Jon Baird was appointed in the role of the lead researcher CottonInfo Tech Lead – nutrition.

During the project, Jon developed new research extension materials and collaborations within

the cotton industry to further improve grower’s knowledge and nutrition management

practices. Within the project there was a major revision to the annually produced Australian

Cotton Production Manual – nutrition chapter. The ACPM is a cornerstone for the industry and

delivers a standard for best management practices for Australian cotton growers and industry

personnel. The revision was based on recent data detailing N fertiliser losses in field tailwater

and quantification of N fertiliser movement within the soil profile. In addition, the project

developed specific nutrition management guidelines outlined for dryland cotton systems. The

guidelines gave growers a detailed management strategy similar to what is available for

growers using irrigation water.

As reported in other documents and reports many Australian cotton growers are applying

fertiliser N higher than what is required by the planted crop (industry fNUE was ~10 kg lint/kg

N compared to research optimum range of 13-15 kg lint/kg N). Therefore, a concise effort

was made to better understand the tools and strategies growers and agronomists use to

perform nutrition budgets. Through organised regional face-to-face surveys and nutrition

forums the project evaluated the industry’s thoughts on nutrition management and key goals

and processes which can reduce fertiliser loss and the production of gaseous emissions and

reduce the industry carbon footprint.

Survey results indicate 89% of growers use a nutrient budgeting tool, but the tool was not

the traditional industry developed tool – NutritLogic – but rather individual excel sheet

containing known formulas and factors. Also, growers were willing to utilise enhanced efficient

fertilisers (EEF) and were in favour of fertilisers that have a potential for lower carbon

emissions.

To generate greater industry knowledge and understating of nutrition, the project established

on-farm experiments to investigate N mineralisation utilising the CSD FastStart weather

stations network and an EEF study in the Southern valley. Mineral N dynamics across all the

Australian cotton valleys were monitored throughout the growing season. Research results

indicated application timing affected available mineral N, with pre-plant timing losing mineral

N from the 1st irrigation down to maturity, while in-crop application gave crops a spike of

mineral N during the mid-season months of December/January.

During the project, there was a noticeable drop in the application rate of fertiliser N from

2017/18 to 2020/21 (336 kg N/ha and 253 kg N/ha respectively). The decrease in application

rate had a positive influence on irrigated cotton fNUE (14 kg lint/kg N) which was the first

recorded industry fNUE in the optimum range of 13-18 kg lint/kg N in the last ten years of

CRDC grower survey data. While factors such as smaller production area and higher mineral

N from fields in long fallows may have contributed to the fall in application rate, there has

been a conscious shift in grower attitude to improve their management on nutrition especially

as economic impacts such as low turnout and poor fibre quality are highlighting implications

of excessive N fertiliser use.