Nitrogen Carryover Effects of Various Organic Amendments On Subsequent Season Cereal Production Within Southern Ontario, Canada.

Limited research exists to guide organic cereal producers, who use amendments as their primary Nitrogen (N) source, on the residual effects of these products on the following season’s crop. If significant influences are detected on dry matter yield (DMY) and grain N content (GNC) in the following season this has implications on the producer’s choice of source and the most economical rate of amendment (MERA) to apply. The analysis of residual nitrogen contribution was built upon field experiments completed in 2011 that examined several cereal crops (winter wheat, barley, winter spelt, and corn) on 4 organic farms in southern Ontario. Organic amendments including composted turkey litter, composted dairy manure, fresh broiler litter and an industrial bacterial by-product were applied, in a randomized complete block design, at rates ranging from 0% to 150% of the N requirement for the crop. At 3 sites red clover which had been under-seeded and soil incorporated, was evaluated for its potential in-season N contribution to the crop. At maturity, the crops were harvested for measurements of DMY and GNC. Greater DMY and GNC increases were observed for fresh manures over the composted equivalents and no apparent influence was detected from in-season red clover. In the 2012 growing season, crops were planted based on the rotation used by each producer, which included corn, barley, and oats.  No additional amendments were added in this season. Spring, mid-summer and post-harvest soil Inorganic N was measured at each site. Crops were harvested and analyzed for DMY and GNC.  Based on these field experiments, a modified MERA equation was generated based on the residual effects from amendments, cover crop interactions and grain N content. These modified recommendations are more representative of organic systems which use N sources that can persist in the soils for more than one season.