Agroecological impact of farming systems

Agriculture is a chief cause of environmental degradation through its impact on water resources, loss of habitat, climate change, and pollution. In response major agricultural industries and international organizations (FAO, UNEP), are promoting ecological redesigns for agricultural systems. In Canada, for example, maintaining native pollinator communities and pollination is a growing concern for the continued success of key agricultural sectors. As we face looming global shortages of phosphorus (P), reducing nutrient use and improving nutrient use efficiency is also critical. The overall research objectives are to improve our understanding of the agro-ecological impacts of contrasting farming systems, or systems varying in management intensity, and tradeoffs with productivity. Our recent research showed legumes, an essential component of organic cropping systems, appear to promote soil fungi (mycorrhizae) that enhance plant P use efficiency but the mechanisms involved are poorly understood. Also, the abundance and diversity of larger soil organisms (beetles, earthworms) appear especially sensitive to the enhanced vegetative diversity of organic farming systems. Reduced tillage for green manures may further enhance these benefits including for mycorrhizae but remains unexamined. Finally, the impact of vegetative complexity of crop, margins and landscape, field size, and farm management system on native pollinator abundance and diversity is largely unexamined in North America. Specific research objectives include examination of: (i) crop productivity and soil nutrient (nitrogen and phosphorus) dynamics as effected by farming system (organic and conventional), crop rotation, greater use of legumes, and novel techniques such as reduced tillage management of green manures (ii) the abundance, diversity and activity of soil microbes (bacteria and fungi) as effected by farming system, legumes and reduced tillage management of green manures (iii) the relationship of any shifts in soil microbe populations to nutrient dynamics and the efficiency of crop use of phosphorus, and (iv) on organic and conventional grain farms in eastern and western Canada, the impact of farming system, vegetative (floral resources) complexity, field size and on-farm habitat, plus surrounding landscape complexity, on native pollinator (wild bee) abundance and diversity. Proposed is a multi-scale (small plot, paired commercial farms) research program, which will apply novel techniques and feature interdisciplinary collaborations. The research will elaborate nutrient dynamics and N and P efficiency of low input and organic cropping systems, the above and belowground agro-ecological impacts associated with farming system versus farm practice and intensity of management, and the inherent tradeoffs with productivity that may be associated with enhancing desired ecological attributes.