Grant: Engage Grants Program

Manure application to cropland supplies essential nutrients, increases soil organic matter and reduces erosion. In Atlantic Canada, organic amendments, such as manure and compost, are important sources of soil nitrogen (N). A large portion of N (>50%) in amendments is in an organic form. A portion of this organic N will be released through mineralization during the growing season, and the rest can accumulate in the soil to be released in succeeding years. As a result, a history of manure application can significantly change the nature and release rate of the active organic N pool. Currently in Atlantic Canada, there is no soil N test available and manure or fertilizer recommendations are solely based on crop requirements and estimated credits for amendment and previous crop. This recommendation system ignores the contribution of soil organic N to plant available N which can be up to 200 kg N ha-1 per growing season. The New Brunswick Soil and Crop Improvement Association (NBSCIA) as representative of the producers in New Brunswick has expressed concern over the issue of excess or insufficient use of N in crop production. Production in the region will greatly benefit from development of a soil N test which improves N management, reduce cost of production, improve yield and quality and minimize environmental impacts of excess N. Approaches have been developed to estimate soil nitrogen supply (SNS) under field conditions, but they are time consuming and require information measured at crop harvest so cannot be used when making N recommendations. Laboratory-based chemical tests of soil N mineralization have been explored, but the use of such tests as predictors of SNS has not been developed. The proposed study is a preliminary investigation of the effectiveness of different soil N tests in predicting N uptake by different crops on organically amended soils. The soil test(s) that most accurately predict the field-based indices of SNS will be selected and validated in a large scale study.