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A three-year research project on Kangaroo Island aims to research nitrogen efficiency via legumes in high rainfall cropping. The project focuses on how legumes are fixing N in soils, what nodulations are happening, and how nodulation is working.

From this research, farmers will have a better idea of how much nitrogen the respective legumes fix, how much is utilised by the successive crop, what proportion of the N is slow release and the number of years the residues continue to feed N.

It is hoped to gauge an idea about how well the legume residues retain N in the system and therefore are less subjected to leaching from intense rainfall events that can sometimes occur when spreading nitrogenous fertilisers in winter.

BACKGROUND

KI experiences waterlogging in winter months, so broad beans have become a common crop on the island in recent years as they are tolerant of waterlogging conditions. However in low pH soil conditions, poor nodulation can cause low yields.

As an agronomist, Ms Stanton noticed that canola after lupins were yielding higher than canola after beans.

Start:

March 2016

Finish:

February 2019

Project participants

Agiculture Kangaroo Island: Jenny Stanton

The problem

Different legume crops appeared to be fixing different amounts of nitrogen on Kangaroo Island.

The research

The trial is examining how much N lupins are fixing, compared to beans and subclover.

More information

Jenny Stanton
Agriculture Kangaroo Island
0491 307 008
[email protected]

Research aims

 

The project will target the following questions:

  • What legume crops fix the most Nitrogen in KI soils?
  • How much N do these legume crops fix?
  • How much of the N fixed by the legume is utilised by the following crop/s? Concurrently, how much N is lost through leaching or denitrification i.e. what is the N use efficiency?
  • How many years residual feeding do the various legumes offer?

In the field

Varieties in the trial include Coogee peas, Samira faba beans, Jenabillup lupins, Monti and Gosse sub clover.