Compost no simple soil solution for Mid West citrus growers

A recent study into the use of compost to enhance fruit production in the NACC NRM region showed that this option certainly wasn’t likely to be a “simple solution” for soil enrichment for Midwest citrus growers.

The study was conducted under NACC’s Innovative Farming Demonstration Grants scheme and focussed on “Improving and quantifying soil quality in citrus productions systems on sands in the West Gingin/Moora area”. The compost trial was one of three elements of a broader project, conducted in collaboration with WA Citrus, with the other two investigating the use of cover crops to improve soil health; and the use of gypsum and other calcium products to reduce albedo breakdown in citrus.

Picture: Neil Lantzke
Odeum Holdings property in West Gingin. Picture: Neil Lantzke

The compost trial was conducted on the Odeum Holdings property in West Gingin and was overseen by agricultural consultant Neil Lantzke.

The trial investigated whether applying compost as a mulch to an established citrus orchard on a sandy soil could increase growth, fruit quality and soil health, and as a result, provide real economic benefits to the grower, which is explained in the trial summary.

The soils at the trial site – a seven-year-old Clementine mandarin orchard –  predominantly deep, medium to course-grained siliceous sands – were subjected to three different treatments:   application of compost; application of organic soil conditioner (partially composted material); and no application / control.

The key findings of the trial were:

  1. Application of compost and soil conditioner only resulted in small / relatively insignificant increases in soil qualities in the 10 months following application.
  2. Slightly higher yields were achieved as a result of the compost application – as compared to the control and soil conditioner treatments – but this was considered most likely due to the extra nitrogen supplied by the compost, and not through any actual improvements in soil qualities.
  3. Applying extra nitrogen as inorganic fertiliser is a cheaper option than applying compost – for its fertiliser value alone.
  4. Longer-term trials, possibly with ongoing applications of compost, would be required to determine the full benefits of compost application.
  5. The high cost of compost currently limits its uptake and use by horticulturalists in the region. Transport costs, which increase with distance from the supplier, is a key factor impacting cost and uptake.

You can visit the NACC website for more information and view the full project report.

Other NACC Innovative Farming Demonstration Projects reports are available on the NACC website (link here).  Round 6 of NACC’s Innovative Farming Demonstration grants opens on 21 November 2016.  Local producers are invited to consider what projects/ideas they might like to submit for funding.  For further information, please contact NACC’s Carbon Farming Coordinator Sarah Jeffery on 9938 0110.

This project is made possible with funding from the Australian Government’s National Landcare Programme.

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