Farm Table says:
What is the problem?
Lint yield of irrigated cotton is typically responsive to the application of fertilizer nitrogen (N). However, the applications of high rates of fertilizer N that exceed crop requirements result in unnecessarily low nitrogen recovery efficiency.
What did the research involve?
Nitrogen recovery efficiency (NRE) was determined in four field experiments conducted during the 2014/15 cotton season on the Darling Downs region of Southern Queensland, Australia
Two field sites were established in each of two irrigation systems, overhead and flood-furrow, although only three field sites were used in the analysis due to the impact of disease at one of the overhead irrigation sites.
What were the key findings?
This work is consistent with other studies within the Australian cotton industry in that adequate levels of N uptake to achieve maximum lint yield can be achieved from lower levels of N fertiliser application than are currently being applied commercially.
The application of large amounts of fertilizer N to cotton crops to increase total N supply results in a significant reduction in NRE, compared to when total N supply was sufficient to achieve maximum lint yield.
Improving low NRE across the industry by manipulating the applied N rate to reflect both starting soil N and likely crop requirement is a significant opportunity for the industry, but one that has to be balanced against the financial risk of lower lint yields.