Which approach makes the most cents? Evaluating the effect of land conversion practices on soil health and yields of barley and oats

气候变化正在为北部地区的农业扩张创造机会，这将需要将森林和灌丛转变为生产性农田。从历史上看，由于有机质对土壤的回报较低，以及有利于现有储存物分解的条件，转化导致土壤有机质“库”损失高达50%。这些损失可能会侵蚀土壤健康，因为有机物在决定土壤的物理、化学和生物特性方面起着关键作用，而这些特性是土壤健康的核心。通过覆盖和沉土的过程将木质生物质留在现场可以减轻这些损失，同时是最快速和潜在的成本效益的土地转化方法，但是存在知识空白，需要提出的研究。覆盖后第二年产量的显著下降需要大量施肥，将有机质留在原地的长期效益尚未得到研究，而且尚不清楚现有的土壤健康指标（如康奈尔土壤健康评估（CSHA））是否适用于更多的北方气候。本项目将通过以下方式解决这些差距：2.审查土地转换对土壤健康和土壤有机质的长期影响，并通过测量和比较安大略省北部进行常规覆盖和清理的农场的土壤健康指标，确定监测安大略省北部土壤健康变化的最佳指标。2 .建立田间试验，以检验木屑混交（时间和位置）、施肥率和轮作策略对安大略省北部两种主要粮食作物燕麦和大麦产量、土壤健康和土壤有机质储量的影响；确定土地清理实践的利润空间，以确定安大略省粮食农民最有效，经济和可持续的方法。

Climate change is creating opportunities for agricultural expansion in northern regions, which will demand the conversion of forest and scrub-brush to productive fields. Historically conversion has resulted in losses to the "bank" of soil organic matter of up to 50% because of lower returns of organic matter to the soil and conditions that favor decomposition of existing stores. These losses presumably erode soil health because of the key role organic matter plays in determining the physical, chemical and biological properties of the soil, the heart of its well-being. Leaving woody biomass on-site through the process of mulching and subsoiling could mitigate these losses, while being the most rapid and potentially cost-effective method for land conversion, but there are knowledge gaps that beg for the proposed research. Significant declines in yield in the second year after mulching have required the application of large amounts of fertilizer, the longer term benefits of leaving organic matter on-site have not been studied, and it is unknown if established indicators of soil health e.g. Cornell Soil Health Assessment (CSHA) are applicable in more northern climates. This project will address these gaps by: 1. examining the longer term effects of land conversion on soil health and soil organic matter and identifying the best indicators for monitoring change in soil health in Northern Ontario through measurements and comparisons of indicators of soil health on farms that have mulched and cleared conventionally in Northern Ontario, 2. establishing a field trial to examine the effects of woody residue incorporation (timing and placement), rate of fertilizer application, and rotation strategy on yields of oats and barley, two key grain crops in Northern Ontario, soil health and soil organic matter stores, and 3. determining the profit margins of land clearing practices to identify the most effective, economical and sustainable approach for Ontario's grain farmers.