CottonInfo Nitrogen Management Trials: Macquarie

Amanda Thomas - The findings of the Trials conducted by CottonInfo

Farm Table says:

The trials continue to demonstrated that nitrogen availability is impacted by a range of factors, making a generic nitrogen application unrealistic.

What is the problem?

Replicated Nitrogen Fertilizer Use Efficiency trials were rolled out across most of the cotton growing regions last season by the CottonInfo Regional Development Officers with an aim looking further into where our nitrogen (N) ends up and how efficiently it was used. The trial aimed to go beyond the typical rate trial and take into account:

  • The N in the soil before the crop;
  • What was removed by the crop and seed N sampling;
  • What N was left in the treatments after crop removal;
  • The relationship between seed N percentage and Nitrogen Fertilizer Use Efficiency The effect on yield of the different rates of N and track the N within the cropping cycle.

What did the research involve?

The trials are located in Auscott Macquarie with soil type Grey clay. The rainfall averages 160mm between October and March. Treatments were applied to plots that were eight rows wide on 1.5m beds each treatment was replicated four times across the field.

What were the key findings?

Seasonal review There was a gappy plant stand in some places but extensive plant counts showed these were consistent across all treatments (7–8 plants/m), once established the crop grew well and tended to fill in most of the gaps, the season had 35 cold shock days and 40 hot days above 35°C. There was 2430 DD (long term average 2140DD)

Final Comment

Conclusion Many relationships that can occur with in the cotton crop were examined by the CottonInfo nitrogen trial. This is the second year we have conducted the trials. The main take home message is that nitrogen was not the limiting factor for the 2014-2015 season. The results showed the same yield for $200/ha less nitrogen fertilizer applied. This yield is dependent on the contribution of the pre-plant soil nitrogen and the in crop mineralization of nitrogen.

2015 - Amanda Thomas - The findings of the Trials conducted by CottonInfo
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