Nitrogen use efficiency just got real!

04 Feb 2022

Phil's top five strategies in cropping systems

Tablelands Telegraph - February 2022

Phil Cranney, Senior Land Services Officer, Pastures

In 2016, one of my favourite movies, “Hunt for the Wilderpeople” set in New Zealand, was released. Back home, April 2016 saw the end of an El Nino event that started in April 2015. 2016 went on to record some very handy rainfall totals throughout the region. For example, Mandurama (Gallymount, Homeleigh) received a New Zealand like winter rainfall and exceptionally low solar radiation numbers throughout June and September. The months of May, June, July and September in 2016 were significantly higher than the median for the Mandurama weather station.

“S... just got real” is one of the humorous quotes in this iconic New Zealand movie.

On farms across Australasia, nitrogen use efficiency just got real, due to the skyrocketing prices of nitrogen-based fertilisers. The cost of a tonne of urea in 2016 was approx. $300/tonne, now farmers are having to pay $1,400/tonne.

So, how do we use an expensive but essential agricultural input/resource more efficiently? Here are my top five strategies for nitrogen use efficiency in cropping systems on the Central Tablelands:

1. Clean Fallow. 2012 research done by NSW DPI researcher, Colin McMaster showed that for every 1mm of soil moisture conserved by spraying weeds, you stopped the loss of 0.56kg of nitrogen loss/Ha.
2. Integrate legumes in your rotation. Approx. 25kgs N/Ha can be fixed per 1 tonne of legume biomass grown this equates to an approx. $140/Ha saving.
3. Soil test. Knowing the numbers has the potential to save money and maximise nitrogen fixation in legumes by addressing soil constraints.
4. Refine your rotation to suit the 2021 stubble load. With the large cereal stubble load comes the opportunity to add enormous amounts of organic matter to your soils. A legume phase can help speed up microbial activity by reducing the C:N ratio and maximise nitrogen fixation.
5. Use a commercial agronomist to estimate yield potential. Soil moisture and other agronomic factors will determine the yield potential of your crop, therefore returns from additional nitrogen inputs can be objectively assessed.

Furthermore, assess the overall ability of your cropping system to withstand lower commodity prices with these higher input costs. This may be the catalyst to shift your enterprise focus away from chasing crop yields through large nitrogen inputs, to a rotation that includes more pulses and/or pasture legumes.

As part of the FARM (Farmers Adapting to Risks and Markets) Project, funded by the Federal Government National Landcare Program, we are seeking expressions of interest from farmers to enter two of their paddocks in Yield Prophet. Please call Phil Cranney for more details - 0458 745 478.