MPfN - enhancing nutrient use in cotton

The issue​

aerial shot of large green cotton fieldSubstantial amounts of nitrogen (N), sourced from both soil organic matter mineralisation and fertiliser, may be lost from irrigated cotton-producing soils. Soil phosphorus (P) may also be depleted under long-term irrigated farming systems. Strategies of fertiliser and irrigation management are needed to address both short-term nutrient losses and long-term depletion of soil fertility.​


To increase understanding of the relationships between soil and fertiliser N & P supply, fertiliser placement, fertiliser timing, and irrigation strategy to achieve greater N use efficiency (NUE) and improved P soil nutrition.

What we are doing​

  1. two people standing on variable rate applicator attached to back of tractorFour seasons of field experiments at the Australian Cotton Research Institute, Narrabri investigating the impact of irrigation scheduling and N and P management strategies on cotton productivity and nutrient use efficiency.​
  2. Three seasons of on-farm case-studies/trials near Moree, Gunnedah and Narromine.​
  3. Testing of archived soils sampled from previous cotton experiments to determine whether soil P has declined due to cropping or increased with fertiliser management.​

Outputs and/or outcome​

  • N Runoff loss during irrigation can be > 20% of applied N. This loss can be reduced by split-N or using polymer-coated urea.​
  • N volatilisation from water-run ammonia can >23% applied N​
  • Split N application increased yield compared to all pre-plant.​
  • Soil P declines throughout the profile if not fertilised, but accumulates at the surface where P fertiliser is applied.​
  • Yields were optimised when N and P applied, and irrigation was more frequent.​
  • High N fertiliser rates increased biomass but not lint yield​
cotton harvestingWomen taking water sample from tail drainlarge irrigation channel in cotton field with black poly pipe

Partners or collaborators​

Cotton Research and Development Corporation,

Australian Department of Agriculture, Water and Environment


University of Queensland,

University of Melbourne,

University of New England​


Graeme Schwenke