Growers considering adding nitrogen to chickpeas to boost yield should save their money, according to the results of recent trial research.
Trials by the Northern Grower Alliance and funded by the Grains Research and Development Corporation found that adding nitrogen to crops did not have any impact on yield, making the additional cost and potential loss in nitrogen (N) fixing ability a double hit.
The research was conducted over two years in response to observations by agronomists and growers that chickpeas planted in higher N soils had increased yield.
The research covering eight different sites across NSW and Queensland looked at the impact of various nitrogen application rates: 0kg/ha, 23kg/ha and 46kg/ha in the first year and 10kg/ha and 50kg/ha in the second year.
Also trialled were two application timings: at planting and in crop, and with or without Rhizobia inoculation.
Northern Grower Alliance Research Manager Lawrie Price said the results were fairly conclusive, with none of the research sites showing any significant increase in yield to N application rate.
“In relatively low-yielding seasons there was no consistent impact on yield from the addition of nitrogen alone in chickpeas, across a wide range of starting soil nitrate levels,” Mr Price said.
However, Mr Price said both 2012 and 2013 were low rainfall, poor yielding years and the project was initiated following observations during the wet, high yielding season of 2011 that paddocks with high N levels were yielding best.
“It is possible that during a wet season it might be of benefit so research would need to be conducted during a wet year to draw any conclusions about those conditions,” Mr Price said.
He said that significant yield increases would need to be seen to offset the cost of the fertiliser and the lost N fixation, with on average about 100-160kg/ha of additional grain needed to offset nitrogen fertiliser cost and lost nitrogen fixation.
Mr Price said future trials involving chickpeas were likely to look at the addition of phosphorus and potassium, although treatments involving N will continue to be included.