Vermicompost - vermadaption

Whether it is a changing climate, extreme weather events, new technologies, or market forces, farmers have always adapted. The requirement to adapt shows no signs of slowing down, indeed it is likely that continual adaptation will be required for the ongoing sustainability and profitability of all agricultural enterprises. Sometimes however, adaption becomes a case of what is old is new.  This was indeed the case for a recent SQNNSW Innovation Hub project run near Stanthorpe, Queensland.

Charles Darwin noted that the humble worm may be the most important animal in the history of the world. These fabulous creatures, of the composting variety, were at the heart of the project which aimed to demonstrate the benefit of worm poop, known as vermicast, in a horticulture setting.

Vermicast has long been known for its beneficial properties. It is known as a soil conditioner, a source of nutrients and beneficial soil microbes as well as improving soil structure. Despite these benefits, the application of vermicast or vermicast extracts is not a common practice.

The project involved local tomato and sunflower farmer Scott Carnell, agronomist Andrew Woodford (from Wilshire and Co, now HybridAg), Jen from Worms Downunder (who provided a commercial scale worm farm, vermicast and vermicast extract), as well as Wim Linstrom (Stanthorpe Node) and Cameron Leckie (Regional Soil Coordinator) from the SQNNSW Innovation Hub.

The demonstration project included the delivery and operation of a worm farm to produce vermicast from local materials, the regular application of vermicast extract to a sunflower and tomato crop and the incorporation of vermicast from two different feedstocks into the potting mix for tomato seedlings.

The most promising results occurred with the tomatoes planted in a potting mix containing 13% vermicast. In all cases the tomatoes grown with the vermicast outperformed the controls. However, the tomatoes grown with vermicast that included paunch as feedstock (and an initial inoculation with a HybridAg biological product) more than doubled the yield at first harvest compared with the control strips.

The impact of the vermicast extract varied. For the sunflowers, the plants treated with the extract were taller and had a thicker stem diameter with the differences narrowing by the end of the growing season. Regular soil biology tests conducted using the microBiometer indicated a trend of higher microbial activity, but a comprehensive soil microbiology test completed at the end of the growing season produced nearly identical results. These results suggest that the vermicast extract provided the plants with a ‘head start’ compared to the control.

The results of the vermicast extract applied to the tomato crop were inconclusive.

Based on these results, the next step will be upscaling with plans to plant a complete block of tomatoes grown in a vermicast mix. Due to time constraints, the project originally relied upon vermicast extract provided by Worms Downunder. With the worm farm now producing castings, it is also planned to brew vermicast extract on-site. A number of important lessons were learned as a result of the project. It highlighted the importance of on-farm experimentation and in particular the requirement to test and adjust with any practice change in the context of the whole farming system. It has also highlighted challenges with upscaling smaller scales demonstrations to commercial reality, such as being able to purchase tomato seedlings raised in a vermicompost mix.

Potential opportunities for commercialization resulting from the project include local vermicompost production from local feedstocks as well as the production of seedlings using vermicast.

The project highlighted a research gap, with little information being available on the best approach to apply and use vermicast and vermicast extracts in sandy soils.

Whilst seemingly small changes such as the incorporation of vermicast into a farming system won’t change the world, it is these incremental adaptions that will help farmers to meet the challenges of the future. 

Contact

For more information on this project, please contact Wim Linstrom (wim.linstrom@unisq.edu.au) or Cameron Leckie (cameron.leckie@unisq.edu.au).

The SQNNSW Hub Regional Soil Coordinator is supported by the Australian Government’s National Landcare Program.