Biology Of Nitrogen Release From Pulses

GRDC - V S R Gupta Vadakattu, P Piana-Muschietti (CSIRO Agriculture & Food Waite Campus) and Lindsay Bell (CSIRO Agriculture & Food Toowoomba) and Therese McBeath (CSIRO Agriculture & Food Waite Campus)

Type: Research Paper
Knowledge level: Advanced

Farm Table says:

The authors of this paper note in the conclusion: "Factors affecting N release after pulse crops include (i) amount of shoot residue biomass at the end of the growing season, (ii) N content and quality (e.g. C:N ratio) of the legume residues, (iii) environmental conditions; mainly rainfall over the fallow period before the next crop and (iv) soil microbial composition following the legume crop. The amount of aboveground plant biomass from different pulses not only limits the amount of C inputs for microbial activity but also limits potential N inputs from legume plant biomass. As the quality and N content of pulse crop residues defines the amount of N added to the system it consequently influences the N mineralisation and tie-up (immobilisation) processes. The rate and timing of the availability of N from pulse stubble to the following crop is determined by the rate of decomposition and immobilisation (tie-up) by the soil micro-organisms. However, the significance of these effects varies depending upon stubble load, time and type of burning and other agronomic factors". Please access the full paper via the link below if this research interests you.

The take home messages from this GRDC funded research are below. Please access the full paper via the link below for methodology, references, acknowledgements and discussion.

Take home messages from the paper include:

  • All grain legume (pulse) crop residues generally have higher concentrations of nitrogen (N) and lower C to nitrogen ratio than cereal crops.
  • The rate and timing of availability of N from pulse stubble to the following crops is determined by stubble decomposition rate and N immobilisation (tie-up) by soil micro-organisms.
  • N mineralisation/tie-up processes after pulse crops can differ significantly to that after cereal and canola in terms of the (i) timing of release of N from residues (for example; during summer versus early into the following crop), (ii) magnitude of N tie-up during the seedling phase and (iii) the availability of fertiliser N to the cereal crop after a pulse crop.
  • In low fertility soils, the combination of N release from pulse crops and N from fertiliser sources is required to maximise productivity benefits in the following crops.

2020 - Australia - GRDC - V S R Gupta Vadakattu, P Piana-Muschietti (CSIRO Agriculture & Food Waite Campus) and Lindsay Bell (CSIRO Agriculture & Food Toowoomba) and Therese McBeath (CSIRO Agriculture & Food Waite Campus)
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