Adviser Workshop November 2013 – Small Group Discussions on Nitrogen Messages & Gaps (Day 2)

Key Messages

  • Local information required
  • Knowledge gap- how big are the losses in our region
  • Production loss vs greenhouse gas impact
  • Losses via volatalisation are far less from surface applied area than previously thought
  • Losses from denitrification are not only in the form of N, O
  • Nitrogen use efficiency is ordinary
  • Increase soil C can increase N2O (much worse)
  • That N2O equals roughly 300 times C02
  • Crops in 50% efficiency. Livestock – 30% off
  • N in OM has to be processed through the microbial population before it is available and many factors drive that especially C:N balance
  • If lots of extra carbon can lock up N
  • Different forms of carbon – POC, HOC, ROC will influence possible losses
  • Volatilizations NOT a big even in low pH, temp, NH4 plus cone plus water (if one ore more is missing)
  • Denitrification pathway- if severe water logging goes straight to N2, not only as N2 loss however as more O2 appears, get increase N20 less N2
  • Lots of opportunity to be more efficient
  • Inhibitors may have a plan in high water logged soils as they dry out
  • If can improve pore space then the possible time in the damaged zone (>60% water in pore space) is reduced
  • N2O 300x more impact than CO2
  • Greater risk in high RF and water logged conditions
  • Split N and Inhibitors can reduce N2O
  • 10% volatalisation- ROT NH2+ NOT N2O
  • Worst case in low- M Rainfall current practice systems
  • N2) @ 65-85% water filled pore space N2 > 85%
  • Its all too hard
  • The N2O losses in lower rainfall are insignificant
  • Unless there is an N2O emission cost the simple remedy is to increase N rate
  • N rate is a key driver of N2O emissions
  • Variability is high
  • It’s a fine line between N20 and N2 losses
  • Claimed efficiency of inhibitors doesn’t match reality
  • Match supply with demand
  • Volatalisation losses of applied area are low

Potential Applications

  • Matching N timing and rate with plant demonstration and water logging events
  • Ammonium uptake referencing plants have a role
  • Not much in inhibitors- time spent better elsewhere
  • Getting N Rates right is important
  • Spreading SOA on high CaCO3 soils can result in volatile losses
  • Application timing based on weather events (e.g. what to spread before 10mm not 50mm)
  • Inhibitors (cost vs benefit)
  • In crop application
  • Local information required
  • Fill research gaps in cotton system/ soil types- NUE
  • Can demonstrate we can make improvements in N2O emissions between drained (e.g. raised bed) and un-drained land
  • Working out how to introduce carbon into the system to promote improved pore space- but not allow it to drive the increase in N2O by use of inhibitors, stop water logging, make ‘bucket’ bigger
  • Improve water use by improved pasture management- perennials – take some highly water logged areas out of crop into pasture
  • Timing of N application can be tailored to conditions e.g. water in soil, avoid before rain soil type
  • Catch crops
  • Soil structure activities are good- e.g. gypsum, raised beds, drainage, deepripping, spading
  • Improving inhibitor efficiency? Recognising when they will work
  • Decision tools, enhance effectiveness and cost benefit of costly inhibitors
  • Regional alerts on N2O emissions
  • Ag Machinery efficiency (diesel) exhaust emissions

Knowledge Gaps

  • How to measure water logging squeeginess test)
  • Measuring N2 release
  • Gaps in the whole N audit
  • C/N ratios of residues
  • Bullshit peddlers in the NUE space
  • If decrease waterlogging by amelioration- how important is it?
  • Microbial activity through the soil profile
  • Drainage
  • Pulse crops/ pasture legumes are included in emissions??
  • Timing N
  • Liquids – uptake/ losses
  • Local data on inhibitors
  • Understanding in detail loss pathways and mechanism for loss
  • Role of inhibitors- when, where, type, rate, economics
  • Application of research on when to apply N to create new messages e.g.- dairy model? Model (create RoT)
  • How different sources (e.g. compost, stubble) contribute to the ‘pools’ over time
  • How to control the losses of N2O from urine- e.g. diets
  • How might we ‘catch crops?’
  • What are realistic efficiency targets what should be aiming for?
  • Applications for high rainfall pasture areas
  • Water filled pore space- is this water logging?
  • Confirm losses
  • Confirm breakdown periods and pathways- give e.g. 20mm on dry or wet soils as case studies
  • Performance of inhibitors,
  • Cost/ benefit calculator
  • Greenhouse gas emissions impact
  • Modeling tool to learn?
  • What’s happening to N- local (N cycle)- seek clarity Baldock (extra N) S. N budget (re costings)