Seasonal soil moisture and nitrogen availability project

During June 2015, the North East Catchment Management Authority (NECMA) provided funds to Riverine Plains Inc to install and monitor soil moisture probes in cropping paddocks at 11 sites across the Rutherglen region of Victoria through the Soil moisture probe network project.

The objective of this project was for growers to understand how knowledge of stored soil moisture can inform their decisions about applying fertiliser. For  example, if the soil profile has sufficient moisture, growers might decide to apply enough nitrogen (N) during spring to satisfy the full crop requirement. However, if there is limited stored soil moisture, growers might only apply a smaller amount
of fertiliser, as the crop would depend entirely on in-crop rainfall events to reach maturity.

The project also involved measurements of deep soil nitrogen (DSN) post-harvest and pre-sowing to account for the amount of nitrogen mineralised over summer.
Additional funding from the Sustainable agriculture Victoria: Fast tracking innovation initiative, made possible with the support of the Foundation for Rural and Regional Renewal (FRRR) through the William Buckland Foundation, allowed
DSN sampling (broken into incremental depth samples) at each of these sites.

By connecting the results from soil nitrogen sampling to soil moisture status, growers can predict if the stored nitrogen will be available to the crop through the year, or if it will be lost through leaching (due to accumulation of nitrogen at depth under high soil moisture conditions).

The Benchmarking soil nutrient status in connection with soil water storage and soil type in cropping systems project is supported by NECMA through funding from the Australian Government’s National Landcare Program. This project
commenced in 2016 and continued throughout 2017 to extend the work undertaken during 2015.

Some of the soil moisture probe sites from the original Soil moisture probe network project were relocated into the Boorhaman area through a partnership with the Boorhaman Landcare Group. Soil moisture monitoring and DSN sampling continued until pre-sowing 2017, with a full soil chemistry analysis undertaken at each site during June 2017 to assist in developing a network of benchmark sites through the region.

Aim
The aim of this project was to increase the understanding of nitrogen availability and movement across and between seasons, to understand how nitrogen availability is intimately related to soil moisture status and to understand the variability in soil chemistry within the Rutherglen–Boorhaman region.

Results from this work has been published in Research for the Riverine Plains and is available via the following links:

Downloads:

• 2018 Seasonal soil moisture and nitrogen availability – Rutherglen and Boorhaman regions
• 2016 Seasonal soil moisture and nitrogen availability (PDF 4.4 MB)