Alternative crop sequences deliver results
Author: Sarah Jeffrey | Date: 25 Aug 2017
An innovative approach to crop sequencing could deliver valuable gains in yield, water use efficiency and nitrogen management, as well as reduce root lesion nematode populations, according to the latest results from a farming systems research project being conducted across Queensland and New South Wales.
The project is a flagship investment for the Grains Research and Development Corporation (GRDC) and is examining the impacts of different crop sequences on various aspects of the farming system in terms of both productivity and profitability.
The combined experimental program consists of six regional sites stretching from central Queensland to central west NSW and includes a core site at Pampas on the eastern Darling Downs.
While the regional sites are comparing a set of five to eight system modifications to the local baseline farming system, the core site is comparing 34 different system treatments, which vary in their crop intensity (the number of crops sown/year), the use of break crops and/or legumes, and nutrient supply strategy.
Each of these systems are based on differences in key decision points or rules which impact the broader farming system such as how much soil water is required to sow the crop, which crop should be grown and how much nutrient to supply.
CSIRO senior farming systems scientist Dr Lindsay Bell presented some early findings from the project at last week’s GRDC Grains Research Update at Jondaryan saying some interesting results were emerging, particularly where less traditional crops were incorporated into the rotation.
“It’s demonstrated that alternative crops like canola and durum wheat can have a positive impact on root lesion nematode populations and subsequent grain yields as well as system water or nitrogen use efficiency,” Dr Bell said.
“Crop sequences incorporating those crops achieved higher system water use efficiency ($ returned per mm of water used) and higher nutrient use efficiency (kg grain nitrogen (N)/kg N used) compared to the baseline systems.”
Some clear differences in crop grain yields have been observed under the different crop sequences and systems including the effect of the preceding crop on the yield of the mungbean double crop in summer.
“The trial work so far has seen higher mungbean yields following canola than other winter crops such as wheat or faba beans,” Dr Bell said.
“It’s likely that lower root lesion nematode populations (Pratylenchus thorneii) contributed to these results which may have also reduced the impact of Fusarium wilt.
“Pratylenchus thornei numbers increased dramatically with double crops of susceptible varieties while resistant varieties or fallows have seen populations decline.
“The build-up of nematode populations and their impact on mungbean yields demonstrates that growing two successive susceptible crops is high risk practice and should be avoided in paddocks where nematode populations are already present.
“At the same time, the impact on soil water availability and subsequent crop yields should be taken into account when assessing double crop options in the farming system.
“A double crop of mungbeans reduced planting soil water and yields of the subsequent sorghum crop compared to maintaining a fallow.”
The project is also monitoring the impact of cropping intensity on system water use efficiency which has shown to be slightly higher with higher crop intensities (three crops over two years) than in systems with only one crop per year.
“Increasing crop frequency has increased the capture and use of water by crops but this has not greatly altered the returns from the system in terms of $/mm rain as yet,” Dr Bell said.
“However, low intensity systems (e.g. < 0.5 crops per year) are less water use efficient and so far have lower returns and profit per hectare.”
For more information on the research, access a copy of Dr Bell’s GRDC Update paper `Improving productivity and sustainability of northern farming systems: what have we learnt so far from the Pampas systems experiment?'.
Dr Lindsay Bell
CSIRO senior farming systems scientist
0409 881 988
Sarah Jeffrey, senior account director
Cox Inall Communications
0418 152 859