Assessing alternatives

Location: Table Top, NSW

Enterprise: Angus cattle

Producer: Marcus Richardson

Soil type: Grey and red loams

Pasture type: 60% arable land with phalaris and clover; about 7% lucerne; 33% native pastures (non-arable)

Faced with low returns after eight consecutive years of poor seasons and keen to look at different approaches, Holbrook Landcare Network members found there was little information available on using alternative fertilisers.

The group sought MLA funding through the PDS program to answer the question: Carp, kelp or Christmas Island – where to next for fertilisers? 

The project compared seven products, which were chosen to be representative of the wide array of products available locally. They were assessed for effects on growth, quality and composition of pasture, and on the chemical, microbiological and physical properties of the soil. 

The products were applied in line with manufacturers’ recommendations on paddocks typical of the area. The study used two controls: no added fertiliser; and single superphosphate applied at 10.8kg phosphorus/ha. 

According to cattle producer Marcus Richardson, the ability to assess fertilisers in terms of cost per nutrients supplied was a valuable lesson from the project. 

“At one of the field days we were shown how to calculate fertiliser cost as cents per kilogram of phosphorus, potassium, and so on,” Marcus said. “That gives a really easy and effective way of assessing the different fertilisers in terms of what they actually deliver to the paddock.” 

The replicated field study showed that none of the alternative products significantly affected pasture growth, quality or composition, and nor did any significantly affect soil softness, or soil chemical or microbiological properties. 

Super confident 

Agronomist Jeff Hirth, who coordinated the field trials for the Holbrook group, said paired-paddock evaluations showed very small and inconsistent differences in live weight changes (of cattle grazing the pastures), but these were not of economic benefit to the producers. 

The results indicated that most of the alternatives supplied little or no phosphorus, nitrogen or sulphur. In contrast to single superphosphate, which annually supplied 10.8kg phosphorus/ha and 13.5kg sulphur/ ha, only two of the alternatives tested supplied phosphorus in the first year. One supplied 64.2kg/ha and the other 7.4kg/ha. Additionally, one other alternative supplied moderate levels of potassium (35kg/ha) each year. 

“We found that none of the products tested were significantly different to super, so it reaffirmed our confidence in super,” Marcus said. 

Chris Cumming, Executive Officer of Holbrook Landcare Network, said as well as assessing the fertiliser alternatives, the project was important in demonstrating the value of evidence-based decision-making. 

MLA is combining the results of several other alternative fertiliser projects togetherwith this project. Gerald Martin, Southern Coordinator of MLA Producer Demonstration Sites, said this will provide a fuller picture of the value of alternative fertilisers. 

“The value of fertiliser is affected by the inherent fertility, particularly phosphorus levels, at the start of trials,” Gerald said. 

“The combined results, which will bring together individual trials from different sites and overall results for various fertilisers, will enable wider application of this work. It will also give each product a five-year opportunity to show its value.” 

Lessons learned 

  • Assess the value of fertilisers based on the amount of nutrients they supply.
  • Make decisions based on solid evidence.
  • Conducting research on paddocks representative of the region gave results that were immediately relevant on-farm.
Do you have any questions on fertilisers - or any other on-farm topic - that you'd like to ask an MLA expert? To ask your question, email the feedback editor at info@mla.com.au (include 'feedback - ask the expert' in the subject line) and you'll get to see your question answered in the next edition of feedback.
Table Top, NSW
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