Research probes microbes' role in crop nutrient uptake
Australian research is beginning to reveal the impact of farming practices on soil microbiology and how this affects the supply of yield-boosting nutrients to crops.
Funded by the Grains Research and Development Corporation (GRDC) through its Soil Biology Initiative II suite of research projects, scientists say they are developing fresh knowledge which could lead to new avenues for nutrient management by growers.
Soil microbiologist Lori Phillips, who works for the Victorian Department of Environment and Primary Industries, says research is aimed at determining the make-up of microbial communities in the soil, their role in nutrient cycling and how farming practices influence microbial activity.
“We’re not at the point of making blanket recommendations yet, but we are hoping to bring soil microbiology to the stage where soil chemistry got to 20 years ago,” said Dr Phillips.
“We want to know what’s going on in our soils, who’s there and what they are doing.”
Dr Phillips’ research is primarily in the area of nitrogen (N) transformation in cropping soils.
“In agricultural systems, N is the single largest variable input cost for growers and the least effectively used of all the inputs that go into the soil system,” she said.
“When adding N into the system you have this extraordinarily complex community of soil microbes which will pick up the N and transform it in all sorts of ways, some of which are beneficial to grain growers and an awful lot of which are not beneficial.
“We’re trying to find out how growers can improve N use efficiency in their soils and how, when adding fertiliser into the system, the percentage of that fertiliser that plants are actually able to take up can be increased.
“If you’re adding 100 kilograms of N into your system and your plants are only taking up 10kg, what’s happening to the other 90kg? We want to know whether we can increase the amount plants are taking up.”
Dr Phillips, who has been speaking at GRDC grains research Updates in the southern region about her studies, said there were “a million different factors” that impacted on N uptake.
“But first and foremost, it’s the microbial communities within the soil and what they do with the N that has the biggest impact on what’s happening to that N.”
GRDC Soil Biology Initiative II researchers are now developing an understanding of how N is processed in the soil system and which microbes are responsible for processing it.
“We’re getting a better understanding of the overall linkages between soil microbial communities and we are determining how very specific management practices impact those communities.”
Dr Phillips said research was exploring whether previous crops influenced microbial community functioning in subsequent cropping years; whether differences in the amount and quality of residue/stubble impacted microbial communities responsible for transforming organic and mineral N to plant-available N; and whether agronomic practices such as tillage and depth of fertiliser placement could be strategically used to manipulate N-cycling microbial communities.
“There are all sorts of little tweaks we are looking at that growers could use with their existing farming technologies to start shifting the balance in their favour in terms of which organisms within the soil are working at any given point in time.”
Dr Phillips said the GRDC-funded project had generated an unprecedented level of detail on how agronomy, soil chemistry and soil biology interacted to influence agricultural productivity.
“Our findings are extending our fundamental understanding of how agronomic practices influence soil microbiology and how both may be managed to improve the synchronisation of N supply with crop demand in Australian soils.
“Understanding which soil microbes are active in N cycling at what time opens up new avenues for nutrient management.”
Dr Phillips said future nutrient management options may include:
- Making informed decisions on paddock-specific tillage practices after specific crops
- The generation of new inhibitors which target alternate pathways within the N cycle. Management of organic N-cycling communities is the key to optimising N use and fertiliser efficiency
- Strategic timing of fertiliser application, specific to residue type from previous crops.
To view an interview with Lori Phillips, please visit www.youtube.com/theGRDC or watch the video on this page.
More information about GRDC’s Soil Biology Initiative is available via www.grdc.com.au/soilbiology.
Caption: Soil microbiologist Lori Phillips says current research is aimed at determining the make-up of microbial communities in the soil, their role in nutrient cycling and how farming practices influence microbial activity. Image DEPI Victoria.
Lori Phillips, DEPI Vic
03 9032 7141
Sharon Watt, Porter Novelli
GRDC Project Code DAV00106
Region South, West, North