattery 02 6030 4500

*Tony Fay is an agronomist with the Victorian Department of Natural Resources.