Activity 26

The effects on soil biology, soil chemistry, and water quality of amending organically managed soils with struvite

Organic grain and forage producers need to alleviate deficiency in a variety of soil types with low availability of soil phosphorus (P), while avoiding non-renewable P sources. The European Commission Directorate General for Agriculture and Rural Development Expert Group for Technical Advice on Organic Production (EGTOP) has announced that struvite produced utilizing the Pearl process is in compliance with Organic Principles. The Pearl process results in a product which has consistent phosphorus content and can be crystallized from human and livestock wastewater streams with allowed organic processing aids. This form of struvite is noted as deserving of fair evaluation as an allowed synthetic in organic systems. It is extremely low in heavy metals and salts and as a recycled source of P, struvite has potential to substitute for non-renewable sources, while reducing the amount of P transported downstream to surface waters at risk of eutrophication.

Struvite produced with the Pearl process is renewable and has low water solubility. For this reason, we propose research to define how Pearl struvite application may be anticipated to alter grain and forage yields, soil health, arbuscular mycorrhizal root colonization, and runoff water quality in organic systems. With the assumption that this product is compliant with Organic Principles, we also anticipate the knowledge produced through this research will allow for recommendations to be made about appropriate rates of application to maximize yield and minimize impact on soil health, arbuscular mycorrhizal root colonization, and runoff water quality in organic systems.

Research is proposed to evaluate the agronomic and environmental implications of struvite application across a range of soils, rates, and spatial scales of research (pots, plots, and field trials). The team members in this project will:

  • evaluate the impacts of struvite as a P source for organically managed soils that are low in soil test phosphorus, which is an indicator of plant-available phosphorus;
  • identify differences in AMF root colonization with various rates of struvite application and contrasting soil P forms;
  • identify changes in soil P form and availability following application of struvite to soils with low soil test P, with contrasting pH and texture, and
  • examine differences in P export with runoff after the application of struvite to fields with low soil test P.

Research participants will cooperate with the Canadian Organic Grower magazine to ensure that this information is shared widely across Canada and to complement associated peer reviewed journal publications.

The research results will fill an information gap that will help the international organic sector evaluate if Pearl struvite has a place in more resilient agriculture and on the approved synthetic inputs lists of the Canadian Organic Standard of the Canadian General Standards Board and the National Organic Program of the USDA.

Results and Materials

Activity researchers

Name   Organization/Location
Henry Wilson (Activity Leader)
AAFC- Brandon Research and Development Centre
Kim Schneider (Activity Leader) AAFC Guelph
Martin Entz University of Manitoba
Merrin Macrae University of Waterloo
Derek Lynch Dalhousie University
Paul Voroney University of Guelph
Stephen Crittenden AAFC- Brandon Research and Development Centre