New test helps to identify rhizobia strains in legume pastures. 

It is a fact in a mixed farming enterprise that a well nodulating legume pasture (or legume crop) is not only a vital source of feed for livestock but is also an asset in subsequent crops due to the fixation of valuable crop available Nitrogen (N). Table 1 indicates the potential N available from a 100% legume pasture to the following crops.

Table 1:

100% legume pasture

Dry Matter t/ha

Fixed available N kg/ha- Year 1

Fixed available N kg/ha- Year 2

1

8

4

2

16

8

3

24

12

4

32

16

5

40

20

6

48

24

 

Table 1 references a legume pasture at 100% with the assumption that nodulation is as efficient as possible which sadly is not the reality in a lot of cases. The efficiency of N fixation relies on such things as:

  1. Root health- what do the roots look like?
  2. Soil health and nutrition- pH and availability of key nutrients?
  3. Herbicide use and history?
  4. Which rhizobia are in the nodules?

Until now the first 3 were quite easy to investigate and discover the information by:

  1. Visual assessments- there is nodules on the roots so it must be fixing N?
  2. Soil sampling- good indicator of key macro nutrients and pH which is an indicator for rhizobia survival.
  3. Chemical history in crops and pastures are easy to source through on farm record keeping and farmer knowledge of the paddocks. However the fourth point has always just been based on the assumption:
  4. Which rhizobia are in the nodules- should be the same rhizobia that I inoculated my seed or pasture with?

This question can now be easily answered thanks to the MALDI ID test. The MALDI ID test has been developed by Dr Sofie De Meyer in conjunction with the Centre for Rhizobium Studies and Murdoch University.

This test involves sending off a sample of fresh root matter from a legume pasture in a specially designed sampling pack. The roots are processed and run through a spectrometer to give an ID of the strains of rhizobia present in the root nodules. This identification in conjunction with visual nodule scoring of the root systems can then help you to determine if the correct strains of rhizobia are present in your soils or if the paddock needs to be re inoculated prior to next season.

The MALDI ID test can be conducted anytime in season and can be accessed through your local CSBP Area Manager.

Luke Dawson
By Luke Dawson
- Senior Agronomist
Luke was raised on the family farm at Warralakin east of Mukinbudin before completing a degree at the Muresk Institute of Agriculture. 

Luke started with CSBP in 2005 as a trainee Area Manager and has since worked as an Area Manager based in Hyden, Esperance, and Dalwallinu and District Manager for the Central Midlands District, now based in Kwinana as the Senior Agronomist. 

Luke brings a strong nutritional background to the role, as well as a focus adding value through CSBP's services. 

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