The heavy rains experienced in February this year took most of us by surprise and while rains are always welcome, floods, erosion and other consequences created a need for mitigation across many Wheatbelt properties.

Many of the effects of heavy rainfall events are easily seen in the paddock, but what happens below ground level and how are soils affected? Thanks to funding from the WA State Government Department of Parks and Wildlife (Swan River Trust) under the Healthy Soils, Healthy Rivers Project, 20 local farmers are getting to test just that.

The farmers were already participating in Round 4 of a Nutrient Use Efficiency project that involves soil testing to measure the nutrient use efficiency of their cropping program.  The initial soil tests for these farmers were conducted in early January prior to any rainfall events, but due to the extra funding, the initial tests are now able to be compared to soil tests that have occurred in the last couple of weeks. The nitrogen levels, in particular, have been re-tested as nitrogen is easily moved within the soil and summer rainfall events mineralises nitrogen from the atmosphere. The sites have been re-tested for Nitrogen levels in the topsoil (0-10cm) and subsoil depths of 10-30cm and 30-50cm.

The results are currently only just coming in, however, early trends point clearly toward significant increases in Nitrogen, particularly within the top soil samples.  The following graph shows the increase seen on one of the sample sites already completed.

Wheatbelt NRM will be collating the results from all 20 trials and presenting information back to both the growers involved and the industry to create a better understanding of the effects that heavy rainfall events may have on differing types of Wheatbelt soils.

This information is expected to improve on growers’ capacity to make informed decision on nutrient application rates.

For more information on this project please telephone Chris Kennedy on 9670 3110 or email ckennedy@wheatbeltnrm.org.au.