Increasing the effectiveness of nitrogen fixation in pulse crops through development of improved rhizobial strains, inoculation and crop management practices

Expansion of the pulse industry is seeing crops increasingly sown on soils that are challenging to plant establishment and growth. In these areas, pulses are often grown in the paddock for the first time or, have been infrequently grown and are therefore likely to benefit from rhizobial inoculation. In these situations, soil constraints such as acidity, particularly when combined with practices such as dry sowing or the application of pesticides to seed, can profoundly affect the success of nodulation and subsequent performance of the pulse crop. The work undertaken in this project aims to select improved rhizobial strains for hostile soils and develop inoculation practices that minimise the potential impact of fertiliser and crop protection applications, to maximise rhizobial survival, nodulation and nodule function. These improvements will broaden the adaptation of pulses to soil types and areas where they are currently not widely grown. A comprehensive case for the replacement of rhizobia strain WSM-1455 with strain SRDI-969 for faba, tick and broad bean (Group F) has been endorsed by the National Rhizobium Steering Committee, paving the way for its use in commercial inoculants in 2023. The new strain is being tested by 19 growers in 2022. A DNA test to measure rhizobia number in soil for three inoculant groups (E/F, N and G/S) has been released to growers via the SARDI PREDICTA® platform. Publications, including Inoculating Legumes: Practice and Science, have been revised.