Agroecological impact of farming systems

农业对水资源、栖息地丧失、气候变化和污染的影响是环境退化的主要原因。为此，主要农业工业和国际组织（粮农组织、环境规划署）正在促进农业系统的生态重新设计。例如，在加拿大，维持本地传粉媒介群落和授粉是关键农业部门持续成功的一个日益受到关注的问题。随着全球磷短缺的迫近，减少养分利用和提高养分利用效率也至关重要。总体研究目标是提高我们对对比农业系统或不同管理强度系统的农业生态影响的理解，以及对生产力的权衡。我们最近的研究表明，豆类作为有机种植系统的重要组成部分，似乎可以促进土壤真菌（菌根）提高植物磷的利用效率，但所涉及的机制尚不清楚。此外，大型土壤生物（甲虫、蚯蚓）的丰度和多样性似乎对有机耕作系统中增强的营养多样性特别敏感。减少绿色肥料的耕作可能进一步增强这些益处，包括菌根，但仍未得到检验。最后，在北美，作物的营养复杂性、边缘和景观、田地大小和农场管理系统对本地传粉媒介丰度和多样性的影响在很大程度上尚未得到研究。具体的研究目标包括：(i)作物生产力和土壤养分（氮和磷）动态受农业系统（有机和传统）、作物轮作、豆类的更多使用以及绿色肥料的减少耕作管理等新技术的影响；（ii）受农业系统影响的土壤微生物（细菌和真菌）的丰度、多样性和活性；（iii）土壤微生物种群的任何变化与养分动态和作物磷利用效率的关系，以及（iv）在加拿大东部和西部的有机和传统谷物农场，农业系统，植物（花卉资源）复杂性，田地大小和农场栖息地以及周围景观复杂性对本地传粉者（野生蜜蜂）丰度和多样性的影响。提议的是一个多尺度（小地块，配对的商业农场）研究项目，将应用新技术并以跨学科合作为特色。该研究将详细阐述低投入和有机种植系统的营养动态和氮磷效率，耕作系统与耕作实践和管理强度相关的地上和地下农业生态影响，以及可能与增强所需生态属性相关的生产力的内在权衡。

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.