Farm Table says:
Biological activity and organic matter – component 1
What is the problem?
Growers, particularly no-till, are very concerned about microorganisms in the soil and how they are affected by farming practices. They know that what they do can affect the way in which microorganisms cycle nutrients and deliver them to the plant. Most grower decision making has been based on assumptions and/or anecdotal evidence about the impact of no-tillage on microbial populations and their functions. The information from this project should enable more informed decisions.
Microbial functions including organic matter turnover are likely to be different in soils under no-tillage compared with cultivated soils.
This research tested the impact of tillage practices on soil microbial processes, organic matter, and crop yields.
What did the research involve?
- treatments and measurements – in all cropped treatments at both sites, crop residues were retained after harvest.
- At Gabby Quoi Quoi, the trial was located on a deep sand. Tillage treatments were well defined and represented a wide range of disturbance from extreme cultivation (rotary hoe) to no-tillage (triple disc drill)
- achievements – at Corrigin, treatments were not strongly defined
- benefits to industry – this project provides knowledge about the impact of various tillage practices on microbial processes that deliver nutrients to plants and other soil organisms, and on grain yields
What were the key findings?
- Expected outcome
-An increased understanding of the effect of tillage systems (no-tillage vs cultivation) on microbial processes that cycle carbon (C) and nitrogen (N) in soils and impact on crop production.
- Economic outcomes
-on the soil types studied, growers can use low levels of tillage for controlling resistant weeds and diseases without negative effects on soil biology or future yield
- Environmental outcomes
-soil health can be maintained on these soil types with the current ‘conventional cultivation’ (single pass prior to sowing).
-A recent small study (funded by CSIRO) on sandy soils in the southern wheat belt of WA indicated that the findings on tillage practices, at the two main sites used in this project, may not apply to more fragile soils subject to wind erosion or water repellency.
“This gives growers some flexibility to manage resistant weeds and root diseases with strategic cultivation if needed. In contrast, intense cultivation (rotary hoe) had significant impacts resulting in reduced microbial biomass and microbial functions compared with other tillage treatments.”