Influence of management practices on weed communities in organic cereal production systems in Saskatchewan

Management practices on organic farms in Saskatchewan are largely unstudied, as are their effect on weed populations and soil quality. The objective of this study was to document what management practices are used on organic farms, classify those practices into management systems and determine if those management systems affect weed populations and soil properties. During the 2002 growing season 73 organic fields in the province of Saskatchewan were surveyed. Three components comprised the data set for each field: a management questionnaire, weed counts, and soil samples that were collected and analyzed for various soil properties. Classification of the management practices identified farming systems: the diverse cropping system, the diverse cropping system using green manure, the low diversity cropping system using summerfallow, and the moderately diverse cropping system using perennials in rotation. Ordination of weed data and the four systems was done with redundancy analysis. It determined that the farm management systems only accounted for 5% of the variation in the weed populations. The only system that affected the weed populations was the moderately diverse cropping system using perennials in rotation. Soil properties were compared among the different management systems. Soil properties were not different between the diverse cropping system using green manure, and the low diversity cropping system using summerfallow. The system that included perennials in rotation had significantly lower pH, electrical conductivity, soil organic matter, phosphorous and potassium levels. The nutrient levels in all systems were low, underscoring the importance of nutrient additions to export farming systems