The right balance: management strategies for plugging organic soil health constraints and moving forward
Certified organic acreage on the Canadian Prairies (MB, SK and AB) comprises over 80% of the national organic production area (Canadian Organic Growers (COG), February 2015). Some of these organic lands have declining productivity, a fact that threatens the sustainability of Prairie organic farming. The basis for declining soil productivity has, up to now, been poorly understood. However, soil ecologists have recently discovered that nitrogen (N) and phosphorous (P) limitations are partially caused by the lack of carbon fueling biological nutrient cycling. This revelation has been a game changer in the way we look at managing organic soils. The proposed research aims to reset the C, N, P balance in order to increase productivity of organically-managed soils. One C-enrichment approach is to use more and different plant species grown opportunistically within the grain cropping system. We hypothesize that with greater C coming from plants (through free photosynthesis), the amount of compost required to improve these soils is much less than earlier anticipated. We also plan to recalibrate the tools for making N and P recommendations to also include C as an element to be managed. As part of the work, this study will gain knowledge from the two longest-running organic field studies in Canada – the Glenlea study located in the dry, subhumid region of Manitoba and the Alternative Cropping System study located in semi-arid Scott, SK. By including these long-term studies, we will be able to tap into almost 5 decades of collective experience.
In other cases, farmers have devised soil management systems that already provide a good balance of C, N, P and other nutrients. These farms are referred to as high functioning, at least as far as nutrients and energy flows into the soil are concerned. But these farms face new challenges – usually from pests. This is indeed very logical. As more abundant nutrient resources and C-based energy are consistently available, more organisms will take notice and begin to consume them. Specifically, more continuous plant cover living root material resulting from cover cropping is thought to favour soil-dwelling pests that would otherwise go through a period of food deprivation. Therefore, we have assembled a group of scientists skilled at analyzing how such high functioning systems attract and support pests, and what biological strategies can be employed to reduce pest burden on the system. By better understanding the "who", "what", "when", "why", and "how", of pest behaviours and how they might be suppressed in high functioning organic grain and vegetable systems, we will provide important information for other farmers to use as overall productivity of all organic farms increases.
The technology developed in this project will be transferred to the farmers and other stakeholders in a timely and effective manner through “show me” field days, and other communication strategies including fact sheets and social media. We will also interact with emerging biological industries that will eventually be needed to support the growing number of high functioning organic farms.
Together, the anticipated outcomes of the proposed research include 1) a systematic evaluation of the use of cover cropping and municipal green waste compost as a soil amendment to bolster fertility and soil organic carbon in organically managed soils, 2) incorporation of a soil C component into the Whole Farm Nutrient Management Tool that can be ground truthed using long-term organic cropping systems, and 3) new knowledge of soil heath and pest behaviour in a highly-functioning organic farm system.
Final Report Summary
The Prairie region produces most of Canada’s organic grain and pulse crops, and the growing market demand for these products is bringing new farms into organic production. Some Prairie organic farms are highly productive, but others are experiencing yield declines. Reasons for the declines are not well understood, although soil phosphorus (P) deficiency is one well-documented issue. Recent research has shown that insufficient soil carbon (C) inputs may be another significant limitation. Understanding what makes organic farming systems productive or unproductive is important to their long-term sustainability and growth in Prairie Canada.
This project used a systematic, multi- and transdisciplinary approach to characterize positive aspects as well as challenges in high functioning organic systems, with a view to identify solutions that can be adapted for low functioning organic systems. A high functioning organic farm in southern Alberta underwent investigation and was used for comparison to a low functioning organic system in Scott, Saskatchewan. Assessments included biological (soil, insect, weed populations) assessments, soil biophysical analysis, and economic considerations.
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Publications and Other Resources
|Bobbi Helgason (Activity Leader)||AAFC, Saskatoon Research and Development Centre|
|Reynald Lemke (Activity Leader)||AAFC, Saskatoon Research and Development Centre|
|Martin Entz||University of Manitoba|
|Joanne Thiessen Martens||University of Manitoba|
|Francis Larney||AAFC, Saskatoon Research and Development Centre|
|Julia Leeson||AAFC, Saskatoon Research and Development Centre|
|Haley Catton||AAFC Lethbridge|
|Newton Lupwayi||AAFC Lethbridge|
|Charles Geddes||AAFC Lethbridge|
|Tom Forge||AAFC Summerland|