Nodulation counts are probably one of the most intensive assessments we do at SFS. Nodulation counts involve a few steps that ultimately result in comprehensive understanding of how nodulation has occurred on faba beans.

One of the trials for the Pulse Development and Extension is a soil amelioration trial.

This trial is designed to evaluate how liming, incorporation and inoculant rates could help to alleviate acidic soils and potentially help faba beans to increase root and shoot growth, nodulation and grain yield.

There are 8 different treatments which consist of either liming or no liming, incorporation or no incorporation or 1x inoculant rate or 4 x inoculant rate.

In order to determine how the three different factors (liming, incorporation or inoculant) impact or interact together on nodulation, nodulation counts are done once that crop has been well established, but before canopy closure occurs.

Plants were collected from each plot, they need to be carefully dug up as to make sure all the roots are intact and that the whole root system is collected.

Once collected, the roots of each plant are washed to remove any dirt and make it easier to count nodules. As the trial is also looking at root and shoot development, the root and shoot parts of the plant are individually weighed. These will then be dried, giving us a dry matter (DM) weight which helps to evaluate the root: shoot ratio. Before the roots are dried they are inspected, and every nodule is counted.

Nodules can vary in both size and amount for faba beans and can range from 0-245 nodules per plant. The average across all the treatments were around 18 nodules per plant.  The treatment with the highest number of nodules was treatment 3, which is Lime incorporation, x4 inoculant rate, at 32.4 nodules per plant.

The results from the nodulation, root/shoot development and branch assessments, from each treatment will be statistically analysed and will provide insights into the treatments and the interactions.

All these assessments will help determine what impact each treatment is having on the development of the faba bean.

In November another assessment of peak biomass will be collected to see how the treatments impact the amount of biomass. This will helps us to calculate harvest index, once grain yield has been harvested.

The results from this trial will be very interesting and hopefully give great insight into managing faba beans on acidic soils!

By Greta Duff, Senior Research & Extension