Guidelines for organic amendment experiments to enable attribution of yield to plant nutrition or soil amelioration

Corinne Celestina1, James Hunt1, Ashley Franks2

1 Department of Animal, Plant and Soil Sciences, AgriBio the Centre for AgriBiosciences, La Trobe University, Bundoora VIC 3086,,
2 Department of Physiology, Anatomy and Microbiology, La Trobe University, Bundoora VIC 3086


Organic amendments such as manures, composts and plant residues are often used as alternatives to inorganic fertilisers or to ameliorate physicochemical soil constraints. Crop yield responses to the application of organic amendments could be due to plant nutrients contained in the amendment, the amelioration of (sub)soil constraints, or some combination of both factors. However, if experiments are designed incorrectly these factors can be confounded, leading to difficulties in accurately ascribing yield responses to nutrition or amelioration. We suggest guidelines for design, conduct and analysis of organic amendment experiments which will allow the correct attribution of yield responses. These include: identifying genuine soil constraints, selecting proper control treatments, and using appropriate sampling protocols to assess treatment differences.


The Australian Society of Agronomy is the professional body for agronomists in Australia. It has approximately 500 active members drawn from government, universities, research organisations and the private sector.

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