Matching crop demand to fertiliser inputs is fundamental to produce high yielding crops in a cost effective manner.
Fertiliser is the primary input cost for many growers in the low to medium rainfall zone, and may be a costly exercise if there is no return on investment.
We all know and understand the principle of marginal returns when it comes to applying fertiliser. There is a point in which adding extra nutrients into the system will achieve less of a yield increase than the application before.
This principle is also applicable for the financial consequence of input application, where the return gained by adding extra is less than the return on the prior input. It will get to the point where by adding extra (for example, 1t/ha of nitrogen) the financial return will actually be less than the cost of applying.
The question should often be whether there is a need to apply certain fertilisers each year, or can you get a greater return by identifying deficiencies pre-sowing and budget accordingly. Soil sampling pre sowing is a great way to identify which nutrients are lacking in soils and what quantity is available for the coming season, thus being able to assist with what rate need to be applied.
Research undertaken at BCG’s main research site at Warmur in 2016 investigated the response of wheat to different rates of nitrogen, phosphorus, sulphur and zinc. The site was soil sampled pre–sowing so there was a thorough understanding of the nutrient status.
Results from this research yielded some interesting outcomes which were quite evident in a season with a wet spring. The results showed no yield response to the application of zinc and sulphur while response varied with rate in nitrogen and phosphorus. This aligned with the soil test results which stated there was sufficient zinc and sulphur levels in the soil, reiterating the importance of soil sampling.
Understanding if there will be a yield response due to fertiliser application is the first step in ensuring that all fertiliser inputs are as cost effective as possible.
Haying off can result from the over application of nitrogen, while not enough means that possible yield is being left behind. Both resulting in a negative financial effect on the business.
By using this information and considering seasonal forecast growers are able to budget and plan accordingly.
BCG will again be conducting soil sampling in 2017. For more information follow the link to the Soil sampling flyer 2017, or complete your expression of interest online or by phoning the BCG office on 03 5492 2787.
Further research about nutrient management can be found here: https://www.bcg.org.au/planning-nutrition-for-2016/
For interpretation of the results from the BCG fertiliser response in wheat trial at Warmur make sure you get your copy of the 2016 BCG Seasons Research Results compendium, which will be made available to BCG members at the Trials Review Day on the 17 February.
This article appeared in the Stock and Land on February 8, 2017.
